Image: Zebra Mussel (Dreissenia polymorpha)
Caption: Zebra mussels are native to the Caspian Sea and were introduced in ballast water in 1982 in Lake St. Clair in the Great Lakes. Over the past 20 years, zebra mussels have quickly spread in waterways in the Eastern US. Their larvae, which are called veligers, float downstream to even New Orleans. Zebra mussels attach to any hard surface, including bridges, boats, water intake pipes, native mussels, and each other. They attach with a strong fiber known as a byssal thread, which holds the zebra mussel in place even after the animal has died. Zebra mussels can even live on a soft bottom. One layer of mussels settles and forms a "suicide layer" for other animals to attach to. Zebra mussels filter out plankton, the base of the aquatic food chain. They do this very well: each one inch zebra mussel can filter one liter of water per day. This leaves little food for other animals, including gamefish. Also, along with the plankton, zebra mussels filter out toxins, which concentrate in their bodies and can contaminate larger game fish. Zebra mussels also reproduce quickly: one female can make up to 2 million eggs per year. Zebra mussels have been known to clog the intake pipes in municipal water supplies, causing cities to have to shut off water until pipes could be unclogged. When they die, their sharp shells wash onto the beach, and they smell awful. Although zebra mussels have not yet reached Mobile Bay, they can live in brackish water and in salinity up to 10ppm for one tidal period.
Source: Auburn University Marine Extension and Research Center
Jody Scanlan, Project Coordinator
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