Life history traits of Lepetodrilus nux in the Okinawa Trough, based upon gametogenesis, shell size, and genetic variability

Because marine benthic animals usually form metapopulations via larval dispersal, a firm grasp of life-history traits is essential to understand the larval dispersal processes and population dynamics of marine benthic communities. Deep-sea hydrothermal vents are ephemeral environments, but they support benthic communities of high biomass. Lepetodrilus nux is one of the most abundant and widely distributed limpets in deep-sea hydrothermal vent fields in the Okinawa Trough. In the present study, life-history traits of L. nux were investigated at 4 vent sites: Izena Hole, Minami-Ensei, Irabu, and Hatoma Knolls. New distributions of L. nux in the Minami-Ensei and Irabu Knolls are described, and genetic analyses suggest that L. nux exists as a metapopulation in the Okinawa Trough vent fields, with higher genetic diversity in the northern part and lower diversity in the southern part. Histological data reveal that L. nux is gonochoristic, and that it employs internal fertilization and possibly continuous reproduction. Individuals mature at relatively smaller size compared with those of other Lepetodrilus species in the East Pacific Rise (EPR) and Mid-Atlantic Ridge (MAR). Population size-frequency distributions differed among vent sites. Size-frequency differences among populations may result from complex environmental variability, such as hydrothermal vent activity and ocean current systems, which influence dis persal and succession of deep-sea vent fauna. These life history traits suggest that L. nux is an opportunistic colonizer, and explain its wide distribution in patchy and ephemeral deep-sea vent fields.