Identification of the host fish species for glochidia of the triangle floater, Alasmidonata undulata, (bivalvia, unionidae) :a species of special concern for North America

McGrail, Patricia
Tom Wessels, MA
Department of Environmental Studies
Freshwater pearl mussels, members of the family Unionidae, play an important role in aquatic ecosystems. As filter feeders, they serve as water clarifiers, accumulate and concentrate pollutants, filter organic debris and are important secondary consumers of phytoplankton. Unionaceans are useful biomonitors due to their long life span, and growth and reproduction rates which are directly related and responsive to environmental conditions. The host fishes for Alasmidonta undulata were identified as part of an ongoing mussel monitoring program in the Piscataquag River Watershed, Hillsboro County, New Hampshire. Since 1992, the American Fisheries Society has listed Alasmidonta undulata as a species of special concern for North America, indicating that minor changes in the habitat may cause the species to become threatened or endangered (Williams, et al. 1993). Eight species of fish were collected using seine and backpack electrofisher. Each species was infected in the laboratory and observed daily for attached glochidia. Water from the tanks was filtered for observation of sloughed off glochidia or metamorphosed juveniles. Fish hosts identified were common shiner (Notropis cornutus), black nose dace (Rhinichthys atratulus) and longnose dace (Rhinichthys cataractae). Host fishes release metamorphosed juvenile mussels in approximately 30 days at 15 ºC. The identification of the host fish for Alasmidonta undulata glochidia is important in understanding and protecting the limited populations of the mussel in the Piscataquog River Watershed.

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