POTENCIAL BIOEROSIVO DE Diadema mexicanum (Echinodermata: Echinoidea) EN CUATRO ARRECIFES DEL PACÍFICO MEXICANO

Abstract

Abstract Bioerosion plays an important role in the balance of carbonates on reef communities, because it weakens the coral structure thus making it prone to damage by environmental factors. Dead coral is then covered by algae and sea urchin populations can add to the damage. This process is not well understood and it is known to be aggravated by anthropogenic activities. The objective of this paper was to determine seasonally the level of bioerosion caused by the sea urchin Diadema mexicanum in Cabo Pulmo, B.C.S., Isla Isabel and Islas Marietas, Nay. and La Entrega, Oax. along the Mexican Pacific. On each locality we estimated sea urchin density, size structure and coral cover. Bioerosion was determined experimentally by analyzing the carbonates removed by feeding and spine activities. D. mexicanum was smaller and less abundant in Cabo Pulmo, but the highest density was registered in La Entrega. Regarding size, medium-size echinoids removed more carbonates by feeding activity. Coral and algal cover were higher in La Entrega and less in Isla Isabel. Bioerosion levels were also higher in La Entrega whilst Cabo Pulmo showed the lowest values. In general, the Mexican Pacific showed low values of bioerosion caused by echinoids compared to other countries, because it acts as an algal biomass controller. We conclude that to date, D. mexicanum does not represent a threat to coral communities, however a continuous monitoring of sea urchin populations are recommended.