Pisidium supinum
Schmidt 1850
Common Name:
Humpbacked peaclam
Synonyms and Other Names:
humpback/hump-backed pea/pill clam, pisidiid clam
Identification:
This triangular, somewhat inflated bivalve has a height to length ratio of approximately 0.9. The shell displays distinct beaks with an oblique ridge, thick hinge teeth, and cardinal teeth that are relatively far from the anterior denticles. The dorsal side of the shell is very short and rounded, the anterior side is straight and long but starts to round ventrally, and the posterior side is relatively blunt. There are around 16–18 striae per mm on the shell surface (Clarke 1981, Mackie 2000).
Size:
can grow to around 4.5 mm in length (Clarke 1981, Mackie 2000).
Native Range:
Pisidium supinum is native to Eurasia, including Iceland (Clarke 1981).
Great Lakes Nonindigenous Occurrences:
Pisidium supinum was recorded for the first time in the Great Lakes basin in Lake Ontario in 1959. It is also present in Lake Erie. It may have been present in the Great Lakes much earlier than 1959 (Clarke 1981, Corkum 2000, Grigorovich et al. 2003, Johnson and Mathesons 1968, MacIsaac 1999).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Pisidium supinum are found here.
Full list of USGS occurrences
Table last updated 5/2/2024
† Populations may not be currently present.
* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
Ecology:
Pisidium supinum is generally rheophilic, preferring lotic waters in canals and rivers, although it can tolerate more lentic waters in lakes. It is usually found in coarse sand, silty sand, or mud. In North America P. supinum is much more common in the Ottawa River and the St. Lawrence River than the Great Lakes. It is very sensitive to eutrophication but is resilient to both low waters and floods in the River Issel, Netherlands, where it can reach densities of 24,000 individuals per m2 (Bishop and Hewitt 1976, Extence et al. 1999, Hinz et al. 1982, Mackie 2000, Mouthon 1996, Piechocki and Strzelec 1999, Reckendorfer et al. 2006, Smit et al. 1994, 1995, Zettler 1996).
Pisidium supinum filter feeds on planktonic algae and specifically prefers diatoms. It filters suspended material from the water column mostly via movements of its foot and cilia but can directly ingest deposits from the sediments as well (Lopez and Holopainen 1987, Mackie 2000).
Pisidium spp. are hermaphrodites and ovoviviparous with relatively low reproductive output. They produce a few young per brood and around one or two broods per year (Boycott 1936).
Means of Introduction:
Pisidium supinum was probably introduced by the shipping industry, likely via solid ballast, which was in use at the turn of the century (Grigorovich et al. 2000).
Status:
Established where recorded.
Great Lakes Impacts:
Current research on the environmental impact of Pisidium supinum in the Great Lakes is inadequate to support proper assessment.
Potential:
No particular adaptations, life history traits, or reproductive traits appear to convey a competitive advantage to P. supinum over native species, nor have any adverse impacts been observed (Mackie 2000). However, research on this species is currently limited.
There is little or no evidence to support that Pisidium supinum has significant socio-economic impacts in the Great Lakes.
This species does not appear to have any impacts on human health or recreation.
There is little or no evidence to support that Pisidium supinum has significant beneficial effects in the Great Lakes.
This species does not appear to have any significant commercial or research value.
Management:
Regulations (pertaining to the Great Lakes region)
There are no known regulations for this species. Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Biological
There are no known biological control methods for this species.
Physical
There are no known physical control methods for this species.
Chemical
A wide array of chemical molluscicides are available, but are not species-specific and may harm native species to a greater extent than non-natives.
Molluscicides are typically classified as either oxidizing or non-oxidizing compounds. Oxidizing chemicals include chlorine, chlorine dioxide, chloramines, ozone, bromine, hydrogen peroxide, and potassium permanganate. Non-oxidizing chemicals (including organic film-forming antifouling compounds, gill membrane toxins, and nonorganics) can be classified into several distinct groups: quanternary and polyquaternary ammonium compounds; aromatic hydrocarbons; endothall as the mono (N,N-dimethylalkyl amine) salt; metals and their salts (e.g., copper sulfate formulations); and niclosamide (including some formulations of Bayluscide). Bayluscide was initially developed as a sea lamprey larvicide, but has molluscicidal activity. While some of these products are biodegradable, many require detoxification or deactivation to meet state and Federal discharge requirements (USACE 2012).
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
Pisidium supinum is considered endangered or rare in some regions of its native range in Europe. It is also debated whether or not it is indigenous to North America. Fossil deposits have been found in Alberta and Idaho, but it is most common at present in the Great Lakes and St. Lawrence. Most recent authors believe it is introduced from Eurasia (Clarke 1981, Herrington 1962, MacIsaac 1999, Mackie 2000, Quinn et al. 1996, Reckendorfer et al. 2006).
References
(click for full reference list)
Author:
Kipp, R.M., J. Larson, and A. Fusaro
Contributing Agencies:
Revision Date:
11/26/2019
Citation for this information:
Kipp, R.M., J. Larson, and A. Fusaro, 2024, Pisidium supinum Schmidt 1850: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=2391&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 11/26/2019, Access Date: 5/2/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.