COMPOSITION AND DENSITY OF JUVENILE CORALS AT TWO DEEP REEFS IN SAN ANDRÉS ISLAND, COLOMBIAN CARIBBEAN

Abstract

Coral recruitment determines the maintenance, renovation and future of the coral community. In order to determine the composition, density and importance value of scleractinian juvenile corals (<2 or < 4 cm of diameter; depending of the species) two localities were sampled (Reggae Nest and El Faro) at the deep leeward terrace site of San Andres Island. Also, in 47 quadrants of 1m2 distributed throughout a guide line, frequency of partial mortality, total diseases and depredation signs in juvenile corals were quantified. A total of 397 juveniles of 16 species were registered. The average density and richness of juveniles were not significantly different between Reggae Nest and El Faro. The average density of both localities was high compared to other colombian reefs and lower compared to other reefs in the Caribbean. The species with higher importance value, Agaricia agaricites, Scolymia sp. and Porites astreoides, represented 54.9% of all juveniles, similar to other Caribbean reefs. The genera of juveniles with higher importance value index were not the same as the dominant adults (ej. Montastrea, Colpophyllia, Diploria and Siderastrea); since Montastrea annularis and Diploria sp. showed the lowest importance value as juveniles. The coral communities of Reggae Nest and El Faro, deteriorated in the last decades, could recover naturally, considering the following evidence: 1) high juvenile coral density compared to the Colombian Caribbean; 2) high richness of juveniles, 16 from the 23 coral adults species reported for the island; 3) high percentage of common species between juveniles and adults (maintenance of each population); 4) low partial mortality (0.7%; 3 of 397 juveniles) and bleaching found in juvenile corals (0.5%; 2 juveniles of 397). It is still needed to verify if these juveniles are fugitive species, they have long term survival, or the community of builder species maybe being replaced.