Contrasting oceanographic conditions during larval development influence the benthic performance of a marine invertebrate with a bi-phasic life cycle

摘要

The pelagic life and benthic life of marine invertebrates with bi-phasic life cycles have often been studied separately, with the assumption that metamorphosis deletes larval history. However, it is now recognized that larval history can condition the post-metamorphic performance of benthic juveniles and ultimately contribute to the shaping of adult population dynamics. In the present study, we evaluated late larval and early juvenile performance of the green crab Carcinus maenas in Ria de Aveiro (Portugal) over 4 consecutive larval supply events in 2013. Larvae collected from the plankton were kept in the laboratory without food and under controlled conditions. Following metamorphosis, juvenile crabs were either exposed to starvation or provided with food ad libitum (Artemia nauplii). Juveniles were stocked until they either died or reached the 5th juvenile crab instar. Results showed that larval size at metamorphosis shifted along supply events, with this being reflected in early benthic life. Overall, optimal growth conditions did not delete the larval history experienced by the megalopae (and their previous zoeal stages) collected from each supply event. We analysed the influence of upwelling index in larval and early juvenile performance using general additive models, with the upwelling index explaining a significant percentage of the deviance recorded. Overall, contrasting trophic conditions experienced during larval life promoted a variation in larval size at settlement, which was carried over into early benthic life. A unifying integrated framework is therefore needed to better understand the population dynamics of marine invertebrates with bi-phasic life cycles and the role played by latent effects.