GIM�NEZ, L; Biologische Anstalt Helgoland, Foundation Alfred Wegener Institute for Polar and Marine Research, Marine Station : Functional links among life phases and the consequences for individual performance in decapod crustaceans

I review the effects of past environmental conditions on traits and performance in decapod crustaceans. I consider two critical points of the life cycle: the hatching of larvae and the metamorphosis to the juvenile phase. Biomass at hatching, larval developmental rates, and tolerance to food limitation are positively correlated with egg biomass. In estuarine crabs, larval performance may result from the combined effects of osmotic conditions on the allocation of reserves per egg, the loss of biomass during embryogenesis, and the acclimation state of individuals. The ability to acclimate varies intraspecifically, among broods from different estuaries. Effects of larval environment on performance of juveniles may occur as the consequence of responses to parental habitat cues or variable larval development. Lack of parental cues leads to a delay in the metamorphosis, to reduced size and biomass. Variability in larval development, i.e. the existence of alternative developmental pathways with varying number of stages, produces a complex effect. Longer pathways are followed more frequently if larvae hatch with low biomass or if they experience food or osmotic stress. Larvae following a long pathway may metamorphose later but with an increased size and biomass, and a high tolerance of food limitation. Field-oriented approaches to evaluate the effects of past environmental conditions on present performance are, in decapod crustaceans, indeed a great challenge due to the mobility of most of the life stages. Ongoing research in this topic evaluates the natural patterns of variability in quality of settling larvae, and the consequences for juvenile survival and growth.