Connectivity through ontogeny: fish population linkages among mangrove and coral reef habitats

Abstract

Most evidence for ontogenetic migration of fishes from mangroves to coral reefs has been based on cross-sectional studies of <2 yr duration that have not considered annual variability in recruitment. Taking a longitudinal approach of following cohorts over time, we evaluated evidence for mangrove-derived replenishment of 10 coral reef fishes by drawing on data from 2 concurrent fish monitoring efforts conducted in Biscayne National Park, Florida, USA, over the period 1999 to 2007. Annual indices of abundance were calculated for fish estimated to be age-0 to 4 + in both habitats, and correlation analyses, with appropriate temporal lags, were performed. Statistically significant (p < 0.05; r 2 = 0.30 to 0.71) correlations between juvenile abundances in mangrove habitats and adult abundances on the reef tract 1 to 2 yr later emerged for 4 species: Abudefduf saxatilis, Lutjanus apo- dus, L. griseus, and Sphyraena barracuda. This is one of the few longitudinal studies that uses juve- nile abundance indices to test mangrove-reef ontogenetic connectivity. Our results have potential utility for nursery habitat assessment, marine reserve design, and for forecasting species-specific year-class strength on the reef, where most fishing is directed.