Marine habitat structure and health status heterogeneity effects on coral reef fish assemblages in Martinique
Résumé
The relation between habitat degradation and fish communities structure was assessed at 12 sites along the Martinique Caribbean coast in two different habitat types: bank reef and fringing reef. Four health index (from very good to very degraded) were used to qualify the reef status, each site belonging to one of the 4 categories. Fish and benthos data were collected using visual census at a depth of 8 to 13m. Fish were counted during 2 passes (4m belt and 2m belt) along a 50m long transect: 1) number and size class of mobile and fearful species and 2) territorial species. Point intercept was used for the benthos (100pt/transect). Each site was sampled twice in triplicate during both the dry and wet season, 2007. Univariate (abundance, species richness, diversity index) and multivariate statistics (PERMANOVA, PCoA, CCA) were used to analyze the data. Comparison were made between the fish assemblages and the different habitat attributes. The analysis of the fish population structures was performed on key species (abundant species, commercial species), principal families and trophic groups. Preliminary results show differences in fish species composition, abundance and biomass according to health status and habitat type. The information will be compiled to model fish assemblages changes with reef health status