Environmental influences on the relationship between juvenile and larval growth of Atlantic croaker Micropogonias undulatus

Abstract

For marine organisms with bipartite life cycles, there is growing recognition that juvenile traits may be dependent on previous larval history. The potential correlation between juvenile and larval stages is important to recognize, as growth rates in juvenile fish have been proposed to be an indicator of habitat quality. We investigated whether juvenile and larval growth are positively or negatively related using the estuarine-dependent fish Atlantic croaker Micropogonias undulatus as a model species. The relationship between juvenile and larval growth was examined using both a laboratory study, in which fish were held in individual containers with constant water temperature and salinity, and replicated field experiments, which spanned a range of environmental conditions. There was no relationship between juvenile and larval growth rates in the laboratory experiment. However, results from the field study suggest that a positive relationship between juvenile and larval growth was associated with high levels of freshwater runoff that displaced juvenile croaker from nursery areas to downstream habitats, in which they had reduced feeding success. Variability in the correlation between juvenile and larval growth for the 27 cohorts examined (fish hatched during the same 1 wk period) was independently explained by change in salinity (a proxy for freshwater runoff) and feeding ability (percentage of fish with empty stomachs). Future research should recognize the role that variable environments play in our ability to detect the relationship of life-history traits between ontogenetic stages. © Inter-Research 2007.