Size and Performance of Juvenile Marine Invertebrates: Potential Contrasts Between Intertidal and Subtidal Benthic Habitats

SYNOPSIS. Newly settled or hatched juveniles of marine benthic invertebrates generally experience very high mortality. Juvenile mortality can profoundly affect adult populations, but little is known about how individual variation in juvenile quality affects performance. Several recent studies have demonstrated that differences in size, larval nutrient stores, or larval feeding history can strongly affect the performance (measured as growth and survivorship) of juveniles. Additional research suggests that the strength of the effect of juvenile size on performance may be mediated by variation in environmental stress in the intertidal, a habitat characterized by strong fluctuations in abiotic factors. The major sources of juvenile snail mortality are likely to differ in intertidal and subtidal habitats; abiotic stresses related to exposure, such as desiccation, are important in the intertidal but far less severe in subtidal environments. Previously observed trends in hatching or settlement size between intertidal and subtidal species from three gastropod taxa may be due to differing selective regimes acting on initial juvenile size.