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Simpsonaias ambigua 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Unionoida Unionidae

Scientific Name: Simpsonaias ambigua Say, 1825
Common Name(s):
English Salamander Mussel
Synonym(s):
Simpsoniconcha ambigua (Say, 1825)

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2ce ver 3.1
Year Published: 2017
Date Assessed: 2015-07-15
Assessor(s): Bogan, A.E., Woolnough, D. & Seddon, M.B.
Reviewer(s): Lopes-Lima , M. & Ormes, M.
Contributor(s): Cordeiro, J. & Seddon, M.B.
Justification:
This species occurs throughout the upper Mississippi River drainage and as far south as the Cumberland River drainage of Tennessee, but it is now gone from many locations and is considered as State Heritage Ranking S1-S2 in most of the states where it remains.  In general this species is rare throughout its range. Whilst population decline started during the long periods of dam construction and has been ongoing for many decades, there is evidence from  catchments surveys suggesting that population decline is still ongoing and that the unique habitats favoured by the mud-puppy, it's host species, are in decline. It is estimated to have been lost from 35-45% of the range (NatureServe maps, 2011 showing loss in 24 of 51 catchments).

This species is listed Vulnerable because whilst the current area of occupancy (AOO) is not known and the extent of decline in AOO is not known with accuracy, the loss of historical sites is indicative of a significant population reduction (more than 30%) over the past three generations.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is widespread but localised throughout eastern North America,  where it's distribution in part is apparently related to the distribution of its glochidial host, the Mudpuppy (Necturus maculosus). The species was known throughout the upper Mississippi River drainage and as far south as the Cumberland River drainage of Tennessee, but it is now gone from many locations. It is recorded from the Lake St. Clair, Lake Huron, and Lake Erie drainages; and from the Ohio River System, the Cumberland River System (Red River, Kentucky), and the upper Mississippi River System (Illinois, Iowa, Wisconsin, Missouri and Arkansas). In Minnesota, it is present only in the lower St. Croix River where it is rare and localized (Sietman 2003). It is considered to be possibly Extinct in Iowa and New York States. In Canada, it is known from the Sydenham River and a potentially extant occurrence in the Thames River in London, Ontario (Cudmore et al. 2004).

Whilst having a large range, the species is found in unique habitat: under large flat rocks where it's intermediate host species, the Mudpuppy lives. This species is difficult to find with normal search techniques, hence all surveys must use species specific survey techniques.

It is estimated to have been lost from 35-45% of the range (NatureServe maps, 2011 showing loss in 24 of 51 catchments).
Countries occurrence:
Native:
Canada (Ontario); United States (Arkansas, Illinois, Indiana, Iowa - Possibly Extinct, Kentucky, Michigan, Minnesota, Missouri, New York - Possibly Extinct, Ohio, Pennsylvania, Tennessee, West Virginia, Wisconsin)
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:1337087
Number of Locations:50-721Continuing decline in number of locations:Yes
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is rare throughout its range, although it may be locally abundant where found (Watters et al. 2009). While this species is easily overlooked, intense searches in areas where the species has previously been indicative of a gradual decline (Stansbery 1970, Clarke 1985). In Ohio, it is considered extant at about 12 locations throughout the state (Watters et al. 2009). Sietman (2003) reports it has been extirpated from the Mississippi River below St. Anthony Falls and portions of the Minnesota River drainage in Minnesota. It has not been collected in Illinois for over 30 years (Cummings and Mayer 1997). Some expansion has occurred in western Pennsylvania where it was not known historically within the upper Ohio River basin (Bogan and Locy 2009). In Canada, it has been extirpated from the Cedar and Detroit Rivers by the zebra mussel and only a single population remains in the Sydenham River in Ontario (Metcalfe Smith and Cudmore Vokey 2004) and possibly Lower Thames (Watson et al. 2000, Cudmore et al. 2004).

It is estimated to have been lost from 35-45% of the range (NatureServe maps, 2011 showing loss in 24 of 51 catchments). It lives for about 10 years, but most individuals are only 4-5 years old (Watters et al. 2009).

The unique habitats favoured by the mud-puppy, it's host species, are in decline.  The host species is still considered to be Least Concern, although it is also in decline.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:The preferred habitat is in sand or silt under large, flat stones in creeks and rivers of all sizes and lakes (Parmalee and Bogan 1998, Watters et al. 2009). Its presence is presumably linked to the Mudpuppy (Necturus maculosus). Cudmore et al. (2004) provides the following habitat information for Canada: found in all types of clear, freshwater habitat, including creeks, streams, rivers and lakes; it is found on a variety of substrates (mud, silt, sand, gravel, cobble or boulder) in areas of swift current. It is rarely found with other mussel species (Watters et al. 2009). The species is difficult to find with normal search techniques (must be species specific).

The host species, Mudpuppy, occurs in North America (USA and Canada) from southern Manitoba to southern Quebec, south to Oklahoma, northern Louisiana, northern Mississippi, northern Alabama, and northern Georgia (Conant and Collins 1991) and is considered to be Least Concern (IUCN SSC Amphibian Specialist Group 2015).
Systems:Freshwater
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):4-10

Use and Trade [top]

Use and Trade: There is no known trade in this species.

Threats [top]

Major Threat(s): Like most mussels, the Salamander Mussel is sensitive to river impoundment, siltation and channel disturbance. Pollution from point (industrial and residential discharge) and non-point (siltation, herbicide and surface run-off) sources is also a great threat to mussels impacting water and habitat quality. Much population decline may have happened during the long periods of dam construction. However there is limited evidence from the data on catchments surveys that are available to suggest that population decline is still ongoing and that the unique habitats favoured by the Mudpuppy are in decline. In the northern part of the range the species also appears to be impacted by the invasive Zebra Mussel (COSEWIC 2011). The host species is still considered to be Least Concern, although it is also in decline.

Conservation Actions [top]

Conservation Actions: As with all unionid bivalves, maintaining water quality, flow, and ensuring that the host species are present is essential.

This species is found in a few protected areas, including St Croix National Scenic Waterway (Minnesota and Wisconsin) and lower Wisconsin State Riverway (Wisconsin).

It is considered threatened in many US States with National rating of N2 (Cordeiro, 2008) (Arkansas (S1), Illinois (S1), Indiana (S2), Iowa (SX), Kentucky (S2S3), Michigan (S1), Minnesota (S2), Missouri (S1), New York (SH), Ohio (S3), Pennsylvania (S1?), Tennessee (S1), West Virginia (S1), Wisconsin (S2)).

In Canada it is considered Endangered (COSWEIC, 2011). The Salamander Mussel is now protected under the Canadian Species at Risk Act as well as the Ontario Endangered Species Act which provides protection against harm to individuals and varying degrees of habitat protection. In addition to the protection provided under SARA and the provincial ESA, Simpsonaias ambigua is included in a SARA multi-species recovery strategy for five mussels (Morris and Burridge 2006). These strategies outline research and monitoring; management; stewardship; and outreach priorities for the recovery of the Salamander Mussel as well as the other aquatic species addressed within.

Citation: Bogan, A.E., Woolnough, D. & Seddon, M.B. 2017. Simpsonaias ambigua. The IUCN Red List of Threatened Species 2017: e.T20247A62905797. . Downloaded on 11 December 2017.
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