Ecology and Reproductive Strategy of a South Louisiana Freshwater Mussel, Glebula rotundata (Lamarck) (Unionidae:Lampsilini)

Female Glebula rotundata (Lamarck 1819) were examined every two weeks from August 1978 through November 1979. The population was reproductively active, i.e., marsupium functioning as a brood pouch, from March through early October. Females recharge soon after discharging glochidia larvae, thus initiating another cycle. Each female clam may reproduce three times a year. This reproductive cycle is atypical of other Lampsilini. Two species of sunfish, Lepomis cyanellus and Lepomis macrochirus, served as suitable hosts for G. rotundata under laboratory conditions. Glochidia successfully metamorphosed after attaching to gill filaments and fins of these species. Our studies suggest that fish near large populations of G. rotundata avoid parasitism by G. rotundata glochidia, and recruitment of young clams is low. Glebula rotundata larvae were found on two estuarine fish species Trinectes maculatus and Anchoa mitchilli, which may explain the occasional presence of G. rotundata in estuarine habitats.