Abstract

On the coast of Puerto Viejo de Azua a barrier reef, about 7 km long, encloses a lagoon of about 8Km2. The shore is bordered with mangroves and the bottom of the lagoon is covered by seagrass beds mainly composed of Thalassia testudinum. Three different methods were used to sample the fishes according to the biota: with a specific hoop-net in the mangrove areas, with a seine net in the seagrass beds and by visual surveys in the coral reef areas. The data obtained were submitted to a factorial analysis and several indices were calculated (species richness, numbers and biomass, Shannon and Pielou indices) as well as the proportions of the main trophic categories. A total of 114 species was observed in Puerto Viejo lagoon. From a qualitative point of view, fish communities typical of each habitat in the lagoon were characterized. Fish biodiversity was conversely correlated with a tetigeneous gradient, decreasing from the shore to the barrier reef. Fish biomass was found to be low in the mangrove areas and relatively high in the seagrass beds. However, the fish community was mainly composed of juveniles. First-order carnivorous fishes dominate near the mangroves and in the seagrass beds whereas herbivorous fishes were the most abundant in the reef areas. The low level of equipment of fisheries, more particularly the lack of boats able to work offshore, leads the fishermen to overexploit fishes in the lagoon. The low number of fishes with a marketable size reflected the impact of this activity.

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