Features: The Mapleleaf Mussel (Quadrula quadrula) is a medium-sized, freshwater bivalve that grows to about 12 cm in length. The shell is thick, squarish in outline and ranges in colour from yellowish green to dark brown. The outer shell surface is characterized by two rows of nodules radiating outward from the beaks. The nacre is white. It is most often found in medium to large rivers in firmly packed substrate. The life cycle follows the basic pattern of freshwater mussels: sperm released into the water by males fertilize eggs held by females in a pouch (called "marsupium") in the gills. When the larvae reach an intermediate stage called the glochidia, they are released in mucus packets. The released glochidia are dispersed and attach to the gills of channel catfish. Here the larvae continue their growth until they are juveniles, when they fall to the substrate and are a free-living mussel.

Status: Threatened Provincially and Nationally

Range: This mussel species ranges from Manitoba to Pennsylvania in the north, and to Texas and Alabama in the south. In Canada, this species is limited to the Red River and some tributaries in Manitoba, and to larger rivers draining into Lake St. Clair and Lake Erie in southern Ontario. Range Maps

Threats: This species occurs in areas of high human population density, which are affected by industrial, municipal and agricultural water pollution. Like most North American freshwater mussels, the Mapleleaf Mussel is threatened by habitat loss and degradation as well as by the detrimental effects of exotic species, in particular the zebra and quagga mussels (Dreissena polymorpha and D. bugensis). It has disappeared from the Great Lakes and connecting channels due to zebra mussels, but it seems to be doing well in other locations.

Protection: The Mapleleaf Mussel is a provincially threatened species, and receives legal protection under Ontario's Endangered Species Act, 2007. Fisheries are managed and fish habitat is protected under the Fisheries Act. Multi-species recovery strategies have previously been approved for several freshwater mussel species whose distributions partially overlap with the Mapleleaf Mussel. Recovery teams for these species are currently engaged in the implementation of recovery actions that will benefit the Mapleleaf Mussel within these watersheds.

Text Sources: Carney, Metcalfe-Smith and Watkins 2006

Last Modified Date: October 2008