CARACTERIZACION ESTRUCTURAL DE LA COMUNIDAD BENTONICA EN EL ARRECIFE DE MAHAHUAL, MEXICO

Abstract

Coral reefs make up an important ecological ecosystem due to its high diversity, productivity and structural complexity where the structure and composition are attributes determining its health and how it works. Currently the reefs have been taking a gradual deterioration, caused primarily by natural phenomena and anthropogenic activities. Hurricanes are considered one of the natural agents that mostly impact the distribution and abundance of the reefs’ species and causing structural changes in the long term. On August 2007 the Mahahual reef was affected by the Dean hurricane (category 5). As a result, the structure and composition of the macrobenthos was measured before and after the hurricane (2205 and 2008) with the purpose of determining the possible changes to the structure of the reef community. The samplings were taken from the shallow and deep water areas of the Mahahual reef (Quintana Roo, Mexico), by means of photographic transects. Coverage data were obtained from species of corals, octocorals, sponges, and the type of substrate. In 2005 a total of 69 species were registered from which the corals represented the highest richness (29 species), Pseudopterogorgia bipinnata, Montastraea faveolata and Agaricia agaricites were the dominant species. In 2008, 66 species were recognized with the sponges representing the largest species. Species such as Pseudoterogorgia bipinnata, Agaricia agaricites and Montastraea franksi were dominant during this year. Significant differences were found in the richness, diversity and equity (through the t test) contrasting the years 2005 and 2008. Likewise, the macrobenthos coverage was reduced by 13% in 2008, therefore the substratum came to occupy this area. The shallow and deep water areas of the reefs showed a reduction on the macrobenthos coverage in 2008, but the deeper zone was the most affected showing a decrease of 16.34%. In respect to the structure of the community, the diversity, the equity and the richness presented significant differences in this zone. Therefore, the organisms that nowadays dominate the Mahahual reef are macrobenthonic species, due to their life history have been developed and proliferated by natural events such as the Dean hurricane. Likewise, basament with macroalgae, basement and recent dead coral have a high coverage suggesting that after the path of hurricane Dean, the Mahahual reef structure was altered, creating this a pioneer work for establishing long term changes on this reef.