What is happening to freshwater species?
Freshwater environments are some of the most biologically diverse on Earth. From hippos to goldfish, ducks to dragonflies, there are to date 126,000 freshwater dependent species of animal and plant occupying less than 1% of Earth’s last surface. This incredible concentration of flora and fauna means these habitats are akin to coral reefs and tropical rainforests. Among this encyclopaedia of life are fish adorned with kaleidoscopic colour, dolphins and sharks which have adapted life in rivers, and plants which survive by clinging on to rocks in rapid flowing riffles.
This astonishing wealth of life is at risk of being lost. Freshwater ecosystems are hotspots not only for biodiversity, but also for endangerment. Based on a sample of 3,358 monitored populations of 880 species, the abundance of life in freshwater habitats is estimated to have fallen by 83% between 1970 and 2014 (WWF 2018) – far outstripping the pace of decline in marine or terrestrial habitats. The IUCN Red List of Threatened Species (the Red List) is the globally recognised tool for assessing the risk of species’ extinction. Of the freshwater species comprehensively assessed through the Red List, approximately one third are under immediate threat of extinction (IUCN 2017). Freshwater fish and amphibians, both freshwater-dependent species, compete for the unwanted title of the vertebrate group most threatened with extinction.
For example, in North America alone 53 species of freshwater fish have gone extinct since the start of the 20th century – a rate of extinction which is at least 877 times the natural rate for freshwater fish (Burkhead 2010). Many of the same developments which drove those North American extinctions are now playing out in tropical basins where freshwater fish diversity and endemism are much higher (e.g. see Winemiller et al., 2016). In 2013, the Asian Development Bank rated more than 80% of Asia’s rivers as ‘in poor health’ due to dams and pollution (Asian Development Bank 2013).
Drivers of decline
The decline in freshwater biodiversity has been intimately tied to human engineering of freshwater environments and their associated transition from natural habitats to industrial waterways. This has seen freshwater systems pushed further and further away from the natural conditions in which species evolved, disrupting their ecological functioning, often at great biological, social and economic cost.
The cumulative impact of such diverse threats, combined with gaps in knowledge and increasingly pronounced shifts in global and local climates, explain why freshwater species are so imperilled.
What conservation action is being taken?
Given the scale and pace at which we are losing freshwater species, one might expect a highly developed global conservation effort. However, the world’s freshwater ecosystems are under-inventoried and their protection receives a disproportionately low level of funding and attention.
Over the past decade, there has been a greater recognition of the role of freshwater environments as examples of “natural capital”, with green and blue infrastructure often proving to be more cost-effective than further engineering interventions in providing many of the services upon which our societies depend. Planning paradigms such as “Integrated Water Resource Management’’ have begun to place a value on the ecological functionality of freshwater environments and a number of major NGOs undertake important work on large-scale river basin planning in partnership with local and national governments, which is slowly changing planning approaches for the better.
However, at the site or species-specific scale there, there has been a dearth of conservation action (e.g. see Reis 2013). This can be problematic for freshwater species given that many freshwater environments are localised, with the evolution of species with small geographic ranges, often confined to a single lake or drainage basin (i.e. endemic species) (Dudgeon & Strayer, 2010). While some taxonomic groups such as waterbirds, river dolphins, crocodiles, turtles and salmonids have received some conservation attention, for the majority of freshwater species there have been very few targeted interventions.
Remarkably, there is no international conservation NGO dedicated to conserving the species that live within freshwater ecosystems The Ramsar Convention has drawn the attention of Government’s around the world to the value of wetland habitats (not lakes or rivers), yet 49% of the freshwater sites listed under the Convention do not have management plans and there is no certainty on whether they are being managed effectively for freshwater species (Finlayson et al., 2018).
Freshwater conservation receives just 3.2% of grant funding from European environmental foundations (Cracknell et al., 2016) and an analysis by Synchronicity Earth of freshwater conservation funding from 2012-2015 showed that only 6.6% went towards projects which specifically targeted the conservation of one or a subset of freshwater species. This concurs with findings of other major funding analyses –biodiversity itself is a very peripheral focus of most water-related conservation. The bottom line is that not enough (and in many cases, nothing at all) is currently being done to prevent the extinction of freshwater species.
Asian Development Bank, 2013, Asian Water Development Outlook 2013, Asia-Pacific Water Forum
Dudgeon D., 2012, Threats to freshwater biodiversity globally and in the Indo-Burma Biodiversity Hotspot, in: Allen D.J, Smith K.G, Darwall W.R.T, The Status and Distribution of freshwater biodiversity in Indo-Burma. IUCN, Cambridge
Finlayson C.M, Arthington A.H, Pittock J, 2018, Freshwater Ecosystems in Protected Areas, Routledge
IUCN, 2017, The IUCN Red List of Threatened Species, Accessed 31.018, Version 2017-2, http://www.iucnredlist.org
Liermann C.R., Nilsson C., Robertson J., Ng R.Y., 2012, Implications of Dam Obstruction for Global Freshwater Fish Diversity, BioScience 62, (6), pp.539-548
Reis R.E, 2013, Conserving the freshwater fishes of South America, International Zoo Yearbook 47 (1) pp. 65-70
World Water Assessment Programme (WWAP), 2009, The United Nations World Water Development Report 4: Water in a Changing World. UNESCO and Earthscan
Winemiller, K.O., McIntyre, P., Castello, L., Fluet-Chouinard, E., et al. (2016). Hydropower expansion in the Amazon, Congo and Mekong – a looming threat to global biodiversity. Science 351 (6269): 128-129.
WWF, 2018, Living Planet Report – 2018: Aiming Higher. Grooten M and Almond R.E.A (Eds.) WWF, Gland, Switzerland