Chapter 3 North Carolina Species
3.6 Freshwater Mussels 3.6.1 Introduction
North America has the richest freshwater bivalve mollusks, also called mussels, fauna with approximately 50 genera that are members of the Family Unionidae representing more than 350 species (Haag 2012, Graf and Cummings 2021, Newton et al. 2023) . Currently, there are over 60 species of freshwater mussels found in the wild in North Carolina. The majority are in the Family Unionidae and are the species for which more data are available. There are also native and nonnative species of “pea clams” from the Families Corbiculidae (Basket Clams) and Sphaerlidae (Fingernail Clams) that are found in the state, but there is less known about these species. Freshwater mussels are filter feeders with a diet that varies across habitats and among species but primarily consists of microscopic particulate matter such as phytoplankton, zooplankton, bacteria, and organic detritus (Vaughn and Hakenkamp 2001; Haag 2012) . Mussels live most of their lives burrowed in the bottom of a stream or lake, and depending on species and season, they may be closer to the substrate surface (warm seasons) or burrow more deeply during colder seasons (Amyot and Downing 1991, 1997; Watters et al. 2001; Schwalb and Pusch 2007; Haag 2012) . When population density is high, mussels can be the dominant biomass and exert control over the structure of an aquatic community (Vaughn and Hakenkamp 2001) , as demonstrated in locations that have large populations of the nonnative Asian Clam. Most mussel species have a complex life history that includes a reproductive process dependent on an obligate larva parasite on fish called a glochidium, which has important ramifications for many aspects of mussel ecology and conservation (Layzer and Scott 2006) . Recolonization is dependent on the successful parasitizing of a host fish and subsequent movement of the infected host fish into water that provides suitable habitat for the mussel (Layzer and Scott 2006) . Freshwater mussels are one of the most imperiled fauna; many have undergone drastic declines, and many are predicted to go extinct in the next few decades (Eckblad and Lehtinen 1991; Bogan 1993; Neves 1993; Shannon et al. 1993; Wilson et al. 1995; Neves et al. 1997; Vaughn and Taylor 1999; Vaughn and Hakenkamp 2001, Newton et al. 2023) . Conservation recommendations for the associated habitats have been incorporated into the aquatic natural community descriptions in Chapter 4 (Section 4.2). Additional recommendations can be found in the river basin descriptions (Section 4.5). The following paragraphs provide information about species identified by the Freshwater Mussel Taxa Team as SGCN and other priority species for research or management, and for which work has been conducted to implement conservation and management recommendations. 3.6.2 Comparison of 2015 and 2025 Priority Species The 2025 Freshwater Mussel Taxa Team evaluated 52 species for conservation concern, knowledge gap, and management concern priorities. Some species may be considered a priority
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2025 NC Wildlife Action Plan
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