U.S. Fish & Wildlife Service March 2019 Conserving South Carolina’s At-Risk Species: www.fws.gov/charleston www.fws.gov/southeast/endangered-species-act/at-risk-species Species facing threats to their survival

Brook floater the South Carolina/Georgia state line. It Threats (Alasmidonta varicosa) is also found in Flat Creek and the Lynch- The brook floater is particularly sensitive es River; however, the brook floater is to habitat degradation (silt, nutrient and only found in portions of this river with sewage loads, pollution) caused by poor good water quality and stable stream- agricultural practices, development, loss banks. South Carolina counties where the of riparian corridors, impoundments, off- brook floater is known to occur are: road motor vehicle use, and other water Chesterfield, Edgefield, Greenwood, Ker- quality issues. Impacts from over- shaw, Lancaster, McCormick, Oconee, collection and competition with exotics and Saluda. species such as the Asiatic clam (Corbicula fluminea) and the zebra mussel (Dreissena polymorpha) have also been documented. Brook floater/Photo credit: Allen Barlow Management/Protection Needs Description Protect the brook floater and its habitat The shell of the brook floater is oblong, from further degradation by following long and rhomboid with the anterior mar- best management practices and protection gin abruptly curved the ventral margin of riparian areas, especially those portions long and gently concave centrally. along Flat Creek in the Lynches River Growth ridges are marked by concentric drainage. Encourage responsible land use ridges. The outer surface is generally planning and promote good land steward- smooth except on the posterior slope; it is ship practices through educational pro- yellowish, greenish or covered with dark Brook floater range map - Canadian Wildlife grams. Conduct surveys to determine the greenish rays in juveniles. The outer sur- Service Environment Canada presence and location of the brook floater face becomes brownish with rays partially in South Carolina and continue to monitor obscured or almost black in adults. The Habitat known populations. inner shell surface is whitish or bluish- The brook floater is found in high relief white often with salmon, pink or purple streams among boulders in sand. References in the beak cavity. Maximum shell length COSEWIC Assessment and Status Report for this species is 70 mm (2.8 inches). Status on the Brook Floater Alasmidonta varico- Identification keys are provided in Bogan This species has disappeared from 60-80 sa in Canada - 2009 and Alderman (2004) for South Carolina. sites range-wide and its current global NatureServe. 2015. NatureServe Explor- status is vulnerable (G3). There has been er: An online encyclopedia of life [web Range a sharp decline in numbers where present application]. Version 7.1. NatureServe, The brook floater is found along the east with significant declines being noted in Arlington, Virginia. Available http:// coast from eastern Canada to the Savannah Massachusetts, New York, Pennsylvania, explorer.natureserve.org. River basin in South Carolina and Geor- New Jersey, Rhode Island, Virginia, South Carolina Department of Natural gia. In North Carolina and South Caroli- North Carolina, and South Carolina. It is Resources—State Wildlife Action Plan: na, populations are small, isolated, and not ranked in South Carolina, but is cur- 2010-2015. have limited extents. In South Carolina, rently a species of special concern in this the brook floater occurs in several streams state. The U.S. Fish and Wildlife Service Contact in the Steven’s Creek basin including Bea- was petitioned to list the species in April U.S. Fish & Wildlife Service verdam, Stevens, Turkey and Mountain 2010 and published a substantial 90-day South Carolina Field Office Creeks. The most viable southern popula- finding in September 2011 indicating list- 843/727-4707 tion may be in the Chattooga River near ing may be warranted. [email protected]