RECOVERY OF THE LONG-SPINED SEA URCHIN DIADEMA ANTILLARUM IN CURACAO (NETHERLANDS ANTILLES) LINKED TO LAGOONAL AND WAVE SHELTERED SHALLOW ROCKY HABITATS

摘要

Prior to the 1983 Caribbean-wide mass mortality of the long-spined sea urchin Diadema antillarum Philippi, the urchin was a dominant herbivore on Curacao's reefs (Bak et al., 1984). Teenstra (1836) first mentioned the existence of shallow sub-tidal aggregations of this species inside Schottegat Bay, Curacao. Mean densities documented on the island at various shallow leeward, southwest coast sites during the 1960s to early 1980s ranged between 3 and 20 m~(-2) (Smith, 1968; Juliana, 1974; Bak and van Eys, 1975; van Eys, 1976; Bauer, 1980; Geerlings, 1981; Bak et al., 1984; Carpay, 1985). In contrast, the species was almost completely lacking from the wave-exposed northeast coast of the island (Wanders, 1976). Van den Hoek et al. (1978) described the tendency of the species to aggregate into distinct depth-zones on the reefs of Curacao, according to the availability of shelter. In the decade prior to the mass mortality event, the two study sites for which data are available had already begun to show significant declines in urchin density, which likely represented a natural fluctuation (Bak et al., 1984; Carpay, 1985). However, mass mortalities began abruptly in early October 1983 and by the end of that month, documented mortalities were 97.396-100% and the urchin densities averaged only 0.01 m~(-2) (Bak et al., 1984).