Essay, Research Paper: Zebra Mussels In America's Waterways

Although widely unknown to the American public, many of America's waterways are in extreme danger from something besides pollution. A new organism has been introduced that has the possibility to be deadlier than any pollution imaginable. This new threat is the zebra mussel (Dreissena polymorpha). A zebra mussel is a fresh water mussel that filters every bacteria in a water system until there is nothing left, including the zebra mussel. This can swiftly cripple any body of water.

Zebra mussel are believed to have been transported to America from somewhere in Europe in the mid 1980s. They have spread throughout many parts of the United States including the Mississippi River, Lake Erie, the Hudson River, Lake Champlain, and New York Harbor. They have also begun to migrate into the Passaic River. Currently, the mussels have been restricted to connected lakes, rivers, and other waterways. It is suggested that the zebra mussel could flourish in any United States waters and most of Canada's southern waters. To further migrate into new northern waters, the zebra mussels would have to be attached to a seagoing vessal. Migration to new unconnected waters would only be possible if carried by a marine bird.

The first effects of these mussels appear to be good. They filter out water until it is crystal clear. Each mussel can filter about one quart of lake water per day. This would be an improvement in many cases (especially the Passaic River), but the mussels do not stop there. They continue to filter until every bacteria and algae have been destroyed. When all plant life has been destroyed, animal life will soon follow. Fish will run out of food. Any animal living on the fish, such as some types of reptiles and birds, will also eventually be destroyed. The only thing left will be a desolate but clear lake or river. This could be a mass destructive end to America's fresh water ecosystem.

The Mississippi River contains more endemic species of mussel than any other river system. On the river, St. Croix National Scenic Riverway in Wisconsin is home to about two dozen species of fresh water mussels. They too, are endangered by the foreign zebra mussel. It is estimated that the zebra mussels may destroy up to fifty percent of these mussels within a decade. However with proper precaution, this can be greatly reduced. The staff at the St. Croix Riverway have been diving once a month to check the hulls of boats, marinas, and native mussel beds to be sure zebra mussels are not becoming entrenched. "The park was in a position of having to react quickly, given how rapidly zebra mussels were spreading," says Sue Jennings, resource management specialist for St. Croix. "Our plan has been very successful---I think that the task force has done an excellent job of joining together to formulate a plan...to slow the spread of zebra mussels into the St. Croix."

Zebra mussels have also begun to take their toll on the Great Lakes. First thrown into the small Lake St. Clair, the mussels soon appeared in Lake Erie in 1989. The female mussels soon began to lay eggs. A female zebra mussel can lay a million eggs in a two- to three-year lifetime. "By 1990 we had tens of thousands of zebra mussels per square meter on reefs, islands, anywhere there was a solid surface," says John Hageman. "We had calculations of forty to fifty thousand zebra mussels per square meter. One clump at a power plant intake in Monroe, Michigan, had four hundred thousand per square meter."

Zebra mussels attach themselves to any hard surface. Power washing, sandblasting, or scraping are the easist and quickest way to temporarily remove the pesky mussels. Blasting the tough mussels from structures has become a multimillion dollar surprise expense along the lakeshore. The estimated costs for repair, replacement, and control of the zebra mussels is several billion dollars annually. According to Hageman, the zebra mussels have also literally wiped out freshwater clams in the lake. Not only are they stripping the algae source from other freshwater species, they are also smothering the clams by gluing themselves to their shells.

It is also now suspected that the mussels have an additional bad side. They inject PCBs and other toxic organochlorines into the food chain. Without the mussels, these may have otherwise have remained harmlessly bound to sediments. As biologist David Culver of Ohio State University puts it, "With zebra mussels in the lake, something that might have settled safely on the bottom can be turned into nice, quivering, contaminated protoplasm that something---like a freshwater drum of a diving duck---will eat." This also makes fish contaminated and unable to eat. "The point is, it may have been safer to have the contaminants in the sediments," says Jeffrey M. Reutter, who is director of Ohio State's Stone Laboratory, the oldest freshwater biological field station in the United States.

The introduction of the zebra mussel is indeed a cause for alarm. If nothing is done, there may be little fresh water life left in America as soon as a few decades. This is not the first alien species introduced into our waterways, however. The Great Lakes alone have hosted the sea lamprey with the opening of the Welland Canal in the early 19th century, and the ruffe, a spiny perch, which was dumped by a Russian freighter. There were also many others. The zebra mussel is just another new alien threat. If treated and watched, the mussels can be held from migrating and controlled. We have to watch ourselves also. Dumping bilges and washing boat trailors will have to be manditory to stop continued growth. Most likely, if cared for, zebra mussels will not overgrow out of control. They will just be another mussel surrounding the many other species in America's waters. Then, the waters of tomorrow will be clean and under control for everyone to enjoy.


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