Juvenile reef fish growth and survival related to subregional patterns of primary production

Abstract

For coral reef organisms with bipartite lifecycles, the ontogenetic shift from the pelagic larval stage to the benthic environment is often associated with high mortality that may be influenced by the local environment as well as individual traits that alter vulnerability to predation. Habitat variability such as food availability and competition for resources can influence traits such as growth and size, ultimately affecting mortality rates as well as the strength or direction of trait-mediated mortality. In this study, we examined subregional patterns of early life-history traits (ELHTs) of a model coral reef fish (bicolor damselfish: Stegastes partitus) in environmentally and oceanographically distinct regions of the Florida Keys, USA: the relatively more productive lower Keys (LK) and the more oligotrophic upper Keys (UK). Fish arrived to reef habitats with similar larval ELHTs (larval growth, pelagic larval duration, settlement size) but experienced higher mortality in the LK. Despite variability in mortality rates, patterns of selective mortality were similar between the UK and LK. For juvenile fish, growth during the first 4 days post-settlement was significantly faster in the LK compared to the UK, potentially linked to higher productivity and food availability. Results of this study indicate that environmental variability in settlement habitat at subregional spatial scales can affect post-settlement growth and survival of young fish soon after they transition to the demersal juvenile stage in coral reef environments.