One-quarter of freshwater fauna threatened with extinction
In a new Nature article, some 88 scientists and IUCN collaborators from all over the world involved in a twenty-year IUCN effort to assess various groups of freshwater animals have reported that a quarter of the planet's freshwater fauna is threatened with extinction.
Fishers at a landing site on Lake Edward in Uganda.
Jos Snoeks, © RMCA Tervuren
Typical of a quiet crisis is that few people are aware of it. The strong decline of biodiversity in freshwater systems worldwide is one such quiet crisis. To a large extent, what happens under water is a case of ‘out of sight, out of mind’. For a long time, freshwater systems and their fauna and flora have been neglected in comprehensive assessments, conservation management plans, planning of protected areas, and even in the renowned UN sustainable development goals.
Some 88 scientists and IUCN collaborators from all over the world, involved in a twenty-year IUCN effort to assess various groups of freshwater animals, have just reported in Nature that a quarter of the planet's freshwater fauna is threatened with extinction.
A co-author of the report, Jos Snoeks of the AfricaMuseum and KU Leuven has been working with IUCN for two decades and was involved in many assessment projects and regional workshops in Africa. He says that the results of the global report also apply to Africa but, as is typical for tropical regions, the fish diversity in sub-Saharan Africa is very rich, with many species being data deficient. In other words, reliable data for their assessment are missing.
“One also has to take into account that for African freshwater systems, the scientific work underpinning these analyses is far from completed. Many lakes, rivers and other wetlands have not been properly explored, and over a thousand fish species remain to be scientifically described,” he stresses, “so there is a real worry that species disappear before they even have been discovered”.
He adds that some aquatic systems in Africa are quite unique. “Within the African Rift valley lakes, one finds the largest concentration of vertebrate species on earth, with Lake Malawi as the front-runner with more than 1,000 fish species. Less than half of them have been described. The Congo system is also exceptional; it is one of the fish species-richest rivers in the world after the Amazon. And also here an estimated several hundred species still have to be described.
But other issues are also at stake. Snoeks explained that in Africa, more so than in other continents, inland fisheries provide a major source of animal protein, micronutrients and vitamins to millions of people. If overfishing and other threats to freshwater systems and their organisms continue, then these fisheries themselves are threatened in their sustainability.
The Nature publication also discusses the manifold threats that freshwater animals face, which differ between animal groups and regions. The highest concentration of threatened species that may already be extinct is found in Lake Victoria. Snoeks explains that this is due to a combination of threats. “Over the last forty years, we have seen the Lake Victoria ecosystem deteriorating. Prominent factors responsible for this are the introduction of several non-native fish species amongst which the Nile perch, a large predator; the arrival of water hyacinth, an invasive floating plant that has covered large areas in the lake; overfishing; sedimentation; and pollution owing to the strong increase in human populations living along banks and shores”.
The Africa Museum is one of the world’s leading institutes for studies on African freshwater fishes and has played a prominent role in training many African fish biologists.
Read the original publication One-quarter of freshwater fauna threatened with extinction here.
More information on African fishes can be found on Fishbase for Africa.