Freshwater mussel glochidia infesting anadromous Gaspereau below a hydroelectric generating station: implications for mussel conservation

The Wolastoq | Saint John River (W|SJR) in New Brunswick, Canada, is regulated by hydroelectric dams with the largest and furthest downstream being the Mactaquac Generating Station (MQGS). River regulation can disrupt ecosystem connectivity by restricting access to upstream habitat for fishes and parasitic mussel larvae dependent on fishes for dispersal. Following installation of the MQGS, the number of Gaspereau (Alewife, Alosa pseudoharengus [Wilson, 1811]) and Blueback herring, Alosa aestivalis [Mitchill, 1814]) that spawn in that region of theW|SJR has increased dramatically. We assessed ectoparasitic freshwater mussel glochidia on Gaspereau captured at the MQGS and found 100% infested with an average of 43.2 glochidia per fish. Glochidia infested gill rakers, with increasing intensities from the first to fourth gill arch ( P