Great Lakes face stresses from run-off, invaders

10-04-2011 // Andrew Stern

This excerpt is from Reuters.

Leilani Munter

The five lakes, which contain one-fifth of the world's fresh water and supply tens of millions of people, may be "veering close to ecosystem collapse," the report by the National Wildlife Federation said.

"Too much food is causing massive algal blooms in Lake Erie and other coastal systems, while too little food is making fish starve in Lake Huron's offshore waters," said the group's Great Lakes director, Andy Buchsbaum.

There are many problems afflicting the Great Lakes, which in other ways have grown healthier after years of pollution.

This past summer, Lake Erie was choked by toxic algae blooms up to 2 feet thick and 10 miles wide, and algae coated some Lake Michigan coastlines. Water treatment removes the toxin, at a cost, but often creates an unpleasant odor, one of the report's authors, Julie Mida Hinderer, said in an interview.

In deeper water, prolific quagga mussels have beaten out zebra mussels and colonized vast stretches of the lake bottoms, filtering out vital plankton that is the base of the lakes' food web. This has starved small fish such as alewives, bloater fish, and rainbow smelt that in turn has hurt populations of top lake predators such as whitefish and salmon.

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