Host fishes and infection strategies of freshwater mussels in large Mobile Basin streams, USA

We investigated host fishes, timing and modes of glochidial release, and host-attraction strategies for 7 species of freshwater mussels from the Buttahatchee and Sipsey rivers (Mobile Basin), Alabama and Mississippi, USA. We determined hosts as fish species that produced juvenile mussels from laboratory-induced glochidial infections. We established the following primary mussel/host relationships: Elliptio arca with Etheostoma artesiae and Percina nigrofasciata; Fusconaia cerina with 6 species of minnows (Cyprinidae); Lampsilis ornata with Micropterus salmides; Medionidus acutissimus with 8 species of darters (Percidae); Obovaria unicolor with Ammocrypta beani, A. meridiana, and Etheostoma artesiae; Pleurobema decisum with Cyprinella venusta; and Quadrula asperata with Ictalurus punctatus. For most mussel species, host use was similar to that of closely related species indicating that, in general, this trait is highly conserved at the generic level. Four mussel species used host-attraction strategies that targeted their specific host fish. Fusconaia cerina and P decisum released glochidia in conglutinates that elicited feeding responses from fishes in the field and in the laboratory. Gravid female Lampsilis ornata and M. acutissimus displayed mantle lures. Host-attraction strategies were less apparent for E. arca and Q. asperata, but these species released glochidia in association with copious mucous secretions, which may serve to entangle fishes, facilitating host infection. No host-attraction strategy was apparent for O. unicolor.