Features: The mudpuppy mussel (Simpsonaias ambigua) is a small (50 mm long), thin-shelled, freshwater mollusc with a smooth, yellow or brown shell. Scientists have had trouble fitting this species into phylogenies of the molluscs, and are not sure who its closest relatives are, so they have placed it in a genus on its own. This species gets its name because of its parasitic association with the mudpuppy (Necturus maculosus). The larval stage of the mussel life-cycle (called "glochidia") attaches to the gills of the mudpuppy and feeds off its tissues until ready to transform into the juvenile. Juveniles will drop off the mudpuppy, settle into the substrate and then grow into adults. Freshwater mussel species all have the parasitic life stage, but all but the mudpuppy mussel use fish as their host. Adults are usually found burrowed in sand under flat rocks, which is where Mudpuppies prefer to live. They feed by filtering algae and bacteria from the water. They are also preyed upon by mudpuppies.

Status: Endangered Provincially and Nationally

Range: The mudpuppy mussel was distributed in central North America from Ontario south to Kentucky and Arkansas, west to Minnesota. This distribution broadly overlapped the distribution of the mudpuppy. Today, it is considered a globally rare species. In Ontario it is known from four sites in a 50 km stretch of the East Sydenham River, and possibly one site on the Thames River. Range Maps

Threats: The mudpuppy mussel is at the northern limit of its range in Ontario and may never have been abundant here. There are just three historical records of this species in Ontario - too few to draw definitive conclusions about declines here. Some scientists believe that the species may be undercounted because it is small, easy to miss and clumped in its distribution. Nevertheless, it has likely been affected by the same threats that have caused declines in two-thirds of all North American freshwater mussels - siltation, pollution and invading species. Forest clearance and agricultural development adjacent to streams increases silt levels and can smother mussels. Chemical and biological pollution from urban and farm development can negatively impact mussels. The invasion of the zebra mussel into the lower Great Lakes may have affected the mudpuppy mussel, as the new species will attach to mussel shells and interfere with feeding and respiration.

Protection: The provincial Endangered Species Act, 2007, provides protection for the endangered mudpuppy mussel. This species may be provided with general protection given by habitat sections of the Fisheries Act, as well as the provincial Planning Act, which addresses development in riparian areas. Collection and harvest of mussel species is controlled through the Ontario Fishery Regulations. An ecosystem-based, multi-species recovery plan is currently being prepared for the mudpuppy mussel and other species at risk in the Sydenham River.

Text Sources: Watson et. al. 2000

Last Modified Date: October 2008