Yellow lampmussel (Lampsilis cariosa) COSEWIC assessment and status report: chapter 2

Executive Summary

Yellow Lampmussel
Lampsilis cariosa

Species information

The Yellow Lampmussel, Lampsilis cariosa (Say, 1817) is a bivalve mollusc up to 110 mm in length and almost oval in outline when viewed from the side. The exterior surface is glossy, bright yellow or reddish brown in colour, typically with several fine radiating lines on the upper posterior slope of the shell. The interior of the shell is white to pink in colour and there are several strong hinge teeth. In living animals, the soft parts of the body (called the mantle) are visible between the shell valves. The edges of the mantle that can be seen are smooth and pigmented with grey streaks and dots and, in the female, have a brightly coloured flap with an ‘eye’ spot.

Distribution

This is a species of the Northeast Atlantic Slope of North America, ranging from Georgia in the south to Nova Scotia in the north. Currently in Canada L. cariosa is known from only two localities: the Sydney River, Cape Breton County, Nova Scotia and the lower Saint John River and tributaries near Fredericton, New Brunswick. A historic record from the Saint François River, near Drummondville, Quebec is in need of confirmation. The range of the species is declining and all populations north of New York State are isolated.

Habitat

This species is typically found in faster flowing sections of larger rivers, especially on sand and gravel bottoms in riffles. However, in the north of its range it also occurs in lakes. The habitat in Sydney River includes a lake with wave-washed and vegetated shorelines and a lower river section dammed as a freshwater reservoir. Within this habitat the mussels live in water depths of 0.5 – 6.0 meters preferring areas of sandy substrate with low macrophyte cover. Generally they live in alkaline waters with pH above 7.0.

Biology

The soft parts of the body, inside the protective shell, include a muscular foot for anchorage and mobility, and paired gills for respiration, filter feeding and early larval development. The sexes are separate. Early larval development within females is followed by a period of parasitic life where the young develop while attached to the gills or fins of a host fish. White and Yellow Perch (Morone americana and Perca flavescens) have been identified as suitable hosts. After an undetermined period of development upon host fish, the young mussels drop into the bottom sediment where they grow to adult size. Yellow Lampmussels are filter feeders taking plankton and organic detritus from the water. The main predator of the adult mussels is muskrats. 

Population sizes and trends

Base-line studies carried out in the Sydney River in 2001 and 2002 report a species density of 0.4 - 0.8 –individuals per with total usable habitat area estimated at 2.52 km². Preliminary studies in 2002 on the Canaan River, a tributary of the Saint John River, suggest population densities in the same range as Nova Scotia and adjacent Maine. Although the Yellow Lampmussel continues to have a wide distribution in the lower Saint John River system, there is some evidence that the species’ range in New Brunswick has been reduced over the past century. Further work is needed to estimate overall abundance of Yellow Lampmussel in New Brunswick, but the large size of the lower Saint John River, the extensive area of suitable habitat, the results of recent surveys, and preliminary density estimates for the Canaan tributary, together suggest that the lower Saint John and tributaries harbor most of the Canadian population.

Limiting factors and threats

Location of the Nova Scotia population within a suburban environment, with associated pollution and development issues, is of concern. A dam constructed in 1902 maintains current water levels in the Sydney River. A dam breach would lead to a decline in L. cariosa habitat. Lampsilis cariosa populations in the lower Saint John River presently seem to have few threats (Sabineet al. In press). However, Sabine et al. (In press) suggest that further study on the effects of low, late summer, water levels on L. cariosa in terms of elevated water temperatures, exposure, and saline penetration are required. The current downstream limit of L. cariosa on the Saint John River coincides extremely closely with the current upstream limit for saltwater intrusion. During periods of low water the saline front penetrates farther inland. Sabine et al. (In press) observed some mortality in late August and early September 2001, a particularly dry year. They suggest that some of this mortality may have been due to low water levels and elevated water temperatures over sandbars during months in which lowest water levels occur in the river annually.

Special significance of the species

The Yellow Lampmussel is considered to be threatened throughout its range in the United States and in some watersheds it is believed to have been extirpated or is at least endangered. In Canada there are currently only two known populations, one occurring in the Sydney River, Nova Scotia, and the other occurring in the Saint John River, New Brunswick. The Sydney River population is disjunct from the Saint John River population with at least 500 km separation. The apparent size and presumed genetic integrity of these isolated L. cariosa populations, as well as current lack of zebra mussels (Dreissena sp.) in either the Saint John or Sydney River systems, suggests that these Yellow Lampmussel populations could play an important role in the future conservation of the species globally.

Existing protection or other status designations

There is no specific protection for the Yellow Lampmussel in Canada. Its habitat is only protected through general municipal, provincial and federal guidelines regarding the environment, fish habitat and domestic water supply areas. Along-term volunteer monitoring program aimed at detecting declines in the size and health of the Sydney River L. cariosa population is currently being developed by the Atlantic Coastal Action Program of Cape Breton.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and it is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC) Footnotea
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR) Footnoteb
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD) Footnotec
A wildlife species for which there is inadequate information to make a direct, or indirect, assessment of its risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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