Plants and Animals

Sagittunio nasutus Eastern pondmussel

Key Characteristics

The Eastern pondmussel is a medium to large (to 6 inches, average about 3 inches), elongate mussel with a thin but sturdy, greenish-yellow to brown shell, with narrow green rays sometimes visible. Identifying features include a bluntly pointed posterior end, straight dorsal and curved ventral margins, and a low, wide beak. The nacre varies in color from white to iridescent pinks and blues.

Status and Rank

US Status: No Status/Not Listed
State Status: E - Endangered (legally protected)
Global Rank: G4 - Apparently secure
State Rank: S2 - Imperiled


CountyNumber of OccurrencesYear Last Observed
Alcona 1 Historical
Alger 1 1940
Allegan 1 2002
Arenac 2 1932
Bay 5 1926
Benzie 2 1925
Cheboygan 11 2019
Emmet 8 2018
Huron 3 1964
Iosco 5 2000
Macomb 4 1940
Monroe 15 2014
Montcalm 1 2015
Montmorency 1 1925
Ogemaw 1 1957
Oscoda 1 2013
Presque Isle 3 2005
Roscommon 1 2015
Saginaw 6 2010
St. Clair 8 2016
St. Joseph 1 Historical
Tuscola 1 Historical
Wayne 28 2019

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Preferring fine sand to mud substrates, the Eastern pondmussel inhabits lakes and ponds, as well as slackwater areas of canals, rivers and streams (Metcalfe-Smith and McGoldrick 2007).

Specific Habitat Needs

Sandy substrate needed in: Great lake, littoral, benthic; Great lake, pelagic, benthic; Inland lake, littoral, benthic; Inland lake, pelagic, benthic; Mainstem stream (3rd-4th order), pool.

Natural Community Types

  • Great lake, littoral, benthic
  • Great lake, pelagic, benthic
  • Inland lake, littoral, benthic
  • Inland lake, pelagic, benthic
  • Mainstem stream (3rd-4th order), pool
  • River (5th-6th order), pool

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Maintaining habitat integrity is essential to the survival of the Eastern pondmussel, and mussels in general. Dredging, impoundments, construction and dam removal negatively affect this species. Where these activities occur, monitoring to assess impacts, and mitigation measures such as relocation of potentially affected specimens, should be carried out. Healthy populations of host fish are critical to the maturation and dispersal of glochidia, and should also be managed for. As unionid mussels have shown particular sensitiviy to pollutants such as ammonia (Wang et al. 2007), chlorine (Valenti et al 2006), and heavy metals (March et al. 2007, Valenti et al. 2005, Wang et al. 2007), high water quality standards must be met. The treatement of lake areas with herbicides and pesticides containing copper should be avoided where Eastern pondmussel is present.  Non-point source pollution and altered stream hydrology should also be addressed to ensure the viability of unionid mussel populations.  Zebra mussels attach to native mussels and restrict movement and feeding, eventually causing mortality. The extirpation of entire native mussel communities has often been the result (Schloesser et al. 1996). Preventing the spread of zebra mussel adults and larvae by cleaning boat hulls, trailers, scuba and fishing gear, is critical in maintaining Eastern pondmussel populations.

Active Period

Gravid from first week of August to fourth week of May

Survey Methods

Visual and tactile search using scuba or glass-bottom buckets. Tactile search (by hand) is especially important where water turbidity and pebbles/rocks make visual detection difficult. After identification, live mussels should be planted back into the substrate anterior end down. Surveys should not take place after heavy rains or during periods of high water as these conditions can make detection much more difficult.  Methods of documenting survey effort include: searching a large measured area, e.g. 128m2; taking multiple quadrat samples; and recording search time (person hours). For all methods, at least some excavation of substrate (by hand, 5-10cm down) should be done to detect buried mussels.  Searching a large measured area or timed searches are generally better for detecting rare species and generating a species list than quadrat sampling. These two methods allow more types of microhabitats and a larger area to be covered. Quadrat sampling is better suited for documenting changes in density and other statistical analyses at the site level (Strayer and Smith 2003).

Glass-bottom bucket less than waist deep water

Survey Period: From first week of June to first week of October

Time of Day: Daytime

SCUBA greater than waist deep water

Survey Period: From first week of June to first week of October

Time of Day: Daytime


Technical References

  • COSEWIC. 2007. COSEWIC assessment and status report on the Eastern pondmussel Ligumia nasuta in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. 34pp.
  • Grabarkiewicz, J. and W. Davis. 2008. An introduction to freshwater mussels as biological indicators. EPA-260-R-08-015. U.S. Environmental Protection Agency, Office of Environmental Information, Washington, DC.
  • March, Ferrella A., F. James Dwyer, Tom Augspurger, Christopher G. Ingersoll, Ning Wang, and Christopher A. Mebane. 2007. An evaluation, of freshwater mussel toxicity data in the derivation of water quality guidance and standards for copper. Environmental Toxicology and Chemistry 23(10): 2006-74.
  • Ortmann, A.E. 1919. Monograph of the naiades of Pennsylvania. Part III. Systematic account of the genera of the naiades. Annals of the Carnegie Museum 8:222-365.
  • Scholesser, Don W., Thomas F. Nalepa, Gerald L. Mackie. 1996. Zebra Mussel Infestation of Unionid Bivalves (Unionidae) in North America. American Zoology 36:300-10.
  • Valenti, T.W., D.S. Cherry, R.J. Currie, R.J. Neeves, J.W. Jones, R. Mair, and C.M. Kane. 2006. Chlorine toxicity to early like stages of freshwater mussels (Bivalvia: Unionidae). Environmental Toxicology and Chemistry 25(9):2512-18.
  • Valenti, T.W., D.S. Cherry, R.J. Neves, and J. Schmerfeld. 2005. Acute and chronic toxicity of mercury to early life stages of the rainbow mussel, Villosa iris (Bivalvia: Unionidae). Environmental Toxicology and Chemistry 24(5):1242-6.
  • Wang, N., C.G. Ingersoll, I.E. Greer, D.K. Hardesty, C.D. Ivey, J.L. Kunz, W.G. Brumbaugh, F.J. Dwyer, A.D. Robers, T. Augspurger, C.M. Cane, R.J. Neves, and M.C. Barnhart. 2007. Assessing contaminant sensitivity of early life stages of freshwater mussels (Unionidae): Chronic toxicity testing of juvenile mussels with copper and ammonia. Environmental Toxicology and Chemistry. 35pp.
  • Watters, G. Thomas, Michael A. Hoggarth, and David H. Stansbery. 2009. The Freshwater Mussels of Ohio. The Ohio State University Press, Columbus. 421 pp.