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 zon es of three coral reef complexes in the Mexican Caribbean are presented. Th e number of fish species registered varied considerably between reefs with a maximum found on the Mahahual reef slope. Generally, the maximum number o f fish species and biomass were registered on the reef slope and the minimu m on the back reefs. The greatest species number and flow diversity were ob tained 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 n ot evident, but there were marked differences between biomass or production in each trophic group. Preliminary analysis suggests differences in trophi c structure and energy flow between semi-protected and unprotected areas. T he comparative analysis of this nested set of models using trophic macrodes criptors may provide a useful index of anthropogenic impacts in coral reef ecosystems. (C) 1998 The Fisheries Society of the British Isles.