Wavy-rayed Lampmussel

Lampsilis fasciola

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 Wavy-rayed Lampmussel (Lampsilis fasciola) is one of five species of the genus Lampsilis that occur in Canada and has the following characteristics:

  • yellow or yellowish-green in colour with numerous thin wavy rays;
  • rays may be narrow and individual, or thin and coalesced into wide rays, but are always wavy with numerous interruptions;
  • inside of shell (nacre) may be white or bluish-white;
  • shells are rounded at both ends, while top and bottom are nearly parallel;
  • shells are usually less than 75 mm long, but may reach 90-100 mm in length;
  • smooth shell surface, except for concentric wrinkles and growth rests;
  • the beak (raised part at the top of the shell) is elevated and beak cavities are moderately excavated; and
  • triangular teeth at the front edge of the hinge are short and divergent, and there are two in each half of the shell.

Habitat

The Wavy-rayed Lampmussel has historically been found in 13 U.S. states and the lower Great Lakes drainage of Ontario. Currently in Ontario, they are found in the Lake St. Clair delta and the St. Clair River, and four other watersheds: the Ausable, Grand, Maitland, and Thames rivers and associated tributaries. Recent population estimates suggest that the Wavy-rayed Lampmussel populations are gradually improving in southern Ontario, with the exception of the Lake St. Clair population.

The Wavy-rayed Lampmussel lives mainly in gravel or sand bottoms of riffle areas in clear, medium-sized streams. As it usually burrows into the substrate, it may be particularly sensitive to siltation. The Wavy-rayed Lampmussel is a moderately long-lived, sexually-dimorphic species with a lifespan of at least 10 years, but rarely more than 20 years. Spawning likely occurs in late summer and the glochidia (larvae) are released the following May-August. In females of the genus Lampsilis, the edge of the mantle has evolved into a minnow-shaped lure that is used to attract potential fish hosts when glochidia are ready to be released. Two hosts for this species have been identified in Ontario: the Smallmouth Bass (Micropterus dolomieu) and the Largemouth Bass (Micropterus salmoides).

Like all species of freshwater mussels, the Wavy-rayed Lampmussel filters its food from the water. Bacteria and algae are its primary food sources.

Threats

The dominant threats to most Wavy-rayed Lampmussel populations are declining habitat quality and overall habitat loss resulting from poor water quality. Similar to most freshwater mussels, the Wavy-rayed Lampmussel is extremely sensitive to a number of chemical contaminants, including copper, ammonia and chloride, particularly during their glochidial and juvenile life phases. An estimated 15 per cent of the Wavy-rayed Lampmussel's historic habitat is also overlapped by the invasive Zebra Mussel (Dreissena polymorpha), primarily in the St. Clair River and delta. Due to the Zebra Mussels' ability to attach themselves directly to hard surfaces (such as other freshwater mussels), Zebra Mussels directly impair the Wavy-rayed Lampmussels' ability to feed, respire, reproduce and move.

Further Information

Wavy-rayed Lampmussels, once considered an endangered species under the Species at Risk Act, have been found in such promising numbers that their status was reassessed in 2010 to be considered for downlisting.

Wavy-rayed Lampmussels are bottom-dwellers found in Ontario's lakes and rivers. They initially survive by attaching to bass gills and feeding on their nutrients for the first few weeks – with no ill effects to the bass. The Lampmussel uses a visual lure to attract bass, so clear water is essential to its survival. And their survival has benefits to the aquatic ecosystem as a whole.

Lampmussels have an important impact on the ecosystem in a number of ways. To begin with, they are biological filters that help to clean the water. A single mussel can filter up to 40 litres of water per day. They also ensure the physical stability of the river bottom, prevent erosion, and provide important habitat for other species. Lampmussels are also great indicators of aquatic health, because, as particularly sensitive creatures, they are usually one of the first to disappear from an unhealthy ecosystem. So their increased number is definitely something to be happy about.

Buoyed by greater funding thanks to the original species at risk designation, researchers were able to further investigate and understand Wavy-rayed Lampmussel populations, and were thrilled to find greater numbers. DFO researchers in Ontario's Grand River partnered with a local bass tournament in 2006 and were amazed to find that as many as 45 percent of Smallmouth Bass brought in by anglers were carrying immature mussels.

For further information, visit the SARA Registry Website.

Wavy-rayed Lampmussel

Wavy-rayed Lampmussels (Lampsilis fasciola)

Lampsilis fasciola (Rafinesque, 1820)
Male (left) | Female (right)

Photos by National Water Research Institute

Scientific Name: Lampsilis fasciola
SARA Status: Special Concern (March 2013)
COSEWIC Status: Special Concern (April 2010)
Region: Ontario

Distribution of the Wavy-rayed Lampmussel as described in the following paragraphs

Map showing distribution of Wavy-rayed Lampmussel 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.

Wavy-rayed Lampmussel

Photo: Shawn Staton, DFO

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