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Great Lakes Article:

Alien species problem must remain priority
Port Clinton News Herald
Editorial
08/19/03


The growing belief that zebra mussels may be causing a "dead zone" in Lake Erie provides further evidence of the importance of efforts to control invasive species in the nation's waterways.

Researchers are finding that the thumbnail-size zebra mussel and the Quagga mussel are altering the food chain and habitat in the lake.

Those researchers think that those changes are behind the low-oxygen area that is a dead zone in the lake.

High levels of phosphorus are believed to be behind the dead zone that occurs in the central basin of the lake between sping and fall. Colder, more dense water stays at the bottom and cannot be replenished with oxygen, creating an environment in which it is difficult to sustain life.

Scientists are focusing on three theories on what's causing the high phosphorus levels: climate, increased phosphorus releases from farms and sewage treatment plants and internal changes in the lake.

Many are pointing to changes caused by the mussels that have replaced tiny animal and plant life that once floated in the water.

This makes the water clearer, allowing algae to grow at deeper levels.

The mussel problem is becoming more complicated as the quagga, which lives in lower temperatures and deeper waters, has become more dominant than the zebra mussel.

Scientists and public officials have been trying for years to gain control over the invasive species, fearing the possible impact on existing species and the Great Lakes in general.

Most of the dozens of alien species introduced into the Great Lakes arrive in the water that ships carry in ballast tanks. Ships take on tons of water in the Caspian or Black Seas for stability while crossing the Atlantic, and larvae or baby fish are sucked in. When the ships dump their ballast in the Great Lakes, they also dump the alien species.

Some introduced species have been devastating. The United States and Canada spend $15 million a year to control the lamprey, a snakelike bloodsucker that attaches itself to larger fish. The lamprey almost drove the native lake trout to extinction when it first expanded into the Great Lakes.

The zebra mussel is a fast growing filter-feeder that clings to boats and pilings and jams water intake pipes. Combatting the pesky mussel in the Great Lakes costs the United States $100 million a year.

The cost and the variety of alien species demonstrate the seriousness of this situation overall.

The importance of Lake Erie and the Great Lakes in general to our environment, our economy and our quality of life makes the problem especially serious to us.

Local officials must keep the pressure on to be sure that this situation is addressed on a national level.


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