Eastern Pondmussel

Ligumia nasuta

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Eastern Pondmussel (Ligumia nasuta) was once among the most common species of freshwater mussels in the lower Great Lakes of Ontario. It is a medium-sized mussel (average length is 7 cm) and a member of the family Unionidae. It has the following features:

  • shell is thin, but strong, narrow and long;
  • shell colour ranges from yellowish- or greenish-black (juveniles) to dark brown or black (adults);
  • inside of the shell (nacre) can be purple, pink or silvery white;
  • raised part (beak) is located in the back quarter of the shell and is low and slightly raised above the hinge line;
  • back (posterior) ridge is well-developed, distinct and angled near the beak; back end has a distinct blunt point;
  • front (anterior) end is rounded; bottom edge of the shell (ventral margin) is broadly curved;
  • females have a swelling along the back bottom edge that is lacking in males; and
  • shell surface is rough with concentric wrinkles and visible growth lines.

Habitat

The Eastern Pondmussel, as its name suggests, is found only in eastern North America. In the United States, the range of the Eastern Pondmussel is limited to the lower Great Lakes through New York to New Hampshire and in coastal rivers to South Carolina. In Canada, this mussel species has only ever been found in Ontario. It is believed that this mussel has been lost from more than 90 per cent of its historical Canadian range in the Great Lakes and their larger connecting channels. Remaining populations are small, declining and limited to the St. Clair River delta, Lyn Creek (near Brockville) and Long Point Bay (Lake Erie), though recently, several small populations have been found within the coastal wetland habitats bordering Lake Ontario.

The preferred habitat of the Eastern Pondmussel is nearshore, sheltered areas of lakes or slow-moving streams and rivers in substrates of fine sand and mud at depths up to 4.5 m. Spawning likely occurs in late summer and the glochidia (larvae) are released the following spring. Like most other freshwater mussels, the glochidia are parasitic on fish. In this case, the female Eastern Pondmussel attracts a host fish with special tissues on her body called “mantle lures” that look like food, such as fish, leeches or amphipods (shrimp-like crustaceans). When a fish strikes at the lure, the female mussel releases glochidia into its mouth. The glochidia then attach to the host fish as they flow through its gills. Here they will remain until they reach their juvenile, free-living stage and drop off into the substrate below. Adult mussels are essentially sessile and may move only a few meters along the substrate.

The known host fishes for this species in Canada are the Brook Stickleback (Culaea inconstans), Pumpkinseed (Lepomis gibbosus) and Yellow Perch (Perca flavescens).

Like all species of freshwater mussels, the Eastern Pondmussel filters its food from the water. Bacteria and algae are its primary food sources.

Threats

The most serious threat to the Eastern Pondmussel continues to be the introduction of the invasive Zebra Mussel (Dreissena polymorpha). Since the mid-1980s, more than 90 per cent of the area once occupied by the Eastern Pondmussel has become infested with Zebra Mussels, which attach to and smother native mussels or outcompete them for food and habitat. Habitat loss and degradation from human activities, including water pollution, increasing siltation and nutrient loading, also threaten remaining Eastern Pondmussel populations found in Ontario.

Further Information

For more information, visit the SARA Registry.

Text Sources: COSEWIC assessment and status report on the Eastern Pondmussel in Canada, 2007; DFO. Recovery Potential Assessment of Eastern Pondmussel, Fawnsfoot, Mapleleaf and Rainbow in Canada; DFO CSAS. Sci. Advis. Rep. 2010/073; Metcalfe-Smith et al. Photo Field Guide to the Freshwater Mussels of Ontario, 2005.

Eastern Pondmussel

Eastern Pondmussel

Eastern Pondmussel

Scientific name: Ligumia nasuta
SARA Status: Endangered
COSEWIC Status: Endangered
Region: Ontario

Map showing distribution of Eastern Pondmussel in Canada as described in the following paragraphs

Map showing distribution of Eastern Pondmussel in Canada.

Did You Know?

Freshwater mussels are molluscs, soft-bodied animals without a skeleton (invertebrates), that live on the bottom of streams, rivers, lakes and ponds. They use a muscular foot to burrow and crawl and have a pair of hinged shells. Mussels are filter feeders — nature's water purifiers — and are food for other wildlife like fishes, otters, mink, muskrats and some birds. They are also among the most endangered creatures in the world.

The interior and exterior of an Eastern Pondmussel shell

The interior and exterior of an Eastern Pondmussel shell
Photo credit: Environment Canada

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