|Titre :||How effective is protected area designation for the conservation and restoration of freshwater biodiversity? A systematic evidence review.|
|Auteurs :||Mike Acreman, Auteur ; Manuel Angel Duenas-Lopez, Auteur|
|Type de document :||Rapport|
|Editeur :||[S.l.] : WWF-UK, February 2019|
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
|En ligne :||https://www.wwf.org.uk/sites/default/files/2019-02/QSR%20Protected%20Areas%20and%20Freshwater%20Biodiversity%20Final%20Report%2020%20February%202019.pdf|