Zebra mussels are a fresh water mollusk that have invaded the Great Lakes region. Originally discovered in 1988 in Lake St. Claire, these invasive species have disrupted the marine ecology. For divers, these creatures have helped and hurt our diving in the Great Lakes. Even boaters have been effected as boats that do not have the special paint on the bottom can attach zebra mussels to the hull. Many cities who use the Great Lakes for their drinking water source have been affected by the invasion of the zebra mussels.

What is a Zebra Mussel

Zebra mussels are native to the Ponto-Caspian region (Black, Azov, and Caspian seas) in eastern Europe. They are about the size of a human fingernail and can grow to a maximum of four centimeters. They are known to reproduce quickly. Females can lay between 30,000 to 1,000,000 eggs each year. They get their name from the striped pattern on their shell. All though, not all bear this pattern. Zebra mussels and the closely related and ecologically similar quagga mussels are filter-feeding organisms. They remove particles from the water column, increasing water clarity and reducing pollution. Some particles are consumed as food, and feces are deposited on the lake floor. The zebra mussel can exists for up to five days out of the water.

The life span of a zebra mussel is four to five years. A female zebra mussel begins to reproduce at two years of age. In terms of reproduction, zebra mussels are among the most prolific of all animals. Spawning usually begins in the months from late spring to early summer by free-swimming larvae, which are microscopic in size, thus invisible to the naked human eye. About two to five percent of zebra mussels reach adulthood.

Impact on the Great Lakes

It has been theorized that the zebra mussel was inadvertently introduced to North America and Canada by ocean going vessels from eastern Europe that dumped their ballast water into the Great Lakes. This ballast water coming from eastern Europe contained the zebra mussels.

With the quick reproduction rate, the zebra mussel has spread to all of the Great Lakes and even surrounding areas. Since the zebra mussel can live out of the water for up to five days, they can quickly spread to other bodies of water by boaters who don’t clean off their boats, anchors, chains or lines. Divers can also spread zebra mussels by not rinsing off their equipment after diving in bodies of water that are infected.

The introduction of the zebra mussel into the Great Lakes ecology has many effects:

• Improved visibility for scuba divers as each zebra mussel filters a quart of water a day.
• Damage to shipwrecks
• Clogging of water intakes of municipal water supplies and hydroelectric companies
• The migration of other filter feeders whom relied on the food in the water now being eaten by zebra mussels

Some have found that chlorine will kill the zebra mussel. However, it will kill off everything else. Recent studies have shown that zebra mussels do not attach to copper-nickel alloys, which can be used to coat water intake grates, buoys and boats. The cost of fighting the pests at power plants and other water-consuming facilities is $500 million a year in the U.S., according to the Center for Invasive Species Research at the University of California, Riverside

References and Photo Credits:
USGS
Zebra Mussels on Wikipedia