Tiny zebra mussels cause big problems when they damage boats and pipes and decrease populations of other aquatic creatures. The mussels first entered the United States in 1988 after stowing away in the ballast water of European ship that passed through Lake St. Clair, a small lake connecting Lakes Huron and Erie. Just a few years after their arrival, they began causing problems that continue to affect people and wildlife.
About Zebra Mussels
Zebra mussels are a type of small freshwater mollusk now found in the Great Lakes, other small lakes in the region and in the Illinois, Hudson, Arkansas, Tennessee, Ohio, Cumberland and Mississippi rivers. The mussels have a hard, striped shell and range in size from 1 to 2 inches in length. The zebra mussel has a byssus, an external organ that contains a series of threads. The mussels use these threads to secure themselves to hard surfaces in the water. Problems occur when hundreds or thousands of zebra mussels attach themselves to an object.
The presence of zebra mussels caused a decline in both commercial and recreational fishing in the affected lakes and rivers. Zebra mussels eat algae, which deprives young fish and fish larvae from the food they need to survive. When the fish population declines, so does the bird population, as some species of birds feed on fish. Zebra mussels also kill other species, such as clams. Large numbers of mussels attach themselves to the clams, preventing them from opening their shells to obtain food. Eating fish caught in zebra mussel-infested waters could increase human exposure to pollutants. Mussels filter water through their shells to obtain algae, but they also absorb pollutants during the filtering process. People ingest these pollutants when they eat the fish that eat the mussels.
Boating and Beaches
Thousands of zebra mussels clinging to the hull of a boat add weight to the boat and slow it down. Mussels can cause significant damage when they attach themselves to boat motors and cooling systems. Zebra mussels also affect boating safety. They adhere to docks and buoys, damaging these items and causing buoys to sink due to the combined weight of the mussels. A beach covered with thousands of zebra mollusks isn’t appealing to swimmers and can be dangerous. Zebra mussel shells are sharp and can cut feet.
Power and Water Treatment Plants
Clean water and electricity, basic requirements of life for most people, can be affected when a colony of zebra mussels makes it home in water intake pipes used by power and water treatment plants. Large numbers of the mussels in the pipes reduce the plants’ ability to pump water. Plants might even shutdown temporarily if the mussels completely clog pipes. Removing zebra mussels from pipes is a difficult, expensive and time-consuming process. Companies use scrapers, air, hot water or chemicals to get rid of them. Placement of filters and other physical barriers in the pipes can help prevent the mussels from re-entering the pipe.