Trophic models of protected and unprotected coral reef ecosystems in the south of the Mexican Caribbean

General models of the energy flow of the back reef, reef Dent and slope zones of three coral reef complexes in the Mexican Caribbean are presented. The number of fish species registered varied considerably between reefs with a maximum found on the Mahahual reef slope. Generally, the maximum number of fish species and biomass were registered on the reef slope and the minimum on the back reefs. The greatest species number and flow diversity were obtained in the Mahahual reef. The individuals recorded for the fish feeders were also of greater size in the Mahahual reef Maximum activity and biomass were found in the deeper Boca Paila and Tampalam habitats. The production and biomass trophic ratios used in this work were shown to be indicators of trophic tendencies of reef fish. However, the relative differences between piscivorous, carnivorous, herbivorous and zooplankton feeder fishes were not evident, but there were marked differences between biomass or production in each trophic group. Preliminary analysis suggests differences in trophic structure and energy flow between semi-protected and unprotected areas. The comparative analysis of this nested set of models using trophic macrodescriptors may provide a useful index of anthropogenic impacts in coral reef ecosystems. (C) 1998 The Fisheries Society of the British Isles.