Abstract

Corals represent the main key species for coral reefs. Coral-built structures shelter numbers of Invertebrate and fishes representing the major part of the stock of species harvested by coastal tropical fisheries. Caribbean coral communities have presented increasing signs of decay since nearly 30 years due to a conjunction of natural and anthropogenic factors. It is urgent to develop indicators able to characterize the state of health of coral communities and to provide a tool for monitoring the dynamics of their evolution. In the present study we tested two bio-indicators on the reefs of Guadeloupe Island submitted to different levels of threat: 1) the measurement of the rate of necrosed tissues on the adult corals. This indicator is both related to the instantaneous state of health of the coral community and to the potential mortality rate of adult corals; 2) the recruitment of young corals that represents the potential of regeneration of communities. On reefs with low anthropogenic pressure, coral communities are characterized by a higher abundance of adults presenting a minimal rate of necrosis in comparison with reefs submitted to higher stress. Species richness and abundance of young corals are also higher on less threatened reefs. Necrosis affects more specifically massive reef-building species (Montastrea faveolata, M. cavernosa, Colpophyllia natans, Diploria strigosa). The most resistant species are r strategy (Favia fragum, Siderastrea radians, Agaricia agaricites, Porites astreoides…). These species tend to predominate in the coral communities of the most degraded reefs in the adult as well as in the juvenile populations.

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