Diversity and abundance variation of dominant mollusk species in the coral zone of La Entrega, Oaxaca.

Abstract

Bimonthly samplings were carried out from October 2002 to August 2003 at La Entrega reef. With the collected material the mollusk community associated to the coral Pocillopora damicornis was characterized in order to compare its current structure with that which it showed during 1994-1995. We observed that diversity had not changed significantly. However, it did show changes in the abundance of the dominant taxa. Particularly an increase in the number of organisms of the genus Lithophaga and of Quoyula madreporarum along with the decrease of Muricopsis zeteki and Cantharus spp. These species are closely related to various processes that occur within the reefs, such as bioerosion of the corals. Thesespecies have found optimal conditions for colonization and development within the fragile structure of the reef that in a larger time scale could generate an ecological imbalance, as has occurred in other coral reefs around the world.