February 19, 2020

Julian Olden, a UW professor of aquatic and fishery studies, is a member of a global working group that aims to reverse the rapid worldwide decline in freshwater ecosystem biodiversity by advising international agreements. 

Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one-third of all vertebrate species. This biodiversity is declining dramatically: Globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but coordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to bend the curve of freshwater biodiversity loss. Priority actions include accelerating implementation of environmental flows; improving water quality; protecting and restoring critical habitats; managing the exploitation of freshwater ecosystem resources, especially species and riverine aggregates; preventing and controlling nonnative species invasions; and safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological Diversity and the Sustainable Development Goals and roles for national and international state and nonstate actors.

Humans have caused widespread planetary change, ushering in a new geological era, the Anthropocene (a term first coined in the 1980s by Eugene F. Stoermer, a freshwater biologist). Among many consequences, biodiversity has declined to the extent that we are witnessing a sixth mass extinction. Recent discourse has emphasized the triple challenge of bending the curve of biodiversity loss while also reducing climate change risks and improving lives for a growing human population. In 2020, governments will review international agreements relevant to this challenge, including the Convention on Biological Diversity (CBD) and the Sustainable Development Goals (SDGs). There is a brief window of opportunity now to set out recommendations that can inform these agreements and guide future policy responses.

Nowhere is the biodiversity crisis more acute than in freshwater ecosystems. Rivers, lakes, and inland wetlands (such as deltas, peatlands, swamps, fens, and springs) are home to an extraordinary diversity of life. Covering less than 1% of Earth’s surface, these habitats host approximately one-third of vertebrate species and 10% of all species, including an estimated 70 species of freshwater-adapted mammals, 5700 dragonflies, 250 turtles, 700 birds, 17,800 fishes, and 1600 crabs. The levels of endemism among freshwater species are remarkably high. For instance, of the fish species assessed for the freshwater ecoregions of the world, over half were confined to a single ecoregion.

Freshwater ecosystems also provide services to billions of people, including impoverished and vulnerable communities. However, the management of freshwater ecosystems worldwide has frequently prioritized a narrow range of services for macroeconomic benefit at the expense of habitats, flora and fauna, and the diverse benefits they provide to communities. Consequently, the current rate of wetland loss is three times that of forest loss, and populations of freshwater vertebrate species have fallen at more than twice the rate of land or ocean vertebrates. Of the 29,500 freshwater dependent species so far assessed for the IUCN Red List, 27% are threatened with extinction. Among these, an estimated 62% of turtle species, 47% of gastropods, 42% of mammals, 33% of amphibians, 30% of decapod crustaceans (crabs, crayfish, and shrimps), 28% of fishes, and 20% of birds are at risk. Populations of freshwater megafauna, defined as animals that reach a body mass of 30 kilograms, declined by 88% from 1970 to 2012, with the highest declines in the Indomalaya and Palearctic realms (−99% and −97%, respectively).

The causes of these declines have been comprehensively synthesized, but no global framework exists to guide policy responses commensurate with the scale and urgency of the situation, and actions to safeguard freshwater biodiversity have been “grossly inadequate”. Recommendations to address immediate threats to and underlying drivers of global biodiversity loss have focused mainly on terrestrial ecosystems, such as forests and grasslands or have emphasized particular conservation strategies, such as enhancing protected area coverage and condition. Although they are valuable, these proposals have either assumed, simplistically, that measures designed to improve land management will inevitably benefit freshwater ecosystems, or they have neglected to consider freshwater biodiversity at all. Anthropogenic threats distinct to freshwater ecosystems, especially those linked to hydrological regimes and loss of connectivity, have been insufficiently considered in international conservation agreements and conventional conservation strategies, impeding investment in appropriate policy and management measures and contributing inadvertently to the disproportionately high losses of freshwater species and habitats.

In this article, we present an Emergency Recovery Plan to reverse the rapid worldwide decline in freshwater biodiversity. This plan extends the concept of species recovery plans established in legislation such as the US Endangered Species Act 1973 and the Australian Environment Protection and Biodiversity Conservation Act 1999. Given the speed and extent of collapse in freshwater biodiversity, parallels can be drawn with postdisaster recovery situations, and we have deliberately used the word emergency to convey the urgency with which conservationists, water managers, stakeholders, and policymakers must act to avoid further deterioration of habitats and to promote recovery of biodiversity. The plan is novel in this conceptual foundation, in its focus on solutions (rather than documentation of threats) and in its explicit recommendations for international agreements, especially the CBD and the SDGs.