EVALUACION RAPIDA DE ESTRUCTURA Y SALUD DE LAS FORMACIONES CORALINAS DE LA ISLA DE MALPELO (PACIFICO COLOMBIANO)

Abstract

Malpelo, a small rocky offshore island that supports one of the few coral populations in the eastern Pacific, was visited on June 1-5, 1999 with the purpose of evaluating the status of the coral communities. Using rapid visual methods, the cover of major categories of sessile organisms and the health condition of the coral species were assessed at 8 stations between 11 and 31 m depth. “El Arrecife”, which is the largest coral formation in Malpelo, seems to have suffered a 20% reduction of the live coral cover since 1972 when a mean value of 65% was recorded. This decline, which probably was originated by the 1982-83 strong bleaching event that affected widely the American Pacific, is reflected also by the present levels of recent coral mortality: mean of 23% at “El Arrecife”. Nevertheless, live hard corals continue as the dominant (mean 45%) bottom category in this formation, followed by the crustose calcareous algae (27%). As in 1972, Porites lobata is in general the most abundant hard coral species but Pocillopora spp. can dominate in the shallow zone. Among observed coral degradation agents and signs, current mortality was also frequent but affected only small areas of the colonies and was related to diseases or fish grazing in most cases. The presence of coral diseases in the Colombian Pacific is here recorded for the first time; the most frequent is similar to the White Band Disease (WBD) and was observed attacking Pocillopora spp. An event of strong wind and ocean swell occurred during this study, resulting in considerable physical damage on reef structure and coral colonies at “El Arrecife”. This damage included extensive fragmentation of Pocillopora branches, as well as overturning, fragmentation and scraping of many colonies of massive species.