Ebonyshell Host Identification and Reproductive Biology

The ebonyshell (Fusconaia ebena) is an abundant and commercially important species of freshwater mussel that has been nearly extirpated from the Upper Mississippi River by the effects of navigational dams on its primary fish host, the skipjack herring. I investigated the reproductive biology of ebonyshell to understand factors limiting its reproduction and to investigate the possibility of captive propagation for population restoration. Ebonyshell have been observed brooding embryos from May to September. The long brooding season of ebonyshell might be explained if 1) individuals reproduce once annually but asynchronously, or if 2) individuals produce multiple broods annually. I examined ebonyshell in the Lower Mississippi (MO), Lower Ohio (OH), Black (AR), White (AR), and Tennessee River (KY, TN) systems to investigate the reproductive cycle. I also made repeated observations over 2 months on a collection of ebonyshell caged in Kentucky Lake. The fertilization success of ebonyshell broods in the Lower Ohio, Black, White and Tennessee rivers was generally high, in contrast with low fertilization observed in the White and Meramec Rivers (AR, MO). I tested 21 fish species as hosts for ebonyshell and identified goldeye (Hiodon alosoides) as a suitable host for the first time. Goldeye was also found to be an effective host for another widespread and commercially important species, the washboard (Megalonaias nervosa)