Creatures and plants living in rivers and lakes are the most threatened on Earth because their ecosystems are collapsing, according to scientists.
They urged the creation of a new partnership between governments and scientists to help stem extinctions caused by humans via pollution, a spread of cities and expanding farms to feed a rising population, climate change and invasive species.
Governments globally had aimed to slow the losses of all species by 2010.
"Massive mismanagement and growing human needs for water are causing freshwater ecosystems to collapse, making freshwater species the most threatened on Earth," according to Diversitas, an international grouping of biodiversity experts.
Extinction rates for species living in freshwater were "four to six times higher than their terrestrial and marine cousins." Fish, frogs, crocodiles or turtles are among freshwater species.
"The 2010 target isn't going to be met," said Hal Mooney, a professor at Stanford University, who is chair of Diversitas.
Diversitas will hold talks among more than 600 experts in Cape Town, South Africa, from today to Friday to discuss ways to protect life on the planet.
World leaders agreed at a 2002 Earth Summit in Johannesburg to achieve by 2010 a "significant reduction in the current rate of loss of biological diversity."
"Changes to ecosystems and losses of biodiversity have continued to accelerate ... Species extinction rates are at least 100 times those in pre-human times and are expected to continue to increase," Georgina Mace of Imperial College in London, vice-chair of Diversitas, said in a statement.
Dams, irrigation and climate change that is set to disrupt rainfall are all putting stresses on freshwater habitats. Canals allow plants, fish and other species and diseases to reach new regions.
"You can travel from France to Russia without going to the sea anymore," Klement Tockner of the Leibnitz Institute of Freshwater Ecology and Inland Fisheries, told Reuters. "Mixing is much faster and more severe than in marine and terrestrial habitats." By 2025, some experts predict that not a single Chinese river will reach the sea except during floods, with tremendous effects for coastal fisheries in China, Diversitas said.
Dr Tockner said freshwater ecosystems covered 0.8 percent of the Earth's surface but accounted for about 10 percent of all animals.
The UN has also turned sceptical about achieving the 2010 goal after long saying that it was too early to judge.
In Cape Town, experts will try to work out better goals for slowing extinctions, by 2020 and beyond.
Anne Larigauderie, executive director of Diversitas, urged creation of a new panel for monitoring extinctions modelled on the Intergovernmental Panel on Climate Change (IPCC), whose findings are approved both by scientists and governments.