- Scientific name: Lampsilis radiata
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
Description
Eastern lampmussel
Eastern lampmussel is a medium to large-bodied mussel that rarely exceeds 12.7 cm (5 in) in length. Shells are either subovate or subelliptical in shape. Shells are thick and valves may range in degree of inflation. Ventral-posterior end of mature females is typically broadly rounded, and females may be more ovate and inflated than males. However, some females are difficult to distinguish from males. Anterior end is rounded, and the posterior slope is broad. The beaks are not prominently raised above a slightly curved hinge line. The nacre is typically white but may be pink or salmon too. The periostracum ranges from yellowish green (often in younger animals) to brown with numerous green or black rays. Left valves have two straight lateral teeth and two pseudocardinal teeth. The right valve has two pseudocardinal teeth and a single straight lateral tooth (Smith 1991, Bogan 2002, Nedeau 2008).
Life cycle and behavior
Eastern lampmussels are essentially sedentary filter feeders that spend most of their lives partially burrowed into the bottoms of rivers, streams, lakes, and ponds. Eastern lampmussel, like all freshwater mussels, have larvae (called glochidia) that must attach to the gills or fins of a vertebrate host to develop into juveniles. Reproduction occurs in late summer to early fall and females may be found brooding viable glochidia year-round. Brooding females possess a swollen and pigmented area of the mantle immediately anterior to the siphon apertures, combined with two fleshy appendages used to lure host fish closer for infection. Glochidia are rounded (C or D shaped) and lack prominent hooks. Reported host fish include: yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomeiu), black crappie (Pomoxis nigromaculatus), rock bass (Ambloplites rupestris) and pumpkinseed (Lepomis gibbosus). In a lab setting, eastern lampmussel transformed only on largemouth bass and yellow perch (Eads et al. 2015).
Female eastern lampmussel displaying her lure to attract a host-fish.
Distribution and abundance
Eastern lampmussel is an Atlantic-slope endemic species, ranging from the Pee Dee River in North Carolina to the St. Lawrence River Basin, and extends as far west as Lake Ontario. Eastern lampmussel is considered secure throughout much of its range; however, little is known
about Massachusetts populations. In Massachusetts, the eastern lampmussel occurs in the Housatonic, Westfield, Lower and Middle Connecticut, Chicopee, Nashua, Merrimack, Concord, Charles, Blackstone, Taunton, and Cape Cod watersheds. While the range in Massachusetts is quite large and the species is not uncommon, it is rarely locally abundant. The most abundant populations seem to occur in coastal plain ponds in the southeast and Cape Cod.
Distribution in Massachusetts.
1999-2024
Based on records in the Natural Heritage Database.
Habitat
Eastern lampmussel is a habitat generalist, occupying a variety of waterbody types including large and medium-sized rivers, small streams, lakes, and ponds. In rivers, they can be found in a variety of substrate types from slack waters with fine depositional sediments to high velocity currents with gravel and boulder substrates (Bogan 2002, Nedeau 2008, Nedeau 2012). In lacustrine environments, they have been found in the littoral zone exposed to considerable wave action, as well as sandy and muddy pools at depths greater than 9 m (30 ft; Nedeau 2008).
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Lake habitat typical for eastern lampmussel.
Threats
Because eastern lampmussels are essentially sedentary filter feeders, they are unable to flee from degraded environments and are vulnerable to the alterations of water bodies. Eastern lampmussel occurs in lakes and rivers, and the threats in these two habitats are different. Overlapping threats include nutrient enrichment, sedimentation, other forms of pollution, non-native and invasive species, and the many consequences of urbanization. River populations of alewife floater are threatened by alteration of natural flow regimes, encroachment of river corridors by development, habitat fragmentation caused by dams, and a legacy of land use that has greatly altered the natural dynamics of river corridors (Nedeau 2008). Lake populations are challenged by intense development, modification and recreational use of sensitive shoreline habitats, accelerated eutrophication, water level regulation, and more frequent cyanobacteria blooms. Invasive plants and animals, such as European milfoil and basket clam (Corbicula fluminea), are having severe impacts on the fragile ecology of coastal plain ponds. The ultimate consequences on eastern lampmussel and other native species are not completely known, but the prognosis is bleak. In addition, the long-term effects of regional or global problems such as acidic precipitation, mercury, and climate change are considered severe but little empirical data relates these stressors to mussel populations. In combination with the above stressors (e.g., water withdrawals, eutrophication), effects from climate change including sustained droughts and warmer water temperatures, threaten eastern lampmussel populations by reducing water levels, and creating more suitable conditions for cyanobacteria blooms particularly in lentic systems that have shown to cause mussel kills.
Likely the highest risk to eastern lampmussel are likely related to the quality and quantity of water in its habitats. In regulated rivers, the species is often missing or found in low abundances from otherwise suitable habitat and may be affected by alterations to the natural hydrologic cycle. Even small dams may act as a barrier to dispersal for host fish. Nevertheless, dam removals require adequate protective measures to ensure that short-term changes in habitat do not affect population viability.
Conservation
Survey and monitoring
Standardized surveys are critically needed to monitor known populations, evaluate habitat, locate new populations, and assess population viability at various spatial scales (e.g., stream, watershed, state). Survey efforts should continue to search for new populations particularly in coastal watersheds and expand our knowledge on species distribution in extant watersheds every 5 years or to the extent feasible. Establishment of long-term monitoring sites in extant watersheds are needed to acquire critical demographic and population trend data where this species overlaps with state-listed mussel species. Monitoring these sites should occur annually in multi-year blocks or as needed.
Management
Discovery and protection of viable mussel populations is critical for the long-term conservation of freshwater mussels. Currently, much of the available mussel occurrence data are the result of limited presence/absence surveys. Coastal plain ponds and large coastal rivers are critical to the long-term viability of eastern floater in Massachusetts, and these habitats are also experiencing intense development pressure and recreational use. Understanding this threat and developing conservation and management strategies is a high priority for MassWildlife’s Natural Heritage Endangered Species Program (NHESP). Other conservation and management recommendations include: understand the effects of shoreline development and recreational use of lakeshores; maintain naturally variable river flows and lake water levels, and limit water withdrawals; identify, mitigate, or eliminate sources of pollution, including excess nutrients, to water bodies; identify dispersal barriers for host fish, especially those that fragment the species range within a river or watershed, and seek options to improve fish passage or remove the barrier; maintain adequate vegetated riparian buffers along rivers and lakes; and protect or acquire land at high priority sites.
Research needs
A better understanding of host fish relationships is needed; this information might help guide fisheries management at fishways. Habitat mapping of large rivers can aid in evaluation of suitable physical habitat and direct future survey effort. Climate change projections for water temperature and water levels in occupied and potential watersheds for species introduction are also needed to assess current and future population risks to drought and cyanobacteria blooms and identify potential refuges. Investigation of impacts of invasive species, particularly basket clam (Corbicula fluminea), on eastern lampmussel is needed.
Acknowledgements
MassWildlife thanks Peter Hazelton for providing significant support to this document.
References
Bogan, A.E. 2002. Workbook and Key to the Freshwater Bivalves of North Carolina. North Carolina Museum of Natural Sciences, Raleigh, NC. 105pp.
Eads, C.B., J.E. Price, and J.F. Levine. 2015. Fish hosts of four freshwater mussel species in the Broad River, South Carolina. Southeastern Naturalist 14(1):85-97.
Kneeland, S.C., and J.M. Rhymer. 2008. Determination of fish host use by wild populations of rare freshwater musselsusing a molecular identification key to identify glochidia. Journal of the North American Benthological Society 27:150 160.
Nedeau, E.J. 2008. Freshwater Mussels and the Connecticut River Watershed. Connecticut River Watershed Council, Greenfield, Massachusetts. 132pp.
Nedeau, E.J. 2012. Freshwater Mussel Survey in the Connecticut River for the Turners Falls and Northfield Mountain Hydroelectric Projects: FERC PROJECT #1889, 2485. Report prepared for FirstLight Power Resources. Biodrawversity, Amherst, Massachusetts. 12pp.
Smith, D.G. 1991. Keys to the Freshwater Macroinvertebrates of Massachusetts: including the Porifera, Colonial Cnidaria, Entoprocta, Ectoprocta, Platyhelminthes, Nematophora, Nemertea, Mollusca (Mesogastropoda And Pelecypoda), and Crustacean (Branchiopoda and Malacostraca). Department of Zoology, University of Massachusetts, Amherst, Massachusetts. 236pp.
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| Date published: | March 31, 2025 |
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