Do protected areas conserve freshwater biodiversity?

 
The Convention on Biological Diversity (CBD) has an ambitious vision: “By 2050, biodiversity is valued, conserved, restored and wisely used, maintaining ecosystem services, sustaining a healthy planet and delivering benefits essential for all people”. To achieve this vision, the CBD set out 20 so-called Aichi Targets to be met by 2020. Yet, in 2020 biodiversity is still significantly declining with no apparent slow down. The steepest biodiversity decline of all has been observed in freshwater ecosystems, where one third of species assessed are considered to be at risk of immediate extinction (IUCN, 2018) and where vertebrates have declined at twice the rate of those within terrestrial and marine ecosystems (WWF, 2018).

The establishment of protected areas is a backbone conservation measure recognised by Aichi Target 11, which aims for at least 17% of global inland waters to be protected by 2020. There’s evidence that progress has been made as 15% of global inland waters are now thought to be within protected areas (Bastin et al., 2019). Furthermore, Ramsar sites (wetland sites designated to be of international importance under the Ramsar Convention) have continued to increase; there are now 2341 sites which cover 2.5 million km² of inland waters across 170 countries (Ramsar, 2019). Yet, given this apparent progress, why is freshwater biodiversity continuing to decline in such a dramatic way?  One indication may come from the apparent patchy coverage of protected areas, for example within parts of Asia and Africa. Bastian et al. (2019) found that less than 5% of inland waters are protected, whilst Abell et al. (2017) found that only around 10% of large rivers and Reis et al. (2017) discovered that only around 11% of seasonal wetland is protected globally.

Don’t forget the small print…

Aside from having a sufficient coverage of protected areas, what else could be happening to cause such dramatic losses in freshwater biodiversity?  Are we missing something important? Why is the ‘small print’ essential for making protected areas more effective for the conservation and restoration of freshwater biodiversity?

WWF-supported research is providing some insight into this critical question.  A recent research objective was to understand the benefits that protected areas have had for freshwater species to date, and under what circumstances they had been successful or had failed to conserve freshwater biodiversity.  To do this we undertook a Quick Scoping Review (QSR), led by Professor Mike Acreman. QSR’s provide a standardised non-biased approach to searching and analysing the available scientific literature on a pre-defined topic.  Our search criteria identified publications containing evidence of empirical data (for example, maintenance or increase in the population size of a species or improvement in habitat) compared to a counterfactual. Although described as “quick”, this approach is still relatively time-consuming. The study took over six months, analysed around 2500 papers and was peer reviewed with the support of world-leading experts, including by Professor Angela H. Arthington.

Results

The review identified 75 case studies which set out to describe how freshwater wildlife changed with protected area designation and the design and management across a broad range of species and global geographies. Of these 75 case studies:

• 51% showed a positive outcome;
• 33% showed a neutral outcome;
• 16% showed a negative outcome.

This doesn’t mean that other protected areas are not effective, but just that no evidence has been published to show if this has or has not been the case. Very few studies recorded reasons why the protected area had been successful, but multiple reasons were provided for the reported neutral and negative impacts. These included a lack of enforcement, habitat degradation, installation of dams, over-abstraction of water, invasive non-native species and other environmental problems (such as climate change or poor landscape management). 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 within a number of case studies.

The review of 75 case studies identified eight lessons that are considered essential for protected area implementation to have a positive impact for freshwater biodiversity:

Lesson 1: Monitoring and research are necessary to understand that effectiveness should be built into management of protected areas.

Lesson 2: Protected areas need to be of sufficient size and configuration to connect diverse elements of the waterscape and maintain their biodiversity.

Lesson 3: Areas designated to protect terrestrial ecosystems can contribute to freshwater biodiversity protection if they are located, designed and managed appropriately.

Lesson 4: Incorporating the conservation of aquatic habitats, including hydrological regime, water quality and riparian vegetation into protected area strategies is vital to maintaining freshwater biodiversity.

Lesson 5: Protected areas should be free of external and internal pressures from inappropriate, illegal or unregulated land and water management.

Lesson 6: Well-managed protected areas can provide a refuge for native species against invasive non-native species.

Lesson 7: Meeting socio-economic protected areas objectives, such as grazing, tourism and recreation, may result in a trade-off against biodiversity.

Lesson 8: Laws and regulations associated with protected areas need to be enforced, but regulation activities should involve engagement of local communities.

The full review has been published by Conservation Letters and is available here: https://conbio.onlinelibrary.wiley.com/doi/10.1111/conl.12684