Zebra Mussel

Zebra mussels and the closely related and ecologically similar quagga mussels are filter-feeding organisms; they remove particles from the water column. Zebra mussels process up to 1 litre (0.26 US gal; 34 US fl oz) of water per day, per mussel. Some particles are consumed as food, and faeces are deposited on lakes floor. Nonfood particles are combined with mucus and other matter and deposited on lake floors as pseudofaeces. Since the zebra mussel has become established in Lake Erie, water clarity has increased from 15 cm (6 in) to up to 1 m (3 ft) in some areas. This increased water clarity allows sunlight to penetrate deeper, enabling growth of submerged macrophytes. These plants, when decaying, wash up on shorelines, fouling beaches and causing water-quality problems. Lake-floor food supplies are enriched by zebra mussels, which filter pollutants from the water. This biomass becomes available to bottom-feeding species and to the fish that feed on them. The catch of yellow perch increased five-fold after the invasion of zebra mussels into Lake St. Clair. Zebra mussels attach to most substrates, including sand, silt, and harder substrates, but usually juveniles prefer harder, rockier substrates on which to attach. Other mussel species frequently represent the most stable objects in silty substrates, and zebra mussels attach to and often kill these mussels. …