Current patterns of freshwater use are creating a crisis for much of the world, and cannot be sustained if human populations reach 10,000 million by the year 2050 as predicted, the conference was told.
This warning imposes responsibilities on scientists who study freshwater ecosystems to understand better the factors and processes that affect the world's inland waters to ensure their protection and restoration, according to Prof Carolyn Burns of the University of Otago, New Zealand.
In her address as president of International Association of Limnology, she said many regions of the world had only the remnants of once large wetland ecosystems.
"On a global scale, the loss of wetlands, and the species they contain, represents one of the greatest reductions in biological diversity this century," she said.
The loss of wetland biodiversity had been brought about by a variety of assaults including drainage, infilling, eutrophication, burning, pollution and the intentional and accidental introduction of exotic (non-native) species.
These threats had been heightened by changes in land use and water quality; attempts to improve fisheries, "biological control programmes" involving the use of exotic species, and the spread and intensification of aquaculture involving exotic species and aggressive native species that escape into the wild.
Genetic diversity had also been threatened by the development and release of genetically modified organisms, she said.
The environmental and economic difficulties caused by the spread of the zebra mussel from the US (it has been found in Ireland in recent years), increasing human health problems caused by some bloom-forming cyano bacteria and the spread of waterborne disease caused by giardia and cryptosporidium also illustrated how the threat could manifest itself.
"Our abilities as scientists to predict and manage the consequent changes in biological diversity and ecosystem structure and function have never been needed more than they are now," Prof Burns said.
