Invasive species threaten Great Lakes
Posted by: Aqua Blog Maven on July 8, 2008 at 8:21 pmFrom NPR:
The blue-green waters of the Great Lakes seem cleaner and clearer than ever before — but while cleaner is good, clearer isn’t necessarily so. “It’s a bad thing because the water looks clean because it’s becoming sterile,” says Cameron Davis, president of the Alliance for the Great Lakes, at a recent visit to a beach in Evanston, Ill.
He says zebra mussels and other invasive species that have worked their way into the Great Lakes filter out the food, making the water clear. At the same time, he says, “it’s really stripping the food base out of the food web, such that we’re really in danger of unraveling the food chain we have in this region.”
Zebra mussels first invaded the Great Lakes through the ballast water of ships from Europe about 20 years ago. Colonies accumulate on the water intake and discharge pipes of power plants, municipal water plants, irrigation systems and even on boat hulls and motors, causing frequent problems. But they wreak havoc on ecosystems because they consume huge amounts of phytoplankton, like algae, effectively starving populations of native fish and other water wildlife.
And now scientists say that another invasive mussel has arrived that might even be doing worse damage to the lakes. The thumbnail-sized quagga mussel, also carried in ballast water, is native to the Russian area of the Black Sea and first began appearing in the Great Lakes about a decade ago. Quagga populations tripled between 2005 and 2007 to a quadrillion, according to National Oceanic and Atmospheric Administration estimates. Quaggas now carpet the bottom of Lake Michigan and parts of the other Great Lakes. To some extent, they are even crowding out the zebra mussels.
The result is fewer and thinner fish being caught by both commercial and recreational fishermen. Read the full text of this article from NPR by clicking here. In a related story also from NPR, find out how dogs are being used to sniff out mussels by clicking here.
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