- Stable isotope analyses can detect interactions between different stages of the annual cycle in migratory animals. We used carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) isotopes to identify non-breeding environments, the strategy of nutrient allocation to eggs, and potential carry-over effects from wintering areas in Red-necked Grebes Podiceps grisegena breeding in eastern Poland. Strongly positive isotopic signatures in adult grebe feathers compared to freshwater food webs and feathers of locally fledged young suggested that most adults had moulted in marine areas. Enriched isotopic values in the breast muscles of spring-arriving grebes pointed to transfer of marine-derived nutrients to freshwater breeding sites. Isotopic mixing models revealed that egg nutrients were mainly acquired locally. Endogenous nutrients were to some extent mobilised for the formation of albumen (25–26%, 95% credible interval, three-isotope model) and lipid-free yolk (17–18%, two-isotope, δ13C and δ15N model) in early laid clutches, but were little mobilised, if at all, in clutches of females that delayed laying. The non-breeding trophic feeding level, as indexed by δ15N in feathers of grebe females, was related to laying initiation date (greater enrichment, earlier egg production), indicating cross–seasonal effects on reproduction. Both endogenous nutrient transfer to eggs and a high-quality non-breeding diet may facilitate early breeding, which is advantageous in species constrained by short breeding seasons.
- In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world’s lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth’s surface, these ecosystems host at least 9.5% of the Earth’s described animal species. Furthermore, using the World Wide Fund for Nature’s Living Planet Index, freshwater population declines (83% between 1970 and 2014) continue to outpace contemporaneous declines in marine or terrestrial systems. The Anthropocene has brought multiple new and varied threats that disproportionately impact freshwater systems. We document 12 emerging threats to freshwater biodiversity that are either entirely new since 2006 or have since intensiﬁed: (i) changing climates; (ii) e-commerce and invasions; (iii) infectious diseases; (iv) harmful algal blooms; (v) expanding hydropower; (vi) emerging contaminants; (vii) engineered nanomaterials; (viii) microplastic pollution; (ix) light and noise; (x) freshwater salinisation; (xi) declining calcium; and (xii) cumulative stressors. Effects are evidenced for amphibians, ﬁshes, invertebrates, microbes, plants, turtles and waterbirds, with potential for ecosystem-level changes through bottom-up and top-down processes. In our highly uncertain future, the net effects of these threats raise serious concerns for freshwater ecosystems. However, we also highlight opportunities for conservation gains as a result of novel management tools (e.g. environmental ﬂows, environmental DNA) and speciﬁc conservation-oriented actions (e.g. dam removal, habitat protection policies, managed relocation of species) that have been met with varying levels of success. Moving forward, we advocate hybrid approaches that manage fresh waters as crucial ecosystems for human life support as well as essential hotspots of biodiversity and ecological function. Efforts to reverse global trends in freshwater degradation now depend on bridging an immense gap between the aspirations of conservation biologists and the accelerating rate of species endangerment.
- Wetlands can store significant amounts of carbon (C), but climate and land-use change increasingly threaten wetland C storage potential. Carbon stored in soils of freshwater coastal wetlands is vulnerable to rapid saltwater intrusion associated with sea-level rise and reduced freshwater flows. In the Florida Everglades, unprecedented saltwater intrusion is simultaneously exposing wetlands soils to elevated salinity and phosphorus (P), in areas where C-rich peat soils are collapsing. To determine how elevated salinity and P interact to influence microbial contributions to C loss, we continuously added P (~0.5 mg P d−1) and salinity (~6.9 g salt d−1) to freshwater Cladium jamaicense (sawgrass) peat monoliths for two years. We measured changes in porewater chemistry, microbial extracellular enzyme activities, respiration rates, microbial biomass, root litter breakdown rates (k), and soil elemental composition after short (57 d), intermediate- (392 d), and long-term (741 d) exposure. After 741 days, both β-1,4-glucosidase activity (P
- Ce travail s’inscrit dans un projet sur les risques épidémiologiques de la fasciolose et autres trématodoses dans un contexte de biologie de la conservation et de perturbations anthropiques, initié depuis quelques années (Sabourin, 2018) et dont les acquis et les suivis permettent de répondre à des problématiques prégnantes dans le système camarguais. Dans le cadre de ces problématiques globales, le stage vise à (1) étudier l’écologie parasitaire des trématodes au sein de l’hôte définitif bovin, sur cette base, (2) identifier les habitats regroupant les conditions favorables pour abriter les mollusques d’eau douce impliqués dans la transmission des trématodes, (3) caractériser les dynamiques spatio-temporelles des populations de ces mêmes mollusques. Pour ce faire, l'auteur a combiné un échantillonnage systématique des parasites du foie lors des abattages des bovins et un suivi de la dynamique des communautés de mollusques d’eau dans des zones hydrologiquement différentes.
- Cette étude se focalise sur le socio-écosystème méditerranéen de la Camargue : Ici, la riziculture, par son apport conséquent en eau douce, pourrait contribuer activement à la conservation de la biodiversité et aux services écosystémiques associés. À travers cette étude, nous avons identifié un ensemble de 16 services écosystémiques afin de déterminer l’impact d’une réduction de l’eau douce sur l’ensemble du socio-écosystème de la Camargue. Les méthodes appliquées incluent le développement d’une représentation visuelle de chacun des services, une recherche bibliographique approfondie, une phase d’échange avec 16 experts scientifiques et techniques dans différents domaines et une phase d’entretiens avec huit acteurs locaux visant à valider les représentations de ces services et à étudier les évolutions de ces derniers dans le contexte de notre scénario. Cette étude a permis d’identifier et visualiser les flux de services et les éléments principaux (biophysiques, bénéficiaires et responsable de gestion) dont ils dépendent. Les résultats démontrent que la plupart des services sont liés en s’appuyant sur des éléments communs pour leur flux. Ceci démontre bien la complexité du socio-écosystème camarguais. Cette complexité est la source et le facteur moteur de la richesse culturelle et de la biodiversité qui se trouve actuellement en Camargue.
- Structuré en trois parties, le guide propose des préconisations de suivi dans le cadre d'opérations de restauration hydromorphologique en cours d'eau. La partie A est dédiée au contexte général, à la définition du suivi, des différentes échelles et de la chronologie du suivi, et au processus de bancarisation des données. La partie B se présente sous la forme de fiches par type d'opération de restauration hydromorphologique, détaillant le suivi à mettre en place. La partie C détaille les différents protocoles à mettre en place et propose des éléments d'interprétation. Le suivi proposé peut être mis en place sur des cours d'eau permanents, de largeur mouillée d'au moins 1 m et prospectables à pied (hors emprise d'une retenue). Ces restrictions sont liées aux limites d'application des différents protocoles.
- Mené dans le cadre de la Liste rouge nationale, cet état des lieux porte sur le risque de disparition de l’ensemble des poissons d’eau douce recensés sur le territoire métropolitain. Après une analyse de la situation de chacune des 80 espèces, les résultats montrent que 15 espèces sont menacées et 16 autres quasi menacées. Neuf ans après la première évaluation, l’actualisation de la Liste rouge des poissons d’eau douce fait apparaître une situation aggravée. Au terme de l'état des lieux, près d'une espèce sur cinq se révèle menacée. Au total, 39 % sont désormais menacées ou quasi menacées contre 30 % en 2010. Les résultats mettent en évidence les pressions multiples pesant sur ces espèces et leurs habitats naturels. La destruction et la dégradation des milieux constituent les principales menaces affectant les poissons d’eau douce.
- 1. There is a wide consensus that freshwater biodiversity is continuing to decline rapidly at the global scale, with populations of freshwater species estimated to have declined by 83% since 1970. Many organisations, from governments to NGOs, have tried to reverse, halt or at least reduce the rate in this decline by designating protected areas within which laws restrict practices that adversely impact biodiversity and support practices that conserve or restore biodiversity. For example, there are 2,314 Wetlands of International Importance (Ramsar Sites) world-wide, covering 242,409,779 hectares, although many species within them are in decline. WWF is a science-based conservation organisation and needs to understand the evidence of whether protected areas have led to or supported conservation and restoration of freshwater species and why this has occurred. 2. WWF-UK set-up a quick scoping review (QSR) to provide an informed conclusion on the volume and characteristics of an evidence base and a synthesis of what that evidence indicates in relation to the specific question “How does freshwater biodiversity and habitat change with protected area designation, design and management?”. Key principles of this work are that credible evidence reviews must be comprehensive, robust, objective, transparent and repeatable. Furthermore, the QSR should also provide results in an easily accessible manner that facilitates an audit trail from summary statements to underpinning knowledge. 3. The QSR followed recognised standards for conducting evidence reviews for ecological and environmental issues including guidance produced by UK Department of Environment, Food and Rural Affairs and process steps of the PRISMA 2009 checklist. The process included application of the PICO (population, intervention, comparator and outcome) framework. The study was independently peer-reviewed by Professor Angela Arthington. 4. Searches of the Web of Science database (including SciELO) and Google Scholar, requests to experts and institutions and scans of reference lists of review papers and books returned 2586 publications (after removing duplications). Application of strict selection criteria at either full text or title and abstract level identified 44 relevant publications containing 75 case studies. Many returned publications were rejected because they discussed concepts and inferred principles but contained no new data, some calculated protected area coverage as a percentage of the range of species but included nothing on the effectiveness of those protected areas, whilst others published results of species surveys within protected areas but no comparative data outside of the areas or before designation. 5. Key information was captured for each study from the selected publications and input to a searchable database. The only inferred information (i.e. not actually provided by the study authors) was the direction of change of biodiversity or habitat, specifically whether the protected area had been positive, neutral or negative for freshwater biodiversity. If, for example, the fish population within a protected area increased after designation compared to a reference non-designated area, this was considered a positive outcome. If the population was the same, it was considered neutral, whereas if the population was lower in the protected area after designation (compared to the reference area) it was considered a negative outcome. Additional information about each case study, such as the IUCN Protected Area category and the freshwater ecoregion, was found using available web-tools and guidance. 6. The majority of studies compared protected with un-protected areas, with only a few comparing the same area before and after designation. The most common metrics employed were species abundance and richness, followed by diversity (e.g. metrics that capture both species richness and the relative abundance of each species in a sample). Many papers did not specify the management measures employed following designation; of those that did, the most common were fishing restrictions and water management. The case studies were welldistributed across the globe and across ecosystem categories. The highest number of case iv studies were from Asia, within tropical and subtropical floodplain rivers and wetland complexes, category II protected areas, and using fish metrics. The second highest numbers of studies were from the Neotropics, within temperate floodplain rivers and wetlands, category IV protected areas and for birds. 7. Of the 75 case studies, 39 reported positive outcomes, 25 were neutral and 11 were negative, so 52% of the studies showed protected areas to be effective in protecting freshwater biodiversity. Few studies recorded reasons why the protected area had been successful. There was no single cause of lack of success (negative or neutral direction of change); the wide range of causes recorded included fishing (often lack of law enforcement), dominance of environmental variables (such as climate, landscape, pH, river channel geometry), water management (abstraction and dams), invasive alien species and habitat degradation (e.g. from mining or agriculture). 8. Detailed analysis of the effectiveness categories did not highlight strong relationships with other information, such as taxa, basis of inference, IUCN protected area category or freshwater ecoregion. However, 73% of the case studies in tropical and subtropical coastal rivers show positive outcomes for protected areas, which exceeds the 52% overall figure. Negative changes in protected area fish biodiversity were recorded only in studies of rivers (i.e. there were none for lakes, ponds, wetlands or floodplains). The main causes were invasive species, variations in natural environmental variables (such as water pH and temperature) and local disturbances from dredging, mining and deforestation. 9. Several studies, including fish in Thai wetlands and birds on Finnish islands, reported that biodiversity increased with greater protected area size. Studies of fish in Canadian lakes and plants in Australian wetlands concluded that freshwater protected area design should include the entire ecosystem (lake or catchment). However, other studies, e.g. rivers of the southern Western Ghats, India, and Lake Tanganyika, Tanzania, concluded that although terrestrial-based protected areas did not adequately represent the habitat diversity of river systems, they were more effective in supporting higher endemic freshwater species richness than unprotected areas. 10. Conserving aquatic habitat, including the hydrological regime (surface and groundwater), water quality, and riparian terrestrial vegetation, was found to be vital for supporting freshwater biodiversity worldwide, including lizards in Brazil, fish in Mexico, birds in China and wetlands in Spain. One study selected in our review suggested that disconnection of the River Yangtze from its floodplain was a partial cause of reduced numbers of cranes in the Shengjin Lake National Nature Reserve, China. Another considered that lowering of groundwater contributed to degradation of vegetation in Mana Pools National Parks, Zambia. These studies demonstrate the importance of lateral (e.g. river-riparian and floodplain zones) and vertical (e.g. surfacegroundwater) connectivity. No studies found lack of longitudinal connectivity (upstreamdownstream) to be the main cause of negative outcomes for freshwater biodiversity in protected areas, though several authors infer this in discussion. 11. The need to reduce pressures in and around protected areas from grazing, inappropriate land and water management, pollution, tourism or general human disturbance was concluded from studies of wetlands in Tibet and USA, aquatic insects in India and birds in China. Catchment disturbances, e.g. dredging, mining, deforestation, were found to impact biodiversity in protected rivers in Venezuela, Kenya and Italy, and in wetlands across Africa, but protected areas were shown to be effective buffers from adverse external pressures for reptiles in Brazil and fish in India. 12. Invasive species pose threats to freshwater biodiversity within protected areas worldwide, such as fish escaping from farms in Mexico and Spain and invasive weeds in Australia. v 13. Lack of law enforcement in protected areas has contributed to the decline of turtles in Hong Kong, birds in African wetlands and fish in India. In contrast, protection has reduced hunting of reptiles, birds, and mammals in the Amazon, Peru and over-fishing of shrimps in Costa Rica and of eels in France. In Brazil, community-based management approaches have succeeded in reducing poaching of turtle eggs, where formal law enforcement had previously failed. 14. Maintaining traditional management practices that are part of cultural heritage is a central objective of some protected areas, such as burning of upland blanket bog in the UK to maintain grouse shooting and cattle grazing. 15. There are many factors influencing freshwater biodiversity, including the natural distributions of species, variations in topography, river channel morphology, water quality and climate that are not within the control of protected area managers. Informative case studies include Australia’s Murray–Darling Basin, streams in Singapore, karstic pools in Mexico and waterbird habitats in Morocco. 16. Many elected papers provided evidence to support principles of freshwater ecosystem management in protected areas formulated by Finlayson et al. (2018a) and Biggs et al. (2012). The evidence included: designating large landscape units, preferably the entire catchment; protecting areas that conserve biodiversity hotspots, species-rich habitats and threatened species; conserving the natural dynamics of river flows, lake and wetland water levels and water quality; maintaining ecological resilience; and promoting the participation of local peop
- L’objectif principal de cette note intitulée est d’apporter des éléments de compréhension et de méthode pour agir dès aujourd’hui sur les émissions de nutriments et ainsi restaurer et préserver les milieux fragiles vis-à-vis des phénomènes d’eutrophisation identifiés dans le SDAGE Rhône Méditerranée (OF5B).
- L’un des objectifs de notre étude est d’acquérir une meilleure connaissance sur les Odonates du réseau hydrographique du Mazafran, situé au centre-nord de l’Algérie. Cette région, jusqu’à présent inexplorée du point de vue odonatologique, se caractérise par un climat méditerranéen subhumide avec une période sèche qui s’étale sur six mois environ, de mai à la fin d’octobre. La prospection de 19 stations réparties dans le réseau hydrographique du Mazafran, sur une durée de 24 mois consécutifs (d’avril 2013 à mars 2015) nous a permis de recenser 948 Odonates adultes appartenant à 15 espèces. Calopteryx haemorrhoidalis (33,1 %) et Platycnemis subdilatata (20,5 %) sont les plus abondantes et les plus fréquentes d’entre elles. Les résultats révèlent la présence d’Ischnura pumilio, qui, actuellement, n’est plus connu en Algérie que de la Numidie (nord-est du pays) et est rare au Maghreb. Les caractéristiques physicochimiques et climatiques des oueds qui composent le réseau hydrographique du Mazafran, ainsi que l’irrégularité des écoulements qui conduisent, notamment, à l’augmentation de la température des eaux en été, ont un impact considérable sur les stations localisées en basse altitude. Combiné aux rejets d’eaux usées urbaines, aux effluents industriels, à la destruction des lits, aux pompages anarchiques de l’eau à des fins agricoles et à la réduction du couvert végétal dont les Odonates sont fortement dépendants, la destruction des habitats, par l’altération de ses composantes (biotiques et abiotiques) s’avère certaine. / One of the objectives of our study is to increase our knowledge of the Odonata in the Mazafran hydrosystem, located in the centre of northern Algeria. This unexplored region in terms of Odonatology, is characterized by its sub-humid Mediterranean climate, and a dry period spread over six months, from May to the end of October. The prospection of 19 sites distributed along the Mazafran hydrographic system during 24 months, from April 2013 to March 2015, allowed us to identify 948 adults involving 15 species. Calopteryx haemorrhoidalis (33.1 %) and Platycnemis subdilatata (20.5 %) were the most abundant and frequent species. The results revealed the presence of Ischnura pumilio, which is currently relatively rare in the overall Maghreb. Both the physicochemical and climatic characteristics of the various wadi influenced the Mazafran hydrographic system. The seasonal change of flow rate led to a dramatic increase in water temperature and had a considerable impact on sites located at low elevation. Cumulative effects of urban and industrial effluents, river bed degradation, illegal pumping of water for agricultural purpose and reduction of riparian canopy influence the Odonata community and lead to a decrease of species richness and diversity. We urge decision-makers to take urgent steps for the restoration of the natural state and functioning of wadi systems throughout Algeria before their irreversible destruction.
- In a study of the fishes of the Büyük Menderes River Basin, Aegean region of Turkey, two populations of Chondrostoma were found which showed clearly distinctive characters: the population from the Upper B. Menderes (Işıklı Lake) was attributed to C. meandrense Elvira, 1987, while the population from the Çine Stream in the Lower B. Menderes River basin proved to be a hitherto undescribed species: Chondrostoma turnai sp. n. Altogether 24 metric and 7 meristic parameters were compared. The new species is distinguished from C. meandrense and all other cogeners by a combination of the number of lateral line scales, the number of scale rows between the lateral line and the dorsal-fin origin, the number of scale rows of the lateral line and pelvic-fin origin, and the number of gill rakers on the first gill arch.http://www.zoobank.org/urn:lsid:zoobank.org:pub:811C213D-BEDD-4C8C-AE57-BFFA7964781A
- The effects of Hg contamination are presumably widespread across the components of aquatic ecosystems, but investigations have been mainly focused on freshwater fish, because this biota represents a major source of Hg for human populations. Yet, the possible bioaccumulation of Hg on other freshwater meso- and apex-predators (e.g., amphibians, reptiles) has been largely overlooked, especially in Western Europe. In this study, the determinants of Hg concentrations were assessed for the viperine snake (Natrix maura) across 6 populations (>130 individuals sampled in 2016 and 2017) in France and Spain. Specifically, body size, sex, and diet were compared with Hg concentrations measured in ventral scales. Overall, N. maura accumulated Hg in their scales. Sex did not seem to influence Hg concentrations in this species. Significant differences in Hg concentrations were observed between study sites, and these differences were likely to be mediated by site-specific diet. Frog-eating individuals were characterized not only by lower mean values of Hg (0.194 ± 0.018 μg·g−1 versus 0.386 ± 0.032 μg·g−1 for piscivorous individuals), but also by weaker slopes of the body size-Hg relationship as compared to fish-eating snakes, suggesting strong differences in accumulation rates due to food resources. Importantly, the highest slope of the body size-Hg relationship and the highest values of Hg were found in individuals foraging on trout raised by a fish farm, suggesting that fish farming may contribute to Hg contamination in inland freshwater systems. Finally, our results are compared with data on Hg concentrations in other species of aquatic snakes, in order to provide a comparative point for future studies.
- The turbulent surfaces of rivers and streams are natural hotspots of biogeochemical exchange with the atmosphere. At the global scale, the total river-atmosphere flux of trace gasses such as carbon dioxide depends on the proportion of Earth’s surface that is covered by the fluvial network, yet the total surface area of rivers and streams is poorly constrained. We used a global database of planform river hydromorphology and a statistical approach to show that global river and stream surface area at mean annual discharge is 773,000 ± 79,000 square kilometers (0.58 ± 0.06%) of Earth’s nonglaciated land surface, an area 44 ± 15% larger than previous spatial estimates. We found that rivers and streams likely play a greater role in controlling land-atmosphere fluxes than is currently represented in global carbon budgets.
- The Garâa Sejenane is an ancient lake in northern Tunisia that currently houses a mosaic of temporary wetlands. Comparison of modern pollen data and field vegetation surveys shows both a weak regional pollen signal and the homogenization of pollen assemblages at the scale of the garâa. Despite a hiatus between 19,000 and 2230 cal. BP, fossil pollen analyses provide the first Tunisian LGM record and attest to the ancient origin of the lake, which housed some taxa still present locally in the 1950s. The originality of the Pleniglacial surrounding landscape dominated by a juniper steppe contrasted with to the mountain conifer forests in Kroumiria. Lastly, analyses of aerial photographs (1948, 1962, 1984), recent satellite photographs and previous botanical descriptions reveal that the lake has been drying since 1960 because of important anthropogenic activities (drainage, groundwater pumping, cultivation, grazing…). These disturbances have generated profound changes in hydrophytic plant communities (fragmentation, diversity loss, introduction of invasive species…) that are likely to threaten their long-term survival.
- Submerged macrophytes play a key role in north temperate shallow lakes by stabilising clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analysed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterised by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterised by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative propagules facilitating rapid initial growth and that can complete their life cycle by early summer. Later in the growing season these plants are, according to our simulations, outcompeted by periphyton, leading to late-summer phytoplankton blooms. Internal lake restoration measures often coincide with a rapid but transient colonisation by hornworts, waterweeds or charophytes. Stable clear-water conditions and a diverse macrophyte flora only occurred decades after external nutrient load reduction or when measures were combined.
- Higher temperatures and increased environmental variability under climate change could jeopardize the persistence of species. Organisms that rely on short windows of rainfall to complete their life-cycles, like desert annual plants or temporary pool animals, may be particularly at risk. Although some could tolerate environmental changes by building-up banks of propagules (seeds or eggs) that buffer against catastrophes, climate change will threaten this resilience mechanism if higher temperatures reduce propagule survival. Using a crustacean model species from temporary waters, we quantified experimentally the survival and dormancy of propagules under anticipated climate change and used these demographic parameters to simulate long term population dynamics.
- This practical manual of freshwater ecology and conservation provides a state-of-the-art review of the approaches and techniques used to measure, monitor, and conserve freshwater ecosystems. It offers a single, comprehensive, and accessible synthesis of the vast amount of literature for freshwater ecology and conservation that is currently dispersed in manuals, toolkits, journals, handbooks, 'grey' literature, and websites. Successful conservation outcomes are ultimately built on a sound ecological framework in which every species must be assessed and understood at the individual, community, catchment and landscape level of interaction. For example, freshwater ecologists need to understand hydrochemical storages and fluxes, the physical systems influencing freshwaters at the catchment and landscape scale, and the spatial and temporal processes that maintain species assemblages and their dynamics. A thorough understanding of all these varied processes, and the techniques for studying them, is essential for the effective conservation and management of freshwater ecosystems.
Campagne de surveillance 2017 de l’état DCE des lagunes méditerranéennes oligo- et mésohalines françaises pour la physico-chimie, le phytoplancton et les macrophytes. consolidation de l’indicateur macrophytes (2018)Ce rapport présente le bilan des résultats en 2017 des actions programmées dans le cadre du Suivi des Lagunes Oligo- et Méso-halines. Il concerne les diagnostics de l’eau, du phytoplancton et des macrophytes sur 7 masses d’eau : Campignol, Vendres, Bagnas, Marette, Charnier-Scamandre-Crey, La Palissade et Bolmon.
- - Les politiques et enjeux concernant les poissons en milieux lagunaires et cours d'eau - Etat des connaissances sur les poissons et leurs habitats - Continuité écologique et pratiques de gestion : aspect opérationnel en faveur d'une meilleure gestion piscicole sur les lagunes et les cours d'eau en Corse
- En dépit des progrès pour traiter les eaux usées, de nombreux micropolluants se retrouvent dans les milieux aquatiques. Cette pollution invisible à l'oeil nu contribue à la dégradation de ces milieux et au déclin de certaines espèces. Les recherches en sciences de l'environnement et en ingénierie s'avèrent essentielles pour améliorer notre connaissance des micropolluants et des risques associés et inventer de nouveaux moyens techniques pour mieux les surveiller et limiter leur diffusion dans l'environnement, notamment dans les milieux aquatiques. Ceci étant, cette pollution est également un enjeu de société : ce sont nos modes de production et de consommation qui sont responsables de la contamination des milieux aquatiques. In fine, qu'elle soit ou non accompagnée d'innovations techniques, la lutte contre les micropolluants requiert obligatoirement des changements de pratiques dans le milieu professionnel, l'espace public et à la maison.
- This report outlines how the traditionally narrow view of rivers as primarily sources of water and power puts other critical benefits at risk, from freshwater fisheries to natural flood protection for cities and sediment flows that keep the world’s deltas above the rising seas. While these directly benefit hundreds of millions of people, they are often overlooked and remain a low priority for decision makers – until they disappear and crises occur. The report shows how this short-sighted approach that has proven costly across the globe and could result in even greater economic losses in the future. Already, 19 per cent of global GDP comes from watersheds with high or very high water risk, while most of the world’s great deltas – including the Ganges, Indus, Mekong, Nile and Yangtze – are sinking and shrinking.
- Publiés en 2015, les deux premiers volumes présentaient un état des lieux des connaissances sur les espèces exotiques envahissantes et leur gestion (Vol. 1) ainsi qu’un premier ensemble de retours d’expériences de gestion conduites en France métropolitaine et en Europe (Vol. 2), accompagnés de fiches descriptives des espèces. Ils sont désormais complétés par ce troisième volume regroupant les 35 retours d’expériences rédigés entre 2015 et 2018. Portant sur 21 espèces de faune et de flore, dont 12 nouvellement traitées, ce volume comprend également trois retours d’expériences dans les collectivités d’outre-mer. Ces documents sont le fruit d’un travail collectif ayant mobilisé plus d’une centaine de contributeurs et de nouveaux retours sont actuellement en cours d’élaboration.
- Définis comme les portions du territoire, naturelles ou artificielles, caractérisées par la présence d’eau, les milieux humides et aquatiques continentaux présentent une grande diversité biologique. Ils fournissent notamment de l’eau, de la nourriture et un abri à un grand nombre d’espèces telles que les amphibiens et les poissons mais également à de nombreux oiseaux, mammifères et insectes. Ces écosystèmes fournissent également des services aux sociétés humaines, que ce soit pour l’alimentation, les possibilités de loisirs et de tourisme ou la maîtrise des crues, etc. S’inscrivant dans le cadre de l’évaluation française des écosystèmes et des services écosystémiques (EFESE), le présent rapport vise à documenter les principales évolutions récentes et à venir de l’état des milieux humides et aquatiques continentaux, les facteurs à l’origine de leur évolution, et à en traduire les implications en termes de bien être et de soutenabilité. Destinés au gestionnaire public mais également au citoyen, ses résultats fournissent des références nécessaires permettant d’éclairer les décisions concernant ces milieux.
- Ongoing increases in air temperature and changing precipitation patterns are altering water temperatures and flow regimes in lotic freshwater systems, and these changes are expected to continue in the coming century. Freshwater taxa are responding to these changes at all levels of biological organization. The generation of appropriate hydrologic and water temperature projections is critical to accurately predict the impacts of climate change on freshwater systems in the coming decade. The goal of this review is to provide an overview of how changes in climate affect hydrologic processes and how climate-induced changes in freshwater habitat can impact the life histories and traits of individuals, and the distributions of freshwater populations and biodiversity. Projections of biological responses during the coming century will depend on accurately representing the spatially varying sensitivity of physical systems to changes in climate, as well as acknowledging the spatially varying sensitivity of freshwater taxa to changes in environmental conditions.
- It seems improbable that a thin veneer of attached algae coating submerged surfaces in lakes and rivers could be the foundation of many freshwater food webs, but increasing evidence from chemical tracers supports this view. Attached algae grow on any submerged surface that receives enough light for photosynthesis, but animals often graze attached algae down to thin, barely perceptible biofilms. Algae in general are more nutritious and digestible than terrestrial plants or detritus, and attached algae are particularly harvestable, being concentrated on surfaces. Diatoms, a major component of attached algal assemblages, are especially nutritious and tolerant of heavy grazing. Algivores can track attached algal productivity over a range of spatial scales and consume a high proportion of new attached algal growth in high-light, low-nutrient ecosystems. The subsequent efficient conversion of the algae into consumer production in freshwater food webs can lead to low-producer, high-consumer biomass, patterns that Elton (1927) described as inverted trophic pyramids. Human perturbations of nutrient, sediment, and carbon loading into freshwaters and of thermal and hydrologic regimes can weaken consumer control of algae and promote nuisance attached algal blooms.
- This lecture (∼ 45-55 slides) will be aimed at senior undergraduate students and graduate students in aquatic sciences with little background in phycology. This lecture could be used in a Aquatic Ecology or Sciences (Limnology) course, an Ecology course, a Phycology course, Environmental Science. Cyanobacteria that may lead to blooms encompass a wide range of different functional groups. We will present: 1) the evolutionary history of cyanobacteria (2-3 slides) (this helps explain some of their present-day traits) 2) basic biology and physiological/ecological traits of planktonic cyanobacteria that are most often associated with visible biomass accumulations (“blooms”) in freshwater/brackish systems of various regions of the world. Traits to be considered include: capacity for N fixation, nutrient uptake and storage (C, N, P), siderochromes, buoyancy regulation (gas vacuoles, mucilage), life cycles, growth rates vs. loss rates (resistance to grazing), allelopathy (negative vs. positive biotic interactions) Functional groups. Planktonic genera may also produce toxins, contributing to harmful algal blooms. (∼12-14 slides). 3) Cyanotoxins: the principal types of toxins produced and their effects (persistence) will be compared, along with theories as to the biological function of these compounds. (∼ 6 slides) 4) Specific case studies of blooms types under different climates: e.g. scum-forming, metalimnetic, dispersed (∼6) 5) The factors that appear to explain and control cyanobacterial dominance will be presented, including nutrient effects, temperature, and food chain changes. These factors vary across temporal and spatial scales. Evidence for eutrophication and climate change in mediating directly or indirectly the frequency and severity of freshwater cyanobacterial blooms will be considered (∼8-10). 6) Research avenues Controversial or unresolved topics: e.g. invasiveness?, cosmopolitan or geographically restricted (e.g. endemism? in hot spring taxa), toxin concerns and bioaccumulation), nitrogen fixation (“pretenders”), nutrient stoichiometry. Unexplored diversity at different levels (molecular, chemical, taxonomic), techniques for controlling cyanobacteria blooms, the future for cyanobacteria under climate change scenarios (∼4) 7) General references, web resourcess and primary articles. (∼2) 8) Questions and potential experiments for instructors and students will be provided at the end of the lecture (supplementary slides).
- We studied global variation in beta diversity patterns of lake macrophytes using regional data from across the world. Specifically, we examined (1) how beta diversity of aquatic macrophytes is partitioned between species turnover and nestedness within each study region, and (2) which environmental characteristics structure variation in these beta diversity components. Location Global. Methods We used presence-absence data for aquatic macrophytes from 21 regions distributed around the world. We calculated pairwise-site and multiple-site beta diversity among lakes within each region using SOrensen dissimilarity index and partitioned it into turnover and nestedness coefficients. Beta regression was used to correlate the diversity coefficients with regional environmental characteristics. Results Aquatic macrophytes showed different levels of beta diversity within each of the 21 study regions, with species turnover typically accounting for the majority of beta diversity, especially in high-diversity regions. However, nestedness contributed 30-50% of total variation in macrophyte beta diversity in low-diversity regions. The most important environmental factor explaining the three beta diversity coefficients (total, species turnover and nestedness) was elevation range, followed by relative areal extent of freshwater, latitude and water alkalinity range. Main conclusions Our findings show that global patterns in beta diversity of lake macrophytes are caused by species turnover rather than by nestedness. These patterns in beta diversity were driven by natural environmental heterogeneity, notably variability in elevation range (also related to temperature variation) among regions. In addition, a greater range in alkalinity within a region, likely amplified by human activities, was also correlated with increased macrophyte beta diversity. These findings suggest that efforts to conserve aquatic macrophyte diversity should primarily focus on regions with large numbers of lakes that exhibit broad environmental gradients.
- The North American red-eared slider Trachemys scripta elegans, which is nowadays considered among the world’s worst invasive species, could constitute a real threat to native freshwater turtles. Because this species shares the same habitats of the European pond turtle Emys orbicularis since its introduction in the European wetlands, we surveyed populations of both alien and indigenous species in France and Spain in order to determine the diversity of platyhelminth parasites (Monogenea, Polystomatidae) in natural environments and to evaluate the levels of risks associated with parasitism. DNA barcoding procedure based on partial cytochrome c oxydase I sequences revealed ten monogenean parasite species within E. orbicularis populations and/or captive animals among which at least eight could be considered as introduced parasites from American freshwater turtles. Results indicated that host switching could have occurred either in natural environments or in captivity, when indigenous turtles were kept with exotic species, demonstrating that captive turtles could act as reservoirs of parasites. The presence of non-native parasite species within wild populations of E. orbicularis in the European freshwater ecosystems also highlighted the risks that these parasites may pose on the survival of natural turtle’s populations and on the dynamics of native parasites.
- Small ponds comprise a substantial portion of the total area of the Earth’s inland waters. They can be powerful carbon sinks or sources, potentially significant processors of organic carbon. Our understanding of their role is constrained by the absence of information regarding their CO2 fluxes (F CO2) and how these change with wet or dry phases and across distinct pond plant communities. We monitored the F CO2 from 26 neighbouring small ponds over a 2-week drying period in late summer in 2014. The mean F CO2 on day 1 (−641 ± 1490 mg m−2 day−1) represented a net intake across the site. As ponds dried they switched to becoming CO2 sources resulting in a net site emission of CO2 by day 12 (3792 ± 2755 mg m−2 day−1) although flux rates did not vary systematically between plant communities. Significant variability in the F CO2 was observed amongst adjacent ponds on individual sampling days, resulting in marked spatial heterogeneity in CO2 processing. This large degree of temporal and spatial heterogeneity across short time periods and small distances highlights the variability in the F CO2 from temporary systems, making it hard to generalize their role in carbon cycle models.
- In a study of the fishes of the Euphrates River (Persian Gulf basin) three species of Squalius belonging to the cephalus-group were found: The Tohma population was identified as S. seyhanensis and the Merzimen and Hilvan populations as S. berak. The comparison of 28 metric and 5 meristic parameters and morphological characters showed that the populations of the northern Euphrates River drainages are distinct and belong to a hitherto unnamed species. We describe it here as Squalius semae sp. n.http://www.zoobank.org/urn:lsid:zoobank.org:pub:D195B69C-C6CB-4DEB-B85D-5B695F917CE5
- Risk screening tools to identify species with a high or low risk of invasiveness are being increasingly used for effective management purposes. Amongst the available tools, the Fish Invasiveness Screening Kit (FISK) has been used extensively and successfully in large risk assessment (RA) areas, and was recently upgraded to the new generic tool Aquatic Species Invasiveness Screening Kit (AS-ISK). The aim of the present study was to assess with AS-ISK the invasive potential of introduced non-native and translocated fishes in a Mediterranean-type shallow lake (Lake Marmara) located in west Anatolia (Turkey). Based on independent evaluations of 35 species by two assessors, calibration of AS-ISK resulted in a threshold score of -3.65, which reliably distinguished between potentially invasive (high risk) and potentially non-invasive (medium to low risk) fishes. Of the 35 species assessed, 17 were categorised as ‘low risk’ and included native/endemic and translocated natives, and the remaining 18 as ‘high risk’ and comprised non-natives and translocated natives. Carassius gibelio had the highest score in the Climate Change Assessment section, suggesting that it might potentially impact on the native fish fauna under likely climate change scenarios for the RA area. Some cool water non-native (Oncorhynchus mykiss, Salvelinus fontinalis), translocated native (Luciobarbus lydianus) and endemic species (Ladigesocypris mermere) in the catchment will likely be affected negatively by predicted climate change conditions.
- We compiled a list of 148 exotic species in French inland freshwaters, comprising 36 plant species and 112 animals, including 50 invertebrates, 7 amphibians, 1 reptile, 25 fish, 22 birds and 7 mammals. Spatial distribution maps and cumulative analyses for most species indicate that exotic plants are distributed more along the west coast of France and, to a lesser extent, the Rhone basin, whereas exotic animals are clearly clumped in the north-east (Rhine Basin). The rate of introductions has increased exponentially over time. The most recent introductions (since 1992) have occurred in the Rhine Basin, from where they have then spread. Twenty-five species on our list are among the ‘100 worst invasive species of Europe’ (DAISIE) and 11 among the worst in the world (IUCN), with six species included on both lists. The potential cumulative impact of exotic species tends to be heterogeneous across France, though the north-east appears to be more disturbed, especially by animal species. Additional research is needed on criteria for prioritising intervention measures that will help stakeholders make objective choices in the management of exotic species in aquatic ecosystems.
- The Mediterranean Basin biodiversity hotspot is known to be one of the most biologically rich and complex regions on Earth. The north-western part of the hotspot (the area thatcovers all of the Iberian Peninsula, southern France, mostof Italy and Malta) supports important river, lake, karst and wetland systems critical for the survival of threatened and restricted range freshwater species. Within the north-western Mediterranean regionof the hotspot,freshwater Key Biodiversity Areas (i.e.,sites of importance for the global persistence of biodiversity) have been identified.The purpose of this report is to help guide and inform policies and conservation actions for freshwater biodiversity in the region.
- Aim To review existing literature on the ability of waterbirds to spread aquatic alien and invasive species, and to assess the relevance of bird-mediated dispersal for the conservation of freshwater ecosystems. Location Global. Methods Literature Review. Results A systematic review of the literature revealed that quantitative studies investigating dispersal of alien organisms by waterbirds are rare (n = 14). Most studies citing waterbird dispersal rely on anecdotes or inferences from morphological dispersal syndromes. However, evidence from each stage of dispersal (i.e. emigration, transport and immigration) shows that waterbirds can carry alien plants and invertebrates internally and externally; transport them between water bodies at a variety of spatial scales; and deposit viable propagules in sites suited to aquatic invasive species. Main conclusions Our review suggests that waterbirds can and do act as important dispersal vectors for freshwater invasive species. Further experimental and field based research on the numbers and viability of moved alien propagules, and the roles of different species in the bird community, is needed. Furthermore, consideration of the spatially explicit manner in which birds move is imperative to understanding invasive spread. Populations of alien aquatic species in seemingly isolated wetlands can no longer be considered contained if they are able to be spread through waterbird-mediated dispersal, and containment measures must recognize such opportunities for further spread. Changing waterbird movement patterns, driven by climate and land use change, further add to the challenge of managing invasive species and offers an interesting opportunity for future research. The study of waterbird-mediated dispersal of aquatic alien invasive species provides insights not only into species invasions, but more generally into movement ecology, population ecology and biogeography.
- We propose the use of phylogenetic patterns as a tool for monitoring long-term change in plant community structure in small temporary pools, as an alternative to the compilation of species lists across years. This was tested using forty temporary pools from four pool landscapes in Malta. These were followed between November 2014 and April 2015. Each pool was sectored into ‘Aquatic’, ‘Ecotone’ and ‘Terrestrial zones’ and the species present in each zone were recorded. All species data from a landscape were collated by zone, and the net relatedness index (NRI) for the species assemblages in each zone calculated using PHYLOCOM software. The NRI was positive in the ‘Terrestrial’ zones, and negative in the ‘Aquatic’ zones. The ‘Ecotone’ zones followed no discernible pattern. The results suggest that calculating the NRI of plant assemblages in different hydrological zones, and using these phylogenetic ‘signatures’ as a comparative baseline, would be a feasible addition to long-term monitoring programmes for the early detection of long-term environmental changes such as those arising from climatic changes.
- Freshwater fishes in the Balkans display high percentages of endemic species, many being limited to restricted distributions. Their management, for example, through identification of priority areas for conservation or through re-introduction, is hampered by a poor understanding of their taxonomic diversity and interrelationships. We evaluate the identity of a sand goby belonging to Knipowitschia, limited to a single wetland on the Greek island of Zakynthos. Its representatives morphologically differ sufficiently from their congeners to qualify as a separate species. However, in view of the similarity in mitochondrial ribosomal DNA sequences, the evolutionary plasticity of said morphological characters, and in the absence of a taxonomic revision of the Ionian Ecoregion’s Knipowitschia gobies, describing it as a new species seems unjustified and premature. Rather, we advocate that its unique habitus and its vulnerability as the island’s only resident freshwater fish necessitate conservation efforts as a kind of “phenotypically significant unit”. We also propose sand gobies as flagships for wetlands in the region. This case study suggests a possible approach for fish conservation prioritization in the region, taking a precautionary angle in order to avoid taxonomic inflation, which is an imminent risk given the importance of nominal species and endemics in conservation policy.
- Gammarids were exposed to sediments from a deposition site located on the Rhône River (France) downstream of a fluoropolymer manufacturing plant. Gammarids accumulated to various extents four long-chain perfluoroalkyl carboxylic acids (PFCAs) from C9 to C13, one sulfonate, perfluorooctane sulfonate (PFOS) and three of its precursors (the perflurooctane sulfonamide (FOSA), the N-methyl perfluorooctane sulfonamidoacetic acid (MeFOSAA), the N-ethyl perfluorooctane sulfonamidoacetic acid (EtFOSAA) and the 6:2 fluorotelomer sulfonic acid (6:2 FTSA). Whatever the compound, the steady state was not achieved after a 3-week exposure; elimination was almost complete after a 3-week depuration period for perfluorononanoic acid (PFNA), PFOS, the three precursors and the 6:2FTSA. However, this was not the case for long-chain PFCAs, whose elimination rates decreased with increasing chain length. PFAS accumulation in gammarids occurred via the trophic and respiratory pathways, in proportions varying with the carbon chain length and the terminal moiety.
- ABSTRACT The diet of nestling Hooded Crows (Corvus cornix) was investigated in Warta Mouth National Park (W Poland) in the breeding season of 2003. We analyzed 82 food samples of which 79% contained snails and bivalves. Hooded Crows prefer Viviparus spp. instead of smaller but more abundant molluscan species present in the studied area. We suspect that under conditions of the lowland flooded river valleys Viviparus spp., as a relatively large and meaty species, can be eaten without the shell and is a more valuable food source than smaller molluscs.
- Phytoplankton assemblages in two Sicilian water bodies were compared to test the hypothesis that colonization events and the successful establishment of a new species in an aquatic ecosystem may depend on the number of water bodies in a given area and on their relative distance. The two ecosystems are both natural, shallow lakes and they are protected sites hosting a rich avifauna. Lake Biviere di Gela is located in an area with a high density of ponds, whereas Lake Pergusa is an isolated waterbody without other aquatic ecosystems in its surroundings. Both lakes had almost disappeared about 10 years ago because of the over-exploitation of their main inflows. They were therefore re-filled using water from other catchments and their phytoplankton has been sampled since their re-filling. The results show that Lake Pergusa has maintained a species-poor phytoplankton assemblage since its re-filling, whereas Lake Biviere di Gela has been showing progressively richer phytoplankton assemblages during time. The composition of samples collected in nearby located temporary ponds suggests that phytoplankton in this area belongs to a species-rich metacommunity which favored its re-establishment in the lake. Aquatic ecosystems conservation plans cannot thus neglect the role of small waters located in the catchments.
- “Everything is everywhere, but environments selects.” Is this true? The cosmopolitan nature of algae, including phytoplankton, has been highlighted in many textbooks and burnt into the minds of biologists during their studies. However, the accumulating knowledge on the occurrence of individual phytoplankton species in habitats where they have not been seen before, reports on invasive phytoplankton species, and the increasing number of papers with phylogenetic trees and tracing secondary metabolites, especially cyanotoxins, contradict. Phytoplankton species, with rare exceptions, are neither cosmopolitan, nor ubiquists. In this review paper, we provide an overview of the basic patterns and the processes relevant for biogeography of freshwater phytoplankton. The following topics are considered: dispersal agents and distances; survival strategies of species; geographic distribution of different types; patterns of invasions; tools of molecular genetics; and metabolomics to explore dispersal patterns, island biogeography, and associated species–area relationships for algae.
- We estimated growth parameters of Emys orbicularis and Mauremys rivulata in Mediterranean Turkey with the skeletochronological method, using specimens drowned in fyke nets. In adult E. orbicularis, the median age was 8 years in males and 10 years in females. The median age of adult M. rivulata was 10 years for both sexes. Both species reach sexual maturity at an age of 5-7 years. No difference was found in age composition between the sexes.
- The first ever European Red List of Habitats reviews the current status of all natural and semi-natural terrestrial, freshwater and marine habitats and highlights the pressures they face. Using a modified version of the IUCN Red List of Ecosystems categories and criteria, it covers the EU28, plus Iceland, Norway, Switzerland and the Balkan countries and their neighbouring seas. Over 230 terrestrial and freshwater habitats were assessed. The Red List complements the data collected on Annex I habitat types through Article 17 reporting as it covers a much wider set of habitats than those legally protected under the Habitats Directive. The European Red List of Habitats provides an entirely new and all embracing tool to review commitments for environmental protection and restoration within the EU2020 Biodiversity Strategy. In addition to the assessment of threat, a unique set of information underlies the Red List for every habitat: from a full description to distribution maps, images, links to other classification systems, details of occurrence and trends in each country and lists of threats with information on restoration potential.
- L’objectif général de ce travail est d’adapter les grilles DCE de qualité nutriments et phytoplancton (abondance et biomasse) pour les lagunes oligo et mésohalines méditerranéennes. Par la position intermédiaire entre les eaux marines et continentales (douces) la recherche d’indicateurs pour les lagunes oligo et mésohalines peut contribuer à assurer la continuité eaux douces/eaux marines dans l’application de DCE. · Sur la base des relations entre EQRPHY et les concentrations en azote total et phosphore total, des seuils de concentrations pour caractériser les lagunes oligo-mésohalines peuvent être proposés. · Les seuils proposés sont sensiblement supérieurs à ceux des lagunes poly-euhalines. Un tel résultat est attendu compte tenu des niveaux trophiques supérieurs dans les lagunes oligo-mésohalines mis en évidence dans la première partie de ce rapport. · La pertinence des seuils proposés doit être étudiée notamment par comparaison avec les valeurs utilisées pour les lacs d’eau douce. Par rapport aux lagunes poly-euhalines, si l’augmentation des seuils pour le bon état paraît logique, celle pour les états dégradés parait plus discutable. La progressivité des seuils pourrait également être analysée dans le contexte des eaux douces.
- Rédigé à quatre mains par les géographes Jacques Bethemont et Jean-Paul Bravard, ce beau livre, à la fois scientifique et accessible au grand public, rend hommage à la complexité du plus puissant des fleuves français. Né au fond du Valais en Suisse d’un glacier du même nom, le Rhône est l’un des fleuves les plus puissants d’Europe. Ce n’est pas le plus grand, mais ses 812 km l’emmenant d’un glacier suisse à la Méditerranée sont loin de s’écouler tranquillement. Sa nature, son tracé ainsi que les nombreux travaux d’aménagement qui l’ont métamorphosé depuis plus d’un siècle contribuent à lui donner un statut particulier. Jacques Bethemont et Jean-Paul Bravard partagent ici un ensemble de connaissances issues de leurs recherches menées tout au long de riches carrières placées sous le signe de l’eau. Cette somme porte sur l’ensemble du fleuve et de ses affluents, dans une conception à la fois pluridisciplinaire, actuelle, rétrospective et prospective. Ouvrage de référence pour les acteurs du Rhône, mais aussi pour les curieux, Pour saluer le Rhône donne à voir le fleuve dans son entier.
- The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species' life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries.
- Indonesian waters, have been proposed by biologists to be the origin of freshwater eel anguillid. The objective of this study was to investigate molecular phylogenetic relationships and genetic diversity of the seven Indonesian eel taxa based on the cyt b gene. Each eel species was identified by comparison with published sequences, namely Anguilla celebesensis, A. interioris, A. borneensis, A. marmorata, A. bicolor bicolor, A. b. pacifica and A. nebulosa nebulosa. A total of 129 different haplotypes were identified from this study, most of them for the first time, showing haplotype and nucleotide diversities of 0.98 and 4.57 %, respectively. A. bicolor was clearly found to be composed of two subspecies, A. b. bicolor and A. b. pacifica. The first subspecies was split into two major clades supported by a high bootstrap value, with each clade characterized by two diagnostic nucleotides. A. marmorata was also split into two clades, supported by a high bootstrap value. This first study of phylogenetic relationships and genetic diversity from all Anguilla taxa inhabiting Indonesian waters, based on 1115 specimens, is necessary for a local management and conservation of this valuable resource in terms of both biodiversity and economic development.
- Lakes and ponds are scattered on Earth’s surface as islands in the ocean. The organisms inhabiting these ecosystems have thus developed strategies to pass the barrier represented by the surrounding land, to disperse and to colonize new environments. The evidences of a high potential for passive long-range dispersal of organisms producing resting stages inspired the idea that there were no real barriers to their actual dispersal, and that their distribution was only limited by the ecological characteristics of the available habitats. The development of genetic techniques allowed to criticize this view and revealed the existence of a more complex and diverse biological scenario governed by an assortment of historical and ecological factors. In this paper, we review the literature related to the passive dispersal of organisms producing resting stages among inland lentic ecosystems, with special emphasis to temporary ponds, which represent “isolated” ecosystems both in space and in time, and are characterized by high levels of biological diversity. The existence of a sharp decoupling between “dispersal potential” and “actual establishment rates” is stressed, thus urging a definitive overcome of the so-called “Everything is Everywhere” hypothesis in order to gain a proper understanding of the biogeography and ecology of inland water organisms.
- In this review, we aim to draw parallels between the principal concepts of invasion biology, developed mainly for terrestrial plants in temperate regions, with findings for macrophytes recorded in tropical inland waters. In these ecosystems, the most important abiotic and biotic filters influencing invasion success are related to water and sediment conditions, light, disturbance, hydrology and the diversity and density of native species. The main impacts are related to direct and indirect changes in the populations and communities of native macrophytes and other associated organisms. Non-native ecosystem engineer species of macrophytes can affect ecosystems directly, and after affecting ecosystems, their effects can extend to populations and communities. High plant growth rates in the tropics could lead to rapid invasion and larger impacts compared to temperate ecosystems. Although we found many parallels between ecosystems regarding the general concepts of invasion, areas that should receive further investigation in the tropics include (i) the synergistic interaction of multiple invasive species, (ii) the effects of regime shift on invasion success and vice versa and (iii) how climate change will affect the dynamics of macrophyte invasion in tropical ecosystems.
- Le hotspot (point chaud) de la biodiversité du bassin méditerranéen est bien connu pour l'importance que sa biodiversité revêt à l'échelle mondiale, mais l'importance de la biodiversité d'eau douce n'était pas reconnue précédemment. Dans le cadre de ce projet, les ZCB d'eau douce ont maintenant été identifées, cartographiées et validées dans une grande partie du hotspot méditerranéen. à présent, il est important de faire prendre conscience de leur statut en tant que ZCB d'eau douce validées, et de mettre en place des programmes d'actions de conservation adaptées sur ces sites.
- Ce travail a pour objectifs de mettre en évidence la qualité biologique et l’état de santé des eaux courantes du Parc National de Belezma (Réserve de biosphère) à travers une approche multiparamétrique. La biodiversité et les traits de vie des macro-invertébrés benthiques de 4 oueds du Parc (O. Hamla, O. Chaaba, O. Bouilef et O. El Ma) sont analysés en relation avec les facteurs environnementaux : 12 paramètres physico-chimiques de l’eau, caractéristiques globales de l’habitat, degré de pression humaine. La vitesse de l’écoulement de l’eau est généralement très faible à moyenne. Les habitats recensés sont dominés par les galets et les rochers (5 à 90%), les habitats à sable fin et grossier sont peu représentés et ceux à végétation sont totalement absents. L’eau est d’un pH variant entre 7,29 et 8,50, les nitrates et les nitrites ne figurent que par des teneurs infimes. L’eau est douce avec un degré de salinité (0,20% et 0,30%), elle est très faiblement salée et généralement claire (turbidité : 2,8 à 22 NTU). Nous avons recensé un total de 28 taxons de macro invertébrés benthiques répartis en 3 embranchements, 4 classes, 11 ordres et 22 familles différentes. Parmi les insectes, les groupes les plus dominants en nombre sont les diptères (36,85%), les trichoptères (20,92%) ainsi que les éphéméroptères (16,73%). C’est dans l’O. Chaaba où l’on retrouve une biodiversité élevée (richesse totale : 22 taxons ; indice de Shannon : 2,84). Le calcul de l’IBGN montre que la qualité hydrobiologique de l’eau dans les 4 cours d’eau étudiés est globalement qualifiée de moyenne (IBGN entre 9 et 10). Des analyses statistiques faisant appel aux méthodes classiques (CCA : Analyse canonique des corrélations) sont appuyées par des analyses modernes faisant appel aux réseaux de neurones (SOM : Self Organisation Model) sont effectuées afin de décrire les modalités de répartition des populations de macro invertébrés benthiques sous l’influence d’une multitude de facteurs du milieu. / This work aims to highlight the biological quality and health status of flow waters of Belezma National Park (Biosphere Reserve) through a multi-parametric approach. We describe and analyze the biodiversity and life traits of benthic macroinvertebrates of 4 rivers (wadis, Oueds) in the Park (O. Hamla, O. Chaaba, O. Bouilef and O. El Ma) in relation to environmental factors: 12 physicochemical water parameters, global habitat characteristics, degree of human pressure. The velocity of the water flow is generally very low to medium. The habitats are dominated by pebbles and stones (5-90%), fine and coarse sand habitats are poorly represented while plants habitats are completely absent. The water pH is between 7.29 and 8.50, nitrates and nitrites are represented only by trace levels. The water is soft with salinity level (0.20% and 0.30%), it is slightly salted and generally clear (turbidity: 2.8 to 22 NTU). We identified a total of 28 taxa of benthic macroinvertebrates divided into 3 embranchments, 4 classes, 11 orders and 22 different families. Among the insects, the most numerous dominant groups are Diptera (36.85%), Trichoptera (20.92%) and Ephemeroptera (16.73%). High biodiversity (total richness: 22 taxa; Shannon index: 2.84) are noted in O. Chaaba. The evaluated IBGN shows that hydrobiological quality of the water in the 4 streams studied is generally described as ‘’average’’ (IBGN between 9 and 10). Statistical analyzes using conventional methods (CCA: Canonical analysis of correlations) are supported by modern analyzes using the neural networks (SOM: Self Organization Model) are performed to describe the distribution schemes of benthic macro populations under the influence of large environmental factors.
- Nous nous sommes intéressés à un milieu riche et fragile, les zones humides d'un des principaux points chauds de biodiversité, le bassin Méditerranéen. Nous nous sommes basés sur le Living Planet Index utilisé en 2011 pour caractériser l'évolution de la biodiversité de ces milieux. Nous avons cherché à corriger les biais déjà identifiés, en ajoutant de nouvelles séries temporelles et en adaptant le jeu de données au cas précis des zones humides. Nous avons également analysé notre jeu de données afin de savoir s'il était représentatif du peuplement complet et réel des vertébrés des zones humides méditerranéennes. Nos résultats démontrent une tendance globale à l'augmentation (60% depuis 1970) mais qui cache une diminution significative et importante des espèces en mauvais état de conservation. Nous montrons également que l'indice actuel nous renseigne surtout sur les espèces des zones humides d'eau douce et permanentes et n'est donc pas représentatif de toute la diversité méditerranéenne./ We were interested in a rich and fragile environnent, wetlands located in a major biodiversity hotspot, the Mediterranean basin. Our study was based on the Living Planet Index used in 2011 to characterize the evolution of biodiversity of these environments. We tried to correct biases previously identified by adding new time series and adapting the data set to the particular case of wetlands. We also analysed our data set to see if it was representative of the entire and real vertebrate species assemblage of Mediterranean wetlands. Our results show an overall increasing trend (60% since 1970) but actually hiding a significant and substantial decrease of threatened species. We also show that the index provides information especially on freshwater and permanents wetlands species and therefore is not representative of the entire Mediterranean wetland divers ity.
- Invasive alien species (IAS) are considered one of the greatest threats to biodiversity, particularly through their interactions with other drivers of change. Horizon scanning, the systematic examination of future potential threats and opportunities, leading to prioritization of IAS threats is seen as an essential component of IAS management. Our aim was to consider IAS that were likely to impact on native biodiversity but were not yet established in the wild in Great Britain. To achieve this, we developed an approach which coupled consensus methods (which have previously been used for collaboratively identifying priorities in other contexts) with rapid risk assessment. The process involved two distinct phases: Preliminary consultation with experts within five groups (plants, terrestrial invertebrates, freshwater invertebrates, vertebrates and marine species) to derive ranked lists of potential IAS. Consensus-building across expert groups to compile and rank the entire list of potential IAS. Five hundred and ninety-one species not native to Great Britain were considered. Ninety-three of these species were agreed to constitute at least a medium risk (based on score and consensus) with respect to them arriving, establishing and posing a threat to native biodiversity. The quagga mussel, Dreissena rostriformis bugensis, received maximum scores for risk of arrival, establishment and impact; following discussions the unanimous consensus was to rank it in the top position. A further 29 species were considered to constitute a high risk and were grouped according to their ranked risk. The remaining 63 species were considered as medium risk, and included in an unranked long list. The information collated through this novel extension of the consensus method for horizon scanning provides evidence for underpinning and prioritizing management both for the species and, perhaps more importantly, their pathways of arrival. Although our study focused on Great Britain, we suggest that the methods adopted are applicable globally.
- The extraordinary species richness of freshwater fishes has attracted much research on mechanisms and modes of speciation. We here review research on speciation in freshwater fishes in light of speciation theory, and place this in a context of broad-scale diversity patterns in freshwater fishes. We discuss several major repeated themes in freshwater fish speciation and the speciation mechanisms they are frequently associated with. These include transitions between marine and freshwater habitats, transitions between discrete freshwater habitats, and ecological transitions within habitats, as well as speciation without distinct niche shifts. Major research directions in the years to come include understanding the transition from extrinsic environment-dependent to intrinsic reproductive isolation and its influences on species persistence and understanding the extrinsic and intrinsic constraints to speciation and how these relate to broad-scale diversification patterns through time.
- In coastal lagoons with occasional connection to oceans, variations in physicochemical conditions and biological responses can be pronounced. To examine the influence of variable rainfall and tidal flushing, we measured, over a 4-year period, salinity, temperature and dissolved oxygen, and fish abundances, in Devereux Slough, a coastal lagoon occasionally connected to the Pacific Ocean along the California coast. We test the hypotheses that salinity is the primary influence on fish composition, and that fish density is affected by freshwater discharge and by berm breaches. During our sampled years, annual rainfall varied from 188 to 971 mm, and the sand berm separating the Slough from the ocean breached in each year except 2007, a drought period. Average yearly salinity ranged from 7.7 to 37.1 ppt. Hypoxic conditions in the near-bottom water were common each year. The best predictor of the fish composition was salinity, and an indirect correlation with fresh water discharge was responsible for much of the temporal variation in the fish assemblage. The interaction between salinity, state of the estuary mouth (open vs. closed), and precipitation significantly predicted densities of Fundulus parvipinnis (Girard 1984).
- Ce numéro hors-série de la revue Méditerranée est consacré à l’histoire hydroclimatique de la basse vallée du Rhône depuis le milieu du bas Moyen Âge (1300-2000). L’étude hydrologique repose sur un millier d’événements (crues, étiages, glaces fluviales) qui mettent en valeur la violence de huit crises périodiques durant la période du Petit Âge Glaciaire. La première partie est consacrée à la dynamique fluviale à travers les inondations et les métamorphoses des lits fluviaux d’après les cartes anciennes. La deuxième partie étudie les pluies et les sécheresses, avec invasions de sauterelles et étiages exceptionnels, comme celui de 1639. Les grands hivers avec glaces flottantes et arrêtées y font également l’objet d’une étude statistique. Enfin, la troisième partie traite, par l’approche monographique, d’une dizaine d’événements hydroclimatiques extrêmes depuis le XVIe siècle dont l’étude s’en trouve ainsi renouvelée, notamment pour la crue centennale de 1856.
- This IUCN report and accompanying dataset on the status and distribution of freshwater biodiversity in the Eastern Mediterranean, and the associated report and data on the Freshwater Key Biodiversity Areas in the wider Mediterranean Basin represent major advances in provision of information to help incorporate biodiversity needs into water development planning processes within an Integrated River Basin Management framework.Nineteen per cent of all freshwater species assessed here are globally threatened. However, when only those species that are endemic to the region are considered (species which, if lost from the region, will become globally extinct) this level of threat rises to 58.2%. The highest number of threatened species are found within six distinct areas within the region: the coastal Levant and Gulf of İskenderun catchments from the Orontes to the Litani and the Upper Hula basin and Lake Kinneret/Sea of Galilee, the widerTigris and Euphrates lower plains including the Hawizah marshes up to the Diyala River in Iraq and lower Karoun in Iran, the Khabur River including the Ras al-Ain springs (Euphrates catchment) in northern Syria, the Lakes Region of Turkey (including the upper Büyük Menderes, the Köprü River, and Kırkgöz Springs), the lower Çoruh River and otherBlack Sea catchments in north-eastern Turkey, and the lower Aras/Kura River in Azerbaijan and southern Armenia This publication includes an executive summary in English, Turkish, Arabic.
- Dans le cadre de la mise en oeuvre de la DCE sur les lagunes méditerranéennes, des travaux ont été menés depuis 2010 par Ifremer, la Tour du Valat et l’IRSTEA (financements Onema et AERM&C), visant à évaluer la pertinence des indicateurs macrophytes et macrofaune pour les lagunes oligohalines et mésohalines (salinité moyenneIn Chile, mediterranean climate conditions only occur in the Central Zone (ChMZ). Despite its small area, this mediterranean climate region (med-region) has been recognised as a hotspot for biodiversity. However, in contrast to the rivers of other med-regions, the rivers in the ChMZ have been studied infrequently, and knowledge of their freshwater biodiversity is scarce and fragmented. We gathered information on the freshwater biodiversity of ChMZ, and present a review of the current knowledge of the principal floral and faunal groups. Existing knowledge indicates that the ChMZ has high levels of endemism, with many primitive species being of Gondwanan origin. Although detailed information is available on most floral groups, most faunal groups remain poorly known. In addition, numerous rivers in the ChMZ remain completely unexplored. Taxonomic specialists are scarce, and the information available on freshwater biodiversity has resulted from studies with objectives that did not directly address biodiversity issues. Research funding in this med-region has a strong applied character and is not focused on the knowledge of natural systems and their biodiversity. Species conservation policies are urgently required in this highly diverse med-region, which is also the most severely impacted and most populated region of the country.Listed and rare species are abundant in temporary freshwater habitats. Among them, the endemic contingent represents a crucial conservation target particularly in the areas characterized by abundant endemic flora for which the local administrations have a high level of responsibility. The aim of this research was to test how the endemic plants found in Mediterranean temporary ponds were represented in Natura 2000 network in a biodiversity hotspot of the Mediterranean region. The results of our research at regional scale pointed out that the existing Nature 2000 sites provide a limited degree of protection and that the gap analysis should be taken into account when conservation priorities are set.Section 1 - People, Politics and Wetlands Section 2 - Freshwater Wetlands: Ecology, Rehabilitation and Management Section 3 - Estuarine Wetlands: Ecology, Rehabilitation and Management Section 4 - Monitoring Wetlands Section 5 - Guidelines for preparing a Wetland Plan of ManagementThe potential importance of watershed land use types, lake/watershed morphometry/topography and geographic distance as drivers of phytoplankton community composition was evaluated by using data collected from 18 freshwaters (lakes and reservoirs) distributed around Greece. In all freshwaters, phytoplankton species composition showed a strong correlation with the composition of land uses within their watersheds but no correlation with morphometry/topography and geographic distance. Cyanobacteria were found to be associated with artificial and agricultural land use types. Chrysophytes were closely associated to forested areas whereas euglenophytes to industrial, commercial, and transport units. Phytoplankton total biomass was significantly higher in freshwaters with a cover of agricultural and artificial land use >30% in their watersheds. This rather low threshold of agricultural and artificial land use cover might be indicative of the higher sensitivity of Mediterranean freshwaters to eutrophication process. Analysis performed separately for lakes and reservoirs revealed some diverse patterns with lake morphometric/topographic variables significantly affecting similarity in species occurrence. The results demonstrate that land use types reflecting anthropogenic pressures could act as critical drivers explaining phytoplankton structure. Our research suggests that Mediterranean freshwaters could be highly sensitive to land use types within their watersheds, thus landscape structure and configuration should be taken into account toward effective conservation and management plans.The present review with focus on the last decade (2000–2010) aims to (i) collecting the major hypotheses explaining freshwater biodiversity patterns, (ii) identifying the main stressors affecting freshwater biodiversity, and (iii) revealing information gaps regarding ecosystem types, organism groups, spatial and temporal scales to highlight research needs to better propose sound conservation measures. The comparative analysis addresses six organism groups ranging from microorganisms to fish in basins, rivers, lakes, wetlands, ponds and groundwater. Short-term studies at ecoregion and catchment scale focusing on invertebrates, macrophytes and fish in Palaearctic and Nearctic regions dominated. The most frequent hypotheses tested were the landscape filter concept, the species–area relationship, the metacommunity concept. Dominating natural drivers were area, heterogeneity and disturbance. Land use, eutrophication and habitat destruction were identified as most important stressors. Generally, freshwater biodiversity declined in response to these stressors in contrast to increasing biodiversity determined by natural drivers across all ecosystems. Preferred organism groups were fish and invertebrates, most frequently studied in rivers, in contrast to smaller organisms (e.g. bacteria) and, e.g. groundwater being underrepresented. Hypotheses originating from the last century are still tested in freshwater research, while novel concepts are either missing or untested. Protection of freshwater biodiversity is the ultimate challenge since it supports valuable ecosystems services ensuring perpetuation of mankind. For that, comprehensive large-scale studies with holistic approaches are urgently needed.Mediterranean endemic freshwater fish are among the most threatened biota in the world. The Mediterranean basin has experienced substantial reductions in precipitation and water availability, which will worsen with climate change. Current water policy is directed to increase water-supply demands, especially for agriculture, and not to improve water-use efficiency and implement integrated and sustainable water management. Illegal extractions are common, exacerbating problems for important protected areas. Management is needed to mitigate the conflicts between environmental water and human demand, and ensure availability of water to maintain ecological processes and Mediterranean freshwater biodiversity. Water availability is not the only threat, although it is exacerbated by pollution and invasive species. The uneven spatial distribution of threats across the Mediterranean basin requires different strategies to conserve freshwater biodiversity. Implementation of multi-national laws (e.g. Water Framework Directive in the European Union) will help future management of freshwater ecosystems. Management actions must be planned at whole-catchment scales, with collaboration among different countries and water-management authorities. The current reserve area is small compared with other areas in the world and driven by terrestrial interests, and should be evaluated for its effectiveness to protect the Mediterranean freshwater biodiversity.In the most comprehensive assessment of its kind, 4,989 African freshwater species were assessed by close to 200 scientists over a six year period for the IUCN Red List of Threatened Species, including all described species of freshwater fish, molluscs, crabs, dragonflies and damselflies, and selected families of aquatic plants. The findings from this new study give us a unique opportunity to try to influence developers and governments when they are planning freshwater infrastructure projects, which are still in their early stages in most of Africa.Over the last decades, the abundance of common reed has significantly increased in freshwater wetlands of eastern North America, and stands of this species are now commonly alternating with stands of cattails. Since these species share many characteristics, the contact zone between common reed and cattail stands may witness strong interspecific interactions. We surveyed stand dynamics in roadside ditches and freshwater marshes at these contact zones over three years, and we examined the morphological plasticity in response to neighbors. Results indicate that common reed is clearly gaining ground over time, while cattails stands are retreating. We also found annual variability in the spatial dynamics, suggesting that other factors, such as the effect of weather conditions on water level, may affect population processes. Interspecific interactions had a detrimental effect on both common reed and cattail biomass. However, common reed showed morphological plasticity in shoot height, number of nodes, and internodes length, while cattails did not. Our observations suggest that common reed has a net competitive advantage over cattails in roadside ditches and freshwater marshes.In the majority of digeneans infecting Insectivora, the larval stages are found in snails (cercaria) and terrestrial or aquatic invertebrates (metacerearia) The diets of both the Pyrenean desman Galemys pyrenaicus (Talpidae) and aquatic shrews (genus Neomys) include a wide variety of aquatic invertebrates that can acts as the second intermediate host of several species of digeneans. In 2004, sampling was performed in the Py Natural Reserve (French Pyrenees) A total of 912 Bythinella refescens (first intermediate host) and 167 non-mollusuc acquatic invertebrates (second intermediate hosts) were studied for the detection of larval stages of digenans Two species of digenean trematodes were recovered as cercariae and metacercariac. These two species were Pseudocephalotrema pyrenaica (Lecithodendriidae) and Skrjabinophusetus neomydis (Nanophyetidae). In snails their general prevalence was 20.4% and 1.97% respectively In the second intermediate hosts the corresponding prevalence rates were 22.15% and 3%, respectively. The study of larval digenenans of invertebrates can be used to detect the presence of small mammals.Waterfowl ecologists consider ducks important players in patterns and processes of freshwater ecosystems. Limnologists and Fish biologists, on the other hand, historically have "a bottom-up" view of the same systems, often regarding waterbirds as "background noise" compared to other biotic influences. Evidence for and against these largely opposing views is reviewed, focussing on European dabbling duck studies. In oligo- and mesotrophic wetlands at low breeding density, their role is likely to be overshadowed by biotic interactions between fish, invertebrates and plants. Conversely, many other freshwater systems may be affected by dabbling ducks in various ways, acting as dispersers of invertebrates and plants, as predators, and as eutrophicators. It is concluded that dabbling ducks, affect freshwater systems more profoundly than has hitherto been acknowledged. In their turn, freshwater ecosystems affect the ducks' population ecology. In a less comprehensive treatment, the evidence for the major paradigms addressing population limitation in dabbling ducks is discussed briefly from a European perspective. It is concluded that top-down (predation) as well as bottom-up (food limitation) processes may both affect population size, but evidence for either is correlative, necessitating more experimental Studies based on explicit predictions from pattern-oriented studies. In a discussion of the prospects for adopting a more adaptive management approach for European dabbling ducks, it is argued that a lack of information about annual variation in recruitment and harvest rates are major obstacles to understanding population change and for adopting a more adaptive management. A compilation of European studies about density dependence in Mallard Anas platyrhynchos indicates that population regulation may be a common phenomenon in this species, with possible important ramifications for research as well as management programmes.
Truite aux oeufs d'or et rivière d'émeraude: enjeux et conflits potentiels autour de la pêche sportive dans la vallée de la Soca. In: Vie locale, ruralité, tourisme et paysages dans l'aire méditerranéo-alpine. Regards croisés franco-slovènes sur la durabilité. BARTHES A. & SANDOZ A. (2009)
Apports sédimentaires du Rhône à la mer. Variabilités séculaires et impacts des aménagements. In: Le golfe du Lion. Un observatoire de l'environnement en Méditerranée. MONACO A., LUDWIG W., PROVANSAL M. & PICON B. (2009)Aquatic macrophytes are aquatic photosynthetic organisms, large enough to see with the naked eye, that actively grow permanently or periodically submerged below, floating on, or growing up through the water surface. Aquatic macrophytes are represented in seven plant divisions: Cyanobacteria, Chlorophyta, Rhodophyta, Xanthophyta, Bryophyta, Pteridophyta and Spermatophyta. Species composition and distribution of aquatic macrophytes in the more primitive divisions are less well known than for the vascular macrophytes (Pteridophyta and Spermatophyta), which are represented by 33 orders and 88 families with about 2,614 species in c. 412 genera. These c. 2,614 aquatic species of Pteridophyta and Spermatophyta evolved from land plants and represent only a small fraction (∼1%) of the total number of vascular plants. Our analysis of the numbers and distribution of vascular macrophytes showed that whilst many species have broad ranges, species diversity is highest in the Neotropics, intermediate in the Oriental, Nearctic and Afrotropics, lower in the Palearctic and Australasia, lower again in the Pacific Oceanic Islands, and lowest in the Antarctic region. About 39% of the c. 412 genera containing aquatic vascular macrophytes are endemic to a single biogeographic region, with 61–64% of all aquatic vascular plant species found in the Afrotropics and Neotropics being endemic to those regions. Aquatic macrophytes play an important role in the structure and function of aquatic ecosystems and certain macrophyte species (e.g., rice) are cultivated for human consumption, yet several of the worst invasive weeds in the world are aquatic plants. Many of the threats to fresh waters (e.g., climate change, eutrophication) will result in reduced macrophyte diversity and will, in turn, threaten the faunal diversity of aquatic ecosystems and favour the establishment of exotic species, at the expense of native species.Hypania invalida is a freshwater Polychaeta from the Ponto-Caspian area recently introduced in Western Europe. The aim of this manuscript is to examine its spread in French hydrosystems, to analyse its density in colonised ecosystems and to test the occurrence of a facilitative interaction with Corbicula spp., invasive Bivalvia in many European large rivers. To date H. invalida occurred in the Moselle, the Marne, the Seine, the Rhine and the Rhone Rivers, i.e. the main French hydrosystems. It occurred also in the Meuse River near the border between France and Belgium. The densities observed varied in a broad range and could reach several thousands of individuals by square meter in the channel. At a local scale, the spatial distribution depends on the substrate type constituting the river bottom. In canalised rivers H. invalida reached the highest densities on deposit substrates with an important organic part. When deposit substrates are lacking, H. invalida was aggregated on gravels, pebbles and Corbicula shell bed. The lowest densities were observed on roots and macrophytes. In the Moselle River, the main tributary of the Rhine River, the colonisation was very fast and the resulting densities were the same as in the Belgian Meuse River or in the Rhine River. One year after its introduction on a given site the species can be the prevailing one in term of densities in the channel, with 50% of all collected benthic macro-faunal individuals. No facilitative interaction has been evidenced with Corbicula, some results even indicated that the living molluscs had a negative effect on the Polychaeta. After an explosive demography in the Marne River, the observed densities decreased to a low level varying between several tens and several hundreds of individuals by square meter. These first results suggest that H. invalida has an important ability to spread between hydrosystems but a low competitive value.
Geomorphologie, Ökologie und nachhaltiges Management einer Wildflusslandschaft am Beispiel des Fiume Tagliamento: ein Modellökosystem für den Alpenraum und ein Testfall für die EU-Wasserrahmenrichtlinie (2005)Some problems arising from the sampling and recording of diatoms from acidic freshwater, epiphytic habitats are discussed. This led to further study of data assemblages recorded from more general low pH sites and suggestions for more definitive clusters of diatoms related to narrow pH ranges. Finally, some brief thoughts on the identification of diatoms and the stability of diatom morphology at the species level.
Le domaine public fluvial, un héritage du passé qui module aujourd'hui la réflexion sur la gestion de la biodiversité. Les zones humides de la Loire sous observation. In: Fleuves et marais, une histoire au croisement de la nature et de la culture. BURNOUF J. & LEVEAU P. (2004)Functional group definitions in aquatic ecology vary depending on the type of ecosystem (e.g., marine compared to fresh water ecosystems, stream compared to lake ecosystems). Since the benthic environment functions as the major storage and recycling compartment for virtually all material that flows in the aquatic system, biological processes that take place there are interesting models for identification of the different invertebrate functions. The accurate species function includes the effects of an organism on the abiotic as well as the biotic properties of the habitats. Therefore, a functional group may be defined as a group of species that share common biogeochemical and interspecific attributes. The main difficulty of applying this definition in aquatic ecosystems comes from the high diversity of organism functions (compared to terrestrial systems) that potentially exist at different levels: i) interspecific diversity supported by the large morphological and behavioural diversity of organisms, reinforced by a low degree of species redundancy; ii) intraspecific functional diversity due to changes in life history strategy during the life cycle, and enhanced by optimal foraging theory. The major question remains to find accurate functional group sizes and classifications that permit the distinction of the different biological activities involved in ecosystem key processes without missing other biological functions. After reviewing some of the problems in current functional classifications of benthic invertebrates, we propose a classification system based on the mechanical activities that characterize each species rather than consideration of the multiple consequences of these activities. This sorting strategy will result in a sub-classification of classical feeding groups into more precise functional groups. Such groups as bioturbation groups or functional feeding groups may be composed of representative taxa in both marine and freshwater environments.
Réhabilitation de marais sur un domaine de la basse vallée du Vistre (La Musette). In: Programme national de recherche. Recréer la nature: réhabilitation, restauration et création d'écosystèmes. Principaux résultats scientifiques et opérationnels. CHAPUIS J.L., BARRE V. & BARNAUD G. (2001)Danubian populations of the Pontocaspian mysid Limnomysis benedeni Czerniavsky, 1882, passing through the Main-Danube-Canal, rapidly expanded into waters of the Rhine system. This species is now recorded for the first time from France, where it represents the first true freshwater mysid. Temporal and spatial characteristics of this invasion point to a combination of hydrodynamic and anthropogenic modes of dispersal, which may favour a rapid colonization of the net of navigable inland waterways in France. Limnomysis appears as an omnivorous species in laboratory, but stomach contents indicate that the animals are essentially herbivorous and detritivorous in nature. From known bionomical data, no important effect is expected on the invaded freshwaters at ecosystem level.
First results on migrating shad (Alosa fallax) and mullet (Mugil cephalus) echocounting in a lock on the Rhône River (France) using a split-beam sounder, and relationships with environmental data and fish caught (2000)
Dernières avancées techniques en reproduction des salmonidés d'eau douce: 1. Les lignées gynogénétiques et les clones chez la truite arc-en-ciel. 2. La maîtrise de la reproduction chez les salmonidés d'eau froide (1998)RÉSUMÉ Treize espèces de poissons dulçaquicoles exotiques sont actuellement recensées en Camargue, dans le delta du Rhône. Parmi elles, onze sont naturalisées. Deux écrevisses américaines ont également été recensées. Pour illustrer les modifications intervenues dans les peuplements de poissons à la suite de ces introductions, nous prenons l'exemple d'un canal de drainage. Les impacts potentiels (compétition alimentaire, hybridation) sur les espèces autochtones sont identifiés et discutés. Nous avons tenté de caractériser chez Pseudorasbora parva les traits d'histoire de vie qui ont permis l'établissement rapide de cette espèce exotique dans le canal. Des suggestions sont émises en conclusion, pour une meilleure compréhension des interactions entre espèces introduites et faune autochtone. ABSTRACT Thirteen introduced freshwater fish species were recorded in the Camargue (Rhone Delta, Southern France). Eleven of them have established a population. Two American freshwater crayfishes were also introduced. The example of a drainage canal (studied between 1989 and 1995) was chosen to illustrate the changes in fish assemblages that occurred after those introductions. Depending on the year, the relative abundance (CPUE) of exotic species represented from 27% to 33% of the total catch. The potential impacts of those introductions (diet overlap, hybridization) on natural fish communities are identified and discussed. Life history traits of Pseudorasbora parva, an Asiatic species first recorded in 1993 in the canal, have been studied ; some of them might explain the successful and fast establishment of this species in the Camargue. In conclusion, suggestions and recommendations are proposed for a better understanding of the mechanisms involved in the interactions between introduced species and native communities.
Suivi des frayères potentielles d'Aloses sur la rivière Ardèche en aval de St-Martin-d'Ardèche et le Rhône court-circuité entre le barrage de Donzère-Mondragon et l'embouchure de l'Ardèche. Campagne d'études 1996 (1996)
Distribution et flux de chrome et de mercure dans le Rhône à Arles durant la période Juin 1994-Mai 1995. In: 7° Rencontres de l'Agence Régionale pour l'Environnement Provence Alpes Côte d'Azur Digne-les-Bains 24-27/10/1995 (1996)
Les débits solides du Rhône à proximité de son embouchure durant l'année hydrologique 94-95. In: 7° Rencontres de l'Agence Régionale pour l'Environnement ARPE Provence Alpes Côte d'Azur Digne-les-Bains 24-27/10/1995 (1996)
Le suivi expérimental des charges micro-polluantes véhiculées par le Rhône. In: 6° Rencontres de l'Agence Régionale pour l'Environnement ARPE Provence Alpes Côte d'Azur Saint-Cyr-sur-Mer (FRA) 14-15/11/1995 & GAP (FRA) 16-18/11/1995 (1996)
Les radioéléments artificiels (émetteurs gamma et plutonium) dans le Rhône à Arles en 1994-1995. In: 7° Rencontres de l'Agence Régionale pour l'Environnement ARPE Provence Alpes Côte d'Azur Digne-les-Bains 24-27/10/1995 (1996)Seventy species of exotic or transplanted fish species have been introduced into this region, 60% of them in the last 40 years. The effects of these introductions on endemic species have rarely been described. The few exceptions are: hybridization of Salmo marmoratus with Salmo trutta; the extinction of three endemic species of Phoxinellus in a Turkish lake owing to the introduction of Stizostedion lucioperca; and the spatial displacement of Aphanius in sites where Gambusia affinis occurs. A further phenomenon possibly attributable to the introduction of exotic fish is the increased turbidity in Lake Mikri Prespa following the introduction of Carassius auratus. Because of the paucity of information, the effects of introductions on endemic species remain controversial. It is therefore essential to initiate conservation action plans, for each catchment in wetland areas rich in endemic fish. An awareness campaign directed at land managers and decision-makers on the role and importance of fish in the functioning of aquatic ecosystems must also be undertaken very soon.In Italy, as in several other circum-Mediterranean countries, there is a unique assemblage of endemic freshwater fishes. Speciation processes, especially of endemic primary or near-primary freshwater fish, most probably occurred during the Lago Mare era of the Mediterranean (about 5 million years bp). However, the present-day distribution patterns are surely the result of events that occurred more recently, from the Pleistocene until historical times. However, natural events are now being superseded by anthropogenic interference with fish faunas. Among the various negative human factors the most harmful is the introduction of non-native species, which in Italy are responsible for the present catastrophic situation. Of the 71 species currently with natural self-sustaining populations in Italian waters, only 45 are natives. Of the latter, only 16 (or fewer) have not been subjected to deliberate human transfers. In Italy there about 28 endemic Mediterranean taxa, but most have either been deliberately or accidentally introduced to areas outside their natural range. The result of this persistent practice on a little known and unique fish fauna is zoogeographic pollution, massive cases of hybridization and loss of genetic identity by local native populations. The problem of freshwater fish conservation is not a matter of public concern in Italy. Sport fishing has a political and economic value and introductions are legally carried out and ‘welcomed’ by most fishermen; most biologists and conservationists are either unaware or unconcerned.The present conservation status of the endemic freshwater fish of Spain is reviewed and compared with a former list made in 1986. Ten taxa (species and subspecies) are exclusively endemic to Spanish waters, 13 are Iberian endemics (Spain and Portugal), while three other species are also found in neighbouring European (France and Italy) or African (Algeria) countries. Endemic species belong to the families Clupeidae (33% of the native taxa), Cyprinidae (87%), Cobitidae (100%) and Cyprinodontidae (100%). A greater part of the endemic fish fauna is threatened, since three taxa are endangered, five vulnerable, seven rare and two insufficiently known.The southern, western and north-western regions of Anatolia have abundant freshwater resources in the form of rivers, lakes and lagoons. In the past, these aquatic habitats were unpolluted and had very rich fish populations, but some water courses have started to become polluted in the last 20 years. This is because Turkey is a country that is developing very fast, both industrially and in agricultural terms. As a result of the large numbers of major towns and various types of factory, some species have been particularly affected by industrial pollution and generally the populations of fish living in these habitats have greatly diminished in recent years. The waste waters from these sites are discharged via rivers and lakes into the Sea of Marmara, the Aegean and the Mediterranean Seas. Some factories are equipped with filtration systems or purification plants, but at present most have no form of effluent treatment. Twenty species and ten subspecies of fish are described that are endemic to Turkey and neighbouring countries. One endemic species (Tor canis) is now extinct in Turkish waters, and three species (Alosa fallax nilotica, Aphanius fasciatus and Blennius fluviatilis) are endemic to the northern Mediterranean. It is essential as a first priority that conservation measures are taken to protect certain species and subspecies.The freshwater fish fauna of Greece includes 106 species of which 79 are native primary species. Of these 38 species are endemic to Greece and southern parts of neighbouring countries. Endangered species are divided into three groups: wholly endangered, locally endangered and rare and threatened. In the first group are eight taxa, usually found in a very restricted area (Eudontomyzon hellenicus, Alosa caspia vistonica, Pseudophoxinus beoticus, Ladigesocypris ghigii ghigii, Barbus euboicus, Barbus cyclolepis cholorematicus, Pungitius hellenicus and Knipowitschia goerneri). The second group includes five species with a wide area of distribution but some local populations which are extinct or in obvious decline (Salmo trutta, Pseudophoxinus stymphalicus, Vimba melanops, Valencia letourneuxi, Proterorhinus marmoratus). The third group comprises nine endemic taxa, mainly with a wide distribution in Greece, or widely distributed in Europe but represented in Greece by local populations, sometimes recognized as subspecies (Phoxinellus pleurobipunctatus, Barbus prespensis, Gobio kessleri banarescui, Gobio uranoscopus elimeius, Carassius carassius, Orthrias barbatulus vardarensis, Pungitius platygaster, Knipowitschia thessala, Economidichthys pygmaeus). These taxa often have rare or threatened local populations. The main reasons for the decline of fish species are: agricultural and industrial activity, overfishing, partial or total destruction of many karstic springs, public and private works abstracting water, drainage, irrigation, tourist and industrial installations, dams, mixing of fish faunas of different origin and introduction of exotic species.The conservation of fish and fish communities has received little attention relative to other vertebrates. Yet across Eurasia and North America, numerous important stocks of various fish species have been eliminated and there are now thousands of lakes and rivers which are fishless or possess only degraded communities. The main problems are caused by engineering works, industrial and domestic pollution, acidification, fishing and fishery management, and land use practices. The major conservation objective, perhaps fortified by legislation, must be habitat restoration and management, but short-term programmes can usefully involve translocations, captive breeding and cryopreservation. Fish conservation programmes are needed in every country in order to rescue endangered species and reverse the downward trends facing important fish communities by managing the lake and river systems concerned.Of the 67 species of freshwater fish and one species of lamprey present in Albania, 43 species are endemic to the north Mediterranean area and 13 have been introduced and have established populations. Five other species have been introduced, but do not reproduce. There are no data available on the status, distribution and ecology of the endemic fishes of Albania with the exception of the Salmonidae living in Lake Ohrid (Salmothymus ohridanus, Salmo letnica and Salmo letnica lumi). Data on the morphology and biology of these three salmonids are presented. Research on the freshwater fish of Albania is badly needed.Approximately 64 species of freshwater fish occur in Croatian Adriatic river systems. Fifty of these are native, the remainder being introduced or translocated. Of the 40 species endemic to the Mediterranean area 11 occur only in Croatia. Others are distributed mostly in the karstic area of Bosnia and Hercegovina, some in Montenegro, Macedonia, Slovenia and Italy, while a few are distributed throughout the whole northern Mediterranean. River regulation, hydroelectricity generation and industrial pollution, plus very restricted distributions, are the main causes for endemic fish being endangered. The most important Croatian endemic fish are the six species of the genus Paraphoxinus and Leuciscus ukliva, Leuciscus polylepis, Leuciscus svallize, Aulopyge hugeli, Salmothymus obtusirostris, Knipowitschia mrakovcici, and the endemic subspecies of Salmo trutta.Several — anthropogenic — influences are identified which cause the decline of freshwater fish, such as overfishing, introduction of alien taxa, habitat degradation and habitat loss. Whilst the problem of overfishing and introduction of alien taxa from the point of view of legislation (not implementation!) is relatively easy to handle, the conservation and protection of aquatic habitats proves to be a complex and difficult task. Aquatic habitats — being in a way the ‘vitals’ of their respective ecosystems — are extremely sensitive to harmful influences. They are affected directly or indirectly by a vast number of human activities. Therefore quite a number of different legal issues and also several administrative bodies are involved in the problem. Besides those concerning the use of aquatic resources in general, international instruments exist which aim at preserving habitats and/or their flora and fauna — including aquatic habitats. Among these, the EC Flora, Fauna and Habitat Directive and the Berne Convention explicitly include freshwater fish endemic to the northern Mediterranean region in their appendices. These instruments oblige member states — among others — to conserve these species and their habitats and/or certain sensitive aquatic habitats. They do, however, only establish general obligations which need to be implemented by more detailed provisions in national legislation. The establishment of specially protected areas for protected species (e.g. in France) or the development of recovery plans for endangered species (e.g. in Spain) are two examples. However, research on the subject of national legislation for the protection of endemic freshwater fish should be developed with the aid of local experts. To this end general information on legal and administrative means and methods at a national level is also given.There are 36 species and subspecies of freshwater fish and three migratory species in Portugal. Eleven have been introduced, 13 are endemic to the Iberian Peninsula and two live exclusively in Portugal (Chondrostoma lusitanicum and Rutilus macrolepidotus). Industrica pollution and the introduction of exotic fish species are the most serious conservation problems for Portuguese endemic fish.The native fish fauna of California, like the faunas of other regions of the world with Mediterranean climate, is declining rapidly: 63% of the 115 taxa are extinct or in danger of becoming extinct. The native fishes fall into three major groups: (1) diadromous fishes and their stream-resident derivatives; (2) large, long-lived freshwater dispersant fishes, mostly Cyprinidae; and (3) small freshwater dispersant fishes in isolated inland habitats, such as desert springs. In this respect, the fish fauna of California bears a closer resemblance to the fish fauna of Europe than it does to that of eastern North America. The native fish fauna is in trouble because most of the precipitation occurs in the northern half of the state or at high elevations, while most of the human need for water is in the southern half of the state, at low elevations. The result has been the construction of dams and reservoirs on every major stream in the state and thousands of kilometres of aqueducts. In addition, poor land use has devastated many drainages, introduced fishes have replaced native fishes, and fisheries have depleted some stocks. Major droughts have exacerbated these problems. Most of the extinct or endangered species are either native to small isolated habitats or to big rivers. The fishes have continued to decline despite conservation efforts using such powerful legal tools as the Endangered Species Act, the California Department of Fish and Game Code, and the Public Trust Doctrine. The poor state of California's fish fauna is a strong indication that many other endemic aquatic organisms, much more poorly known than the fishes, are in trouble as well. Protecting fishes will thus help to protect aquatic biodiversity in California. With this in mind, a general plan for protecting California's aquatic biota is presented. The plan has two main components: (1) legal protection for species in immediate danger of extinction and (2) development of a statewide system of protected waters called Aquatic Diversity Management Areas (ADMAs). For the latter component, a framework is presented that consists of (1) criteria for the design of ADMAs; (2) a system for ranking the suitability of aquatic habitats for protection of the native biota; (3) a classification system for California's waters; and (4) a long-term scheme for protecting aquatic biodiversity statewide.There are 35 species and subspecies of fish and two lamprey species in the Adriatic catchment of Slovenia. Five have been introduced and five transplanted. None of the regionally endemic fishes nor the lampreys live exclusively in Solvenia. Of these, Salmo Marmoratus, and Lethenteron zanandreai are threatened while Chondrosoma genei became extinct after the introduction of Chondrostoma nasus nasus into the area around 1960.The fresh waters of the north Mediterranean region possess a unique and diverse ichthyofauna with 229 endemic fish taxa in 13 families. With diverse threats to wetlands in the area and their increasing mismanagement many fishes are under threat and several taxa have become extinct in recent years. Following workshop discussions among specialists, a series of proposals is now put forward which is designed to reverse this trend. Within these proposals is the concept that clean water is desirable for both people and fish and that acceptable compromises must be the way to share this vital resource in the future. Managing water resources in the Mediterranean region is clearly going to be a key feature in the future development of this area and major issues must be resolved soon to avoid serious conflicts over water use in the 21st century.
L'aménagement durable des zones humides: respect de l'environnement et de la diversité biologique. In: L'aménagement des écosystèmes agro-piscicoles d'eau douce en milieu tropical. SYMOENS J.J. & MICHA J.C. (1995)
Sustainable use of the wetlands: respect for environment and biodiversity. In: The management of integrated freshwater agro-piscicultural ecosystems in tropical areas. SYMOENS J.J. & MICHA J.C. (1995)
Relations entre l'habitat physique et les poissons des zones à cyprinidés rhéophiles dans trois cours d'eau du bassin rhodanien: vers une simulation de la capacité d'accueil pour les peuplements (1994)
The impact of desiccation of a freshwater marsh (Garcines Nord, Camargue, France) on sediment-water-vegetation interactions. 3: The fractional composition and the phosphate adsorption characteristics of the sediment (1993)
Méthodes d'évaluation de l'impact radioécologique de l'accident de Tchernobyl sur le fleuve Rhône. In: Environmental contamination following a major nuclear accident. Proceedings of an International Symposium FAO-IAEA-UNEP-WHO Vienna (AUT) 16-20/10/1989 (1990)
Management problems with the differential allocation of fishing rights to sport and commercial fishermen in the Frisian lakes, The Netherlands. In: Management of freshwater fisheries. VAN DENSEN W.L.T., STEINMETZ B. & HUGHES R.H. (1990)
Bacterial populations in freshwater sediments: Factors affecting growth and their ultimate fate. In: Recent Advances in Microbial Ecology. Proceedings of the 5th International Symposium on Microbial Ecology ISME 5 (1989)
Waders and waterfowl in spring 1988 at Eber Golu, Turkey. The importance of freshwater lakes in the western part of Anatolia, Turkey, for migrating waders and waterfowl in spring, with special reference to ruffs (Philomachus pugnans). A case study (1989)
Austropotamobius pallipes and A.torrentium, with observations on their interactions with other species in Europe In: Freshwater crayfish, biology, management and exploitation. HOLDICH D.M. & LOWERY R.S. (1988)
Input of nutrients and suspended matter into the Golfe du Lion and the Camargue by the river Rhone = Apport par le Rhône de nutriments et de matières en suspension dans le Golfe du Lion et la Camargue (1987)
Input of nutrients and suspended matter into the Golfe du Lion by the river Rhône. In: Environmental pollution and its impact on life in the Mediterranean Region 1985. HERRMANN M., KOTZIAS D. & PARLAR H. (1987)
Interaction entre les activités humaines et l'écosystème des eaux courantes à saumon atlantique; étude de deux bassins versants en Bretagne (Scorff, Morbihan et Trieux, Côtes du nord) depuis 1950 (1987)
Models of the O2 and CO2 regimes in shallow ponds. In: Proceedings of the International Scientific Workshop on Ecosystems dynamics in freshwaters wetlands and shallow water bodies Moscow (SUN) 1982. SCIENTIFIC COMMITTEE ON PROBLEMS ON THE ENVIRONMENT SCOPE (1982)Définition des paramètres physiques et chimiques du milieu; caractéristiques liées a la culture, lumière et température, paramètres physiques et chimiques. La flore algale. Les facteurs du développementLes processus de ramification sous leur forme la plus generale constituent un cadre efficace de construction de modeles en dynamique des populations, aussi bien empiriques que theoriques en ce qui concerne les oiseaux. Le concept d'effectif a l'equilibre a une valeur beaucoup plus generale que celui de capacite brute du milieu. La variabilite inter-habitat et les mecanismes de dispersion qu'elle engendre constituent chez les mouettes un mecanisme important de regulation. L'etude des relations entre longevite et masse corporelle permet de distinguer une composante allometrique et une composante non-allometrique dans les strategies demographiques
Critères de qualité des eaux pour les poissons d'eau douce européens. Rapport sur les effets produits par la combinaison de toxiques dans l'eau sur les poissons d'eau douce et sur d'autres formes de vie aquatique (1981)
Le phytoplancton de l'Etang de Berre. Composition spécifique, biomasse et production; relations avec les facteurs hydrologiques, les cours d'eau afférents et le milieu marin voisin (Méditerranée nord-occidentale) (1981)
Travaux sur la taxonomie, la biologie et l'écologie d'insectes torrenticoles du sud-ouest de la France (Ephémèroptères et Diptères: Dixidae, Cecidomyiidae, Rhagionidae et Athericidae), avec quelques exemples de perturbations par l'homme (1981)
Observations des populations aviaires et en particulier des sternes pierregarin (Sterna hirundo L.) et naine (Sterna albifrons Pall.) d'un méandre de la Loire en amont d'Orléans, en rapport avec les variations de niveau du fleuve (1979)
The standing crop of aquatic plants of lowland streams in Denmark and the inter-relationships of nutrients in plant, sediment and water. In: Proceedings EWRS 5th Symposium on Aquatic Weeds 1978 (1978)
Regional meeting on integrated ecological research and training needs in North East Africa and in the Near and Middle East, with emphasis on the ecological effects of irrigation derived from large river basins. Final report. Alexandria (EGY) 24-27/02/1976 (1978)This review is part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report on Europe and Central Asia (ECA) and provides a critical assessment of issues facing decision-makers, including freshwater biodiversity and ecosystem trends as well as drivers of change. Freshwater systems are well established as the most threatened ecosystem type in the ECA region, with the quantity and quality of habitats and abundance of many species rapidly declining. Only about half (53%) of the EU's rivers and lakes achieved good ecological status in 2015 (as defined by the Water Framework Directive in terms of the quality of the biological community), and many lakes, ponds, and streams are disappearing as a consequence of agricultural intensification and inefficient irrigation and urbanisation, combined with climate change. The situation regarding freshwater biodiversity remains highly critical in ECA as many species remain threatened with extinction, including >50% of known species for some groups (e.g., molluscs, amphibians). Drivers of ECA freshwater taxa include the destruction or modification of their habitat, including water abstraction, which affects ∼89% of all amphibian threatened species and ∼26% of threatened freshwater invertebrate species. Of particular concern is the lack of data for freshwater invertebrates. Current status is available for only a minority of species, and the impact of alien invasive species is often unknown, especially in Central Asia. Based on current freshwater biodiversity trends, it is highly unlikely that ECA will achieve either the respective Aichi biodiversity targets by 2020 (i.e., targets 2 to 4, 6 to 12, and 14) or Target 1 of the Biodiversity Strategy.Mediterranean coastal areas are characterised by heavily transformed landscapes and an ever-increasing number of ponds are subjected to strong alterations. Although benthic diatoms and macroinvertebrates are widely used as indicators in freshwater ecosystems, little is still known about the diatom communities of lowland freshwater ponds in the Mediterranean region, and, furthermore, there are few macroinvertebrate-based methods to assess their ecological quality, especially in Italy. This article undertakes an analysis of benthic diatom and macroinvertebrate communities of permanent freshwater ponds, selected along a gradient of anthropogenic pressures, to identify community indicators (taxa and/or metrics) useful to evaluate the effect of human impacts. A series of 21 ponds were sampled along Tyrrhenian coast in central Italy. Five of these ponds, in a good conservations status and surrounded by woodland were selected as 'reference sites' for macroinvertebrates and epipelic diatoms. The remaining sixteen ponds were located in an agricultural landscape subject to different levels of human impact. The total number of macroinvertebrate taxa found in each pond was significantly higher in reference sites than in both the intermediate and heavily degraded ones, whereas the diatom species richness did not result in a good community variable to evaluate the pond ecological quality. The analysis revealed a substantial difference among the compositions of diatom communities between reference ponds and degraded ponds. The former were characterised by the presence of several species belonging to genera, such as Pinnularia sp., Eunotia sp., Stauroneis sp., Neidium sp., all of which were mostly absent from degraded ponds. Furthermore, the taxonomic richnesses of some macroinvetebrate groups (Odonata, Ephemeroptera, Trichoptera, Coleoptera), and taxa composition attributes of macroinvertebrate communities (total abundance, percentages of top three dominant taxa, percentages of Pleidae, Ancylidae, Hirudinea, Hydracarina) significantly correlated with variables linked with anthropogenic pressures. The results of the investigation suggested that diatoms tended more to reflect water chemistry through changes in community structure, whereas invertebrates responded to physical habitat changes primarily through changes in taxonomic richness. The methodologies developed for the analysis of freshwater benthic diatom and macroinvertebrate communities may have a considerable potential as a tool for assessing the ecological status of this type of water body, complying with the European Union Water Framework Directive 2000/60/EC.The Guadiana River basin's freshwater fish species richness, endemicity and threatened status (92% of native species are threatened) highlight the need for a large-scale study to identify priority areas for their conservation. One of the most common problems in conservation planning is the assessment of a site's relative value for the conservation of regional biodiversity. Here we used a two-tiered approach, which integrates an assessment of biodiversity loss and the evaluation of conservation value through site-specific measures. These measures based on the reference condition approach introduce the ability to make objective comparisons throughout the Guadiana River basin, thus avoiding a priori target areas. We identified a set of biodiversity priority areas of special conservation significance-which contain rare taxa as well as intact fish communities-because of their outstanding contribution to the basin's biodiversity. The inclusion of complete sub-basins in these priority areas might guarantee an optimal solution in terms of spatial aggregation and connectivity. However, the high spatial fragmentation to which the Guadiana River basin is submitted due to river regulation highlights the necessity of a systematic approach to evaluate the capability of the identified priority areas to maintain the Guadiana's freshwater fish biodiversity.Identifying the factors influencing the settlement of European eel (Anguilla anguilla) juveniles in continental habitats is crucial to designing effective management and conservation measures for this endangered species. A long-term data series (1993-2008) of European eel and European catfish (Silurus glanis) abundance in a freshwater canal of the Camargue water system (southern France), along with parallel data on water salinity and glass eel abundance in the adjacent VaccarSs lagoon, was analysed to identify the possible causes of decline in eel abundance observed in the canal during the last two decades. A model including glass eel recruitment and catfish abundance as covariates explained 78% of the observed variation in eel settlement success. Results suggest that (1) salinity does not play a significant role in determining the fraction of eels moving from the brackish lagoon to the canal; (2) density dependence affects settlement success, possibly through a reduction of juvenile survival in the adjacent lagoon; and (3) catfish abundance is negatively correlated with eel settlement. We discuss this latter point in terms of possible predation of catfish upon eels and/or inter-specific competition between the two species.The phylogeographic structure of vairone (Telestes muticellus), a primary freshwater fish endangered in a large part of its distributional range, was assessed: (i) to reconstruct the complex dispersion pattern in the upper Tyrrhenian hydrographic basins of Ligury, actually not recognised as peri- Mediterranean ichthyogeographic district, and (ii) to evidence the shape of population genetic structure as useful tool for future conservation strategies. A partial fragment of mitochondrial DNA cytochrome b (497 bp) was sequenced in 109 specimens sampled from eight populations, along an east-west geographic gradient. Fourteen haplotypes were identified, confirming the evolutionary distance between the two co-generic species: T. muticellus as 'Ligurian' clade and T. souffia as 'French' clade. The Nested Clade Analysis (NCA), the population genetic variability and population structure suggested a natural colonization occurred throughout the crossing of Alpine and Apennine watershed. The hierarchical Analysis of Molecular Variance (AMOVA) confirmed a geographic distinction between the populations from western (WTL) and from eastern (ETL) Tyrrhenian basins of Ligury colonised through the river capture processes along the Maritime Alpine watershed (Padano-Venetian district) and along the Apennine watershed (Tuscano-Latium district), respectively. Our results, evidencing the lack of genetic contiguity among vairone populations of the upper Tyrrhenian hydrographic basins of Ligury, allowed to recognise the presence of two management units (MUs) for its conservation.There is growing awareness in Europe of the importance of ponds, and increasing understanding of the contribution they make to aquatic biodiversity and catchment functions. Collectively, they support considerably more species, and specifically more scarce species, than other freshwater waterbody types. Ponds create links (or stepping stones) between existing aquatic habitats, but also provide ecosystem services such as nutrient interception, hydrological regulation, etc. In addition, ponds are powerful model systems for studies in ecology, evolutionary biology and conservation biology, and can be used as sentinel systems in the monitoring of global change. Ponds have begun to receive greater protection, particularly in the Mediterranean regions of Europe, as a result of the identification of Mediterranean temporary ponds as a priority in the EU Habitats Directive. Despite this, they remain excluded from the provisions of the Water Framework Directive, even though this is intended to ensure the good status of all waters. There is now a need to strengthen, develop and coordinate existing initiatives, and to build a common framework in order to establish a sound scientific and practical basis for pond conservation in Europe. The articles presented in this issue are intended to explore scientific problems to be solved in order to increase the understanding and the protection of ponds, to highlight those aspects of pond ecology that are relevant to freshwater science, and to bring out research areas which are likely to prove fruitful for further investigation.The concentrations of the trace metals Zn, Cu, Fe, Cd and Pb were measured in four caridean decapods; Atyaephyra desmaresti, Palaemonetes varians, Parapenaeus longirostris and Aristeus antennatus, from freshwater , estuarine and marine habitats in northeast Algeria variably affected by anthropogenic metal contamination. The two coastal species (P. longirostris and A. antennatus) are a food source for the local population. Accumulated metal concentrations varied interspecifically, and intraspecifically between sites and between seasons, except in the case of Aristeus antennatus. The fresh and brackish water species (Atyaephyra desmaresti and Palaemonetes varians) accumulated more Cd and Pb than their marine counterparts. Results are discussed with respect to anthropogenic inputs and the environmental conditions of the regions studied.We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to September 2001. Fifty-five sites were identified as "Reference sites" and 20 sites were used as "Test sites" to test the model. At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207 taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality, substrate quality and current velocity. Test sites' environmental quality was established from their relative distance to reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model, the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and increasing the number of ellipses that define quality bands.The spread of non-indigenous species and the decline of autochthonous ones are leading to a homogenization of freshwater fauna in terms of systematic units, but the functional consequences are poorly documented. We studied the peculiar case of the lower, French section of the Moselle River where 20 invertebrate species have been introduced since 1854, with a rate increasing exponentially with time. Dredge sampling performed in 1994, 1996, 2000 and 2001 at four sampling stations allowed for an evaluation of faunal changes in terms of composition, structure and function. During this period, no structural changes were recorded in spite of multiple, new and successful introductions. The evaluation of functional modifications was based on a typology of taxa exhibiting homogeneous biological/ecological traits. Functional diversity, measured as the diversity of taxa distribution among functional groupings, revealed a significant increase between 1994/1996 and 2000/2001 because those species that were over-represented during the former period reached more equilibrated densities during the latter. The major, indirect implications of these functional. changes are discussed.The insect orders Megaloptera and Neuroptera are closely related members of the superorder Neuropterida, a relict lineage of holometabolous insects that also includes the Raphidoptera. Megaloptera, composed of the families Sialidae and Corydalidae (including subfamilies Chauliodinae and Corydalinae), has fully aquatic larvae that occur in a wide variety of lotic and lentic habitats, including temporary streams. In total, 2 of 17 families of Neuroptera have aquatic larvae: Nevrorthidae live in the benthos of fast-flowing streams and Sisyridae reside on freshwater sponges. A third family of Neuroptera, Osmylidae, contains some water-dependent species that reside under leaves and rocks along the margins of waterbodies. We recognize 328 extant, described species of Megaloptera (composed of 116 species of Chauliodinae, 131 species of Corydalinae, and 81 species of Sialidae) and 73 species of aquatic Neuroptera (composed of 12 species of Nevrorthidae and 61 species of Sisyridae). Additionally, we estimate that 45 species of Osmylidae are water-dependent, although the ecology of this group is poorly understood. Chauliodinae and Corydalidae are both found in the New World, the Oriental region, and South Africa, but are absent from Europe, the Middle East, Central Asia, tropical Africa, and boreal regions. Chauliodinae is quite speciose in Australia, whereas Corydalinae is absent. Sialidae is most speciose in temperate regions, and is absent from tropical Africa and portions of the Oriental region. Sisyridae and Osmylidae are nearly cosmopolitan, but the relict family Nevrorthidae is limited to Japan, the Mediterranean, and Australia. The discovery of many new species in recent years, particularly among Corydalidae in the Neotropics and China, suggests that our knowledge of aquatic neuropterid diversity is far from complete.Ancient sister lakes are considered to be ancient lakes lying in close geographic proximity, sharing a related origin and significant time of co-existence, usually having hydrological connection as well as a balanced degree of faunal overlap and distinctness. A paradigm for studying sister lake relationships are the ancient lakes Ohrid and Prespa in the Balkans, which are characterized by high degrees of endemicity. Three general patterns of endemic species can be distinguished for these lakes: (1) taxa that are endemic to either lake, with no close relatives in the respective sister lake, (2) closely related but distinct endemic taxa in both lakes (sister species) and (3) shared endemic taxa occurring in both lakes. In the present paper, two endemic freshwater pulmonate gastropod species, Radix relicta (Lake Ohrid) and R. pinteri (Lake Prespa), are used to study the evolution of presumed sister species based on biogeographical and comparative DNA data from world-wide Radix taxa. Phylogenetic, phylogeographical and parametric bootstrap analyses all suggest a sister group relationship of R. relicta and R. pinteri (pattern 2 of endemic diversity). Sister to these two taxa is the widespread R. ampla, which does not occur in the vicinity of lakes Ohrid and Prespa. The southern feeder spring complexes of Lake Ohrid are inhabited by another lineage (Radix sp. 1), which resembles Radix relicta in morphology/anatomy. For Lake Prespa, the widespread R. auricularia was reported in addition to the endemic R. pinteri. Comparative phylogenetic data favour a western Adriatic zoogeographical affinity of lakes Ohrid and Prespa over an Aegean-Anatolian faunal connection. The status of lakes Ohrid and Prespa as sister lakes is evaluated in the light of current knowledge on gastropod speciation and endemism in these hotspots of biodiversity.We studied the impact of urban and industrial activity upon the occurrence and the distribution of pollutants in the fresh estuary of the River Seine. Contamination was investigated under dry weather conditions, by determination of PCB and trace metal levels upstream and downstream of Rouen and the pollutant content of organisms with different positions in the trophic web. PCB contents of roach were higher downstream than upstream of Rouen. Cd levels showed a regular four fold increase from upstream to downstream of Rouen. Cyprinidae (ablet, roach) showed similar PCB or even higher trace metal levels than their predators (Percidae). This result suggests that contaminated food intake was not the main pathway for pollutant accumulation.The Italian goby Gobius nigricans is a running-water-dwelling species inhabiting the Tuscano-Latium district and threatened by several human activities. Many aspects of its biology are currently unknown, such as the dynamic potentialities. Since age determination and dynamic assessment are considered an important tool for a correct management strategy, we aimed to investigate some aspects of the Italian goby life history by applying the fish stock assessment principles, collecting data on fertility, population structure (age-class number), growth (i.e., curvature parameter and asymptotic length), mortality (natural and due to the fishing), and longevity of a central Italian goby population to know the status and dynamic properties of the Italian goby in Mediterranean river systems and to provide a baseline for comparison with other populations. Females are subject to a strong selective pressure to quickly reach a small size to optimize reproductive output, while acquisition of a large size favored males for a more easy access to breeder females (the asymptotic length was higher in males than in females). Moreover, appreciable between-sex differences were found in both growth pattern (the growth rate was lower in females than in males) and dynamic potentialities. In particular, the mortality rate was lower in females, whereas the longevity was slightly lower in males, although the two sexes showed similar values for the two latter properties. There is considerable scope for further work on the G. nigricans growth and other freshwater gobies because information on population and dynamic properties, and assessment of factors affecting growth are still very insufficient.This paper reports the results of a study on a zoosporic fungus (Saprolegniaceae) parasitizing populations of Eudiaptomus intermedius (Copepoda, Calanoida) in mountain lakes located in the Northern Apennines, Italy. The dynamics of this infectious process was previously described in one of the lakes of the study area. The virulence is particularly high at the end of the calanoid reproductive phase, when the fungal hyphae penetrate the host eggs provoking their degeneration. Here new data are presented and the phenology of the host-parasite interaction is comparatively analyzed in different years and in different sites. The occurrence of the parasite was assessed at a regional scale. Possible mechanisms involved in the pathogen dispersal and in the host recognition are proposed, and the ecological impact of the fungal parasitism on the calanoid populations is discussed.The taxonomic status of the freshwater mollusc fauna of the Iberian Peninsula it is reasonably well known, but, unlike other benthic macroinvertebrate, its distribution and ecology has been poorly studied. In this article, I study the relationships between environmental characteristics and distribution and community structure of freshwater molluscs along climatic, hydrological, physicochemical, and heterogeneity gradients in the southwestern Iberian Peninsula. Ninety-four sampling points were analysed, in which, in addition to habitat features, the presence/absence and abundance of species were evaluated. The environmental gradients were measured by use of principal-components analysis (PAC), which orders the variables along two gradients: headwaters-mouth gradient (PC1) and water availability (PC2). According to canonical correspondence analysis (CCA), the main environmental factors related to species distribution and community structure were conductivity, permanency, channel width, turbidity, slope, and distance to the main river axis. The relationship between biodiversity (measured as species richness and the Shannon-Weiner diversity index), the ratio of the number of introduced species to the total number of species (zoogeographic integrity coefficient), and environmental variables was best explained by a regression model incorporating, basically, the permanence of water in streams as the variable that accounted for most of the variance. This study demonstrates that the distribution of freshwater molluscs along a Mediterranean gradient highly stressed by drought depends, mainly, on the hydrological stability and environmental conditions of the headwaters and estuarine sites.We assessed the importance for biodiversity of man-made farm ponds in an agricultural landscape in SW France lacking natural wetlands. The ponds were originally created to provide a variety of societal services (irrigation, visual amenity, water for cattle, etc.). We also assessed the environmental factors influencing invertebrate assemblages in these ponds. Only 18 invertebrate taxa out of 114 taxa occurring in the study area were common to ponds and rivers indicating that the contribution of farm ponds to freshwater biodiversity was potentially high. A Self-Organizing Map (SOM, neural network) was used to classify 36 farm ponds in terms of the 52 invertebrate families and genera they supported, and to specify the influence of environmental variables related to land-use and to pond characteristics on the assemblage patterns. The SOM trained with taxa occurrences showed five clusters of ponds, most taxa occurring only in 1-2 clusters of ponds. Abandoned ponds tended to support higher numbers of taxa, probably because they were allowed to undergo a natural succession. Nevertheless, abandoned ponds were also amongst the largest, so that it remained difficult to separate the effects of pond size and abandonment, although both factors were likely to interact to favour higher taxon richness. The invertebrate communities in the ponds appeared to be influenced mainly by widely acting environmental factors (e.g. area, regionalization of assemblages) with little evidence that pond use (e.g. cattle watering, amenity) generally influenced assemblage composition. Our results support the idea that agricultural landscapes containing man-made ponds make a significant contribution to freshwater biodiversity indicating that protection of farm ponds from threats such as in-filling and pollution can make a positive contribution to the maintenance of aquatic biodiversity. This added value for biodiversity should be considered when calculating the economic costs and benefits of constructing water bodies for human activities.The introduction of some crustacean species has produced alterations of freshwater environments and declines of native species worldwide. The red swamp crayfish, Procambarus clarkii Girard, was introduced in the Southwest Iberian Peninsula in the 1970's, producing severe impacts on rice agriculture and on native biota such as macrophytes, gastropods, native crayfish and amphibians. We studied the distribution of P. clarkii in two areas of SW Iberian Peninsula: the Sado River basin (SW Portugal), an area colonized by this species around 1990, and the Parque Natural del Entorno de Donana (SW Spain), colonized soon after its introduction in the Iberian Peninsula, in the 1970's. Our main goal was to determine which factors limit crayfish distribution, which could help to identify the most effective management practices to contain its spread. Procambarus clarkii was found in most types of water bodies, including small and shallow ones. Distance to a crayfish source was the single predictor variable explaining crayfish occurrence in most types of habitats and in both areas. The only exception was for the Sado permanent stream points, where crayfish presence was negatively affected by an interaction between elevation and flow velocity. Other habitat characteristics have apparently little or no importance for its successful colonization. Moreover, this study indicated that overland dispersal is apparently a frequent phenomenon in this species. Our findings can be used to determine which habitats are most likely to be colonized by the crayfish and to develop practical measures which may limit its spread and minimize its impacts.The Water Framework Directive or WFD constitutes a major step forward in the protection of the aquatic environment and associated habitats, since it legislates for the characterization of surface water bodies across defined ecoregions and the development of ecological monitoring systems based upon elements of the aquatic biota. The Macaronesian archipelagos include the Azores, Madeira and the Canary Islands. The peripheral situation of the Macaronesian islands has set them apart from many European initiatives concerning the implementation of the WFD, which is biased towards better known continental systems. As a result, they have been included in the same ecoregion as the Iberian Peninsula and the Balearic Islands for management purposes. However, because of their oceanic situation and volcanic origin, the freshwater systems of the Macaronesian islands differ strongly from continental systems in watershed morphology and the composition of the biotic assemblages, which merits separate identification rather than inclusion within the larger Iberic-Macaronesian ecoregion and special attention concerning regional implementation of programmes of measures under the Directive.Cumacea and Tanaidacea are marginal groups in continental waters. Although many euryhaline species from both groups are found in estuaries and coastal lagoons, most occur only temporarily in non-marine habitats, appearing unable to form stable populations there. A total of 21 genuinely non-marine cumaceans are known, mostly concentrated in the Ponto-Caspian region, and only four tanaids have been reported from non-marine environments. Most non-marine cumaceans (19 species) belong in the Pseudocumatidae and appear restricted to the Caspian Sea (with salinity up to 13 parts per thousand) and its peripheral fluvial basins, including the northern, lower salinity zones of the Black Sea (Sea of Azov). There are nine Ponto-Caspian genera, all endemic to the region. Only two other taxa (in the family Nannastacidae) occur in areas free of any marine-water influence, in river basins in North and South America. Both seem able to survive in waters of raised salinity of the lower reaches of these fluvial systems; but neither has been recorded in full salinity marine environments. The only non-marine tanaidacean thus far known lives in a slightly brackish inland spring in Northern Australia. The genus includes a second species, from a brackish-water lake at the Bismarck Archipelago, tentatively included here as non-marine also. Two additional species of tanaidaceans have been reported from non-marine habitats but both also occur in the sea.Long-term observations on riverine benthic invertebrate communities enable assessments of the potential impacts of global change on stream ecosystems. Besides increasing average temperatures, many studies predict greater temperature extremes and intense precipitation events as a consequence of climate change. In this study we examined long-term observation data (10–32years) of 26 streams and rivers from four ecoregions in the European Long-Term Ecological Research (LTER) network, to investigate invertebrate community responses to changing climatic conditions. We used functional trait and multi-taxonomic analyses and combined examinations of general long-term changes in communities with detailed analyses of the impact of different climatic drivers (i.e., various temperature and precipitation variables) by focusing on the response of communities to climatic conditions of the previous year. Taxa and ecoregions differed substantially in their response to climate change conditions. We did not observe any trend of changes in total taxonomic richness or overall abundance over time or with increasing temperatures, which reflects a compensatory turnover in the composition of communities; sensitive Plecoptera decreased in response to warmer years and Ephemeroptera increased in northern regions. Invasive species increased with an increasing number of extreme days which also caused an apparent upstream community movement. The observed changes in functional feeding group diversity indicate that climate change may be associated with changes in trophic interactions within aquatic food webs. These findings highlight the vulnerability of riverine ecosystems to climate change and emphasize the need to further explore the interactive effects of climate change variables with other local stressors to develop appropriate conservation measures.Oyster reefs provide structural habitat for resident crabs and fishes, most of which have planktonic larvae that are dependent upon transport/retention processes for successful settlement. High rates of freshwater inflow have the potential to disrupt these processes, creating spatial gaps between larval distribution and settlement habitat. To investigate whether inflow can impact subsequent recruitment to oyster reefs, densities of crab larvae and post-settlement juveniles and adults were compared in Estero Bay, Florida, over 22 months (2005-2006). Three species were selected for comparison: Petrolisthes armatus, Eurypanopeus depressus, and Rhithropanopeus harrisii. All are important members of oyster reef communities in Southwest Florida; all exhibit protracted spawning, with larvae present throughout the year; and each is distributed unevenly on reefs in different salinity regimes. Recruitment to oyster reefs was positively correlated with bay-wide larval supply at all five reefs examined. Species-specific larval connectivity to settlement sites was altered by inflow: where connectivity was enhanced by increased inflow, stock-recruitment curves were linear; where connectivity was reduced by high inflows, stock-recruitment curves were asymptotic at higher larval densities. Maximum recruit density varied by an order of magnitude among reefs. Although live oyster density was a good indicator of habitat quality in regard to crab density, it did not account for the high variability in recruit densities. Variation in recruit density at higher levels of larval supply may primarily be caused by inflow-induced variation in larval connectivity, creating an abiotic simulation of what has widely been regarded as density dependence in stock-recruitment curves.Three aerial photography inventories were used to examine change in submerged aquatic vegetation (SAV) in the tidal freshwater Hudson River over the interval 1997 to 2007. Overall, there was about a 30 % net decline in SAV coverage although there were also many individual areas of expansion. The invasive water chestnut (Trapa natans) did not change appreciably in net cover over the interval, and there was replacement of SAV by water chestnut along with slightly fewer cases of SAV replacing the exotic. A fine-scale (100 m by 100 m quadrats) analysis showed that about 30 % of quadrats that supported vegetation changed by more than 10 % in plant cover and overall SAV was quite dynamic. SAV in the Hudson is limited by light which is in turn controlled by suspended sediment. SAV was rarely found at depths > 1 m below low water, and interannual differences in clarity affected the ability of SAV beds to maintain locally supersaturated levels of dissolved oxygen. We found that location within the River channel (proximity to shore) influenced the magnitude and variability in change in SAV between census periods. The physical nature of the adjacent shoreline also affected the magnitude of change with greater declines in cover in areas next to hard-engineered shore types. SAV in the Hudson is highly dynamic, apparently quite resilient, and the control of light by suspended sediment rather than phytoplankton growth offers a contrast to eutrophication-influenced changes in other estuaries. Management and protection of SAV habitat must recognize the highly variable nature of plant cover and that absence in any particular year does not preclude future appearance of submerged plants at that location.Buzan et al. critique Turner's (Estuaries and Coasts 29:345-352, 2006) analysis of the relationship between freshwater inflow and oyster productivity in the Gulf of Mexico, using 16 years of fisheries-independent data for Galveston Bay. They conclude that the catch-per-unit effort (CPUE; number h(-1)) of marketable oysters increase 1 to 2 years after years with increased freshwater inflows, and they express concerns that water supply managers may mis-apply the results of Turner (Estuaries and Coasts 29:345-352, 2006) to justify a reduced freshwater inflow to Galveston Bay. I find no relationship between the CPUE of oyster spat or marketable oyster density and the commercial harvest, but do find a strong inverse relationship between harvest and river discharge in Galveston Bay. There are three possible factors that may explain why the annual variations in the fisheries-independent data are not coherent with the annual variations in commercial harvest: variable levels of water quality, inconsistent fishing effort, and the fact that the fisheries-independent data are not prorated for the area of the reefs actually fished. I concur, completely, with the apprehension that reductions in freshwater inflow will be implemented without examining the full set of assumptions and consequences, and thereby compromise estuarine ecosystem quality, and perhaps permanently, before mistakes can be seen or reversed.In coastal Louisiana, the development of large-scale freshwater diversion projects has led to controversy over their effects on oyster resources. Using controlled laboratory experiments in combination with a field study, we examined the effects of pulsed freshwater events (freshet) of different magnitude, duration, and rate of change on oyster resources. Laboratory and field evidence indicate that low salinity events (Estuarine rearing has been shown to enhance within watershed biocomplexity and support growth and survival for juvenile salmon (Oncorhynchus sp.). However, less is known about how growth varies across different types of wetland habitats and what explains this variability in growth. We focused on the estuarine habitat use of Columbia River Chinook salmon (Oncorhynchus tshawytscha), which are listed under the Endangered Species Act. We employed a generalized linear model (GLM) to test three hypotheses: (1) juvenile Chinook growth was best explained by temporal factors, (2) habitat, or (3) demographic characteristics, such as stock of origin. This study examined estuarine growth rate, incorporating otolith microstructure, individual assignment to stock of origin, GIS habitat mapping, and diet composition along similar to 130 km of the upper Columbia River estuary. Juvenile Chinook grew on average 0.23 mm/day in the freshwater tidal estuary. When compared to other studies in the basin our growth estimates from the freshwater tidal estuary were similar to estimates in the brackish estuary, but similar to 4 times slower than those in the plume and upstream reservoirs. However, previous survival studies elucidated a possible tradeoff between growth and survival in the Columbia River basin. Our GLM analysis found that variation in growth was best explained by habitat and an interaction between fork length and month of capture. Juvenile Chinook salmon captured in backwater channel habitats and later in the summer (mid-summer and late summer/fall subyearlings) grew faster than salmon from other habitats and time periods. These findings present a unique example of the complexity of understanding the influences of the many processes that generate variation in growth rate for juvenile anadromous fish inhabiting estuaries.Maintaining proper freshwater and marine inputs is essential for estuarine function. Alteration of freshwater flows into small tributaries that traverse the upland-estuarine margin may be especially problematic, e.g., by impacting the nursery areas for juvenile finfish and shellfish. We used stomach contents and stable isotope analysis (delta(13)C, delta(15)N) to examine effects of freshwater flow alterations on the trophic ecology of juvenile common snook (Centropomus undecimalis) in four mangrove creeks with different freshwater flow regimes. Diet diversity in less degraded creeks was greater than in more degraded creeks, and the importance (by % mass) of the top three preys was disproportionately higher in the more degraded creeks. Stable isotope measures of trophic diversity corroborate these trends, suggesting higher intraspecific trophic diversity in less degraded creeks. The difference in diet diversity of juvenile snook may be an indicator of an overall change in ecosystem function and these shifts in food web structure may affect the rate that juveniles of this and other species with similar habitat requirements successfully join the adult population.A nutrient mass balance for the tidal freshwater segment of the James River was used to assess sources of nutrients supporting phytoplankton production and the importance of the tidal freshwater zone in mitigating nutrient transport to marine waters. Monthly mass balances for 2007-2010 were based on riverine inputs, local point sources (including sewer overflow events), ungauged inputs, riverine outputs, and tidal exchange. The tidal freshwater James River received exceptionally high areal loads (446 mg TN m(-2) day(-1) and 55 mg TP m(-2) day(-1)) compared to other estuaries in the region and elsewhere. P inputs were principally from riverine sources (84 %) whereas point sources contributed appreciably (54 %) to high N loads. Despite high loading rates and short water residence time, areal mass retention was high (143 mg TN m(-2) day(-1) and 33 mg TP m(-2) day(-1)). Retention of particulate fractions occurred during high discharge, whereas dissolved inorganic fractions were retained during low discharge when chlorophyll-a concentrations were high. On an annualized basis, P was retained more effectively (59 %) than N (32 %). P was retained by abiotic mechanisms via trapping of particulate forms, whereas N was retained through biological assimilation of dissolved inorganic forms. Results from a limited suite of stable isotope determinations suggest that DIN from point sources was preferentially retained. Combined inputs from diffuse and point sources accounted for only 20 % and 36 % (respectively) of estimated algal N and P demand, indicating that internal nutrient recycling was important to sustaining high rates of phytoplankton production in the tidal freshwater zone.Land weathering by river runoff makes coastal oceans highly variable ecosystems in terms of seawater pH; however, its effects on biological components and, hence, on the coastal ecosystem functioning has been scarcely addressed. In this study, we determined part of the spatial and seasonal variability of the physical-chemical characteristics of seawater, and life history traits of the neritic copepod Acartia tonsa, along an estuarine-to-coastal zone geographic gradient in the southern Pacific Ocean. There, freshwater influences give rise to sharp gradients in pH, salinity, and temperature, which in turn, may affect the fitness of copepod populations inhabiting along the gradient. In fact, most of the studied copepod traits (egg size, ingestion, and egg production rates) were moderately (r (2) = 0.5, pUnderstanding the ecological processes that regulate the production and fate of methane (CH4) in wetland soils is essential for forecasting wetland CH4 emissions. Iron reduction is an important carbon mineralization pathway that is capable of suppressing CH4 production in freshwater wetlands, but our understanding of temperature regulation of iron oxide respiration and the subsequent impacts on CH4 production is limited. We tested the hypothesis that temperature regulates iron reduction rates indirectly through differential effects on Fe(II) oxidation versus Fe(III) reduction, which ultimately determines the size of the microbially labile, poorly crystalline Fe(III) pool. Our study indicates that rates of iron reduction are more sensitive to changes in temperature than rates of iron oxidation, which creates imbalance in the relative proportion of Fe(II) and Fe(III) in the poorly crystalline soil iron pool as temperatures change. Our results suggest that warmer temperatures can cause the Fe(III) oxide pool to decline, limiting the Fe(III) supply to iron reducers and relieving competition for organic carbon with methanogens.Tidal freshwater wetlands (TFW) alter nitrogen concentrations in river water, but the role of these processes on a river's downstream nitrogen delivery is poorly understood. We examined spatial and temporal patterns in denitrification in TFW of four rivers in North Carolina, USA and evaluated the relative importance of denitrification rate and inundation on ecosystem-scale N-2 efflux. An empirical model of TFW denitrification was developed to predict N-2 efflux using a digital topographic model of the TFW, a time series of water level measurements, and a range of denitrification rates. Additionally, a magnitude-frequency analysis was performed to investigate the relative importance of storm events on decadal patterns in N-2 efflux. Spatially, inundation patterns exerted more influence on N-2 efflux than did the range of denitrification rate used. Temporal variability in N-2 efflux was greatest in the lower half of the tidal rivers (near the saline estuary) where inundation dynamics exerted more influence on N-2 efflux than denitrification rate. N-2 efflux was highest in the upper half of the rivers following storm runoff, and under these conditions variation in denitrification rate had a larger effect on N-2 efflux than variability in inundation. The frequency-magnitude analysis predicted that most N-2 efflux occurred during low flow periods when tidal dynamics, not storm events, affected TFW inundation. Tidal hydrology and riparian topography are as important as denitrification rate in calculating nitrogen loss in TFW; we present a simple empirical model that links nitrogen transport in rivers with loss due to denitrification in TFW.Increasing rates of freshwater habitat loss in the Chesapeake Bay (and elsewhere) have renewed interest in the role of freshwater in population integrity for euryhaline fishes. Freshwater habitats may be important nurseries for juveniles of anadromous species. Using length-weight residuals and scales, we determined if body condition and growth of juvenile (Submersed aquatic vegetation (SAV) communities have undergone declines worldwide, exposing them to invasions from non-native species. Over the past decade, the invasive species Hydrilla verticillata has been documented in several tributaries of the lower Chesapeake Bay, Virginia. We used annual aerial mapping surveys from 1998 to 2007, integrated with spatial analyses of water quality data, to analyze the patterns and rates of change of a H. verticillata-dominated SAV community and relate them to varying salinity and light conditions. Periods of declining SAV coverage corresponded to periods where salinities exceeded 7 and early growing season (April to May) Secchi depths wereSouthern flounder Paralichthys lethostigma is a recreationally and commercially important species along the western Atlantic and northern Gulf of Mexico coasts that can exhibit complex early-life habitat-use patterns. Herein, we used an otolith microchemical approach to test the conventional wisdom that juvenile southern flounder spend most of their early life in low-salinity areas of estuaries, focusing on the largely unstudied population in the Mobile-Tensaw Delta, AL. Analysis of strontium/calcium concentrations in otolith cores of age 0 juveniles demonstrated that 68% of these individuals hatched in high-salinity waters before moving into freshwater habitats, with the remaining individuals being spawned in or near freshwater habitat. Further, otolith edge Sr/Ca concentrations revealed that even juveniles used freshwater habitats, particularly during freshwater/oligohaline conditions in our study system. Otolith edge Sr/Ca ratios for fish collected during high-salinity periods differed significantly among collection regions, suggesting seasonal differences in patterns of habitat use between individuals collected upstream (i.e., freshwater habitats) vs. downstream (i.e., euryhaline habitats). These data support the hypothesis that early-life stages of a substantial portion of a coastal southern flounder population use freshwater habitat.Tidal freshwater wetlands (TFW) are situated in the upper estuary in a zone bordered upstream by the nontidal river and downstream by the oligohaline region. Here, discharge of freshwater from the river and the daily tidal pulse from the sea combine to create conditions where TFW develop. TFW are often located where human population density is high, which has led to wetland degradation or destruction. Globally, TFW are largely restricted to the temperate zone where the magnitude of annual river discharge prevents saline waters from penetrating too far inland. The constant input of river water delivers high loads of sediments, dissolved nutrients, and other suspended matter leading to high sedimentation rates and high nutrient levels. Prominent biogeochemical processes include the transformation of nitrogen by bacteria and immobilization of phosphate. A diverse, characteristic vegetation community develops which supports a rich fauna. Biotic diversity is highest in the high marsh areas and decreases in the lower levels where tidal inundation is greatest. Benthic fauna is rather poor in diversity but high in biomass compared to other regions of the estuary. Global climate change is a threat for this system directly by sea level rise, which will cause brackish water to intrude into the fresh system, and indirectly during droughts, which reduce river discharge. Salinity will affect the presence of flora and fauna and facilitates sulfate reduction of organic matter in the soil. Increased decomposition of organic matter following saltwater intrusion can result in a lowering of wetland surface elevation. The papers assembled in this issue focus on how these tidal freshwater wetlands have changed over recent time and how they may respond to new impacts in the future.Tidal freshwater wetlands are complex, species-rich ecosystems located at the interface between tidal estuaries and nontidal rivers. This study conducted on the Patuxent River estuary in Maryland was designed to assess vegetation dynamics over several decades to determine if there were directional changes in the dominant communities. Aerial photographs (1970, 1989, and 2007) documented broad-scale spatial changes in major plant communities. The coverage of areas dominated by Nuphar lutea and Phragmites australis expanded; mixed vegetation and scrub-shrub habitats were essentially unchanged; and Typha and Zizania aquatica communities fluctuated in coverage. Data collected between 1988 and 2010 from permanent plots and transects were used to examine fine-scale changes. Shifts in the importance of some species through time were observed, but there were no directional changes in community species composition. The lack of directional change as measured at a fine scale is characteristic of tidal freshwater wetlands in which variations in the abundance of individual species, especially annuals, are responsible for most short-term change in species composition. Changes in the composition of plant communities are interpreted as responses to variations in vertical accretion, stability of habitat types, invasive plant species, and herbivores. In the future, vegetation changes are likely to occur as a result of the intrusion of brackish water and increased flooding associated with global climate change and sea level rise. This long-term study establishes a baseline from which potential future changes to tidal freshwater wetlands can be better understood.
Juvenile Spotted Seatrout (Cynoscion nebulosus) Habitat Use in an Eastern Gulf of Mexico Estuary: The Effects of Seagrass Bed Architecture, Seagrass Species Composition, and Varying Degrees of Freshwater InfluenceSpotted seatrout (Cynoscion nebulosus) are estuarine residents that have been extensively studied primarily due to their economic importance. Although spotted seatrout have a documented affinity for seagrass beds, there is little information on how seagrass bed architecture, seagrass species composition, and freshwater inflow affect this relationship. The objective of this study was to document patterns in spatiotemporal distribution and abundance of juvenile spotted seatrout (For energetic reasons, iron reduction suppresses methanogenesis in tidal freshwater wetlands; however, when iron reduction is limited by iron oxide availability, methanogenesis dominates anaerobic carbon mineralization. Plants can mediate this microbial competition by releasing oxygen into the rhizosphere and supplying oxidized iron for iron reducers. We utilized a plant removal experiment in two wetland sites to test the hypothesis that, in the absence of plants, rates of iron reduction would be diminished, allowing methanogenesis to dominate anaerobic metabolism. In both sites, methanogenesis was the primary anaerobic mineralization pathway, with iron reduction dominating only early and late in the growing season in the site with a less organic soil. These patterns were not influenced by the presence of plants, demonstrating that plants were not a key control of microbial metabolism. Instead, we suggest that site conditions, including soil chemistry, and temperature are important controls of the pathways of anaerobic metabolism.A 115-year-old railroad levee bisecting a tidal freshwater marsh perpendicular to the Patuxent River (Maryland) channel has created a northern, upstream marsh and a southern, downstream marsh. The main purpose of this study was to determine how this levee may affect the ability of the marsh system to gain elevation and to determine the levee's impact on the marsh's long-term sustainability to local relative sea level rise (RSLR). Previously unpublished data from 1989 to 1992 showed that suspended solids and short-term sediment deposition were greater in the south marsh compared to the north marsh; wetland surface elevation change data (1999 to 2009) showed significantly higher elevation gain in the south marsh compared to the north (6 +/- 2 vs. 0 +/- 2 mm year(-1), respectively). However, marsh surface accretion (2007 to 2009) showed no significant differences between north and south marshes (23 +/- 8 and 26 +/- 7 mm year(-1), respectively), and showed that shallow subsidence was an important process in both marshes. A strong seasonal effect was evident for both accretion and elevation change, with significant gains during the growing season and elevation loss during the non-growing season. Sediment transport, deposition and accretion decreased along the intertidal gradient, although no clear patterns in elevation change were recorded. Given the range in local RSLR rates in the Chesapeake Bay (2.9 to 5.8 mm year(-1)), only the south marsh is keeping pace with sea level at the present time. Although one would expect the north marsh to benefit from high accretion of abundant riverine sediments, these results suggest that long-term elevation gain is a more nuanced process involving more than riverine sediments. Overall, other factors such as infrequent episodic coastal events may be important in allowing the south marsh to keep pace with sea level rise. Finally, caution should be exercised when using data sets spanning only a couple of years to estimate wetland sustainability as they may not be representative of long-term cumulative effects. Two years of data do not seem to be enough to establish long-term elevation change rates at Jug Bay, but instead a decadal time frame is more appropriate.Since 1991, the Caernarvon Freshwater Diversion has been reintroducing Mississippi River water into a previously hydrologically isolated estuary in an effort to restore wetlands. To determine the effect of freshwater inflow on estuarine nekton community structure, a Before-After-Control-Impact study design was applied. As a result of the opening, salinities in the impact area decreased, and the nekton community structure in the estuary changed significantly. Species of economical or ecological importance either increased in biomass or exhibited no response to the opening of the diversion. Higher abundances of small fish were observed in the area receiving freshwater flow, which is an indication that the area serves as a refuge from large marine predators. Because a salinity gradient was established, as opposed to a uniform but lower salinity regime, aquatic habitat was available to nekton species from a wide spectrum of salinity tolerances.Expanding human activities along the freshwater to marine continuum of coastal watersheds increasingly impact nutrient inputs, nutrient limitation of primary production, and efforts to reduce nutrient over-enrichment and eutrophication. Historically, phosphorus (P) has been the priority nutrient controlling upstream freshwater productivity, whereas nitrogen (N) limitation has characterized coastal waters. However, changing anthropogenic activities have caused imbalances in N and P loading, making it difficult to control eutrophication by reducing only one nutrient. Furthermore, upstream nutrient reduction controls can impact downstream nutrient limitation characteristics. Recently, it was suggested that only reducing P will effectively control eutrophication in both freshwater and coastal ecosystems. However, controls on production and nutrient cycling in estuarine and coastal systems are physically and chemically distinct from those in freshwater counterparts, and upstream nutrient management actions (exclusive P controls) have exacerbated N-limited downstream eutrophication. Controls on both nutrients are needed for long-term management of eutrophication along the continuum.Analysis of fisheries-independent data for Galveston Bay, Texas, USA, since 1985 shows eastern oysters (Crassostrea virginica) frequently demonstrate increased abundance of market-sized oysters 1 to 2 years after years with increased freshwater inflow and decreased salinity. These analyses are compared to Turner's (Estuaries and Coasts 29:345-352, 2006) study using 3-year running averages of oyster commercial harvest since 1950 in Galveston Bay. Turner's results indicated an inverse relationship between freshwater inflow and commercial harvest with low harvest during years of high inflow and increased harvest during low flow years. Oyster populations may experience mass mortalities during extended periods of high inflow when low salinities are sustained. Conversely, oyster populations may be decimated during prolonged episodes of low flow when conditions favor oyster predators, parasites, and diseases with higher salinity optima. Turner's (Estuaries and Coasts 29:345-352, 2006) analysis was motivated by a proposed project in a basin with abundant freshwater where the goal of the project was to substantially increase freshwater flow to the estuary in order to increase oyster harvest. We have the opposite concern that oysters will be harmed by projects that reduce flow, increase salinity, and increase the duration of higher salinity periods in a basin with increasing demand for limited freshwater. Turner's study and our analysis reflect different aspects of the complex, important relationships between freshwater inflow, salinity, and oysters.Freshwater pulses to subtropical estuaries often occur on time scales less than 1 week. In particular, introduction of low-level pulses are potentially important during the dry season (November-April) when freshwater is scarce. Determining potential ecological benefits of pulses requires an innovative method of data acquisition at the appropriate spatial and temporal scales. The South Florida Water Management District conducted a pilot study to assess changes in water column attributes with pulse releases to the Caloosahatchee River Estuary (CRE) from January to April 2012. An average inflow of 450 cfs was targeted for a series of freshwater pulses. This study utilized an onboard, flow-through system to record surface water temperature, salinity (S), pH, dissolved oxygen, turbidity, and in situ chlorophyll a (in situ CHL) at 5 s intervals along the 42-km length of the estuary. On each of seven research cruises, the vessel stopped at multiple stations to conduct vertical water column profiles. Salinity increased throughout the CRE as inflow decreased during the study period. Simple correlation and partial least squares regression were used to determine that the downstream locations of the S = 10 isohaline and the maximum CHL concentration (in situ CHLmax) were positively related to inflow. While the in situ CHLmax was located 12-20 km downstream on five of the cruises, it was only a few kilometer from the estuary head on the first (1/12) and last (4/11) dates. It is possible that two circumstances related to freshwater inflow accounted for this pattern. First, water column stratification before January could have stimulated remineralization and primary production. Second, inflow ceased as water temperature increased to 26.0 A degrees C by April to promote algal growth. Further study of the relationships among inflow, water level, flushing time, and CHL is warranted. Future efforts will examine the range of wet season discharge by incorporating a sensor for colored dissolved organic matter to fully connect inflow, salinity, submarine light, and phytoplankton attributes in the CRE.The interaction of plant and microbial communities are known to influence the dynamics of methane emission in wetlands. Plant manipulations were conducted in an organic rich (JB-organic) and a mineral rich (JB-mineral) site in a tidal freshwater wetland to determine if plant removal impacted archaeal populations. In concert, a suite of process-based measurements also determined the effects of plant removal on rates of methanogenesis and Fe-reduction. The microbial populations were analyzed with clone libraries of the SSU ribosomal RNA (rRNA) gene from selected plots, and terminal restriction length polymorphism (tRFLP) of the SSU rRNA and the methyl-coenzyme M reductase (mcrA) gene. Overall, methanogenesis dominated anaerobic carbon mineralization at both sites during the most active growing season. A total of 114 SSU rRNA clones from four different plots revealed a diversity of Euryarchaeota including representatives of the Methanomicrobiales, Methanosarcinales and Thermoplasmatales. The clone libraries were dominated by the Thaumarchaeota, accounting for 65 % of clones, although their diversity was low. A total of 112 tRFLP profiles were generated from 56 samples from 25 subplots; the patterns for both SSU rRNA and mcrA showed little variation between sites, either with plant treatment or with the growing season. Overall these results suggest that wetland soil archaeal populations were resilient to changes in the associated surface plant communities. The work also revealed the presence of novel, mesophilic Thaumarchaeota of unknown metabolic function.Much work in recent years has reported on the role of submarine groundwater discharge (SGD) on coastal biogeochemistry, but most of those studies have focused on temperate or tropical climates where year-round rainfall recharges surficial aquifers. The aim of this work, however, was to examine SGD behaviors in an arid setting-Marina Lagoon on the Egyptian Mediterranean coast. SGD was estimated via radon surveys and time-series measurements in lagoon waters during two campaigns (wet season in March 2009 and dry season in July 2010). Relatively higher values of radon were detected in March (maximum > 30 dpm/L) compared to July (up to 16 dpm/L), which would indicate either enhanced input rates, or lower mixing/atmospheric losses during the wet season. Lower salinity waters within Marina Lagoon were characterized by higher radon and higher concentrations of dissolved inorganic nitrogen (DIN) and silica (DISi), characteristic of groundwater inputs. Based on lagoon and groundwater radon measurements and an advection-diffusion model, SGD average rates between 0.83 to 2.4 x 10(8) L/day were estimated for both surveys. Since no seasonal pattern was detected, we suspect that either (1) SGD is derived from a regional aquifer not influenced by recharge from local rainfall or (2) local water use for irrigation and domestic purposes artificially recharges the surficial aquifer in the dry summer (tourist) months, which compensates for the lack of rainfall occurring at that time.Tidal freshwater marshes exist in a dynamic environment where plant productivity, subsurface biogeochemical processes, and soil elevation respond to hydrological fluctuations over tidal to multi-decadal time scales. The objective of this study was to determine ecosystem responses to elevated salinity and increased water inputs, which are likely as sea level rise accelerates and saltwater intrudes into freshwater habitats. Since June 2008, in situ manipulations in a Zizaniopsis miliacea (giant cutgrass)-dominated tidal freshwater marsh in South Carolina have raised porewater salinities from freshwater to oligohaline levels and/or subtly increased the amount of water flowing through the system. Ecosystem-level fluxes of CO2 and CH4 have been measured to quantify rates of production and respiration. During the first 20 months of the experiment, the major impact of elevated salinity was a depression of plant productivity, whereas increasing freshwater inputs had a greater effect on rates of ecosystem CO2 emissions, primarily due to changes in soil processes. Net ecosystem production, the balance between gross ecosystem production and ecosystem respiration, decreased by 55% due to elevated salinity, increased by 75% when freshwater inputs were increased, and did not change when salinity and hydrology were both manipulated. These changes in net ecosystem production may impact the ability of marshes to keep up with rising sea levels since the accumulation of organic matter is critical in allowing tidal freshwater marshes to build soil volume. Thus, it is necessary to have regional-scale predictions of saltwater intrusion and water level changes relative to the marsh surface in order to accurately forecast the long-term sustainability of tidal freshwater marshes to future environmental change.Water budget parameters are estimated for Shark River Slough (SRS), the main drainage within Everglades National Park (ENP) from 2002 to 2008. Inputs to the water budget include surface water inflows and precipitation while outputs consist of evapotranspiration, discharge to the Gulf of Mexico and seepage losses due to municipal wellfield extraction. The daily change in volume of SRS is equated to the difference between input and outputs yielding a residual term consisting of component errors and net groundwater exchange. Results predict significant net groundwater discharge to the SRS peaking in June and positively correlated with surface water salinity at the mangrove ecotone, lagging by 1 month. Precipitation, the largest input to the SRS, is offset by ET (the largest output); thereby highlighting the importance of increasing fresh water inflows into ENP for maintaining conditions in terrestrial, estuarine, and marine ecosystems of South Florida.At present, phosphorus (P) is seen as the main limiting nutrient for phytoplankton growth in the western Wadden Sea. Six cruises were performed for water sampling at selected stations covering a full tidal cycle for later determination of dissolved and particulate nutrient concentrations. The major P sources were identified on a seasonal basis, by comparing the contribution of freshwater discharge and sediment release, calculated in a previous study, to the concentrations in the water column. A close relationship was found between the pelagic concentrations of dissolved inorganic nutrients and chlorophyll a, with a concomitant decrease in nutrients and increase in chlorophyll. This was observed in early spring and was followed by a later increase in the nutrient concentrations in spring-summer. The low concentrations found for the freshwater and seawater end-members for this period ruled out their importance as nutrient sources, suggesting that this increase resulted mainly from internal recycling in the Wadden Sea. Even though P limitation was observed during most of the year, a potential seasonal change in the limiting nutrient, from P to silica, was observed. The comparison between P supply to the Wadden Sea by freshwater discharge and sediment release showed a much higher contribution of the latter, especially in April-November. To our knowledge, this is the first study clearly presenting internal recycling as the main nutrient source to the western Wadden Sea in spring-autumn, instead of freshwater discharge or the North Sea.We investigated the effects of increasing salinity and inundation on inorganic N exchange and P sorption/precipitation in soils of tidal freshwater floodplain forests (TFFF) of coastal Georgia, USA. Our objectives were to better understand how sea level rise, increasing inundation, and saltwater intrusion will affect the ability of TFFFs to retain nitrogen (N) and phosphorus (P). We collected soil cores (0-5 cm) from three TFFFs that do not currently experience saltwater intrusion and from one TFFF currently experiencing saltwater intrusion and measured NH4-N exchange and PO4-P removal over five simulated 6-h tidal cycles using nutrient-enriched freshwater (30 mu M NH4-N and 5 mu M PO4-P). In a second experiment, we exposed soil cores to three salinities (0, 2, and 5) and two inundation depths (5 and 10 cm) using the same nutrient enrichment. When flooded with nutrient-enriched freshwater, soils from the three TFFFs that do not experience saltwater intrusion removed inorganic N and P in amounts ranging from 5.2 to 10.7 and 2.3 to 4.4 mg/m(2), respectively, and the TFFF soils experiencing saltwater intrusion removed 2.1 to 3.8 mg P/m(2). However, TFFF soils experiencing saltwater intrusion released inorganic N to the water column in amounts ranging from 7.1 to 67.5 mg/m(2). In the second experiment, soils from TFFFs not experiencing saltwater intrusion released NH4-N to the water column when exposed to 2 and 5 salinity, and the amount of N released increased with salinity and number of tidal cycles. In contrast, the same TFFF soils sorbed two and three times more PO4-P when exposed to 2 and 5 salinity than when exposed to 0 salinity. P removal on a mass basis was greater under 10 cm of inundation, but the efficiency of removal was greater under the 5 cm flooding depth. Our findings suggest that saltwater intrusion caused by sea level rise will promote N release into the water column through organic matter mineralization and/or ion exchange and may promote P sorption, or precipitation of P with metal cations. In addition, release of N and resulting increased N/P could exacerbate eutrophication of estuaries in the future.Historic changes in water-use management in the Florida Everglades have caused the quantity of freshwater inflow to Florida Bay to decline by approximately 60% while altering its timing and spatial distribution. Two consequences have been (1) increased salinity throughout the bay, including occurrences of hypersalinity, coupled with a decrease in salinity variability, and (2) change in benthic habitat structure. Restoration goals have been proposed to return the salinity climates (salinity and its variability) of Florida Bay to more estuarine conditions through changes in upstream water management, thereby returning seagrass species cover to a more historic state. To assess the potential for meeting those goals, we used two modeling approaches and long-term monitoring data. First, we applied the hydrological mass balance model FATHOM to predict salinity climate changes in sub-basins throughout the bay in response to a broad range of freshwater inflow from the Everglades. Second, because seagrass species exhibit different sensitivities to salinity climates, we used the FATHOM-modeled salinity climates as input to a statistical discriminant function model that associates eight seagrass community types with water quality variables including salinity, salinity variability, total organic carbon, total phosphorus, nitrate, and ammonium, as well as sediment depth and light reaching the benthos. Salinity climates in the western sub-basins bordering the Gulf of Mexico were insensitive to even the largest (5-fold) modeled increases in freshwater inflow. However, the north, northeastern, and eastern sub-basins were highly sensitive to freshwater inflow and responded to comparatively small increases with decreased salinity and increased salinity variability. The discriminant function model predicted increased occurrences of Halodule wrightii communities and decreased occurrences of Thalassia testudinum communities in response to the more estuarine salinity climates. The shift in community composition represents a return to the historically observed state and suggests that restoration goals for Florida Bay can be achieved through restoration of freshwater inflow from the Everglades.Despite the fact that Anguilla rostrata (American eel) are frequently captured in salt marshes, their role in salt marsh food webs and the influence of human impacts, such as tidal restrictions, on this role remains unclear. To better understand salt marsh trophic support of A. rostrata, eels were collected from tidally restricted and unrestricted salt marsh creeks within three New England estuaries. Gut contents were examined, and eel muscle tissue was analyzed for carbon and nitrogen stable isotope values and entered into MixSir mixing models to understand if salt marsh food sources are important contributors to eel diet. Data suggest that eel prey rely heavily on salt marsh organic matter and eels utilize salt marsh secondary production as an energetic resource over time, and thus can be considered salt marsh residents. Gut contents indicate that A. rostrata function as top predators, feeding primarily on secondary consumers including other fish species, crustaceans, and polychaetes. Higher A. rostrata trophic position measured upstream of reference creeks suggests that severe tidal restrictions may result in altered food webs, but it is not clear how this impacts the overall fitness of A. rostrata populations in New England salt marshes.Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (a parts per thousand currency sign0.1 psu), low oligohaline (1.1-1.6 psu), and high oligohaline (2.6-4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N m(-2) year(-1), respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g m(-2) year(-1)) over the five study years. Our data suggest that alternative processes, such as the rate of decomposition and potential for N mineralization, on tidal swamp sites undergoing salinity-induced state change may be more important for controlling N biogeochemical cycling in soils than differences among sites in N loading via litterfall.The goals of this study were to quantify organic matter source utilization by consumers in the freshwater-dominated region (East Bay) of a high river flow estuary and compare the results to consumers in marine-influenced sites of the same estuary to understand how organic matter utilization by consumers may be changing along the salinity gradient. We used the results from these evaluations to establish the baseline against which we isotopically determined trophic level for consumers in East Bay. Average isotope values for consumers sampled in East Bay ranged from -20.1aEuro degrees to -24.8aEuro degrees for carbon and from 8.9aEuro degrees to 14.3aEuro degrees for sulfur. These values were well-constrained by the four identified sources: plankton, benthic organic matter, macroalgae, and terrestrial detritus. Application of a concentration-corrected mixing model resulted in contributions of benthic production and detrital sources (averaged over the food web) to East Bay consumers of 41% and 33%, respectively, with the remainder made up of plankton and benthic macroalage. While benthic organic matter was an important organic matter source for consumers at both sites, we found that the influence of terrestrial detritus varied significantly throughout the bay. Terrestrial detritus contributed only 18% of average total organic matter in organisms inhabiting marine-influenced sites. Although terrestrial detritus did contribute to all consumers examined, most fish species in Apalachicola Bay reflect a greater reliance on autochthonous sources. Our results suggest that, while terrestrial detritus does appear to be a major contributor to commercially important shellfish species (most notably oysters and penaeid shrimp), it is not the major source fueling the diversity of secondary production in Apalachicola Bay. Thus, production in Apalachicola Bay is highly dependent on riverine influx in two ways: (1) economically important bivalves and crustaceans are being fueled by terrestrial organic matter supplied by river flooding and (2) secondary and above consumer fish species are supported by in situ production which, in turn, is reliant on nutrients supplied by the Apalachicola River. These findings are significant in light of decisions regarding water usage and river flow restrictions in the Apalachicola-Chattahoochee-Flint drainage basin. The results of this study confirm that in situ estuarine organic matter is the dominant source supporting secondary production in this river-dominated estuary.Geochemical mixing models were used to decipher the dominant source of freshwater (rainfall, canal discharge, or groundwater discharge) to Biscayne Bay, an estuary in south Florida. Discrete samples of precipitation, canal water, groundwater, and bay surface water were collected monthly for 2 years and analyzed for salinity, stable isotopes of oxygen and hydrogen, and Sr2+/Ca2+ concentrations. These geochemical tracers were used in three separate mixing models and then combined to trace the magnitude and timing of the freshwater inputs to the estuary. Fresh groundwater had an isotopic signature (delta O-18 = -2.66aEuro degrees, delta D -7.60aEuro degrees) similar to rainfall (delta O-18 = -2.86aEuro degrees, delta D = -4.78aEuro degrees). Canal water had a heavy isotopic signature (delta O-18 = -0.46aEuro degrees, delta D = -2.48aEuro degrees) due to evaporation. This made it possible to use stable isotopes of oxygen and hydrogen to separate canal water from precipitation and groundwater as a source of freshwater into the bay. A second model using Sr2+/Ca2+ ratios was developed to discern fresh groundwater inputs from precipitation inputs. Groundwater had a Sr2+/Ca2+ ratio of 0.07, while precipitation had a dissimilar ratio of 0.89. When combined, these models showed a freshwater input ratio of canal/precipitation/groundwater of 37%:53%:10% in the wet season and 40%:55%:5% in the dry season with an error of +/- 25%. For a bay-wide water budget that includes saltwater and freshwater mixing, fresh groundwater accounts for 1-2% of the total fresh and saline water input.Abundance of estuarine biota can vary with freshwater inflow through several mechanisms. One proposed mechanism is that the extent of physical habitat for an estuarine species increases with flow. We estimated the contribution of variation in habitat volume to the responses of eight species of estuarine nekton to changes in freshwater flow in the San Francisco Estuary. Resource selection functions for salinity and depth were developed for each species (and for five additional species) using five monitoring data sets. The TRIM3D hydrodynamic model was run for five steady flow scenarios to determine volume by salinity and depth, and resource selection functions were used as a weighting factor to calculate an index of total habitat for each species at each flow. The slopes of these habitat indices vs. flow were consistent with slopes of abundance vs. flow for only two of the species examined. Therefore, other mechanisms must underlie responses of abundance to flow for most species.Understanding spatial and temporal variation in chemical constituents across salinity gradients is essential for using proxies to track riverine inflow, mixing processes, and migration of mobile fauna. We analyzed the freshwater endmembers and mixing curves of a suite of trace element concentrations (Mg, Ca, Mn, Sr, and Ba) and stable isotope ratios (delta O-18 and Sr-87/Sr-86) in tributaries and estuaries of the south Texas coastal bend region. While Sr/Ca and Sr-87/Sr-86 were consistent across tributaries due to the dominance of carbonate bedrock underlying the region, Ba/Ca showed some river-specific variation perhaps due to upstream urbanization. In contrast, both Mn/Ca and delta O-18 showed a high degree of variability between 2 years due to their sensitivity to redox conditions and net evaporation, respectively. Mixing curves for Ca and Sr were moderately curvilinear, suggesting the potential importance of alternative processes altering mixing relationships, such as submarine groundwater discharge (SGD). Mixing of Mg was linear and consistent with conservative behavior, while Ba showed a low salinity peak and there was no apparent mixing relationship for Mn. Mixing of Sr-87/Sr-86 was curvilinear as expected, although the steepness of the mixing curve was lower than expected under linear mixing assumptions, further indicating the possible influence of SGD. Unexpectedly, delta O-18 values were elevated above marine values across the entire salinity gradient, perhaps due to drought conditions during the sampling period. Together, these results point to the individualistic spatiotemporal dynamics of chemical constituents and illustrate the care that must be taken when choosing an appropriate proxy for salinity.To test species composition and biomass responses to excess nutrients, herbaceous plants of tidal freshwater and oligohaline wetlands in a Chesapeake Bay subestuary were fertilized with nitrogen (N), phosphorus (P), both N and P (N + P), or not fertilized (Control) for 4 years. In marshes, the N treatment increased abundance measures of perennials but decreased those of annuals while the P treatment increased annuals and decreased perennials. In swamps, however, perennials increased in response to P. Total herbaceous aboveground biomass production was not limited by N, P, or N + P in marshes or swamps. These findings suggest that annual species are more susceptible than perennials to P limitation, possibly due to lack of a large perenniating root organ and lower susceptibility to mycorrhizal inoculation. Furthermore, eutrophication effects are likely to vary between swamp and marsh habitats and depend on whether the dominant nutrient supplied is nitrogen or phosphorus.Lowe et al. (Estuaries and Coasts, 34:630-639, 2011) hypothesized that juvenile southern flounder Paralichthys lethostigma (Jordan and Gilbert 1884) would migrate from the Gulf of Mexico into the Mobile-Tensaw River Delta (AL, USA) and use low-salinity (oligohaline/freshwater) habitats during, at least, a portion of their first year of life. Thus, they analyzed the Sr/Ca ratio profiles along the sagittal otoliths of southern flounder collected in the Mobile-Tensaw River Delta and observed that one third of the flounders had low Sr/Ca levels in the otoliths' core and throughout the otolith, suggesting that these fishes hatched in freshwater or low-salinity habitats where they spend the majority of their life. The other two thirds of southern flounder showed high levels of Sr/Ca ratio in the otoliths' core following a marked decline of Sr/Ca ratio, which then maintained along the remainder of the otolith. This pattern was interpreted as larvae hatched in higher salinity waters before entering the Mobile-Tensaw River Delta; however, in this paper, I list several arguments to support an alternative interpretation for this pattern. I suggest that the high levels of Sr/Ca ratios in the otoliths' core of southern flounder does not reflect the saline conditions where larvae hatched, instead it reflects the location where the female progenitor hydrated the eggs. Thus, adding my interpretation on the data of Lowe et al. (Estuaries and Coasts, 34:630-639, 2011), it seems that southern flounder might hatch in or near freshwater habitats and the migration of southern flounder into an estuarine ecosystem to spawn might exist.Research strategies for investigating the freshwater-inflow requirements of estuarine fishes often integrate life-history information and correlative analyses of inflow and fish abundance. In tidal rivers, however, some fish have affinities for embayments, oxbows, and smaller tributaries, often referred to collectively as river "back-waters". The objective of this study was to determine whether freshwater and estuarine fish assemblages differed between backwaters and the mainstem of the tidal Caloosahatchee River, a highly managed river system located in an urban setting in southwest Florida. Nonmetric multidimensional scaling of 21.3-m seine data revealed that fish assemblages did indeed differ between the backwater and mainstem habitats in each of three river sections. Univariate analyses identified species that differed in abundance between the habitats, which included ecologically and economically important fishes in the region. For example, striped mullet Mugil cephalus and pinfish Lagodon rhomboides were more abundant along the river's mainstem; common snook Centropomus undecimalis and bluegill Lepomis macrochirus were more abundant in the river's backwaters. For those species that were more abundant along the mainstem of the river or showed no difference, studies that measure changes in the distribution and abundance of these species with varying inflow along the mainstem of the river are justified. However, for species that were more abundant in backwater areas, geomorphological features should be considered in the design of studies that assess factors affecting fish use.Tidal freshwater forested wetlands are dynamic, complex ecosystems that typically occur in large, floodplain river estuaries throughout the world. The estuarine portion of the Columbia River, in the Pacific Northwest region of North America, is exceptionally large and extends from the Pacific Ocean to the head of tide at Bonneville Dam, located at river kilometer (RKm) 233. Our study focused on the freshwater portion of the estuarine gradient (RKm 40 to RKm 233) of the Columbia River estuary and the corresponding continuum of hydrologic regimes and biotic communities. Several diverse forested wetland community types occurred along this freshwater estuarine gradient with major shifts in community composition corresponding to the transition from predominantly tidal to predominantly fluvial hydrologic regimes. We quantitatively characterized the floristic structure, species composition, and species richness of these tidal wetlands. Additionally, we documented variation in the avifaunal and insect assemblages associated with the floral structure. We found that freshwater tidal forested wetlands in the lower reaches of the estuary were characterized by high vegetation species richness and complex forest and scrub-shrub ecosystems, while tidal wetlands in the upper reaches of the estuary displayed a greater diversity of wetland ecosystems (forested, scrub-shrub, emergent, and aquatic bed) but comparatively lower species richness. A transitional area in the mid-estuary contained forested wetlands that exhibited some similarities to estuarine forested wetlands in both the upper and lower reaches. Likewise, avifauna and insect assemblage composition transitioned along the tidal freshwater estuarine gradient. Differences in geomorphological and hydrological regimes along the estuarine gradient appear to be the factors controlling the variation in tidal freshwater forested wetland characteristics and species composition. A thorough understanding of this complex and understudied system is necessary for predicting the potential impacts of hydrologic regime alterations and climate change and for guiding ongoing restoration efforts in the region.We conducted monthly bioassay experiments to characterize light and nutrient use efficiency of phytoplankton communities from the chlorophyll-a maximum located in the tidal freshwater region of the James River Estuary. Bioassay results were interpreted in the context of seasonal and inter-annual variation in nutrient delivery and biomass yield using recent and long-term data. Bioassay experiments suggest that nutrient limitation of phytoplankton production has increased over the past 20 years coinciding with reductions in point source inputs and estuarine dissolved nutrient concentrations. Despite increasing nutrient stress, chlorophyll concentrations have not declined due to more efficient nutrient usage. Greater CHLa yield (per unit of N and P) may be due to feedback mechanisms by which the presence of toxin-producing cyanobacteria inhibits grazing by benthic and pelagic filter-feeders. Seasonal patterns in nutrient limitation indicate that phytoplankton in the James respond to variations in inflow concentrations of dissolved nutrients. This association gives rise to an atypical pattern whereby the severity of nutrient limitation diminishes with low discharge in late summer due to minimal dilution of local point sources inputs by riverine discharge. We suggest that this may be a common feature of estuaries located in proximity to urbanized areas.Longitudinal variation in factors affecting phytoplankton production were analyzed to better understand the mechanisms that cause the formation of a chlorophyll maximum within the tidal freshwater James River. Phytoplankton production was two- to threefold higher in the region where persistent elevated chlorophyll concentrations occurred. Near this site, the morphology of the James transitions from a narrow, deep channel to a broad expanse with shallow areas adjoining the main channel. Shallower depths resulted in greater average irradiance within the water column and suggest that release from light limitation was the principal factor accounting for the location of the chlorophyll maximum. Grazing rates were low indicating that little of the algal production was directly consumed by zooplankton. Low exploitation by zooplankton was attributed to poor food quality due to high concentrations of non-algal particulate matter and potential presence of cyanobacteria. Metabolism data suggest that two thirds of net primary production was respired in the vicinity of the chlorophyll maximum and one third was exported via fluvial and tidal advection. Comparison of water column and ecosystem metabolism indicates that the bulk of respiration occurred within the sediments and that sedimentation was the dominant loss process for phytoplankton.Sediment accretion was measured at four sites in varying stages of forest-to-marsh succession along a fresh-to-oligohaline gradient on the Waccamaw River and its tributary Turkey Creek (Coastal Plain watersheds, South Carolina) and the Savannah River (Piedmont watershed, South Carolina and Georgia). Sites included tidal freshwater forests, moderately salt-impacted forests at the freshwater-oligohaline transition, highly salt-impacted forests, and oligohaline marshes. Sediment accretion was measured by use of feldspar marker pads for 2.5 year; accessory information on wetland inundation, canopy litterfall, herbaceous production, and soil characteristics were also collected. Sediment accretion ranged from 4.5 mm year(-1) at moderately salt-impacted forest on the Savannah River to 19.1 mm year(-1) at its relict, highly salt-impacted forest downstream. Oligohaline marsh sediment accretion was 1.5-2.5 times greater than in tidal freshwater forests. Overall, there was no significant difference in accretion rate between rivers with contrasting sediment loads. Accretion was significantly higher in hollows than on hummocks in tidal freshwater forests. Organic sediment accretion was similar to autochthonous litter production at all sites, but inorganic sediment constituted the majority of accretion at both marshes and the Savannah River highly salt-impacted forest. A strong correlation between inorganic sediment accumulation and autochthonous litter production indicated a positive feedback between herbaceous plant production and allochthonous sediment deposition. The similarity in rates of sediment accretion and sea level rise in tidal freshwater forests indicates that these habitats may become permanently inundated if the rate of sea level rise increases.Natural patterns of freshwater delivery to the Florida Bay estuary have been disrupted by flood-control and water-supply projects. Restoration efforts are likely to alter salinity regimes and patterns of nekton distribution and abundance. Spatial and seasonal community structure differences were analyzed for small-bodied and large-bodied nekton collected by fisheries-independent monitoring from 2006 through 2009 in the northeastern basins of Florida Bay. The small-bodied nekton community was dominated by resident fish that may be indicators of ecosystem health because they spend their lives within the bay and are not directly influenced by human harvest; the large-bodied nekton community was dominated by transient and, in some cases, economically important species. Differences in community structure revealed a gradient in similarity that was associated with freshwater influence, as determined by salinity variability over the study period. These observed changes associated with salinity regimes within and between basins underscore the importance of monitoring communities before and after alterations in freshwater inflow.The aim of this study was to propose an index [Index of Biotic Integrity for the Rio de la Plata (IBIRP)] formulated from a minimum of information-rich metrics related to biological integrity for evaluation of the coastal freshwater tidal zone of the Rio de la Plata estuary. A total of 23 sites were selected along 170 km of shoreline (34A degrees 27'10aEuro(3) S, 58A degrees 30'21aEuro(3) W and 35A degrees 23'28aEuro(3) S, 57A degrees 08'50aEuro(3) W), being influenced by different land uses. We explored 36 biotic descriptors (designated candidate metrics), each of which is considered as an environmental indicator, and selected four metrics: two related to phytoplankton assemblage (planktonic cyanobacterial density and phytoplanktonic total density) and two linked to benthic assemblages, the diatoms (percent most tolerant taxa), and the invertebrates (percent Tanaidacea). The metrics that were chosen to integrate the IBIRP provide valuable information about the biotic integrity both in terms of time and space. The multimetric index can assume values between 0 (very bad status) andLowe et al. (Estuar Coast 34:630-639, 2011) used Sr/Ca in the otoliths of juvenile southern flounder (Paralichthys lethostigma) to demonstrate the importance of low-salinity habitats in the northern Gulf of Mexico during early life. While otolith cores indicated that most southern flounder originated in high-salinity environments (elevated Sr/Ca in otolith core) and moved into lower salinity habitats (decreased Sr/Ca outside of the otolith core), approximately one third of the sampled individuals had otolith core chemistry that indicated spawning or hatching in or near freshwater habitats (low Sr/Ca throughout the otolith). Morais (Estuar Coast 34:630-639, 2012) proposes a different interpretation: he suggests that the high Sr/Ca found in 68 % of juvenile otolith cores (and low Sr/Ca just outside of the core region) may be due to females hydrating their eggs in offshore (high-salinity) waters, with spawning, hatching, and egg/larval development all actually occurring in low-salinity environments (his "sea-run mother" hypothesis). While there is ample literature supporting the importance of maternal contributions to otolith microchemistry during vitellogenesis, it is our contention that such contributions ultimately depend on the ecology and reproductive physiology of each species. Further, a mass inshore migration of adult southern flounder during their spawning season is counter to the well-documented life history patterns for this species throughout its range. While we appreciate Morais' perspective, we continue to stand by the conclusion of our original paper.Nueces Estuary is a relatively shallow, microtidal estuary which receives inputs from a significant industrial and urban area and from a semi-arid drainage basin. Nitrogen (N) loadings were compiled using FLUX model and flow X concentration calculations for four annual periods spanning a range of inflow volumes. For each annual period, N budgets were developed, supported by water and total dissolved solids budgets. Budget compilations include materials transported in tidal exchange with the Gulf of Mexico and with neighboring bays. Wastewater discharge contributes twice as much N to the bay than inflows from the Nueces River. Net flows and tidal entrainment of materials from neighboring bays contribute 24-32% of total loadings except during flood flows of the Nueces River. Atmospheric deposition to the estuary surface provides 8% of N loading. Despite low tidal amplitude and a restricted Gulf pass, tidal entrainment losses are the main vehicle of export, except during flood flows, when net flows to the Gulf become important. The system exports much more of its total N load than would be expected from its water residence time, possibly facilitated by ship channel longitudinal transport. Denitrification accounts for 30-40% of all N lost. Uncertainties in components of the budget are estimated and included in compilations of confidence bounds for N budget components.The effects of fortnightly, semidiurnal, and quaterdiurnal lunar tidal cycles on suspended particle concentrations in the tidal freshwater zone of the Seine macrotidal estuary were studied during periods of medium to low freshwater flow. Long-term records of turbidity show semidiurnal:and spring-neap erosion-sedimentation cycles. During spring tide, the rise in low tide levels in the upper estuary leads to storage of water in the upper estuary. This increases residence time of water and suspended particulate matter (SPM). During spring tide periods, significant tidal pumping, measured by flux calculations, prevents SPM transit to the middle estuary which is characterized by the turbidity maximum zone. On a long-term basis, this tidal pumping allows marine particles to move upstream for several tens of kilometers into the upper estuary. At the end of the spring tide period, when the concentrations of suspended particulate matter are at their peak values and the low-tide level drops, the transport of suspended particulate matter to the middle estuary reaches its highest point. This period of maximum turbidity is of short duration because a significant amount of the SPM settles during neap tide. The particles, which settle under these conditions, are trapped in the upper estuary and cannot be moved to the zone of maximum turbidity until the next spring tide. From the upper estuary to the zone of maximum turbidity, particulate transport is generated by pulses at the start of the spring-map tide transition period.The coastal marshlands of the Nueces estuary, Texas depend upon periodic freshwater inundation to support current community structure arid promote further establishment and expansion of emergent halophytes. Decades of watershed modifications have dramatically decreased freshwater discharge into the upper estuary resulting in hypersaline and dry conditions. In an attempt to partially restore inflow, the U.S. Bureau of Reclamation excavated two overflow channels re-connecting the Nueces River to the marshlands. Freshwater-mediated (precipitation and inflow) changes in tidal creek and porewater salinity and emergent marsh vegetation were examined over a 5-yr period at three stations in the upper Nueces Marsh with the aid of a Geographical Information System (GIS). Two stations were potentially subjected to freshwater inflow through the channels, while one station experienced only precipitation. Decreased tidal creek and porewater salinity were significantly correlated with increased freshwater at all stations (R(2) = 0.37 to 0.56), although porewater salinities remained hypersaline. GIS analyses indicated the most considerable vegetation change following freshwater inundation was increased cover of the annual succulent Salicornia bigelovii. Fall inundation allowed seed germination and rapid expansion of this species into previously bare areas during the subsequent winter and following spring. The station affected by both inflow and precipitation exhibited greater S. bigelovii cover than the station affected solely by precipitation in both spring 1999 (58.7% compared to 27.9%) and 2000 (48.6% compared to 1.9%). Percent cover of the perennial Batis maritima temporarily increased after periods of consistent rainfall. The response was short term, and cover quickly returned to pre-inundation conditions within 3 mo. Prolonged inundation led to long-term (>2 yr) decreases in percent cover of B. maritima. Our results suggest that the timing and quantity of freshwater inundation strongly dictate halophyte response to precipitation and inflow. Brief periods of freshwater inundation that occur at specific times of year alleviate stress and promote seed germination and growth, but extended soil saturation can act as a disturbance that has a negative impact on species adapted to hypersaline conditions.Eight meadows of the seagrass Thalassia testudinum Banks err, Konig representing a gradient of freshwater influence in Charlotte Harbor, Florida (United States), were sampled on it bimonthly basis from April 1995 to August 1996. Spatial and temporal variation in the density, biomass, productivity, and epiphyte loads of short shoots were determined. Physical factors such as water temperature, salinity, and light extinction coefficients were also measured. Areal blade production (g dw m(-2) d(-1)) of T, testudinum was not strongly associated with water temperature, salinity, or the amount of subsurface irradiance reaching the bottom at each station. Variation in production could be described by a linear combination of the independent variables water temperature and salinity. Water clarity (expressed as the percent of subsurface irradiance reaching the bottom) was positively related to salinity The lack of a clear relationship between water clarity and areal production was probably due to water clarity being highest during times of the year when water temperatures were too cold to support growth of T. testudinum. Our results suggest that seagrass light requirements determined by averaging irradiance levels measured during the growing season might be more relevant than those established by averaging light measurements collected throughout the year. The use of field studies for estimating lower salinity tolerances of seagrasses might be inappropriate for those systems where water clarity is positively associated with salinity.We sampled nekton (fishes and decapod crustaceans) in submerged aquatic vegetation (SAV) (Potamogeton nodosus, Najas guadalupensis), in emergent marsh vegetation (Sagittaria spp. and Scirpus americanus), and over unvegetated bottom associated with three islands in the Atchafalaya River Delta, Louisiana. The purpose of our study was to quantify nekton densities in these major aquatic habitat types and to document the relative importance of these areas to numerically dominant aquatic organisms. We collected a total of 33 species of fishes and 7 species of crustaceans in 298 1-m(2) throw trap samples taken over three seasons: summer (July and August 1994), fall (September and October 1994), and spring (May and June 1995). Fishes numerically accounted for > 65% of the total organisms collected. Vegetated areas generally supported much higher nekton densities than unvegetated sites, although bay anchovies Anchoa mitchilli were more abundant over unvegetated bottom than in most vegetated habitat types. Among vegetation types, most species showed no apparent preference between SAV and marsh. However, inland silversides Menidia beryllina and freshwater gobies Gobionellus shufeldti were most abundant in Scirpus marsh in summer, and blue crabs Callinectes sapidus were most abundant in SAV (Potamogeton) in spring. Several species (sheepshead minnow Cyprinodon variegatus, rainwater killifish Lucania parva, and blue crab) apparently selected the vegetated backmarsh of islands (opposite of riverside) over streamside Scirpus marsh. Freshwater gobies, in contrast, were most abundant in streamside Scirpus marsh. Densities of juvenile blue crabs were high (up to 17 m(-2)) in vegetated delta habitat types and comparable to values reported from more saline regions of Gulf Coast estuaries. Shallow vegetated habitat types of the Atchafalaya River Delta and other tidal freshwater systems of the Gulf Coast may be: important nursery areas for blue crabs and other estuarine species.Fluctuations in freshwater input may affect the physiology and survival of submerged aquatic vegetation (SAV) occurring in oligoaline to mesohaline estuarine regions. Controls on the distribution of the freshwater angiosperm Vallisneria americana, were investigated by transplanting ramets. Pots (3.8-1) containing ramets were distributed among four sites (upstream site [least saline], donor site, near downstream site, and far downstream site [most saline]) in the Caloosahatchee Estuary (Southwest Florida) during wet (May-August) and dry (October-February) seasons. During 2-4 mo of each season, physiological indicators were monitored, including photosynthesis, glutamine synthetase activity, and protein content in shoots, and carbohydrates and total nitrogen and carbon in shoot and subterranean tissues. Where the physical environment (light or salinity) was suboptimal, all physiological indices, except photosynthetic rate, showed similar stress responses, which ranged from a slow decline to a rapid drop in physiological function. Levels of soluble carbohydrates decreased in response to unfavorable conditions more rapidly than did insoluble carbohydrates. Shoot protein of V. americana declined prior to transplant death, suggesting that measuring protein content may provide a rapid assessment of physiological health. V. americana transplants at the low-salinity upstream site died during both wet and dry season experiments, likely in response to light limitation and/or partial burial by sediments. At the far downstream site, death occurred within 2-4 wk, and was attributable to elevated salinities (> ca. 15 parts per thousand). Comparison of physiological responses with salinity and light regimes at the donor and near downstream sites suggest that light may ameliorate salinity stress. This study demonstrates that V: americana, nominally classed as a freshwater macrophyte, is capable of a remarkable degree of halotolerance.Tidal freshwater marshes are critical buffers that exist at the interface between watersheds and estuaries. Little is known about the physical dynamics of tidal freshwater marsh evolution. Over a 21-mo period, July 1995 to March 1997, measurements were made of biweekly sediment deposition at 23 locations in a 3.8-ha tidal freshwater marsh in the Bush River subestuary of the upper Chesapeake Bay. Biweekly accumulation showed high spatial and temporal variability, ranging from -0.28 g cm(-2) to 1.15 g cm(-2). Spatial variability is accounted for by habitat differences including plant associations, elevation, and hydrology. Temporal variability is accounted for by interannual climate variability, the growth cycles of marsh plants, stream marsh interactions, forest-marsh interactions, and animal activity.We studied interactions between animal disturbance (geese, carp, and muskrat) and elevation in a field experiment in tidal freshwater marshes of the Patuxent River, Maryland, United States. Vegetation changes were recorded in fenced and unfenced plots in high and low marsh community types for 2 yr using measurements of areal cover and within-plot frequency (which were averaged to create a dominance index), Leaf Area Index (LAI), and aboveground biomass. We related tight environment to differences in vegetation using below-canopy measurements of Photosynthetically Active Radiation (PAR). In the low marsh, total cover of all species, cover of annual species, biomass, and LAI were significantly higher in plots fenced to exclude animals (exclosures) than in unfenced plots (fenced/unfenced total cover = 76/40%, annual cover = 45/10%, biomass = 936/352 g m(-2), LAI = 3.3/1.4). PAR was significantly lower in fenced than unfenced plots (fenced/unfenced = 115/442 mumol s(-1) m(-2)). Despite the strong effect of fencing on biomass, species richness per plot (i.e., the number of species per plot, or species density) was not affected significantly by fencing in the low marsh. Most of the observed differences in cover, biomass, LAI, and PAR were due to variation in the abundance of the herbaceous annual species Bidens laevis (dominance index fenced/unfenced = 45/10%) and Zhania aquatica (30/12%). In the high marsh community, fencing had only minor effects on plant community composition and did not significantly affect species richness, cover, biomass, PAR, or LAI. Our results show that animals can dramatically affect low marsh vegetation, primarily via physical disturbance or herbivory of shallowly rooted seedlings of annual species.The benthic invertebrates and fishes of the estuarine, lower stream areas, and wetlands of Pearl Harbor were sampled from 1997-1998 as a companion study to marine inventories conducted in Pearl Harbor. The first comprehensive assessment of the area found that nonindigenous species comprise the dominant portion of the biota. A total of 191 aquatic species in 8 phyla were identified in the estuarine reaches of Pearl Harbor. Nonindigenous species dominated and comprised 48% of the species, whereas only 33% were native and 19% were cryptogenic. Two new nonindigenous species to Hawaii were found during this study: a species of fang-toothed blenny (Omobranchus ferox) and an estuarine hydrobiid snail (Pyrgophorus cf. coronatus) introduced from the Philippine Islands and the Caribbean, respectively. No single geographic region predominates as a source of aquatic species introductions into the Pearl Harbor area, although more species come from the Americas than other areas. Fifty-seven percent originated from the Americas, 30% from Asia and the Pacific, 5% from Australia/New Zealand, 5% show a world-wide distribution, and fewer than 3% of species originated from Africa. The majority of nonindigenous species appear to arrive from five major sources: intentional and accidental aquarium releases; intentional biocontrol releases; intentional food source releases; ballast water or hull fouling releases; and brought in with airplanes. Non-native species will likely continue to increase in the freshwater and estuarine portions Pearl Harbor because of the wide variety of sources from which introductions take place.We studied the macroinvertebrate fauna of a rocky shore in the freshwater tidal Hudson River during 1992-1994, the early years of the zebra mussel (Dreissena polymorpha) invasion. The macroinvertebrate community was numerically dominated by chironomids, nematodes, oligochaetes, gastropods, zebra mussels, and planarian flatworms. The community was a mixture of species typical of stony warm water rivers and lake shores, freshwater generalists, and semiterrestrial species. Overall marroinvertebrate densities were moderate to low (2,800-14,600 m(-2)). Density was a strong function of season and elevation, with consistently low densities in the early spring and in the intertidal zone. This pattern suggests that physical harshness (alternating submergence and desiccation; ice and low temperatures) limits the distribution of invertebrates at this site. Zebra mussels occurred at our study site chiefly below the low tide mark, but only at moderate abundance (usuallySince 1991, Mississippi River water has been diverted at Caernarvon, Louisiana, into Breton Sound estuary. Breton Sound estuary encompasses 1100 km(2) of fresh and brackish, rapidly subsiding wetlands. Nitrite + nitrate, total Kjeldahl nitrogen, ammonium, total phosphorus, total suspended sediments, and salinity concentrations were monitored at seven locations in Breton Sound from 1988 to 1994. Statistical analysis of the data indicated decreased total Kjeldahl nitrogen with associated decrease in total nitrogen, and decreased salinity concentrations in the estuary due to the diversion. Spring and summer water quality transects indicated rapid reduction of nitrite + nitrate and total suspended sediment concentration as diverted Mississippi River water entered the estuary, suggesting near complete assimilation of these constituents by the ecosystem. Loading rates of nitrite + nitrate (5.6-13.4 g m(-2) yr(-1)), total nitrogen (8.9-23.4 g m(-2) yr(-1)), and total phosphorus (0.9-2.0 g m(-2) yr(-1)) were calculated along with removal efficiencies for these constituents (nitrite + nitrate 88-97%; total nitrogen 32-57%; total phosphorus 0-46%). The low impact of the diversion on water quality in the Breton Sound estuary, along with assimilation of TSS over a very short distance, suggests that more water may be introduced into the estuary without detrimental affects. This would be necessary if freshwater diversions are to be used to distribute nutrients and sediments into the lower reaches of the estuary, in an effort to compensate for relative sea-level rise, and reverse the current trend of rapid loss of wetlands in coastal Louisiana.The aquatic macrofauna of the Guadalquivir estuary were sampled (1 min mesh persiana net) at 5 sampling sites located along the entire (except the tidal freshwater region) estuarine gradient of salinity (outer 50 kin). A total of 134 fish and macroinvertebrate species was collected but only 62 were considered common or regularly present in the estuary. Univariate measures of the community structure showed statistically significant differences among sampling sites: species richness, abundance, and biomass decreased in the upstream direction, being positively correlated with the salinity. Temporal differences of these three variables were also statistically significant. While a clear seasonal pattern (minimum densities in winter and maximum in spring-summer) was observed for abundance and biomass, no such pattern existed for die number of species. Mysids was the most dominant group throughout the estuary (96% to 99% of abundance; 49% to 85% of biomass), although fish biomass was also important at the outer estuary (36% to 38%). Multivariate analyses indicated highly significant spatial variation in the macrofaunal communities observed along the salinity gradient. These analyses suggest that the underlying structure was a continuum with more or less overlapping distributions of the species dependent on their ability to tolerate different physicochemical conditions. There were also significant temporal (intermonthly + interannual) variation of the estuarine community; the relative multivariate dispersion indicated that monthly variation was more considerable (relative multivariate dispersion > 1) at the outer part of the estuary during the wet year (last 20 km) and was higher in the inner stations during the dry year (32 to 50 kin from the river mouth). Since a clear negative exponential relationship was observed between the freshwater input (from a dam located 110 km upstream) and water salinity at all sampling stations, it is concluded that the human freshwater management is probably affecting the studied estuarine communities. While the higher seasonal (long-term) stability of the salinity gradient, due to the human control of the freshwater input, may facilitate the recruitment of marine species juveniles during the meteorologically unstable early-spring, the additional (short-term) salinity fluctuations during the warm period may negatively affect species that complete their lifecycle within the estuary.Detritus from terrestrial ecosystems is the major source of organic matter in many streams, rivers, and estuaries, yet the role of detritus in supporting pelagic food webs is debated. We examined the importance of detritus to secondary productivity in the Sacramento and San Joaquin River Delta (California, United States), a large complex of tidal freshwater habitats. The Delta ecosystem has low primary productivity but large detrital inputs, so we hypothesized that detritus is the primary energy source fueling production in pelagic food webs. We assessed the sources, quantity, composition, and bioavailability of organic matter among a diversity of habitats (e.g., marsh sloughs, floodplains, tidal lakes, and deep river channels) over two years to test this hypothesis. Our results support the emerging principle that detritus dominates riverine and estuarine organic matter supply and supports the majority of ecosystem metabolism. Yet in contrast to prevailing ideas, we found that detritus was weakly coupled to the Delta's pelagic food web. Results from independent approaches showed that phytoplankton production was the dominant source of organic matter for the Delta's pelagic food web, even though primary production accounts for a small fraction of the Delta's organic matter supply. If these results are general, they suggest that the value of organic matter to higher trophic levels, including species targeted by programs of ecosystem restoration, is a function of phytoplankton production.A mathematically transparent model for long-term solute dynamics, based on an oscillating reference frame, is applied to the analysis of the mixing process in estuaries. Classical tidally-averaged transport models for estuaries, all derived in some way from the Fractional Freshwater Method of Ketchum (1951) are reinterpreted in this framework. We demonstrate that in these models, the dispersion coefficients obtained from salinity profiles are not always a good representation of the mixing intensity of other dissolved constituents. In contrast, the hypothesis of equal coefficients is always verified in our oscillating coordinate system, which is almost devoid of tidal harmonics. The mathematical representation of the seaward boundary condition is also investigated. In the tidally-averaged Eulerian models, a fixed Dirichlet boundary condition is usually imposed, a condition that corresponds to an immediate, infinite dilution of the dissolved constituent beyond the fixed estuarine mouth. This mathematical representation of the estuarine-coastal zone interface at a fixed location is compared with the case of an oscillating location, which protrudes back and forth into the sea with the tide. Results demonstrate that the mathematical representation of the seaward boundary condition has a significant influence on the resulting mixing curves. We also show how to apply our approach to the prediction of mixing curves in real estuaries.As humans continue to influence the quantity, timing, and quality of freshwater input to estuaries, it is becoming increasingly common for policies to be enacted that mandate the establishment of freshwater inflow criteria that will serve to preserve and protect estuarine ecosystems. This paper reviews the scientific literature describing how changes in freshwater inflow affect estuaries, proposes a conceptual model that explores the roles of scientists, citizens, politicians, and managers in the management of freshwater inflow to estuaries, and uses the model to explore the ways in which freshwater inflow is managed in a variety of estuaries. The scientific review is organized to provide an overview of the connections between freshwater inflow (in terms of the quantity, quality, and timing of water delivery), estuarine conditions (such as salinity and concentrations of dissolved and particulate material), and estuarine resources (such as the distribution and abundance of organisms), and to highlight our understanding of the causative mechanisms that underlie the relationships among these variables. The premise of the conceptual model is that the goal of estuarine freshwater inflow policy is to protect those resources and functions that we as a society value in estuaries, and that management measures use scientific information about the relationships among inflow, conditions, and resources to establish inflow standards that can meet this goal. The management approach can be inflow-based (flow is kept within some prescribed bounds under the assumption that taking too much away is bad for the resources), condition-based (inflow standards are set in order to maintain specified conditions in the estuary), or resource-based (inflow standards are set based on the requirements of specific resources), but each of these is carried out by regulating inflow. This model is used as a framework to describe the development of freshwater inflow criteria for estuaries in Texas, Florida, and California.When rivers are impounded, the reduction in downstream flow can produce important and often adverse effects, especially in the estuarine environment. One or more dams have been proposed for the Olifants River system in the Western Cape, South Africa. This estuary has an extensive area of salt marsh that was examined to see whether it required occasional flooding with freshwater to wash out accumulated salts. The dominant salt marsh species, Sarcocornia pillansii, occurred in supratidal and floodplain areas where the water table was shallowest, the soil moisture highest, and the soil electrical conductivity lowest. Aerial photographs and simulated runoff data showed that no flood had covered the floodplain during the previous 80 years. The data indicate that salt marsh plants use saline groundwater during the dry months of the year in order to survive, but use the short season winter rainfall period with low salinity conditions to grow and reproduce. This study demonstrated that live roots of S. pillansii reached the water table during the dry season. Tissue and soil water potentials, the relationship between vegetation cover, depth to the water table, and electrical conductivity of the groundwater support the conclusion that saline groundwater is the only source of water during the drier months of the year. Freshwater flooding of the river in winter may be important because it covers the supratidal area with less saline water and reduces the depth to the water table on the floodplain. This makes the groundwater more accessible to the halophytes growing on the floodplain.The Lower Hillsborough River, Florida is a short (16 ion) riverine estuary which has a dam located at its upstream end. Salinity below the dam is influenced by freshwater that hows over or through the structure. Depending on location in the estuary, the response of salinity to changes in upstream freshwater inflows is normally not instantaneous, but lags behind the freshwater release. An analytical approach and a laterally averaged two-dimensional hydrodynamic model were used to examine the response time of salinity in the Lower Hillsborough River to changes in freshwater inflows from the upstream reservoir. A series of case studies were conducted using the model to determine how salinity in the river within one kilometer below the dam would respond to changes in freshwater inflows. The model results suggest that the time lag of salinity in the river depends on whether the upstream freshwater inflows are increasing or decreasing, as wed as their magnitude. While the time lag for salinity is about six to eight days for decreasing inflows, it is much shorter for increasing inflows depending on the magnitude of the now release.We report here the response of the water column and phytoplankton biomass of a large lagoonal estuary to a record freshwater discharge event which followed from extraordinary hurricane activity. In the fall of 1999, three hurricanes passed over eastern North Carolina coast in a 7-wk period: Hurricane Dennis (August 24-September 5), Hurricane Floyd (September 14-17), and Hurricane Irene (October 13-16). The hurricanes delivered record rainfall to the watersheds of the Pamlico Sound, North Carolina, the second largest estuary in North America. Hurricane Floyd was followed by a 500-yr flood that displaced 80% of the volume of the Sound and delivered half the annual nitrogen (N)-nutrient load to this N-limited system. After Hurricane Floyd, buoyancy stratification restricted the mixed layer depth, dissolved inorganic nitrogen (DIN) in surface waters increased, and surface chdorophyll biomass increased up to 4-fold. Chlorophyll biomass did not increase to the potential indicated by residual DIN because of light-limitation attributable to suspended particulates, phytoplankton pigments, and colored dissolved organic material (CDOM). The discharge waters created hydrological conditions and supplied materials that we interpret to have both stimulated and restricted phytoplankton blooms. The effects of the discharge event on the hydrology and phytoplankton of the Pamlico Sound persisted about 6 months, after which it returned to its pre-event condition, attesting to the resilience of the system.The papers in this special issue were presented in a special session during the 2001 biennial conference of the Estuarine Research Federation held in St. Pete Beach, Florida. The session, "Freshwater inflow: Science, policy and management," was focused on issues related to reduced freshwater inflow to estuaries. The session brought together scientists, managers, and regulators, and included presentations on the estimation of freshwater input to estuaries, development of ecological indicators to assess changes in inflow, management strategies used to set freshwater requirements, and experiences with the reintroduction of freshwater to restore inflow.Despite progress in the past decade, researchers struggle to evaluate the hypothesis that environmental conditions compromise immunity and facilitate new disease outbreaks. In this chapter, we review known immunological mechanisms for selected phyla and find that there are critical response pathways common to all invertebrates. These include the prophenoloxidase pathway, wandering phagocytic cells, cytotoxic effector responses, and antimicrobial compounds. To demonstrate the links between immunity and the environment, we summarize mechanisms by which immunity is compromised by environmental conditions. New environmental challenges may promote emergent disease both through compromised host immunity and introduction of new pathogens. Such challenges include changing climate, polluted environment, anthropogenically facilitated pathogen invasion, and an increase in aquaculture. The consequences of these environmental issues already manifest themselves as increased mortality on coral reefs, pathogen range expansion, and transmission of disease from aquaculture to natural populations, as we summarize in a final section on recent marine epizootics.Animals are important in nutrient cycling in freshwater ecosystems. Via excretory processes, animals can supply nutrients (nitrogen and phosphorus) at rates comparable to major nutrient sources, and nutrient cycling by animals can support a substantial proportion of the nutrient demands of primary producers. In addition, animals may exert strong impacts on the species composition of primary producers via effects on nutrient supply rates and ratios. Animals can either recycle nutrients within a habitat, or translocate nutrients across habitats or ecosystems. Nutrient translocation by relatively large animals may be particularly important for stimulating new primary production and for increasing nutrient standing stocks in recipient habitats. Animals also have numerous indirect effects on nutrient fluxes via effects on their prey or by modification of the physical environment. Future studies must quantify how the importance of animal-mediated nutrient cycling varies among taxa and along environmental gradients such as ecosystem size and productivity.The daily time budget of Coots Fulica atra was calculated from 36 hours of observation during January and February 1997-1999 on flooded meadows at Lake Brabrand, eastern Jutland. Groups of 5-66 Coots were scan-sampled (Altmann 1974) every three minutes for an hour. The day was divided into three time periods, 08:00-11:00, 11:00-14:00 and 14:00-17:00. Feeding and swimming were the dominant activities (Table 1) and most birds were feeding at the water surface. No differences in activity partitioning were detected among the time periods. Feeding activity, however, increased significantly from 72% in January to 78% in February.Context. Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concern. Predator species, including the freshwater crocodile (Crocodylus johnstoni), are susceptible to cane toad toxins when ingested. Upstream populations of freshwater crocodiles are smaller than downstream counterparts because of limited resources. We measured the impact of cane toad arrival on densities of these upstream populations. Aims. Our aim was to determine whether the influx of cane toads had a negative impact on populations of upstream 'stunted' freshwater crocodiles. Methods. Population surveys for crocodiles were conducted in three upstream creek systems, using day-and night-based survey methods, before the arrival of cane toads in the area. These surveys were repeated under similar conditions following the arrival of cane toads, to compare the distribution and densities of freshwater crocodiles and, hence, measure the impact of cane toads. Key results. There were significant declines in crocodile density at two survey sites following the arrival of cane toads, and we found dead crocodiles and cane toad carcasses with crocodile bite marks. The third site showed no change in density. There was a decline in mean density across all sites from 3.0 crocodiles km(-1) to 1.1 crocodiles km(-1) following the arrival of cane toads. Conclusions. There was an overall decrease in crocodile densities and a reduction in distribution following the arrival of cane toads into the survey area. Dead crocodiles and evidence of their having eaten cane toads strongly suggest that these declines were caused directly by the arrival of cane toads into the area. One site showed no apparent change other than an increase in wariness, which may reflect the distribution of available feeding and shelter resources among the three sites. Implications. These results suggest that upstream freshwater crocodile populations are highly susceptible to cane toad toxins, and that impacts on their population can include local extirpation. Considering their morphological and possibly genetic distinctiveness, the loss of these unique populations is of conservation concern.Adult sex ratios vary considerably among populations of single species and across years, but the best evidence is drawn from species with temperature-dependent sex determination. It is difficult to disentangle the effects of bias in the production of the sexes and the effects of a range of other factors contributing to biased adult sex ratios. In this paper, we survey sex ratios across populations of a species constrained to produce 1:1 offspring sex ratios by genotypic sex determination and show considerable variation in adult sex ratios. Raw adult sex ratios of Emydura macquarii emmottii were significantly biased in nine of the 11 populations examined. In all but one case, the bias was strongly in favour of males. Part of the bias in sex ratio was attributed to the differing ages of maturity of males and females-males mature younger than females-which leads to more male cohorts being included in the calculations of sex ratio than female cohorts. However, correcting for this effect brought the sex ratios of the populations closer to parity, as expected, and accounted for an overall 62% of the male surplus evident in the adult sex ratio. Even so, it was insufficient to explain the strong male bias (1.2-2.9) in five of the nine populations initially showing such bias. This provides support to those who advise caution in interpreting adult sex ratio data for freshwater turtles in the context of demography, sex allocation or evaluating the impact of climate change.Since they were declared a protected species in 1971, populations of saltwater crocodiles ( Crocodylus porosus) have increased in the tidal rivers, freshwater swamps and marine waters of the Northern Territory. The recovery of the C. porosus population has been accompanied by an increase in the incidence of ` problem crocodiles' that represent a threat to people in freshwater and marine habitats. Despite the implications for human safety, little is known about C. porosus populations in the freshwater reaches of rivers, well upstream of tidal influence. In this study, we examined the density and body- size structure of C. porosus populations in three freshwater rivers using a combination of data from spotlight and helicopter surveys conducted between the 1980s and 2005, and the inland extent of C. porosus using distribution records in the Northern Territory. Since the 1980s, the density of C. porosus in upstream, freshwater reaches of the Daly and Roper rivers has increased, as has the inland extent of C. porosus on the Daly River. Although C. porosus was not detected in spotlight surveys of the Victoria River, helicopter survey and anecdotal records indicate that C. porosus was present after 1989. In all, 52.1% of the crocodiles sighted in spotlight surveys were 2.1 - 3.4 m long. Distribution records show that C. porosus occurs up to 235 km inland and at elevations of up to 126 m above sea level. The potential distribution of C. porosus is likely to be similar to that of barramundi ( Lates calcarifer), a readily identifiable diadromous fish that must spawn in estuarine waters and occurs at elevations of up to 178 m above sea level. Because the density and inland extent of C. porosus in freshwater rivers is likely to increase, it is recommended that: ( 1) programs communicating crocodile awareness use the linkage between the presence of barramundi and the potential presence of C. porosus; ( 2) that crocodile warning signs be erected in upstream areas within the potential range of C. porosus; ( 3) that research be conducted on developing techniques to detect and exclude C. porosus from swimming areas; and ( 4) that widespread systematic surveys be undertaken to document the inland extent of C. porosus.Two species of freshwater turtle coexist in the Bellinger River: Elseya georgesi is common but limited to the Bellinger River, whereas Emydura macquarii is widespread but rare in the Bellinger River. The Bellinger River population of E. macquarii has been proposed as a distinct subspecies, so it may be endangered. Survivorship, fecundity, growth, size and age were determined for El. georgesi and the finite rate of increase (lambda) was estimated by a life-table analysis using mark - recapture data from surveys between 1988 and 2004. These parameters were compared with those of well studied populations of E. macquarii to assess whether modelling the demographic parameters of El. georgesi could serve as a surrogate for estimating the influences of these demographic parameters on. in the Bellinger River population of E. macquarii. We estimated that similar to 4500 El. georgesi inhabit the study area and, despite a size distribution strongly biased towards large individuals, the population is increasing (lambda = 1.15) in the best-case scenario, or slightly decreasing (lambda = 0.96) in the worst-case scenario. Comparing El. georgesi with E. macquarii from the Bellinger River and elsewhere suggests that E. macquarii grows faster, attains greater maximum size, has a greater clutch size and a higher fecundity than El. georgesi. Hence, El. georgesi does not serve as a good surrogate to determine demographic influences on. in E. macquarii.The Burnett River snapping turtle (Elseya sp.) from the Burnett, Mary and Fitzroy river systems is an undescribed Australian freshwater turtle, of which very little ecological information is known. This paper describes the dietary ecology of the species in the Burnett River catchment. Stomach and faecal samples were collected from turtles and an index of relative importance was used to rank food items found in stomach samples. This index indicated that algae and aquatic ribbon weed (Vallisneria) were the dominant food items consumed. No difference in diet was found between males and females. Although the sample size was small, diet appeared to vary slightly seasonally, with Elseya sp. selectively feeding on the flower buds of the Chinese elm tree (Celtis chinensis) and the seeds of the blackbean tree (Castanospermum australe) when these food items were seasonally available. Faecal samples suggest that the most ingested foods ( algae and aquatic ribbon weed) were also the most digestible. Although predominantly herbivorous, Elseya sp. was seen to eat carrion once in the wild.
Aggressive interactions between freshwater turtle, Chelodina oblonga, hatchlings and freshwater crayfish, Cherax spp.: implications for the conservation of the critically endangered western swamp turtle, Pseudemydura umbrinaContext. The toxins produced by cane toads (Rhinella marina) are fatal to many Australian predators that ingest these invasive anurans. To date, the potential economic impact of the cane toad invasion has attracted little attention. Toads have recently arrived at a large impoundment (Lake Argyle) in north-eastern Western Australia, that supports a commercial fishery for silver cobbler (shovel-nosed catfish, Arius midgleyi), raising concern that the toads may inflict significant economic damage by killing fish. Aims. Our research aimed to clarify the vulnerability of silver cobblers to the eggs and larvae of cane toads by determining (a) whether catfish are adversely affected if they prey on toad eggs or tadpoles, and (b) whether surviving catfish learn to avoid cane toad eggs and tadpoles in subsequent encounters. Methods. We conducted laboratory feeding trials to examine feeding responses of catfish to cane toad eggs and tadpoles in early and late developmental stages. Fish that survived exposure to toad eggs and/or tadpoles were re-tested with potential prey of the same sizes and developmental stages four days later. Key results. Our laboratory trials confirmed that some catfish eat toad eggs and die; but most catfish avoided the eggs. Catfish readily consumed toad tadpoles at both early and late developmental stages, but without experiencing mortality; and soon learned not to consume this toxic new prey type. Conclusions and implications. Despite potential frequent episodes of mortality of small numbers of catfish during the wet season, the overall impacts of cane toads on the Lake Argyle fishery likely will be minimal.Context. The increasing intensity and extent of anthropogenically mediated salinisation in freshwater systems has the potential to affect freshwater species through physiological and ecological processes. Determining responses to salinisation is critical to predicting impacts on fauna. Aims. We aimed to quantify the response of wild-caught turtles from freshwater lakes that had become saline in the lower Murray River catchment. Methods. Plasma electrolytes of all three species of freshwater turtle from South Australia were compared among two freshwater sites (Horseshoe Lagoon and Swan Reach), a brackish lake (Lake Bonney) and a saline lake (Lake Alexandrina). Key results. Chelodina longicollis, C. expansa and Emydura macquarii from a brackish lake had higher concentrations of plasma sodium and chloride than those from freshwater habitats. However, osmolytes known to increase under severe osmotic stress (urea and uric acid) were not elevated in brackish sites. Turtles from the highly saline lake were colonised by an invasive marine worm which encased the carapace and inhibited limb movement. Conclusions. Freshwater turtles in brackish backwaters had little response to salinity, whereas the C. longicollis in a saline lake had a significant physiological response caused by salt and further impacts from colonisation of marine worms. Implications. Short periods of high salinity are unlikely to adversely affect freshwater turtles. However, secondary ecological processes, such as immobilisation from a marine worm may cause unexpected impacts on freshwater fauna.Blood sampling is an essential technique in many herpetological studies. This paper describes a quick and humane technique to collect blood samples from three species of Australian chelid turtles ( Order Pleurodira): Chelodina expansa, Elseya latisternum, and Emydura macquarii signata.Context Species vary broadly in their ability to adapt to urbanisation. Freshwater turtles are vulnerable to the loss and degradation of terrestrial and aquatic habitat in urban environments. There have been few publications investigating impacts of urbanisation on freshwater turtles in Australia. Aims We investigated the effects of urbanisation on the distribution and abundance of the eastern long-necked turtle (Chelodina longicollis) in greater Melbourne. Methods We examined occurrence and relative abundance of C. longicollis at 55 wetlands across an urban-rural gradient in relation to site- and landscape-level factors. Occupancy was modelled using the program PRESENCE, and incorporated landscape and habitat covariates. A negative binomial regression model was used to examine the influence of landscape and habitat factors on relative abundance by using WinBUGS. Key resultsC. longicollis occupied 85% of the 55 wetlands we surveyed, and we found no evidence that wetland occupancy was influenced by the variables we measured. However, relative abundance was highest at wetlands with low water conductivity and heavy metal pollution, and in wetlands furthest from rivers. ConclusionsC. longicollis appears to be resilient to urbanisation and is likely to persist in urban landscapes, possibly because of the creation of new wetlands in Australian cities. However, long-term studies focussed on demographic parameters, or survivorship, may elucidate as yet undetected effects of urbanisation. Although no specific management recommendations may be necessary for C. longicollis in urban areas at this time, this species may be in decline in non-urban areas as a result of climatic changes and wetland drying. Implications Our findings suggest that caution is required before drawing generalised conclusions on the impacts of urbanisation on turtles, as the effects are likely to be species-specific, dependent on specific ecology and life-history requirements. Further studies are required to ascertain these relationships for a wider array of species and over longer time spans.A survey of the Kikori River drainage of the Gulf Province of Papua New Guinea identified four species of freshwater turtle. The pig-nosed turtle Carettochelys insculpta and the southern New Guinea soft-shelled turtle Pelochelys bibroni are riverine species. The New Guinea spotted turtle Elseya novaeguineae lives primarily in the tidal freshwater creeks and streams, flooded sinkholes and swamps of the lowland rainforest. The New Guinea painted turtle Emydura subglobosa resides almost exclusively in forest sinkholes and swamps. Pelochelys bibroni was the least-common species, and is probably locally endangered. Greatest turtle diversity occurred in the Karst Plains of the Kikori sub-basin, where there is a greater diversity of habitat available to turtles. Lowest diversity occurred in the highlands, where turtles were present in very low density as introduced populations, brought in from the Kikori lowlands, Mount Bosavi and the Western Province by visiting relatives. Linguistic diversity concurred with turtle diversity of the regions in which the languages were spoken. C. insculpta nests both on riverine sand beaches and on coastal beaches, sand spits and isolated sand bars where the Kikori River discharges into the Gulf of Papua. Adult females and eggs of C. insculpta are harvested heavily by local people for local consumption.The Chelidae is a family of side-necked turtles restricted in distribution to South America and Australasia. While their biology in Australia is reasonably well known, species in New Guinea are very poorly known despite high diversity, especially in the southern lowlands. In this paper, we report on the diversity, distribution, habitat and reproductive biology of the freshwater turtles of the TransFly region of the Western Province of Papua New Guinea, with special emphasis on reproduction of Emydura subglobosa, Elseya branderhorsti and Elseya novaeguineae. Seven species were captured, with reliable records of an eighth. A key to the freshwater turtles of the TransFly region is provided. Harvest methods, consumption, and trade in turtles by the TransFly communities are documented. There is mounting pressure to take advantage of revenue opportunities afforded by the Asian turtle trade, but this is impeded by lack of transport infrastructure. There is also insufficient demographic information on any New Guinean turtle species to make a reasoned judgment on the level of harvest that would be sustainable. Nor is there sufficient information on captive rearing for most species, and where it is available it is not accessible by local villagers. These knowledge gaps need to be addressed and factored into a management plan that is implemented before local communities can capitalise on the commercial opportunities provided by the turtle fauna without risking collapse of the resource and the implications for their concurrent subsistence economy that would follow.Context. While much attention has been paid to the effects of global temperature increases on the geographical ranges and phenologies of plants and animals, less is known about the impacts of climatically driven alteration of water regimes. Aims. To assess how three species of freshwater turtle in Australia's Murray-Darling Basin have responded to long-term decline in river flow and floodplain inundation due to climatic drying and water diversions. Methods. Turtle populations were sampled in a section of the Murray River and its floodplain in 1976-82 following a wet period and in 2009-11 at the end of the most severe drought on record. Catch per unit effort, proportional abundance in different habitat types and population structure were assessed in both periods. Key results. Catch per unit effort in baited hoop nets declined by 91% for the eastern snake-necked turtle (Chelodina longicollis) and 69% for the Murray turtle (Emydura macquarii), but did not change significantly for the broad-shelled turtle (Chelodina expansa). In addition, total catches from a range of sampling methods revealed a significantly reduced proportion of juvenile C. longicollis and E. macquarii in 2009-11, suggesting a fall in recruitment. Key conclusions. The decline of C. longicollis was likely due mainly to drought-induced loss of critical floodplain habitat in the form of temporary water bodies, and that of E. macquarii to combined effects of drought and predation on recruitment. C. expansa seems to have fared better than the other two species because it is less vulnerable to nest predation than E. macquarii and better able than C. longicollis to find adequate nutrition in the permanent waters that remain during extended drought. Implications. Declining water availability may be a widespread threat to freshwater turtles given predicted global impacts of climate change and water withdrawals on river flows. Understanding how each species uses particular habitats and how climatic and non-climatic threats interact would facilitate identification of vulnerable populations and planning of conservation actions.Invasive species are a significant cause of biodiversity declines on a global scale with novel species interactions often causing ecological damage through predation or competition. Red-eared slider turtles (Trachemys scripta elegans) have been introduced to wetlands throughout the world and have negatively impacted native species, particularly other species of turtles. In our controlled feeding experiments in mesocosms juvenile red-eared slider turtles negatively impacted the growth of juvenile red-bellied turtles (Pseudemys rubriventris), an IUCN near threatened species and a Pennsylvania threatened species, through exploitative competition for limited food. In mixed species experimental treatments, in which food resources were abundant, juvenile red-bellied turtles grew significantly faster and ate more food than juvenile red-eared slider turtles. In mixed species experimental treatments, in which food resources were limited, red-eared slider turtles ingested more food, gained mass faster, and maintained body condition while red-bellied turtles lost body condition. There were significant differences in growth rates seen between resource availability regimes. In treatments in which resources were abundant there were no significant differences between turtles housed in mixed species or single species groups. In limited resource treatments red-bellied turtle body condition was significantly different between single and mixed species groups while there were significant differences in mass and body condition for red-eared slider turtles. Our results suggest that one mechanism by which red-eared slider turtles detrimentally impact ecologically similar species is through competition for limited food resources. We hypothesize that growth of red-eared slider turtle populations will lead to population declines of native turtle species throughout their introduced ranges because they use limited food resources more efficiently for their growth and development than native species. (C) 2015 Elsevier Ltd. All rights reserved.Habitat fragmentation is a major reason for the decline and extinction of migratory species. Many host populations for parasites are partly migratory, consisting of both migratory and resident individuals, and we asked the question whether these two subpopulations differ in parasite susceptibility. If so, barriers intercepting migration may change the parasite encystment rate and recruitment. We used the River Ljungan, Sweden, as study system, where eight hydroelectric power plants hinder access of sea-migrating trout to most tributaries. We compared the encystment of the threatened freshwater pearl mussel (Margaritifera margaritifera) larvae on sympatric tributary-resident brown trout and sea-migrating trout (Salmo trutta) as hosts for their parasitic larvae. We also compared eighteen tributary-resident brown trout populations with the sea-migrating trout as hosts for mussel larvae. Encystment decreased faster over time on the tributary-resident trout than on the sea-migrating trout. Encystment was therefore higher on the sea-migrating trout compared to the tributary-resident trout at the time of excystment of the larvae. Growth of encysted mussel larvae was higher on the sea-migrating trout than on the tributary-resident trout. The natural density of the tributary-resident trout populations was lower than that of the sea-migrating trout in the autumn, when the mussels infest the fish, and in early summer, just before the excystment of juvenile mussels from the fish. Estimations of total numbers of encysted mussel larvae per unit stream area were higher on the sea-migrating trout than the tributary-resident trout in the autumn and in the spring at the time of juvenile mussel excystment. The higher mussel larval growth and the higher encystment on the sea-migrating trout imply that even seemingly healthy tributary mussel populations are reduced because of the habitat fragmentation. As sea-migrating trout are threatened or extinct in many rivers, fragmentation may be a large-scale problem, not only for sea-migrating populations, but also indirectly for highly threatened mussel populations. Restoration activities should primarily focus on creating free pathways for original host fish populations instead of sustaining them by supplementary stocking. (C) 2015 Elsevier Ltd. All rights reserved.Freshwaters ecosystems continue to face pressures from pollution, flow regime alterations, habitat destruction and exotic species invasions despite their unique biodiversity. In Europe, National Parks and Special Areas of Conservation aim to provide protection of 'aggregate' biodiversity, yet inspection of priority species lists for these sites often reveals a focus towards terrestrial species. In regions such as the Alps and the Pyrenees, this is a particularly serious problem because climate change and other anthropogenic pressures (e.g. hydropower, tourism) are causing widespread hydrological modification which is likely to drive changes in aquatic species abundance, diversity and distribution. Improved understanding of the diversity of rare plants and animals is necessary so efforts can be cost-effectively targeted to conserve the maximum number of species, whilst a clearer picture of these species' distributions is a precursor to targeting conservation efforts. This paper reports results of a study into the diversity and distribution of 17 endemic mayflies, stoneflies and caddisflies from 598 rivers sites across southern France. Endemic macroinvertebrates were found only at sites in the Pyrenees mountain range with richness peaking at 1500-1800 m above sea level. Nine of these 17 species were recorded fromFreshwater ecosystems in the tropics host a diverse endemic fauna including freshwater crabs, but the rapid loss and deterioration of habitat means that many species are now under imminent threat. Studies on freshwater fish and amphibians suggest a third to half of the species in some tropical freshwaters is either extinct or endangered, but the status of the freshwater crabs is not known. Freshwater crabs, with 1280 species, represent one-fifth of all the World's brachyurans. We therefore undertook a comprehensive IUCN Red List assessment of the freshwater crabs, which was the first time that such a study had been attempted on a global scale for any group of freshwater invertebrates. The conservation status of all known species from the Americas, Africa, Europe, Asia, and Australasia revealed unexpectedly high threat levels. Here we show that about one-sixth of all freshwater crab species have an elevated risk of extinction, only one-third are not at-risk, and although none are actually extinct, almost half are too poorly known to assess. Out of 122 countries that have populations of freshwater crabs,Freshwater ecosystems are among the most threatened in the world. In light of the threats to freshwater biodiversity, it is essential to map the distribution and status of species to ascertain their threat status for prioritizing conservation action. However, while there is agreement that the conservation of freshwater ecosystems depends on whole-catchment management, there are still a wide variety of large-scale mapping methods in use, the advantages and disadvantages of which have not been fully explored. This study shows that area estimation based on minimum convex polygons should not be encouraged for aquatic species. The IUCN definition of area of occupancy (AOO) is a useful term, albeit highly scale-dependent, for assessment of the total approximate area over which a species occurs. However, for aquatic fauna, and perhaps many other organisms, assessment of occurrence should be based on the more accurate point-locality presences only. The IUCN extent of occurrence (EOO), for freshwater catchment species, should be redefined as 'the sum of the smallest hydrological units identified, of presently known, inferred or projected occurrences of a taxon, excluding cases of vagrancy, that are used to estimate the threat to a taxon'. A single hydrological unit is also the conservation or management unit. Here we suggest that this unit is the quaternary catchment. This new mapping approach is more appropriate and practical for use in both management planning and conservation action. We suggest that conservation managers and decision makers facilitate co-operation in freshwater mapping efforts by working at the same spatial scale, i.e. the same hydrological unit. (C) 2009 Elsevier Ltd. All rights reserved.The implications of climate change for terrestrial and aquatic taxa are for their dispersal pole-wards and/or to higher altitudes as they track their climate niches. Here, bioclimatic models are developed to predict how projected climate change scenarios for a northern temperate region (Great Britain) shift the climate spaces (Le. areas of suitable thermal habitat) for 12 freshwater fishes of the Salmonidae, Percidae, Esocidae and Cyprinidae families. Climate envelope models developed in Biomod2 used the current species' distributions and their relationships with current climatic variables, and projected these onto the BCC-CSM1-1 and HadGEM2-AO climate change scenarios (low and high emissions, 2050 and 2070) in full and no dispersal scenarios. Substantial contractions in climate spaces were predicted for native salmonid fishes, with decreases of up to 78% for Atlantic salmon Salmo salar, with these largely unchanged between the dispersal scenarios. Conversely, for the majority of cyprinid fishes, expansions were predicted, including into northern regions where they are current not present biogeographically. Only under the no dispersal scenarios did their predicted distributions remain the same as their current distributions. For all non-salmonid species, the most important climate variables in the model predictions related to temperature; for salmonids, they were a combination of temperature and shifts in annual mean precipitation. As these predictions suggest that there is potential for considerable alterations to the climate spaces of freshwater fishes in Great Britain during this century then regulatory and mitigation conservation actions should be undertaken to minimise these. (C) 2016 Elsevier Ltd. All rights reserved.Shorebirds (Charadriiformes) and their wetland habitats are under threat worldwide. While data exist for shorebird population trends for many parts of the world, two thirds of Australia's populations have not been assessed. We report the results of a large-scale aerial shorebird survey, sampling about a third of the Australian continent over a period of 24 years (1983-2006). Migratory shorebirds have declined by 73%, Australian resident shorebirds by 81%. Of the 10 wetlands supporting the highest number of shorebirds within the survey bands, eight were inland wetlands and only two coastal, emphasising the importance of inland wetlands for shorebirds. Wetland area decreased significantly at four of the 10 main sites. Annual rainfall showed no trends (1983-2005) but water extraction was substantial for four of the 10 wetlands, contributing to reduced flooding extent and frequency. Loss of wetlands due to river regulation is a significant contributor to the drastic decline in shorebird numbers in Australia, largely unrecognized in international conservation agreements in Australia. (c) 2008 Elsevier Ltd. All rights reserved.The establishment of protected areas is one of the main strategies to reduce losses of biodiversity. While a number of studies have evaluated the effectiveness of existing reserves in preserving representative samples of ecosystem and species diversity, there has been no systematic assessment of their effectiveness in terms of conserving evolutionary history. We used comprehensive phylogenies of four lineages of aquatic Coleoptera to investigate (i) the performance of National Parks (NPs) in representing the phylogenetic diversity (PD) of the Iberian Peninsula; (ii) the representation in NPs of the species with the highest conservation priority, as identified from a combination of their evolutionary distinctiveness and vulnerability; and (iii) whether species richness may be a good surrogate of PD when selecting new conservation areas. Our results show that Iberian NPs perform poorly in the preservation of freshwater PD. In most cases PD was not different from a random expectation, but when it did differ, PD in NPs was always lower than that obtained by a random selection of the same number of species. We also found that most of the highly evolutionarily distinct and vulnerable taxa were not covered by any NP. Finally, when additional conservation areas were selected maximizing the number of unrepresented species, the variation in PD could be very high, and as a consequence, depending on the group and the number of areas added, they could preserve much less evolutionary history than when they were specifically selected to maximize PD. (C) 2013 Elsevier Ltd. All rights reserved.Trait analysis has potential to identify species that are vulnerable to climate change, but its predictive strength has not been adequately examined. Conditions during the recent 'Millennium Drought' in Australia's Murray-Darling Basin resembled the projected future climate of the region and provided an opportunity to test the ability of traits to predict population responses to a warmer and drier environment. I used data from a large-scale monitoring program to assess how 14 dietary, life-history and physiological-tolerance traits related to changes in occurrence and abundance of 39 of the basin's freshwater fish species. Species that fared worse under prolonged drought were significantly more likely to have an invertivorous rather than omnivorous diet, a low age at sexual maturity, a small maximum body size, a low spawning temperature, a long spawning season, low fecundity, demersal rather than planktonic eggs, and a low upper thermal limit. Rankings of drought vulnerability of fish species derived from correlations between population changes and traits showed good agreement with a previous assessment of inter-specific variation in resistance to drought, and were corroborated by independent observations of drought responses for some species. Trait analysis should have wide application to identifying species at risk from climate change, provided that sufficient traits are assessed and that adequate consideration is given to variation in trait-vulnerability relationships among different groups of organisms, geographic regions and types of ecosystems. (C) 2013 Elsevier Ltd. All rights reserved.Human alterations to aquatic ecosystems are leading to decreases in species richness and biomass and subsequent changes in community composition. In many cases species losses are non-random: species with traits poorly adapted to the new environmental conditions suffer greater losses. We used long-term data from a southern US river, the Kiamichi River, to evaluate the synergistic effects of regional climate patterns coupled with water management practices on freshwater mussel communities. Mussel communities in the river changed over the 15 year period of this study, with overall densities and species richness decreasing and community structure shifting from assemblages dominated by thermally sensitive to thermally tolerant species. These changes corresponded with a period of very low flows in the river caused by a combination of climate patterns (a regional drought) and local water management practices (decreased reservoir releases). These low flows, coupled with high summer air temperatures, changed the river in many locations from a continuously flowing river to a series of shallow, isolated pools where water temperatures sometimes exceeded 40 degrees C. Altered conditions led to higher mortality rates of thermally sensitive compared to tolerant species. We predict future shifts in river ecosystem function as mussel communities change in response to changing climate and water management. (C) 2010 Elsevier Ltd. All rights reserved.Using the 160,000-km(2) drainage basin of the Madre de Dios and Orthon rivers in the southwest Amazon as a test case, we piloted an approach for large-scale conservation planning for freshwater systems characterized by a near-complete lack of biological and physical data. We used newly available spatial and remote sensing datasets, including spacebome optical and radar observations, and new techniques of spatial data analysis to generate subbasin (>= 100 km(2)), stream, and floodplain and wetland habitat classifications. We then generated a preliminary plan for a network of conservation areas to protect the most intact examples of representative habitat types while maximizing longitudinal and lateral connectivity. Proposed additions for freshwater conservation complement existing reserves and build on earlier conservation planning efforts for terrestrial ecosystems. In the resulting integrated plan, at least 20% of the area of each major freshwater habitat type is represented and two continuous corridors exist from the mouth of the Madre de Dios to its headwaters in the Andes. In total, we highlighted 84 currently unprotected subbasins to fulfill our representation and connectivity goals. About two-thirds of these subbasins were considered relatively undisturbed and are identified as Level I (critical management zones) or Level II (indigenous territories), whereas one-third are potentially degraded and thus were designated as Level III (threat mitigation zones). This exercise provides an example of how newly available remote-sensing datasets and analytical tools may be used to advance freshwater conservation planning, particularly in data-poor regions. (c) 2006 Elsevier Ltd. All rights reserved.Given the widespread degradation of freshwater habitats, assessing the distributions of species that may be negatively or positively impacted should be of general interest. However, determining distributions of freshwater organisms that are small and patchily distributed and attached or sedentary is particularly problematic, as it is time consuming, inaccurate, and nearly impossible when the focal species is rare. Here we illustrate the use of indirect sampling approaches to survey the distribution of the rare freshwater bryozoan Lophopus crystallinus, a priority species in the UK Biodiversity Action Plan [Anonymous, 1999. UK Biodiversity Group Tranche 2 Action Plans. Invertebrates, Vol. 4. Environment Agency, Peterborough, pp. 437-439.1. By utilising two complementary methods for sampling bryozoan propagules (statoblasts), namely the collection of debris samples and sediment cores, we achieved an efficient and integrative sampling of habitats across spatial and temporal scales. Analysis of 154 debris samples, encompassing 62 rivers and lakes, identified at least 16 new populations while analysis of 26 sediment cores provided evidence of current or very recent (in the last 10-20 years) occurrence in a further six localities. These results represent a more than 10-fold increase in the current recorded distribution of the species in the UK. Logistic regression analysis provided evidence that L. crystallinus is generally found in lowland sites and is tolerant of eutrophication. Our study exemplifies how integrative and indirect sampling approaches can greatly aid in assessing the conservation status of rare aquatic species and reveals, in this case, that the focal species is less rare than previously appreciated. (c) 2006 Elsevier Ltd. All rights reserved.Freshwater ecosystems are declining under climate change and land-use change. To maximize the return on investment in freshwater conservation with limited financial resources, managers must prioritize management actions that are most cost-effective. However, little is known about what these priorities may be under the combined effects of climate and land-cover change. We present a novel decision-making framework for prioritizing conservation resources to different management actions for the conservation of freshwater biodiversity. The approach is novel in that it has the ability to model interactions, rank management options for dealing with conservation threats from climate and land-cover change, and integrate empirical data with expert knowledge. We illustrate the approach using a case study in South East Queensland (SEQ), Australia under climate change, land-cover change and their combined effects. Our results show that the explicit inclusion of multiple threats and costs results in quite different priorities than when costs and interactions are ignored. When costs are not considered, stream and riparian restoration, as a single management strategy, provides the greatest overall protection of macroinvertebrate and fish richness in rural and urban areas of SEQ in response to climate change and/or urban growth. Whereas, when costs are considered, farm/land management with stream and riparian restoration are the most cost-effective strategies for macroinvertebrate and fish conservation. Our findings support riparian restoration as the most effective adaptation strategy to climate change and urban development, but because it is expensive it may often not be the most cost-efficient strategy. Our approach allows for these decisions to be evaluated explicitly. (C) 2016 Elsevier Ltd. All rights reserved.In order for an acoustic signal to be an effective source of communication, the signal must be successfully detected and interpreted by the intended receiver. One potential barrier to acoustic communication is background noise. Lotic systems contain a wide variety of habitats including riffles, shoals and waterfalls that can become quite noisy. The increasing prevalence of road and train crossings over small streams, and increased boat traffic in navigable rivers and lentic systems also presents potential anthropogenic noise sources with which vocal fishes did not evolve. The present study investigates the relationship between vocalizations and the natural soundscape of a common fish of the Southeastern United States, the Blacktail Shiner (Cyprinella venusta), and the potential effects anthropogenic noise from bridge crossings may have on the soundscape and acoustic communication in this species. Results revealed a particularly close association of a quiet window in the natural soundscape of C. venusta and dominant frequencies of the courtship vocalization of C. venusta. Results also indicated that C. venusta's acoustic signals propagate short distances, following predictions based on the calculated cutoff frequency of the streams they inhabit, and were masked by noise generated from bridge crossings. Our calculations suggest that road traffic noise propagates to an extent that virtually entire watersheds are impacted by this noise pollution, especially in urban areas. (C) 2015 Elsevier Ltd. All rights reserved.While the importance of nearby terrestrial habitats is gaining recognition in contemporary wetland management strategies, it is rarely recognized that different wetlands are often diverse in their functions of meeting the annual or life-cycle requirements of many species, and that migration between these wetlands is also critical. Using radio-telemetry, we examined terrestrial habitat use and movements of 53 eastern long-necked turtles (Chelodina longicollis) in an area of southeast Australia characterized by spatially diverse and temporally variable wetlands. Male and female C. longicollis exhibited a high degree of dependence on terrestrial habitat, the majority (95%) of individuals using sites within 375 In of the wetland. Turtles also associated with more than one wetland, using permanent lakes during droughts and moving en masse to nearby temporary wetlands after flooding. Turtles used 2.4 +/- 0.1 (range = 1-5) wetlands separated by 427 +/- 62 (range = 401470) In and moved between these wetlands 2.6 +/- 0.3 (range = 0-12) times over the course of a year. A literature review revealed that several species of reptiles from diverse taxonomic groups move between wetlands separated by a mean minimum and maximum distance of 499-1518 m. A high proportion of studies attributed movements to seasonal migrations (55%) and periodic drought (37%). In such cases we argue that the different wetlands offer complimentary resources and that managing wetlands as isolated units, even with generous terrestrial buffer zones, would not likely conserve core habitats needed to maintain local abundance or persistence of populations over the long term. Core management units should instead reflect heterogeneous groups of wetlands together with terrestrial buffer zones and travel corridors between wetlands. (c) 2006 Elsevier Ltd. All rights reserved.Ponds are among the most biodiverse freshwater ecosystems, yet face significant threats from removal, habitat degradation and a lack of legislative protection globally. Information regarding the habitat quality and biodiversity of ponds across a range of land uses is vital for the long term conservation and management of ecological resources. In this study we examine the biodiversity and conservation value of macroinvertebrates from 91 lowland ponds across 3 land use types (35 floodplain meadow, 15 arable and 41 urban ponds). A total of 224 macroinvertebrate taxa were recorded across all ponds, with urban ponds and floodplain ponds supporting a greater richness than arable ponds at the landscape scale. However, at the alpha scale, urban ponds supported lower faunal diversity (mean: 22 taxa) than floodplain (mean: 32 taxa) or arable ponds (mean: 30 taxa). Floodplain ponds were found to support taxonomically distinct communities compared to arable and urban ponds. A total of 13 macroinvertebrate taxa with a national conservation designation were recorded across the study area and 12 ponds (11 floodplain and 1 arable pond) supported assemblages of high or very high conservation value. Pond conservation currently relies on the designation of individual ponds based on very high biodiversity or the presence of taxa with specific conservation designations. However, this site specific approach fails to acknowledge the contribution of ponds to freshwater biodiversity at the landscape scale. Ponds are highly appropriate sites outside of protected areas (urban/arable), with which the general public are already familiar, for local and landscape scale conservation of freshwater habitats. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of > 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m for Malaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6-98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (Freshwater ecosystems represent one of the most threatened broad habitat types globally. Despite containing around a third of all vertebrates, area-based approaches to conservation planning rarely include freshwater species as an explicit target for conservation. Here we describe and apply a globally applicable methodology comparable to those for other groups (i.e. Important Bird Areas) to identify river and lake catchments that represent, or contain, freshwater Key Biodiversity Areas. We discuss the rationale behind the methodology and propose appropriate definitions and quantitative threshold values for the selection criteria. Thresholds are developed through spatial analysis of species information for four comprehensively assessed freshwater taxonomic groups in continental Africa, comprising 4203 species, as recently assessed for the IUCN Red List of Threatened Species (TM). To illustrate application of the methodology freshwater Key Biodiversity Areas are identified across continental Africa, and conservation planning software used to prioritise a network of catchments that captures 99% of the total species complement within catchments covering ca. 20% of the total land area. Within these prioritised catchments only 19% of river length falls within existing Protected Areas suggesting that, given the high connectivity within freshwater ecosystems and their dependence upon catchment management for effective conservation, modification or expansion of the protected area network is required to increase effective conservation of freshwater species. By applying this methodology, gaps in the coverage of freshwater species by existing Protected Areas can be identified and used to inform conservation policy and investment to ensure it is inclusive of, and effective for, freshwater biodiversity. (C) 2012 Elsevier Ltd. All rights reserved.Human-induced changes negatively affect all components of freshwater ecosystems and comprise the major cause of global loss of diversity and the biotic homogenization of freshwater faunas. The high diversity of dragonflies in heavily industrialized areas is therefore paradoxical, to say the least. We compared diversity of dragonflies in three main freshwater habitat types (natural and human-made) occurring in Upper Silesia (Central Europe). We used multivariate methods and diversity indices for a general analysis, comprising both species richness and the species composition of assemblages. We recorded 50 species in mine subsidence pools from the total of 54 sampled species. These included a high proportion of habitat specialists (typically threatened species). We emphasize that secondary habitats (e.g. spontaneously originated mine subsidence pools) should not a priori be regarded as ecological traps, because these often are the available habitats with highest quality. These habitats significantly outweigh ponds in species richness and proportion of habitat specialists. The conservation potential of specific secondary habitats lies in the fact that these habitats can substitute for very rare natural wetlands often restricted to higher elevations. We assume that high diversity in this type of secondary habitats is not random, but rather that it depends on environmental heterogeneity caused by a specific allogenic succession process occurring as a direct consequence of mining. (c) 2011 Elsevier Ltd. All rights reserved.Climate warming is affecting the biodiversity all around the world, resulting in the expansion or contraction of the geographical range of species, and leading to colonisation (winners) and extinction (losers) events in ecosystems. It is crucial for the conservation of biodiversity to identify these potential winners and losers. We focus here on small standing waterbodies in Switzerland and on five taxonomic groups: vascular plants, snails, beetles, dragonflies and amphibians. We first assessed the sensitivity of each species to climate warming through their thermal preferences, using current altitudinal and latitudinal distribution, as a surrogate for temperature. We then evaluated the resilience of species to perturbations through five ecological and biogeographical criteria applicable to the perturbation "warming": dispersal ability, degree of habitat specialisation, geographical extent in the study area, future trend in geographical extent, and future trend of habitat availability for species. Potential winners and losers of a warming climate could be quantified through their thermal preferences. The proportion of potential losers ranged from zero species for snails to 33% of the regional species pool for dragonflies. The set of potential winners was much larger, ranging from 53% for amphibians to 61% for dragonflies. A multimetric index combining the five resilience criteria enabled the further prioritisation of the species along a gradient of extinction risk. This potential threat from climate warming is not reflected by the current Red Lists of dragonflies and amphibians, suggesting that conservation management could gain from a complementary label indicating the degree of sensitivity to warming. (C) 2011 Elsevier Ltd. All rights reserved.Regional-scale biodiversity indicators provide important criteria for the selection of protected areas in conservation, but their application is often hindered by a lack of taxonomic knowledge. Moreover, different indicators include different types of information, sometimes leading to divergent conservation priorities. Madagascar tops the world list of biodiversity hotspots and much conservation effort has been directed toward its threatened plants and vertebrates. In contrast, its highly diverse freshwater invertebrate fauna has received comparatively little conservation attention. We conducted an inventory of Malagasy adephagan water beetles (Coleoptera, Dytiscidae, Noteridae, Gyrinidae, Haliplidae) using a combined morphological and molecular approach. In total, 2043 beetles from 153 sites were sequenced for cytochrome oxidase subunit I (cox1), and species delimitation was carried out using the coalescent-based GMYC model. Phylogenetic relationships of the resulting entities were established using cox1 combined with partial 16S rRNA and 28S rRNA sequences. Ten national parks were assessed for their species richness, phylogenetic diversity (PD) and endemism. We were particularly interested in the contribution of endemic species to PD. Congruence between molecular and taxonomic identifications was high (91%), with 69% of sampled species endemic to Madagascar. Interestingly, we found thatUrbanization fundamentally alters the abiotic and biotic components of landscapes, presenting wildlife with serious challenges to which they must respond in order to avoid excess mortality from urban dangers. In this study, we used radio-telemetry to examine the behavior and survivorship of an Australian freshwater turtle, Chelodina longicollis, in a suburban environment compared to a control group on an adjacent nature reserve. We expected turtles in the suburbs to be less mobile, but the suburban environment did not inhibit the ability of turtles to traverse large areas and make frequent movements among several different wetlands. In fact, suburban turtles were more vagile, moving distances twice as far as those on the nature reserves. Turtles on the nature reserve responded to dropping water levels during drought by estivating for several months in sheltered woodland micro-habitats. Suburban turtles did not estivate terrestrially, in part because their water bodies experienced dampened water level fluctuations and retained water during drought, though the relative unavailability of suitable estivation sites and perceived threats could also account for their avoidance of extended forays into the terrestrial environment. Annual survival rate was 95.3% in the reserves compared to 87.6% in the suburbs, but this 7.7% decrease in survival from road mortality was not significant in our survivorship models. The continued ability of suburban turtles to remain vagile without suffering from high mortality rates is likely a product of the availability of vegetated drainage lines and under-road "box" culverts that allow turtles to travel safely throughout the suburban landscape. (C) 2009 Elsevier Ltd. All rights reserved.Invasive species are frequently blamed for faunal declines, but there is little direct evidence about the pathways, magnitude and size-selectivity of mortality induced by invaders. Top predators are of particular interest in this context, because their removal can generate substantial cascades of secondary effects on community composition. Cane toads (Bufo marinus) are large South American anurans currently spreading rapidly through tropical Australia. Native predators that attempt to consume these highly toxic toads may die as a result. During surveys of the Victoria River in the semi-arid tropical region of the Northern Territory, we documented massive mortality of freshwater crocodiles (Crocodylus johnstoni) at the toad invasion front. Dead crocodiles spanned a wide size range (0.6-2.1 m long) but with significant biases; intermediate-sized animals (0.6-1.5 m long) were more likely to be found dead. Population densities of crocodiles plummeted by as much as 77% following toad invasion, and population size-structures changed. The negative impacts of toads on crocodiles appear to be greater in these hot semi-arid landscapes than in cooler, higher rainfall areas where crocodiles have access to a wider prey base, and the toads are less prone to desiccation and can rehydrate in small, scattered water bodies rather than in the main river. Hence, the impact of cane toad invasion on this top predator may increase with increasing aridity. (C) 2008 Elsevier Ltd. All rights reserved.There are high rates of regional and global extinctions among freshwater species and few chances for recovery. We report here on the rediscovery after 30 years of a small fish, the southern-purple spotted gudgeon (Mogurnda adspersa), once widespread in the southern Murray-Darling Basin of south-eastern Australia. The rediscovery was in a region, the Lower Murray, where temperate riverine and wetland habitats are modified by a broad spectrum of changes including intensive flow regulation and diversions. There was some doubt whether the rediscovered population was a true remnant or a recent introduction, particularly as there was a translocated population in a nearby artificial habitat. Fortunately, a non-government organisation acted to rescue into captivity about 50 specimens as the remaining wetland habitat dried completely, soon after rediscovery, as a consequence of a decade-long drought and water diversions. We describe the habitat and ecology of fish in the rediscovery site, and provide genetic data, both nuclear (50 allozyme loci) and mtDNA (1141 base pairs; two genes), to show that they were true remnants of the regional native population. This information allows clear planning for future recovery including reintroductions, and is a case study that provides strategies, and hope, for conservation and management concerning other modified habitats. Specifically, it highlights the need for a rapid response to conserve threatened species, the recognition of remnant natural values in altered environments, and the treatment of new finds as native until there is alternate evidence. (C) 2015 Elsevier Ltd. All rights reserved.Abiotic and biologically informed classifications are often used in conservation planning as coarse-filter surrogates for species. The relationship between these surrogates and the distribution of species is commonly assumed, but rarely assessed by planners. We derived four abiotic and eight biologically informed classifications of stream reaches to serve as surrogates for biodiversity patterns in the Wet Tropics bioregion, Queensland, Australia. We used stream reaches as planning units and, as conservation targets for each surrogate, we used two percentages - 10% and 30% - of the total stream reach length occupied by each class. We then derived minimum sets of planning units to meet targets for each surrogate and tested the effectiveness of the surrogates by calculating the average achievement of the same targets for predicted distributions of 28 fish species. Our results showed that neither abiotic nor biologically informed classifications were good at representing freshwater fish species; in fact none of the surrogates led to average representation of species better than randomly selected planning units. There were two main reasons for this poor performance. First, none of the surrogates had high classification strength or informativeness about compositional change in fish species within the study region. Second, frequency distributions of probabilities of occurrence for most fish species were strongly right-skewed, with few stream reaches having high probabilities. Combined, these results meant that selection of stream reaches to achieve surrogate targets was effectively random with respect to probabilities of fish species occurrence, leading to poor representation of fish species. We conclude there is a limited basis for using coarse-filter surrogates to represent freshwater fish diversity in this region, and that there is a clear need for research in this as well as other regions if planners are to understand the limitations associated with coarse-filter surrogates for representing freshwater biodiversity more broadly. (C) 2011 Elsevier Ltd. All rights reserved.Changes to population and community structure can have important ecological consequences and raise conservation concerns when causes are anthropogenic; however, signs of stress may not always be apparent. Turtles are long-lived and presence of adults may suggest healthy populations when lack of recruitment is actually threatening persistence. We observed and captured turtles for two years in Point Pelee National Park, Ontario, Canada, and compared our results with those collected 30 years earlier to determine if (1) species relative abundance, (2) sex ratios, and (3) age structure changed over three decades. Extirpation of the spotted turtle since 1972-1973 has altered the park's species assemblage. Evidence also suggests that Blanding's turtles have declined. Sex ratios were similar between time periods for all species except for the painted turtle which has become significantly more male-biased. Size structure for Blanding's and snapping turtles shifted towards larger and presumably older age classes. Our results suggest that limited juvenile recruitment caused the size shift. Heavy predation on turtle nests from a dense raccoon population appears to be the main factor limiting recruitment. Despite protecting a sizable fragment of turtle habitat for a century, Point Pelee has lost one species and only one other species has a large healthy population. Our study illustrates that habitat protection provides no guarantee for species persistence when multiple threats exist and highlights the necessity for monitoring populations of long-lived species. (C) 2007 Elsevier Ltd. All rights reserved.Freshwater ecosystems are key to maintaining biological diversity and for human well-being. Despite their importance, these ecosystems have suffered severe transformations due to anthropogenic activity. Here we present the first priority assessment of freshwater ecosystems in Mexico at the national scale. Because species' compositional and hydrological conditions vary widely across Mexico we divided the territory into seven distinct regions in order to assign different conservation targets for biodiversity surrogates and to consider specific threats according to their impact in each region. The total conservation area network identified is equal to 30% of the country's continental surface, in which more than 94% of the biodiversity surrogates meet their established conservation targets. The regions of the Tropical Pacific and Gulf of Mexico have the largest proportions of priority sites, followed by the Central Highlands, which contains the largest number of irreplaceable sites. Tropical Pacific and the Baja California Peninsula possess the largest proportion of sites with extreme importance for conservation. Nationally, the percentage of priority sites under protection is 15.8%, of which 5.6% are sites of extreme importance, 42% are sites of high importance, and 6% are sites of medium importance for conservation. Our study highlights the importance of conducting conservation prioritization assessments at higher spatial resolution using information that is up to date and doing so in a collaborative way to strengthen decision making. This analysis helps to bridge the research-implementation gap in conservation planning to improve the representation of Mexico's freshwater biodiversity in conservation areas. (C) 2015 Elsevier Ltd. AU rights reserved.Nested systems of biodiversity classification are commonly used for designating protected area networks in terrestrial and marine realms. Whilst terrestrial-style protected areas are largely inappropriate for freshwater systems, the concepts of 'representative' biodiversity and 'complementarity' can be borrowed for freshwater conservation. Cryptic species are commonly found in freshwater macroinvertebrates and fish, and most have restricted distributions relative to the described conglomerate 'species'. This indicates that 'representative' and therefore 'complementary' units of freshwater biodiversity may be smaller than previously appreciated. Using recently detected cryptic species in atyid shrimps from eastern Australia (Atyidae: Paratya australiensis, Caridina mccullochi and C. indistinca), we tested predictions about regional patterns of cryptic assemblage structure, endemism and Phylogenetic Diversity (PD) at the river scale, and discussed their implications for freshwater conservation. Patterns of distribution in these cryptic shrimp species largely corresponded with published distributional patterns of cryptic species in several freshwater fish in eastern Australia, and indicated the presence of four putative ecoregions within a previously recognised freshwater fish province (Eastern Province). However, some rivers had pronounced cryptic endemism, suggesting that rivers may not be 'representative' of one another's biodiversity even within ecoregions. PD and endemism were largely correlated with one another, as endemics typically co-occurred with widespread species at the river scale. This study indicates that cryptic species can contribute to defining patterns of biodiversity at nested spatial scales that may be important for freshwater conservation. (c) 2008 Elsevier Ltd. All rights reserved.Underwater noise pollution is a growing problem in aquatic environments and as such may be a major source of stress for fish. in the present study, we addressed the effects of ship noise and continuous Gaussian noise on adrenal activity in three European freshwater species. Underwater ship noise recorded in the Danube River and two Austrian lakes was played back to fish at levels encountered in the field (153 dB re 1 mu Pa, 30 min). Post exposure cortisol secretion was compared with control situations. Cortisol was measured with enzyme immunoassay techniques (EIA, ng cortisol/l water/g fish) in extracted aquarium water with corrections for fish mass. in the first series, two hearing specialists, the common carp (Cyprinus carpio) and the gudgeon (Gobio gobio) and one hearing generalist, the European perch (Perca fluviatilis) were exposed to ship noise. The noise level was well above hearing thresholds in these species. in a second series, fish were exposed to continuous Gaussian noise at a similar level (156 dB) which is known to induce temporary hearing loss in hearing specialists. All three species responded with increased cortisol secretion when exposed to ship noise. Interestingly, no elevation was observed when fish were exposed to continuous Gaussian noise. Our results indicate that ship noise characterized by amplitude and frequency fluctuations, constitutes a potential stressor in contrast to continuous noise. Surprisingly, the data also demonstrate no apparent differences between species possessing excellent hearing abilities (hearing specialists) and species with poor hearing abilities like perch. (c) 2005 Elsevier Ltd. All rights reserved.Dam removal is increasingly being recognized as a viable river restoration action. Although the main beneficiaries of restored connectivity are often migratory fish populations, little is known regarding recovery of other parts of the freshwater food web, particularly terrestrial components. We measured stable isotopes in key components to the freshwater food web: salmon, freshwater macroinvertebrates and a river specialist bird, American dipper (Cinclus mexicanus), before and after removal of the Elwha Dam, WA, USA. Less than a year after dam removal, salmon returned to the system and released marine-derived nutrients (MDN). In that same year we documented an increase in stable-nitrogen and carbon isotope ratios in American dippers. These results indicate that MDN from anadromous fish, an important nutrient subsidy that crosses the aquatic-terrestrial boundary, can return rapidly to food webs after dams are removed which is an important component of ecosystem recovery. (C) 2015 Elsevier B.V. All rights reserved.We reviewed literature describing the potential for freshwater anthropogenic waterbodies to act as refuges from disturbance. We identified research related to the refuge potential of a wide range of waterbodies, using waterbody names as keywords along with 'artificial' and 'freshwater'. Potential freshwater anthropogenic refuges were more often standing than running waters. Agricultural ponds, rural and urban drainage ditches and transport canals were the most diverse for all aquatic taxa, whereas irrigation infrastructure was least diverse. Comparatively little is known about the refuge role of fire dams, urban artificial ponds, golf course lakes, disused industrial ponds and retaining walls. Local-scale attributes associated with high biodiversity were: presence of macrophytes (for animals), absence of fish (for amphibians, invertebrates), natural bed materials and hydroperiod (all biota). Landscape variables associated with high biodiversity were proximity to and connectivity with other waterbodies and to natural terrestrial vegetation. Moderate levels of management intervention were also associated with higher biodiversity. Many knowledge gaps about the function of anthropogenic refuges within landscapes exist and require further research. One of the most important limitations to the provision of refuges for freshwater biodiversity by anthropogenic waterbodies is the lack of recognition of their actual or potential biodiversity value. Anthropogenic waterbodies need to be recognised for their potential to support biodiversity conservation and climate change adaptation for freshwater species, while being managed to prevent the spread of invasive species. (C) 2013 Elsevier Ltd. All rights reserved.While the collection of fish for the aquarium pet trade has been flagged as a major threat to wild populations, this link is tenuous for the unregulated wild collection of endemic species because of the lack of quantitative data. In this paper, we examine the extent and magnitude of collection and trade of endemic and threatened freshwater fishes from India for the pet markets, and discuss their conservation implications. Using data on aquarium fishes exported from India, we try to understand nature of the trade in terms of species composition, volume, exit points, and importing countries. Most trade in India is carried out under a generic label of "live aquarium fish"; yet despite this fact, we extracted export data for at least thirty endemic species that are listed as threatened in the IUCN Red List. Of the 1.5 million individual threatened freshwater fish exported, the major share was contributed by three species; Botia striata (Endangered), Carinotetraodon travancoricus (Vulnerable) and the Red Lined Torpedo Barbs (a species complex primarily consisting of Puntius denisonii and Puntius chalakkudiensis, both 'Endangered'). Using the endangered Red Lined Torpedo Barbs as a case study, we demonstrate how existing local regulations on aquarium fish collections and trade are poorly enforced, and are of little conservation value. In spite of the fact that several threatened and conservation concern species are routinely exported, India has yet to frame national legislation on freshwater aquarium trade. Our analysis of the trade in wild caught freshwater fishes from two global biodiversity hotspots provides a first assessment of the trade in endangered and threatened species. We suggest that the unmanaged collections of these endemic species could be a much more severe threat to freshwater biodiversity than hitherto recognized, and present realistic options for management. (C) 2013 Elsevier Ltd. All rights reserved.Local ecological knowledge constitutes a potentially useful source of information for conservation, but the quality, limitations and biases of this body of knowledge remain largely untested. The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is a highly threatened freshwater cetacean found in one of the world's most densely populated human environments. The dynamics of porpoise decline remain poorly understood, and local ecological knowledge from fishing communities across its range may represent an important conservation tool for monitoring porpoise population status and quantifying levels of human-caused mortality. We used interview data from an extensive survey of fishing communities across the middle-lower Yangtze drainage to investigate spatial and temporal patterns of porpoise abundance, mortality and population change. Interview data on porpoise relative abundance and decline, especially weekly sighting frequencies, show congruent spatial patterns with data collected from boat-based Yangtze cetacean surveys, demonstrating that informant data can provide accurate quantitative information on these two key parameters of species conservation status. Interview-based collection of local ecological knowledge therefore represents a useful monitoring method for assessing population trends in freshwater cetaceans and other charismatic or distinctive aquatic species, and may be particularly appropriate in regions where resources for regular boat-based surveys are limited. Using local ecological knowledge to identify primary threats to the porpoise population is less straightforward due to probable biases in interview data on porpoise mortality. However, interview data are able to demonstrate that the number of porpoises killed annually in the Yangtze mainstem may have doubled and that the annual mortality rate may have quadrupled over the past two decades, with mortality due to vessel strikes and other factors having increased more in recent years than by-catch mortality. It seems unlikely that fisheries mortality has been the dominant driver of porpoise decline in the Yangtze mainstem, suggesting that regulating regional fisheries may not be sufficient for porpoise conservation. (C) 2012 Elsevier Ltd. All rights reserved.Conservation plans are usually developed for regions that encompass only one environmental realm (terrestrial, freshwater or marine) because of logistical, institutional and political constraints. This is inadequate because these realms often interact through processes that form, utilize and maintain interfaces or connections, which are essential for the persistence of some species and ecosystem functions. We present a conceptual framework for systematic conservation prioritization that explicitly accounts for the connectivity between the terrestrial, marine, and freshwater realms. We propose a classification of this connectivity that encompasses: (1) narrow interfaces, such as riparian strips; (2) broad interfaces, such as estuaries: (3) constrained connections, such as corridors of native vegetation used by amphibians to move between natal ponds and adult habitat; and (4) diffuse connections, such as the movements of animals between breeding and feeding habitats. We use this taxonomy of inter-realm connectivity to describe existing and new spatial conservation prioritization techniques that aim to promote the persistence of processes that operate between realms. (C) 2009 Elsevier Ltd. All rights reserved.Freshwater species and ecosystems are gravely imperiled, particularly within urban landscapes of tropical Asia. In one of the region's most urbanized landscapes (i.e., Singapore), we determined: (1) the importance of six different habitats (i.e., catchment reservoirs, estuarine reservoirs, forest streams, rural streams, ponds and monsoon canals) for conserving the diversity of freshwater molluscs; (2) key environmental factors (e.g., pH) affecting molluscan distribution; (3) important biogeographical determinants (e.g., area) of molluscan richness within each habitat; and (4) the habitat affinities of introduced species. High sampling saturation was achieved at most study habitats with minimal sampling effort, suggesting that the utilization of molluscs as bioindicators can expedite freshwater conservation initiatives. Estuarine reservoirs (6.0 +/- 2.0) had the highest molluscan richness, vis-a-vis catchment reservoirs, forest streams, rural streams, ponds and monsoon canals (3.0 +/- 1.5; 0; 3.3 +/- 2.0; 1.8 +/- 0.5 and 3.5 +/- 0.5 respectively). Both reservoir types possessed species compositions distinct from other habitats and contained majority (76%) of the sampled species. Reservoirs therefore serve to conserve the bulk of local freshwater malacofauna, especially if they are maintained at near-neutral pH levels (i.e., similar to 7.3) and contain large substrates (i.e., rocks). Area was the best predictor of molluscan richness across all habitats, implying that larger freshwater habitats require higher conservation priorities than smaller ones. Introduced (non-native) species (e.g., Pomacea canaliculata) had high affinities for reservoirs, which are in need of monitoring to curb population expansions. The interminable growth of human settlements urgently requires a reconciliatory approach, which includes the ecologically-sound design and management of modified habitats to complement reserves in sustaining native freshwater species. (c) 2005 Elsevier Ltd. All rights reserved.The integration of freshwater and terrestrial biodiversity priorities in systematic conservation planning is a major challenge to conservation planners. Maintaining upstream-downstream connectivity and the influence of catchments on freshwater ecological integrity are some of the issues that make it difficult to reconcile terrestrial and freshwater conservation planning. As a result most conservation assessments are often biased towards terrestrial systems without adequate incorporation of freshwater biodiversity in determining priority areas for conservation. In this paper, we propose a protocol for integrating the assessment of freshwater and terrestrial priorities in conservation planning, based on a case study from Mpumalanga Province in South Africa. The approach involves the separate assessment of freshwater priority areas, and using the outcome to influence the selection of terrestrial priority areas. This allowed both freshwater and terrestrial biodiversity to be incorporated in conservation planning without compromising their unique requirements. To test the effectiveness of this approach, we assessed percentage overlap between freshwater and terrestrial priority areas, target achievement, and the area required to achieve targets. We then compared the outcome from the proposed approach with the separate assessments of freshwater and terrestrial biodiversity priorities, and when both systems are given an equal weighting in a single assessment. The results showed that there was a noticeable improvement in the overlap of priority areas for freshwater and terrestrial biodiversity from 23% to 47%. Target achievement for freshwater biodiversity improved by 10% when terrestrial assessment was based on freshwater priority areas as opposed to terrestrial systems being assessed alone. There was negligible increase in area required, whether there was integration of freshwater and terrestrial biodiversity or no integration. We conclude that the most efficient way to achieve integration in conservation planning is to preferentially select areas where freshwater and terrestrial biodiversity priorities overlap. (C) 2009 Elsevier Ltd. All rights reserved.Protected area networks represent one of the mainstays of global conservation polices and are therefore central to current efforts to maintain biodiyersity. However, a major limitation of most conservation strategies is their bias towards particular taxonomic groups and ecosystems, meaning that many taxa and habitats are often only incidentally protected as a by-product of inclusion within reserves. Here we investigate how effectively protected area networks, not specifically designated for freshwaters, support aquatic biodiversity in the Iberian Peninsula (Spain and Portugal), using data for water beetles, surrogates of overall macroinvertebrate diversity in these habitats. We explore the behaviour of different measures (alpha, beta and gamma) of both taxonomic and functional diversity at different spatial scales. Overall our findings highlight the contrasting performance of reserve systems in the maintenance of either taxonomic or functional diversity, as well as the importance of spatial scale. Iberian reserves perform relatively well in supporting taxonomic diversity of water beetles at the peninsular scale, but the same protected areas poorly represent functional diversity. Such a mismatch cautions against the use of any one diversity component as a surrogate for others, and emphasizes the importance of adopting an integrative approach to biodiversity conservation in aquatic ecosystems. Furthermore, our results often show contrasting patterns at smaller spatial scales, highlighting the need to consider the influence of scale when evaluating the effectiveness of protected area networks. (C) 2015 Elsevier Ltd. All rights reserved.Aquatic ecosystems are connected over large spatial scales, have varied drivers, strong and often conflicting societal interests and interacting management processes. Many of the world's protected areas (> 100,000, similar to 42% of land) include freshwater ecosystems, some specifically declared for freshwater protection, but often supplied by rivers outside their protected boundaries. Such complex socio-ecological systems have considerable challenges. We report on Strategic Adaptive Management (SAM), a management framework that should be implemented, irrespective of resourcing. in protected areas of any river system, ranging from heavily managed or regulated through to pristine rivers. We briefly outline the four stages of the SAM process for aquatic protected areas and present three case studies from South Africa and Australia in different stages of SAM implementation. Progress is incremental, reflecting gaps, problems, and socio-ecological dynamism. Real-world implementation usually means such management is passive although experimentation with environmental flows remains possible. While maturity in SAM is incremental over years or decades, it can and should be applied even if environmental problems are urgent and contentious. The stages of SAM should produce an agreed vision and/or mission among stakeholders, with an appropriate hierarchy of objectives that determines indicators to be measured, allowing ongoing reflection, learning and adaptation. There is no panacea for achieving aquatic conservation, but Strategic Adaptive Management offers hope with its interlinked processes for navigating complexity and learning. SAM in freshwater conservation is progressing because of the imperative for sustainability, history of interaction between scientists and managers and the need for transdisciplinary governance of rivers. (C) 2010 Published by Elsevier Ltd.Environmental DNA (eDNA) is used to detect biodiversity by the capture, extraction, and identification of DNA shed to the environment. However, eDNA capture and extraction protocols vary widely across studies. This use of different protocols potentially biases detection results and could significantly hinder a reliable use of eDNA to detect biodiversity. We tested whether choice of eDNA capture and extraction protocols significantly influenced biodiversity detection in aquatic systems. We sampled lake and river water, captured and extracted eDNA using six combinations of different protocols with replication, and tested for the detection of four macroinvertebrate species. Additionally, using the same lake water technical replicates, we compared the effect of capture and extraction protocols on metabarcode detections of biodiversity using 16S for eubacteria and cytochrome c oxidase I (COI) for eukaryotes. Protocol combinations for capture and extraction of eDNA significantly influenced DNA yield and number of sequences obtained from next generation sequencing. We found significantly different detection rates of species ranging from zero percent to thirty-three percent. Differences in which protocol combinations produced the highest metabarcoded biodiversity were detected and demonstrate that different protocols are required for different biodiversity targets. Our results highlight that the choice of molecular protocols used for capture and extraction of eDNA from water can strongly affect biodiversity detection. Consideration of biases caused by choice of protocols should lead to a more consistent and reliable molecular workflow for repeatable and increased detection of biodiversity in aquatic communities. (C) 2014 Elsevier Ltd. All rights reserved.Declining trends in the integrity of freshwater systems demand exploration of all possible conservation solutions. Freshwater protected areas have received little attention, despite the prominence of protected areas as conservation interventions for terrestrial and more recently marine features. We argue that a dialogue on freshwater protected areas has been neglected both because few models of good protected area design exist, and because traditional notions of protected areas translate imperfectly to the freshwater realm. Partly as a result of this conceptual disconnect, freshwaters have been largely ignored in protected area accounting schemes, even though a number of existing freshwater conservation strategies could qualify according to general protected area definitions. Rather than impose terrestrially-motivated ideas about protected areas onto freshwaters, we propose new vocabulary -freshwater focal area, critical management zone, and catchment management zone - that can be used in conjunction with IUCN protected area categories and that recognize the special ecological dynamics of freshwaters, and in particular the critical role of fluvial processes. These terms, which attempt to diffuse concerns about locking away essential ecosystem goods and services, move us toward consideration of protected areas for freshwaters. This conceptual shift, which acknowledges that freshwater conservation may occur remotely from freshwater features, opens the door for improved integration of freshwater, terrestrial, and marine concerns in protected area design and management. (c) 2006 Elsevier Ltd. All rights reserved.Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network coversAssessment of the Odonata assemblage at the Laguna de Zóñar (a Ramsar Site in Spain) to determine the effect of a rotenone treatment that was intended to control the invasive carp at the lake. The results suggest that the treatment did not harm the Gomphidae or Libellulidae at the lake* Dispersal via animals (zoochory) is a primary mechanism for seed exchange between habitat patches. Recent studies have established that many plant species can survive waterbird gut passage. To quantify the patterns and consequences of waterbird-mediated dispersal, information on ingestion and gut passage must be combined with bird movement data. Such analysis has recently revealed seed dispersal kernels by migrating waterbirds. However, since many waterbird populations are largely resident, and migrating populations spend only a minor part of the main dispersal season (autumn–winter) on active migration, daily regional-scale movements probably cause more frequent dispersal. * We synthesized high-resolution empirical data on landscape-scale movements and seed gut passage times in a key disperser species, the mallard (Anas platyrhynchos), using a spatially explicit, mechanistic model to quantify dispersal distributions resulting from daily autumn–winter movements. We evaluated how landscape composition and seed traits affect these dispersal patterns. * The model indicates that mallards generate highly clumped seed deposition patterns, dispersing seeds primarily between core areas used for foraging and resting. Approximately 34% of all dispersed seeds are transported to communal roost areas, which may function as reservoirs for mallard-dispersed species, and 7% are transported between foraging areas. Landscape-dependent movement patterns strongly affect the dispersal distributions, resulting in multi-modal dispersal kernels, with dispersal distances increasing with fragmentation of freshwater foraging habitat. Seed size-related gut retention times determine the proportion of seeds being dispersed away from the ingestion area, with larger seeds (20 mm3) having a 8–10% higher potential for long-distance dispersal than smaller seeds (0·2 mm3), if surviving gut passage. However, twice as many small seeds will finally accomplish long-distance dispersal due to their higher gut passage survival. * Synthesis. Firstly, this study reveals how seed dispersal patterns resulting from daily waterfowl movements are shaped by landscape-dependent differences in movement patterns. Secondly, seed survival appears more important than retention time in determining the scale of long-distance dispersal by non-migrating mallards. We conclude that the frequent flights of staging waterbirds result in directed dispersal over distances inversely related to wetland availability, indicating that they maintain landscape connectivity across a range from wet to increasingly dry landscapes.Captive breeding is the last resort to protect a species that will become extinct because it is incapable of surviving in the wild without human intervention. The freshwater pearl mussel Margaritifera margaritifera is a prime candidate for such action: the species has experienced a recent range-wide decline, particularly in Europe. In Northern Ireland, M.?margaritifera is now only found in six rivers and, because of a lack of natural recruitment in the wild, it has been predicted that these populations will become extinct within 80 years. Consequently, an ex situ breeding program was established with the aim of using a semi-natural method to propagate mussels for restocking. In the present study, we analysed the levels and patterns of genetic diversity in the captive-bred mussels, as well as their parent broodstock and remnant populations from their natal and other rivers in Northern Ireland where M.?margaritifera is still found, to help develop best practice for the captive breeding program. Levels of genetic diversity were high, although there was a strong correlation between genetic diversity and census population sizes, as well as evidence of inbreeding in all populations. Small but significant levels of genetic differentiation were observed between both the captive-bred juveniles and their parent broodstock, and the samples from their source river, indicating a possible founder effect. In addition, three groups of genetically distinct clusters were observed among the remaining natural populations that could be used as the basis for defining conservation units. These findings allow us to make recommendations for efficient management of the captive breeding program, including rotation of the ex situ broodstock on a regular basis to avoid prolonged inbreeding, and the establishment of captive breeding of other populations to reflect genetic differences between putative conservation units in Northern Ireland and elsewhere.The present study reports the first population genetic analysis of Arapaima gigas, an important but critically over-exploited fish species of the Amazon basin. We sequenced two discontinuous mitochondrial DNA regions of 1204 base-pairs (bp) (NADH1 segment) and 1143 bp (ATPase segment) from 139 individuals of A. gigas representing eight localities spanning the Amazon basin from Iquitos, Peru to Macap, Brazil. We discovered 34 haplotypes separated by 44 segregating sites. The two most common haplotypes are shared among all populations and isolation-by-distance appears to be the most important population dynamic, although there is no significant association between geographical distance and genetic differentiation. Observed patterns of differentiation appear to be attributable largely to anthropogenic factors associated with over-exploitation. Greatest haplotypic diversity exists upstream of Manaus and in areas away from large centres of population. The female variance and inbreeding effective population sizes are approximately 150000 individuals and localities in the Amazon basin are connected by gene flow. Naturally low levels of population differentiation and relatively high between-population connectivity is encouraging for the conservation and management of A. gigas. If strategically placed biological reserves were created throughout the Amazon basin to act as sources of emigrants within a source-sink metapopulation model, we believe locally depleted populations can be re-populated and maintained by individuals immigrating from these reserves.1. Maternal reproductive investment is thought to reflect a trade-off between offspring size and fecundity, and models generally predict that mothers inhabiting adverse environments will produce fewer, larger offspring. More recently, the importance of environmental unpredictability in influencing maternal investment has been considered, with some models predicting that mothers should adopt a diversified bet-hedging strategy whilst others a conservative bet-hedging strategy. 2. We explore spatial egg size and fecundity patterns in the freshwater fish southern pygmy perch (Nannoperca australis) that inhabits a diversity of streams along gradients of environmental quality, variability and predictability. 3. Contrary to some predictions, N. australis populations inhabiting increasingly harsh streams produced more numerous and smaller eggs. Furthermore, within-female egg size variability increased as environments became more unpredictable. 4. We argue that in harsh environments or those prone to physical disturbance, sources of mortality are size independent with offspring size having only a minor influence on offspring fitness. Instead, maternal fitness is maximized by producing many small eggs, increasing the likelihood that some offspring will disperse to permanent water. We also provide empirical support for diversified bet-hedging as an adaptive strategy when future environmental quality is uncertain and suggest egg size may be a more appropriate fitness measure in stable environments characterized by size-dependent fitness. These results likely reflect spatial patterns of adaptive plasticity and bet-hedging in response to both predictable and unpredictable environmental variance and highlight the importance of considering both trait averages and variance. 5. Reproductive life-history traits can vary predictably along environmental gradients. Human activity, such as the hydrological modification of natural flow regimes, alters the form and magnitude of these gradients, and this can have both ecological and evolutionary implications for biota adapted to now non-existent natural environmental heterogeneity.Migration is a widespread phenomenon, with powerful ecological and evolutionary consequences. Morphological adaptations to reduce the energetic costs associated with migratory transport are commonly documented for migratory species. However, few studies have investigated whether variation in body morphology can be explained by variation in migratory strategy within a species. We address this question in roach Rutilus rutilus, a partially migratory freshwater fish that migrates from lakes into streams during winter. We both compare body shape between populations that differ in migratory opportunity (open vs. closed lakes), and between individuals from a single population that vary in migratory propensity (migrants and residents from a partially migratory population). Following hydrodynamic theory, we posit that migrants should have a more shallow body depth, to reduce the costs associated with migrating into streams with higher flow conditions than the lakes the residents occupy all year round. We find evidence both across and within populations to support our prediction, with individuals from open lakes and migrants from the partially migratory population having a more slender, shallow-bodied morphology than fish from closed lakes and all-year residents. Our data suggest that a shallow body morphology is beneficial to migratory individuals and our study is one of the first to link migratory strategy and intraspecific variation in body shape.1. Because host-parasite interactions are so ubiquitous, it is of primary interest for ecologists to understand the factors that generate, maintain and constrain these associations. Phylogenetic comparative studies have found abundant evidence for host-switching to relatively unrelated hosts, sometimes related to diversification events, in a variety of host-parasite systems. For Monogenoidea (Platyhelminthes) parasites, it has been suggested that the co-speciation model alone cannot explain host occurrences, hence host-switching and/or non-vicariant modes of speciation should be associated with the origins and diversification of several monogenoid taxa. The factors that shape broad patterns of parasite sharing were investigated using path analysis as a way to generate hypotheses about the origins of host-parasite interactions between monogenoid gill parasites and Neotropical freshwater fishes. Parasite sharing was assessed from an interaction matrix, and explanatory variables included phylogenetic relationships, environmental preferences, biological traits and geographic distribution for each host species. Although geographic distribution of hosts and host ecology are important factors to understand host-parasite interactions, especially within host lineages that share a relatively recent evolutionary history, phylogeny had the strongest overall direct effect on parasite sharing. Phylogenetic contiguity of host communities may allow a stepping-stone' mode of host-switching, which increases parasite sharing. Our results reinforce the importance of including evolutionary history in the study of ecological associations, including emerging infectious diseases risk assessment.Various types of ecosystem-based climate proxies have been used to assess past arctic change. Although lotic records are relatively poor because of the constant reworking of riverine material, high-quality lentic data have been assembled back to the end of the Pleistocene and deglaciation of the circumpolar Arctic. In general, climatic variations in the Holocene, partly due to changes in the shrinking effect of glacier coverage, produced significant temporal and spatial variations in arctic hydrology and freshwater ecosystems. Of particular note were the vast expansions of northern peatlands during major protracted periods of wetting. More recent lake biota and sedimentiological data reflect the general warming trend that has occurred over the last one to two centuries and indicate major changes to freshwater characteristics such as ice-cover duration and thermal stratification. Such data provide an excellent baseline against which future effects of climate change can be both projected and measured.Projected climate change might increase the deposition of nitrogen by about 10% to seminatural ecosystems in southern Norway. At Storgama, increased precipitation in the growing season increased the fluxes of total organic carbon (TOC) and total organic nitrogen (TON) in proportion to the water flux. In winter, soil temperatures near 0 degrees C, common under a snowpack, induced higher runoff of inorganic nitrogen (N) and lower runoff of TOC. By contrast, soil temperatures below freezing, caused by little snow accumulation (expected in a warmer world), reduced runoff of inorganic N, TON, and TOC. Long-term monitoring data showed that reduced snowpack can cause either decreased or increased N leaching, depending on interactions with N deposition, soil temperature regime, and winter discharge. Seasonal variation in TOC was mainly climatically controlled, whereas deposition of sulfate and nitrate (NO(3)) explained the long-term TOC increase. Upscaling to the river basin scale showed that the annual flux of NO(3) will remain unchanged in response to climate change projections.In general, the arctic freshwater-terrestrial system will warm more rapidly than the global average, particularly during the autumn and winter season. The decline or loss of many cryospheric components and a shift from a nival to an increasingly pluvial system will produce numerous physical effects on freshwater ecosystems. Of particular note will be reductions in the dominance of the spring freshet and changes in the intensity of river-ice breakup. Increased evaporation/evapotranspiration due to longer ice-free seasons, higher air/water temperatures and greater transpiring vegetation along with increase infiltration because of permafrost thaw will decrease surface water levels and coverage. Loss of ice and permafrost, increased water temperatures and vegetation shifts will alter water chemistry, the general result being an increase in lotic and lentic productivity. Changes in ice and water flow/levels will lead to regime-specific increases and decreases in habitat availability/quality across the circumpolar Arctic.Despite their generally isolated geographic locations, the freshwaters of the north are subjected to a wide spectrum of environmental stressors. High-latitude regions are especially sensitive to the effects of recent climatic warming, which have already resulted in marked regime shifts in the biological communities of many Arctic lakes and ponds. Important drivers of these limnological changes have included changes in the amount and duration of snow and ice cover, and, for rivers and lakes in their deltas, the frequency and extent of spring floods. Other important climate-related shifts include alterations in evaporation and precipitation ratios, marked changes in the quality and quantity of lake and river water inflows due to accelerated glacier and permafrost melting, and declining percentages of precipitation that falls as snow. The depletion of stratospheric ozone over the north, together with the clarity of many Arctic lakes, renders them especially susceptible to damage from ultraviolet radiation. In addition, the long-range atmospheric transport of pollutants, coupled with the focusing effects of contaminant transport from biological vectors to some local ecosystems (e.g., salmon nursery lakes, ponds draining seabird colonies) and biomagnification in long food chains, have led to elevated concentrations of many persistent organic pollutants (e.g., insecticides, which have never been used in Arctic regions) and other pollutants (e.g., mercury). Rapid development of gas and oil pipelines, mining for diamonds and metals, increases in human populations, and the development of all-season roads, seaports, and hydroelectric dams will stress northern aquatic ecosystems. The cumulative effects of these stresses will be far more serious than those caused by changing climate alone.Arctic freshwater and diadromous fish species will respond to the various effects of climate change in many ways. For wide-ranging species, many of which are key components of northern aquatic ecosystems and fisheries, there is a large range of possible responses due to inter- and intra-specific variation, differences in the effects of climate drivers within ACIA regions, and differences in drivers among regions. All this diversity, coupled with limited understanding of fish responses to climate parameters generally, permits enumeration only of a range of possible responses which are developed here for selected important fishes. Accordingly, in-depth examination is required of possible effects within species within ACIA regions, as well as comparative studies across regions. Two particularly important species (Arctic char and Atlantic salmon) are examined as case studies to provide background for such studies.Matching the trend seen among the major large rivers of the globe, the Amazon River and its tributaries are facing aquatic ecosystem disruption that is affecting freshwater habitats and their associated biodiversity, including trends for decline in fishery resources. The Amazon's aquatic ecosystems, linked natural resources, and human communities that depend on them are increasingly at risk from a number of identified threats, including expansion of agriculture; cattle pastures; infrastructure such as hydroelectric dams, logging, mining; and overfishing. The forest, which regulates the hydrological pulse, guaranteeing the distribution of rainfall and stabilizing seasonal flooding, has been affected by deforestation. Flooding dynamics of the Amazon Rivers are a major factor in regulating the intensity and timing of aquatic organisms. This study's objective was to identify threats to the integrity of freshwater ecosystems, and to seek instruments for conservation and sustainable use, taking principally fish diversity and fisheries as factors for analysis.Climate change is likely to act as a multiple stressor, leading to cumulative and/or synergistic impacts on aquatic systems. Projected increases in temperature and corresponding alterations in precipitation regimes will enhance contaminant influxes to aquatic systems, and independently increase the susceptibility of aquatic organisms to contaminant exposure and effects. The consequences for the biota will in most cases be additive (cumulative) and multiplicative (synergistic). The overall result will be higher contaminant loads and biomagnification in aquatic ecosystems. Changes in stratospheric ozone and corresponding ultraviolet radiation regimes are also expected to produce cumulative and/or synergistic effects on aquatic ecosystem structure and function. Reduced ice cover is likely to have a much greater effect on underwaterClimate variability and change is projected to have significant effects on the physical, chemical, and biological components of northern Canadian marine, terrestrial, and freshwater systems. As the climate continues to change, there will be consequences for biodiversity shifts and for the ranges and distribution of many species with resulting effects on availability, accessibility, and quality of resources upon which human populations rely. This will have implications for the protection and management of wildlife, fish, and fisheries resources; protected areas; and forests. The northward migration of species and the disruption and competition from invading species are already occurring and will continue to affect marine, terrestrial, and freshwater communities. Shifting environmental conditions will likely introduce new animal-transmitted diseases and redistribute some existing diseases, affecting key economic resources and some human populations. Stress on populations of iconic wildlife species, such as the polar bear, ringed seals, and whales, will continue as a result of changes in critical sea-ice habitat interactions. Where these stresses affect economically and culturally important species, they will have significant effects on people and regional economies. Further integrated, field-based monitoring and research programs, and the development of predictive models are required to allow for more detailed and comprehensive projections of change to be made, and to inform the development and implementation of appropriate adaptation, wildlife, and habitat conservation and protection strategies.Humanity has entered a new phase of sustainability challenges, the Anthropocene, in which human development has reached a scale where it affects vital planetary processes. Under the pressure from a quadruple squeeze-from population and development pressures, the anthropogenic climate crisis, the anthropogenic ecosystem crisis, and the risk of deleterious tipping points in the Earth system-the degrees of freedom for sustainable human exploitation of planet Earth are severely restrained. It is in this reality that a new green revolution in world food production needs to occur, to attain food security and human development over the coming decades. Global freshwater resources are, and will increasingly be, a fundamental limiting factor in feeding the world. Current water vulnerabilities in the regions in most need of large agricultural productivity improvements are projected to increase under the pressure from global environmental change. The sustainability challenge for world agriculture has to be set within the new global sustainability context. We present new proposed sustainability criteria for world agriculture, where world food production systems are transformed in order to allow humanity to stay within the safe operating space of planetary boundaries. In order to secure global resilience and thereby raise the chances of planet Earth to remain in the current desired state, conducive for human development on the long-term, these planetary boundaries need to be respected. This calls for a triply green revolution, which not only more than doubles food production in many regions of the world, but which also is environmentally sustainable, and invests in the untapped opportunities to use green water in rainfed agriculture as a key source of future productivity enhancement. To achieve such a global transformation of agriculture, there is a need for more innovative options for water interventions at the landscape scale, accounting for both green and blue water, as well as a new focus on cross-scale interactions, feed-backs and risks for unwanted regime shifts in the agro-ecological landscape.Freshwater ice dominates the Arctic terrestrial environment and significantly impacts bio-physical and socio-economic systems. Unlike other major cryospheric components that either blanket large expanses (e.g., snow, permafrost, sea ice) or are concentrated in specific locations, lake and river ice are interwoven into the terrestrial landscape through major flow and storage networks. For instance, the headwaters of large ice-covered rivers extend well beyond the Arctic while many northern lakes owe their genesis to broader cryospheric changes. The effects of freshwater ice on climate mostly occur at the local/regional scale, with the degree of influence dependent on the magnitude, timing, location, and duration of ice cover, and the size of the water body. Freshwater-ice formation, growth, decay, and break-up are influenced by climatic variables that control surface heat fluxes, but these differ markedly between lakes and rivers. Despite the importance of freshwater ice, there has been a recent reduction in observational recordings.Changes in climate and ultraviolet radiation levels in the Arctic will have far-reaching impacts, affecting aquatic species at various trophic levels, the physical and chemical environment that makes up their habitat, and the processes that act on and within freshwater ecosystems. Interactions of climatic variables, such as temperature and precipitation, with freshwater ecosystems are highly complex and can propagate through the ecosystem in ways that are difficult to project. This is partly due to a poor understanding of arctic freshwater systems and their basic interrelationships with climate and other environmental variables, and partly due to a paucity of long-term freshwater monitoring sites and integrated hydro-ecological research programs in the Arctic. The papers in this special issue are an abstraction of the analyses performed by 25 international experts and their associated networks on Arctic freshwater hydrology and related aquatic ecosystems that was initially published by the Arctic Climate Impact Assessment (ACIA) in 2005 as "Chapter 8 - Freshwater Ecosystems and Fisheries". The papers provide a broad overview of the general hydrological and ecological features of the various freshwater ecosystems in the Arctic, including descriptions of each ACIA region, followed by a review of historical changes in freshwater systems during the Holocene. This is followed by an assessment of the effects of climate change on broad-scale hydro-ecology; aquatic biota and ecosystem structure and function; and arctic fish and fisheries. Potential synergistic and cumulative effects are also discussed, as are the roles of ultraviolet radiation and contaminants. The nature and complexity of many of the effects are illustrated using case studies from around the circumpolar north, together with a discussion of important threshold responses (i.e., those that produce stepwise and/or nonlinear effects). The issue concludes with summary the key findings, a list of gaps in scientific understanding, and policy-related recommendations.The variability of mercury (Hg) levels in Swedish freshwater fish during almost 50 years was assessed based on a compilation of 44 927 observations from 2881 waters. To obtain comparable values, individual Hg concentrations of fish from any species and of any size were normalized to correspond to a standard 1-kg pike [median: 0.69 mg kg(-1) wet weight (ww), mean +/- SD: 0.84 +/- 0.67 mg kg(-1) ww]. The EU Environmental Quality Standard of 0.02 mg kg(-1) was exceeded in all waters, while the guideline set by FAO/WHO for Hg levels in fish used for human consumption (0.5-1.0 mg kg(-1)) was exceeded in 52.5 % of Swedish waters after 2000. Different trend analysis approaches indicated an overall long-term decline of at least 20 % during 1965-2012 but trends did not follow any consistent regional pattern. During the latest decade (2003-2012), however, a spatial gradient has emerged with decreasing trends predominating in southwestern Sweden.Many aquatic mollusks, such as the freshwater pearl mussel (Margaritifera margaritifera), are in decline throughout Europe. The reasons are largely unknown; factors that have been suggested to contribute are river bed compaction due to agricultural practices, eutrophication, or pollutants of various natures. Brittle shells of recently deceased pearl mussels from northern Bavaria with weak calcium incrustations point to the possibility that calcium metabolism is affected. It is known that certain persistent organic pollutants and some heavy metals may induce calcium deficiency in wildlife. Elevated levels of the organochlorine insecticide DD and Its metabolite DDE, as well as of cadmium and some other heavy metals, have been found in pearl mussels. Both classes of environmental pollutants are known to potentially interfere with calcium homeostasis.Fisheries for arctic freshwater and diadromous fish species contribute significantly to northern economies. Climate change, and to a lesser extent increased ultraviolet radiation, effects in freshwaters will have profound effects on fisheries from three perspectives: quantity of fish available, quality of fish available, and success of the fishers. Accordingly, substantive adaptation will very likely be required to conduct fisheries sustainably in the future as these effects take hold. A shift to flexible and rapidly responsive 'adaptive management' of commercial fisheries will be necessary; local land- and resource-use patterns for subsistence fisheries will change; and, the nature, management and place for many recreational fisheries will change. Overall, given the complexity and uncertainty associated with climate change and related effects on arctic freshwaters and their biota, a much more conservative approach to all aspects of fishery management will be required to ensure ecosystems and key fished species retain sufficient resiliency and capacity to meet future changes.Polychlorinated biphenyls (PCBs) have been monitored in perch (Perca fluviatilis), pike (Esox lucius), and Arctic char (Salvelinus alpinus) in reference lakes since the late 1960s. Temporal trends and spatial patterns are currently monitored in nine and 32 lakes, respectively. Overall, PCB concentrations are decreasing. However, this is not consistent for all congeners across all lakes and species. Perch has comparatively low PCB concentrations relative to suggested target levels, but individual congener concentrations in some lakes are concerningly high. No temporal trend is seen for CB-118 and CB-153 in perch, but significant decreasing trends exist for Arctic char and pike, for which monitoring started earlier than for perch. The lower/higher chlorinated congener ratio decreased over time in most lakes, indicating fewer new emissions. CB-118 and CB-153 concentrations in perch show spatial gradients across Sweden, with higher concentrations found near urban/industrial areas.Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.We review known and hypothesized effects of nitrogen (N) deposition owing to human activities on the chemistry, organisms, and ecosystem processes of remote oligotrophic freshwaters. Acidification is the best-known effect of N deposition on water chemistry, but additional effects include increased nutrient availability and alteration of the balance between N and other nutrients. Our synthesis of the literature, framed in a comprehensive model for the effects of N deposition on natural ecosystems, shows that all these effects can reduce biological diversity and alter ecosystem processes in remote freshwaters. N deposition is projected to grow worldwide in the near future and will interact with other global changes. Present effects on these fragile ecosystems may be only early signs of more radical impacts ahead.Large variations exist in the size, abundance and biota of the two principal categories of freshwater ecosystems, lotic (flowing water; e.g., rivers, streams, deltas and estuaries) and lentic (standing water; lakes, ponds and wetlands) found across the circumpolar Arctic. Arctic climate, many components of which exhibit strong variations along latitudinal gradients, directly affects a range of physical, chemical and biological processes in these aquatic systems. Furthermore, arctic climate creates additional indirect ecological effects through the control of terrestrial hydrologic systems and processes, particularly those associated with cryospheric components such as permafrost, freshwater ice and snow accumulation/ablation. The ecological structure and function of arctic freshwater systems are also controlled by external processes and conditions, particularly. those in the headwaters of the major arctic rivers and in the adjacent marine environment. The movement of physical, chemical and biotic components through the interlinked lentic and lotic freshwater systems are major determinants of arctic freshwater ecology.Quantitative indicators are a common means of assessing the complex dimensions of a sustainable freshwater system, and framing scientific knowledge for policy and decision makers. There is an abundance of indicators in use, but considerable variation in terms of what is being measured and how indicators are applied, making it difficult for end-users to identify suitable assessment methods. We review 95 water-related indices and analyze them along their normative, procedural, and systemic dimensions to better understand how problems are being defined, highlight overlaps and differences, and identify the context(s) in which a particular index is useful. We also analyze the intended use, end-users, and geographic scale of application for each index. We find that risk assessment is the most common application (n = 25), with indices in this group typically focusing either on hazard identification (biophysical assessments) or vulnerability of human populations. Indices that measure freshwater ecological health are not explicitly linking these indicators to ecosystem services, and in fact the concept of ecosystem services is rarely (n = 3) used for indicator selection. Resource managers are the most common group of intended end-users (n = 25), but while 28 indices involved consultation with potential end-users, 11 did not specify an intended use. We conclude that indices can be applied as solution-oriented tools, evaluating scenarios and identifying tradeoffs among services and beneficiaries, rather than only assessing and monitoring existing conditions. Finally, earlier engagement of end-users is recommended to help researchers find the right balance among indices' salience, legitimacy, and credibility and thus improve their decision relevance.Species traits have been frequently used in ecological studies in an attempt to develop a general ecological framework linking biological communities to habitat pressures. The trait approach offers a mechanistic alternative to traditional taxonomy-based descriptors. This review focuses on research employing traits as biomonitoring tools for freshwater ecosystems, although the lessons learned have wider application in the assessment of other ecosystem types. 2. We review the support from ecological theory to employ species traits for biomonitoring purposes (e.g. the habitat templet concept, landscape filtering hypothesis), and the subsequent studies that test the hypotheses arising from these theories, and apply this knowledge under real freshwater biomonitoring scenarios. We also include studies that deal with more specific issues such as trait trade-offs and trait syndromes. 3. We highlight the functional trait approach as one of the most promising tools emerging for biomonitoring freshwater ecosystems. Several technical issues are addressed and solutions are proposed. We discuss the need for: a broader unified trait biomonitoring tool; a more accurate understanding of the natural variation of community patterns of trait expression; approaches to diminish the effects of trait trade-offs and trait syndromes; additional life history and ecological requirement studies; and the detection of specific impacts under multiple stressor scenarios. 4. Synthesis and applications. This review provides biologists with the conceptual underpinning for the use of species traits as community descriptors and for freshwater biomonitoring and management. We expect that the functional trait approach will ultimately improve communication to managers and legislators of the importance of protecting freshwater ecosystem functions.Recent advances in freshwater conservation planning allow addressing some of the specific needs of these systems. These include spatial connectivity or propagation of threats along stream networks, essential to ensure the maintenance of ecosystem processes and the biodiversity they sustain. However, these peculiarities make conservation recommendations difficult to implement as they often require considering large areas that cannot be managed under conventional conservation schemes (e.g. strict protection). To facilitate the implementation of conservation in freshwater systems, a multizoning approach with different management zones subject to different management regimes was proposed. So far, this approach has only been used in post hoc exercises where zones were allocated using expert criteria. This might undermine the cost-effectiveness of conservation recommendations, because both the allocation and extent of these zones have never been optimized using the principles of systematic planning. Here, we demonstrate how to create a catchment multizone plan by using a commonly applied tool in marine and terrestrial realms. We first test the capability of Marxan with Zones to address problems in rivers by using a simulated example and then apply the findings to a real case in the Daly River catchment, northern Australia. We also demonstrate how to address common conservation planning issues, such as accounting for threats or species-specific connectivity needs in this multizone framework, and evaluate their effects on the spatial distribution and extent of different zones. We found that by prioritizing the allocation of zones subject to different management regimes, we could minimize the total area in need of strict conservation by a twofold factor. This reduction can be further reduced (threefold) when considering species' connectivity needs. The integration of threats helped reduce the average threats of areas selected by a twofold factor.Synthesis and applications. Catchment zoning can help refine conservation recommendations and enhance cost-effectiveness by prescribing different management regimes informed by ecological needs or distribution of threats. Reliable information on these factors is a key to ensure soundness of planning. Freely available software can be used to implement the approach we demonstrate here. Catchment zoning can help refine conservation recommendations and enhance cost-effectiveness by prescribing different management regimes informed by ecological needs or distribution of threats. Reliable information on these factors is a key to ensure soundness of planning. Freely available software can be used to implement the approach we demonstrate here.1 Invertebrate grazing during the regeneration phase is well known to exert a strong structuring effect in terrestrial plant communities. However, very few studies have investigated the effect of invertebrate herbivores on regenerating freshwater angiosperms, despite the obvious benefits for the development of general theories in plant community ecology. 2 Our study investigated the parameters that determine the sensitivity of the freshwater macrophyte Potamogeton pectinatus L. to herbivory by the pond snail Lymnaea stagnalis (L.). P. pectinatus was raised from winter-collected tubers in aquatic microcosms and submitted to grazing by snails at various densities and starvation levels. 3 Newly sprouted P. pectinatus was much more sensitive to snail grazing than mature plants: survival of newly sprouted plants decreased as snail density increased, whereas the survival rate of mature plants was unaffected by snail density. Moreover, the sensitivity of newly sprouted P. pectinatus to herbivory decreased as its initial tuber mass increased. The damage to newly sprouted P. pectinatus by herbivory increased with snail starvation. However, the presence of an alternative, highly palatable, food (i.e. benthic algae) deflected feeding on P. pectinatus, even by extremely hungry snails. 4 These results demonstrate the potential structuring role exerted by gastropods during the regeneration of freshwater macrophytes, supporting results from terrestrial systems. They also suggest that regenerating plants may avoid invertebrate herbivory by modulating their intrinsic characteristics (e.g. increasing propagule size) or by emerging under favourable environmental conditions (e.g. low invertebrate density, presence of alternative food). Herbivory during the regeneration phase is therefore pivotal to our understanding of plant dynamics in aquatic as well as terrestrial ecosystems, and should be integrated into explicative models of vegetation patterns across various environments.1. Eutrophication is a major threat for freshwater ecosystems. Submerged aquatic plants (macrophytes) can maintain clear water conditions in eutrophic lakes by competing with phytoplankton for light and nutrients. The interactions between macrophytes and phytoplankton may lead to indirect facilitation among plants and the maintenance of high macrophyte diversities in eutrophic conditions. Nonetheless, the role of indirect facilitation in promoting macrophyte-dominated clear water states under eutrophication has never been demonstrated experimentally despite important implications for these ecosystems. 2. We predicted that (i) submerged aquatic plants buffer negative consequences of eutrophication by strongly affecting biotic (phytoplankton) and environmental conditions (light, nutrients) in the water column, (ii) competition with phytoplankton results in indirect facilitation among submerged aquatic plants, and (iii) the response to indirect facilitation depends on the tolerance of submerged aquatic plants to light attenuation by phytoplankton. 3. We experimentally simulated eutrophication through fertilization and manipulated the presence of neighbouring plants in a mesocosm. By manipulating the presence of neighbours with and without fertilization, we were able to test whether competitive or facilitative interactions occur during the eutrophication of lakes. 4. Fertilization caused turbid water states by increasing phytoplankton content and light attenuation. The presence of neighbouring plants reduced phytoplankton growth and promoted survival and biomass production of macrophytes under eutrophication. 5. Synthesis. Indirect facilitation among plants can buffer the direct negative interactions between aquatic plants and phytoplankton. Indirect facilitation may prevent the decline in aquatic plant diversity of freshwater ecosystems threatened by eutrophication. Because the experimental design used here is comparable to the manipulations frequently carried out across a wide range of terrestrial ecosystems, this study may contribute to the comparison of patterns and processes in aquatic and terrestrial environments.Understanding and predicting the likely consequences of anthropogenic disturbance on species and ecosystems is a major prerequisite of achieving the sustainable use of natural resources. It is also a key element in the management of sites with statutory designation. During planning and decision-making processes involving potential disturbance issues, land managers and responsible authorities are often required to take account of the needs and views of a diversity of site user groups. The effects and impacts of disturbance can occur over a range of spatial and temporal scales, and research into these consequences must address this problem. This paper provides (1) an overview of the field and analytical methodologies contributing to the development of an integrated method for collecting multi-scale bird, resource and disturbance data in freshwater systems, and (2) an overview of the drivers and need for such data in sustainable resource management. Whilst the results of the bird-habitat-disturbance modelling arising from these data will be published elsewhere, the types of information that will be generated are illustrated and their potential use within planning and decision-making processes discussed.Scaly-sided Mergansers Mergus squamatus breed on freshwater rivers in far eastern Russia, Korea and China, wintering in similar habitats in China and Korea, but nothing was known of their moulting habitat. To investigate the moult strategies of this species, we combined wing feather stable isotope ratios (males and females) with geolocator data (nesting females) to establish major habitat types (freshwater, brackish or saltwater) used by both sexes during wing moult. Although most Scaly-sided Mergansers of both sexes probably moult on freshwater, some males and non-breeding and failed breeding females appeared to undertake moult migration to brackish and marine waters. Given the previous lack of any surveys of coastal or estuarine waters for this species during the moult period, these findings suggest important survey needs for the effective conservation of the species during the flightless moult period.Indigenous communities worldwide have long relied on their environment for survival. Religious and customary beliefs that foster community conservation have not only bound these communities to ecosystems but also assisted in the conservation of species. We provide an example of how religion fosters the conservation of freshwater fishes in India. Since ancient times rural communities in India have revered fish species as symbols of divine power, and offered them protection in pools associated with temples. Such voluntary, informal institutions and arrangements continue to help conserve several freshwater fish species that are otherwise subjected to anthropogenic pressure in open-access areas. However, religious beliefs in India are waning as a result of increased urbanization, modernization of societies and disintegration of rural communities, and the sustainability of existing temple and community fish sanctuaries is questionable. We discuss the role of temple sanctuaries as an informal conservation strategy for freshwater fishes, and discuss the knowledge and policy gaps that need to be addressed for ensuring their future.Mahseer are popularly regarded by anglers as the king of freshwater fishes, and are valued across the Himalayan and South-east Asian regions. In India, mahseer are important game fish. Mahseer populations and their habitats face a range of anthropogenic threats, however, including unregulated fishing and habitat fragmentation as a result of hydro-development projects. Catch-and-release angling for mahseer attracts both national and international anglers and could provide information about rivers while generating revenue for regional economies. In this context, we evaluated catch-and-release angling records from rivers that flow within two Indian reserves (the Ramganga and Jia Bharali Rivers in Corbett and Nameri Tiger Reserves, respectively). Golden mahseer Tor putitora in the Ramganga and golden and chocolate mahseer Neolissochilus hexagonolepis in the Jia Bharali were the most frequently caught fish species. Catch data suggested these game fish populations are probably not negatively affected by angling activities. Interviews with stakeholders highlighted support for catch-and-release angling, mainly because of its perceived economic benefits. The data obtained in this research could potentially assist with both fish conservation and the protection of associated aquatic ecosystems.To maintain their position within the tidal frame, tidal marshes must accrete upward at approximately the same rate as relative sea-level rise (RSLR), typically accomplished through accumulation of mineral (from fluvial, estuarine, and/or coastal waters) and/or organic (plant-derived) sediments. However, accelerating RSLR and declining fluvial suspended-sediment supplies, along with other direct anthropogenic disturbances, may limit the ability of many marshes to keep pace. This study tests hypotheses addressing the relationship of marsh surface elevation and channel influence to marsh accretion and evaluating marsh response to historic mining disturbance and long-term environmental change, using Dyke Marsh Preserve, a tidal freshwater marsh located along the Potomac River estuary (Chesapeake Bay watershed) as a model system. Variability in sediment characteristics (grain size, organic content, bulk density) and decadal-scale accretion rates (using Pb-210) across the marsh platform is related to ecogeomorphic setting, anthropogenic activities (mining), and long-term changes in river sediment supply and RSLR. In general, sediment on river/tidal-channel banks accumulates faster and is more influenced by fluvially derived sediment than in the marsh interior. Accumulation rates on the banks can be predicted using proxies for sediment supply and availability most of the time; however, these relationships do not hold for the marsh interior, highlighting the role of sediment redistribution and/or complex sediment-vegetation interactions. Development of temporally variable sediment rating curves reveals that suspended-sediment loads of the Potomac River have decreased since the late 1970s, although current loads appear adequate to support accretion on the marsh platform, if net onshore sediment-transport mechanisms exist.The Singapore freshwater crab Johora singaporensis is known only from three streams in Singapore and is among the top 100 most threatened species in the world. It is the only member of the genus Johora, endemic to the Malay Peninsula, to be categorized as Critically Endangered on the IUCN Red List. Extensive surveys conducted over 1 year to determine the extent of the species' distribution revealed that the population has declined significantly at its type locality in Bukit Timah Nature Reserve, Singapore Island's oldest protected forest area. The species remains extant in two unprotected streams in Bukit Batok and Bukit Gombak, which are located outside the nature reserve. Acidification of streams as a result of acid precipitation may be a factor in the decline of the species. If so, this will be the first documented instance of a species being affected negatively by anthropogenic acidification of a tropical freshwater system. The occurrence of this threatened species in a protected area has not, therefore, guaranteed its survival. There is a need for long-term and continuous monitoring of species of high conservation value, together with other measures that focus on habitat protection. Conservation efforts by the National Parks Board of Singapore in collaboration with other government agencies are ongoing in an effort to ensure the survival of this important species.