Zebra Mussel - Ecology

Ecology

Zebra mussels and the closely related and ecologically similar quagga mussels are filter-feeding organisms. They remove particles from the water column. The mussels process up to one gallon of water per day, per mussel. Some particles are consumed as food, and feces are deposited on the lake floor. Non-food particles are combined with mucus and other matter and deposited on lake floors as pseudofeces. Since the zebra mussel has become established in Lake Erie, water clarity has increased from 6 inches to up to three feet in some areas. This improved water clarity allows sunlight to penetrated deeper where macrophyte bacteria can now grow. This bacteria when decaying, can wash up on shorelines fouling beaches and causing water quality problems.

Lake floor food supplies are enriched by zebra mussels as they filter pollution out of the water. This biomass becomes available to bottom feeding species and to the fish that feed on them. The catch of yellow perch increased 5 fold after the introduction of zebra mussels into Lake St. Clair.

Zebra mussels attach to most substrates including sand, silt, and harder substrates. Other mussel species frequently represent the most stable objects in silty substrates, and zebra mussels attach to, and often kill these mussels. They build colonies on Native American Unionid clams, reducing their ability to move, feed and breed, eventually leading to their death. This has led to the near extinction of the Unionid clams in Lake St. Clair and the western basin of Lake Erie. This pattern is being repeated in Ireland where zebra mussels have eliminated the two freshwater mussels from several waterways, including some lakes along the River Shannon in 1997.

In 2012 the National University of Ireland, Galway, said "The discovery of zebra mussels (Dreissena polymorpha) in Lough Derg and the lower Shannon region in 1997 (McCarthy et al 1997, a & b) has led to considerable concern about the potential ecological and economic damage that this highly invasive aquatic nuisance species can cause."