Posted: Oct 02, 2010 12:48 am
World's Rivers in 'Crisis State', Report Finds
ScienceDaily (Oct. 1, 2010) — The world's rivers, the single largest renewable water resource for humans and a crucible of aquatic biodiversity, are in a crisis of ominous proportions, according to a new global analysis.
The report, published Sept. 30 in the journal Nature, is the first to simultaneously account for the effects of such things as pollution, dam building, agricultural runoff, the conversion of wetlands and the introduction of exotic species on the health of the world's rivers.
The resulting portrait of the global riverine environment, according to the scientists who conducted the analysis, is grim. It reveals that nearly 80 percent of the world's human population lives in areas where river waters are highly threatened posing a major threat to human water security and resulting in aquatic environments where thousands of species of plants and animals are at risk of extinction.
"Rivers around the world really are in a crisis state," says Peter B. McIntyre, a senior author of the new study and a professor of zoology at the University of Wisconsin-Madison's Center for Limnology.
The Nature report was authored by an international team co-led by Charles J. Vörösmarty of the City University of New York, an expert on global water resources, and McIntyre, an expert on freshwater biodiversity.
Examining the influence of numerous types of threats to water quality and aquatic life across all of the world's river systems, the study is the first to explicitly assess both human water security and biodiversity in parallel. Fresh water is widely regarded as the world's most essential natural resource, underpinning human life and economic development as well as the existence of countless organisms ranging from microscopic life to fish, amphibians, birds and terrestrial animals of all kinds.
Over many millennia, humans have exerted an increasingly pervasive influence on fresh water resources. Rivers, in particular, have attracted humans and have been altered through damming, irrigation and other agricultural and engineering practices since the advent of civilization. In recent times, chemical pollution, burgeoning human populations, and the accidental as well as purposeful global redistribution of plants, fish, and other animal species have had far-reaching effects on rivers and their aquatic inhabitants.
"Flowing rivers represent the largest single renewable water resource for humans," notes Vörösmarty. "What we've discovered is that when you map out these many sources of threat, you see a fully global syndrome of river degradation."
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