STATUS OF THE POPULATIONS OF THE BLACK SEA URCHIN DIADEMA ANTILLARUM PHILIPPI (ECHINOIDEA: DIADEMATIDAE) AT TAYRONA NATIONAL NATURAL PARK AND PLAYA BLANCA, SANTA MARTA, COLOMBIAN CARIBBEAN

Abstract

Diadema antillarum experienced a mass mortality event between 1983-1984 that dropped its densities about 93 %, a phenomenon that led to a macroalgae dominance in most reefs. This study was performed in Tayrona National Natural Park (PNNT) and Playa Blanca (Bahía de Gaira) to determine the status of the black sea urchin populations. At each site, five 10 m line transects were located perpendicular to each other and the density was estimated by 1 m2 squares; coral community composition and roughness was recorded by video. Size structure was calculated by collecting between 31 and 52 individuals and measuring the diameter and height of the test. The highest mean density was found in Nenguange (1.16 ind/m2) and lowest in Chengue (0.04 ind/m2), both located in the PNNT. Mean test diameter was between 58.84 and 80.60 mm. No relation was found between the main reef components (corals, macroalgae or dead coral) and the sea urchin densities, neither between diversity and uniformity and sea urchin densities. Our results show that the density is in the range of current abundance reported in other Caribbean regions, indicating a slow recovery of populations.