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

• Published in: Hydrobiologia Vol. 851; no. 3; pp. 617 - 632
• Main Authors: Dobbs, K. D. R., Lynn, T. J., Bruce, M. R., Reyes-Prieto, A., Samways, K. M., Curry, R. A., Duffy, M. S.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.02.2024; Springer Nature B.V
• Subjects: Aquatic ecosystems; Baseline studies; Biomedical and Life Sciences; Ecology; Fish; Fish ladders; Fishways; Freshwater; Freshwater & Marine Ecology; Freshwater molluscs; Gills; Glochidia; Hosts; Hydroelectric dams; Hydroelectric power; Inland water environment; Larvae; Life Sciences; Marine fishes; Mollusks; Primary Research Paper; River regulations; Rivers; Symbionts; Upstream; Zoology; Parasitism; Host fish; River regulation; Freshwater mussels; Glochidia; Hydroelectric dam
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-023-05351-y

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  < 0.001). At least one million Gaspereau are passed above the MQGS annually, suggesting that millions of glochidia are simultaneously passed upstream each year with their hosts. We sequenced mitochondrial markers ( ND1 , COI ) to ascertain mussel species and confirm both Alewife and Blueback herring as hosts for Alewife Floater ( Utterbackiana implicata [Say, 1829]). This study provides critical baseline data on symbiotic interactions tightly interwoven in this river ecosystem and demonstrate that river regulation and fish passage considerations are more complex than most management plans account for currently.