12 October 2009
"Catastrophic decline" in freshwater biodiversity
by Kate Melville
Mismanagement and growing needs for water are causing freshwater ecosystems to collapse, making freshwater species the most threatened on Earth with extinction rates 4 to 6 times higher than their terrestrial and marine cousins, say scientists at the DIVERSITAS 2nd Open Science Conference, in Cape Town, South Africa.
Klement Tockner, of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, explains that while freshwater ecosystems cover only 0.8 percent of the Earth's surface, they contain roughly 10 percent of all animals, including an astonishing 35 percent of all vertebrates.
"There is clear and growing scientific evidence that we are on the verge of a major freshwater biodiversity crisis," warns Tockner. "However, few are aware of the catastrophic decline in freshwater biodiversity at both local and global scale. Threats to freshwater biodiversity have now grown to a global scale."
The human implications of this trend are "immense," he adds, because freshwater species in rivers, lakes, ground waters, and wetlands provide a diverse array of vital natural services - more than any other ecosystem type. The problem puts billions of people at risk as biodiversity loss affects water purification, disease regulation, subsistence agriculture and fishing.
Freshwater ecosystems and their species also absorb about 7 percent of the carbon humans add annually to the atmosphere. "Although small in area, these freshwater aquatic systems can affect regional carbon balances," Tockner says. "Freshwater ecosystems will be the first victims of both climate change and rising demands on water supplies. And the pace of extinctions is quickening - especially in hot spot areas around the Mediterranean, in Central America, China and throughout Southeast Asia."
To highlight the ecological and economic importance of freshwater ecosystems, Tockner and colleague Charles Vörösmarty, of the City University of New York, will present their research at the conference and encourage fellow scientists to help formulate clear government policy recommendations and future research priorities.
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