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Leptodea ochracea

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA BIVALVIA UNIONOIDA UNIONIDAE

Scientific Name: Leptodea ochracea
Species Authority: (Say, 1817)
Common Name(s):
English Tidewater Mucket
Synonym(s):
Lampsilis ochracea (Say, 1817)
Mytilopsis fluviatilis Gmelin, 1791
Taxonomic Notes: The generic placement of species Leptodea ochracea is in doubt (Bogan 1996). Smith (2000) proposes movement of ochracea from Leptodea to Ligumia based on similarities in the papilla of Ligumia ochracea and Ligumia nasuta. However, Bogan (1996) and Bogan and Alderman (2004) also include comments by Davis and Fuller (1981) that the type species of Ligumia, Ligumia recta, and Ligumia nasuta are incorrectly grouped together; and question placement in Ligumia. Cordeiro (2003) has shown that the species was actually described earlier than 1817 as Mytilopsis fluvitilis Gmelin, 1791, a species mistakenly synonimized by Isaac Lea in 1817 with Pyganodon cataracta, but Cordeiro has successfully suppressed this senior name in favour of the better known species name ochraceus (ICZN 2005, J. Cordeiro pers. comm. 2003). In North Carolina, Stiven and Alderman (1992) noted conchological and genetic differences of specimens from different habitats as well as significant differences from Lampsilis cariosa and Lampsilis radiata.

A list of synonyms for this species can be found on The MUSSEL project web site (Graf and Cummings 2011).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-03-12
Assessor(s): Cummings, K. & Cordeiro, J.
Reviewer(s): Bohm, M., Seddon, M. & Collen, B.
Contributor(s): Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Justification:
Leptodea ochracea has been assessed as Near Threatened as it is a widespread, though uncommon species along the coastal areas of the Atlantic Slope with noted declines in almost its entire range. As a result, we estimate declines to have been at least in the region of 20-25% over the past three generations (30 years, as generation length is around ten years), specifically taking into account some possible state-level extirpations of the species. Dispersal is limited to coastal plains ponds and rivers with direct connectivity to the Atlantic Ocean. This species almost qualifies for a listing of VU A2ace, and further, more detailed and quantitative population information may lead to a Vulnerable listing in the future.

Geographic Range [top]

Range Description: This species is found along the Atlantic coastal plain from Cape Breton, Nova Scotia, to the Savannah River, Georgia (Johnson 1970).
Countries:
Native:
Canada (New Brunswick, Nova Scotia); United States (Connecticut, Delaware, District of Columbia, Georgia, Maine, Maryland, Massachusetts, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Virginia)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: In Maine, 1997 surveys found 27 populations (29 sites) in four coastal watersheds such as Merrymeeting Bay and the St., George, Penobscot, lower Kennebec, and lower Androscoggin River drainages (absent from Androscoggin, Aroostook,Cumberland, Franklin, Oxford, Washington, and York Cos.) (Nedeau et al. 2000). In Massachusetts, this species is known only from large ponds and their outlets in coastal regions and in the Connecticut River (Smith 2000). In Connecticut, it is known from the lower Connecticut River (Nedeau and Victoria 2003). In Maryland, it is known from the Upper Potomac, Washington Metro, Susquehanna, Elk, and Chester River drainages (Bogan and Proch 1995). In New Jersey, it is known from the middle, lower, and upper Delaware basin (J. Cordeiro pers. comm. 2003). In New York, it is only known from the lower and middle Hudson drainages (Strayer and Jirka 1997). Virginia occurrences are scattered in the York, Ghowan, and Potomac basins (VA NHP pers. comm. 2006). Bogan and Alderman (2004) list South Carolina distribution as the Waccamaw and Savannah River basins only. Recently, it was found at three sites in the Pee Dee River drainage (Little Pee Dee River), South Carolina (Catena Group 2006). In North Carolina, it is known from the Waccamaw (including Lake Waccamaw; Johnson 1984), Pamlico, Roanoke, Lower Tar, and Ghowan River basins (Stiven and Alderman 1992); and possibly extirpated from the Neuse River basin (Bogan 2002); including Bertie, Chowan, Columbus, Edgecombe (extirpated), Halifax, Hertford, Martin, Northampton, Pitt, and Washington Cos. (LeGrand et al. 2006). The species does not occur in Rhode Island (Raithel and Hartenstein 2006) although it may once have (J. Cordeiro pers. comm. 2004). In Canada, this species is secure in New Brunswick (new populations discovered in recent years) but is uncommon to rare in Nova Scotia with populations small and/or declining (Metcalfe-Smith and Cudmore-Vokey 2004).

Some healthy populations exist in Maine in the lakes and rivers of the lower Kennebec and Penobscot River drainages (Nedeau et al. 2000). Massachusetts also harbors some significant populations in the southeastern part of the state (J. Cordeiro pers. comm. 2007). Globally, it appears that New Brunswick harbours a globally significant population (Metcalfe-Smith and Cudmore-Vokey 2004).

Typically, this species is found in low densities across its range. In Maine and Massachusetts, it is generally rare at most sites, but numerous (low hundreds of individuals) at a few sites. In a survey of 61 sites in the Pee Dee basin in South Carolina, it was found at only three sites (Great Pee Dee River and Little Pee Dee River) although typical slackwater habitats were not surveyed primarily (Catena Group 2006).

In New York (Hudson River) it has declined considerably since the introduction of the Zebra Mussel in the 1990s (Strayer and Jirka 1997), possibly to the point of extirpation. The species has been extirpated from Pennsylvania where it formerly occurred in the Delaware basin (Bogan 1993). It seems to be declining throughout its range, particularly in the northeast where it is often scarce where it is found and populaitons are in decline (Nedeau et al. 2000), including parts of Canada such as Nova Scotia (Metcalfe-Smith and Cudmore-Vokey 2004). Taking these declines and some notable possible state-level extirpations into account, we estimate the declines range-wide at around 20-25% percent over the past three generations (30 years).

This species is currently listed as State Endangered in North Carolina (Bogan 2010).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species inhabits ponds, canals, and slow-moving sections of rivers, including artificial impoundments. It is usually found in water bodies close to, but not necessarily connected, to the ocean (Johnson 1970, Nedeau et al. 2000). It is found in a variety of substrates, including silt, sand, gravel, cobble, and occasionally clay. It has a generation length of approximately 10 years (Wick 2006).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): Anecdotal observations (J. Cordeiro pers. comm. 2007) suggest that this species is sensitive to channel modification, pollution, sedimentation and low oxygen conditions. Threats include dams and other impoundments, channelization and dredging. Population declines have been observed in parts of its range since the introduction of the Zebra Mussel in the 1990s (Strayer and Jirka 1997). Although found in close proximity to tidal areas, it is not tolerant of salinity (A. Bogan pers. comm. 2010).

Conservation Actions [top]

Conservation Actions: This species has been assigned a Global Heritage Status Rank of G3G4 - Vulnerable to Apparently Stable (NatureServe 2009). Williams et al. (2010) lists this species as Vulnerable according to the American Fisheries Society (AFS) assessment. Further research regarding the taxonomy, population trends, ecology and threats impacting this species is required. Effective conservation strategies should be implemented to ensure protection for this species and its habitat.

Citation: Cummings, K. & Cordeiro, J. 2012. Leptodea ochracea. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 24 July 2014.
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