Detecting the effects of natural disturbances on coral assemblages in French Polynesia: A decade survey at multiple scales

Author: Adjeroud Mehdi   Chancerelle Yannick   Schrimm Muriel   Perez Thierry   Lecchini David   Galzin René   Salvat Bernard  

Publisher: Edp Sciences

E-ISSN: 1765-2952|18|2|111-123

ISSN: 0990-7440

Source: Aquatic Living Resources, Vol.18, Iss.2, 2010-03, pp. : 111-123

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Coral reefs in French Polynesia, just like many others throughout the world, have been subjected to several natural disturbances including 15 cyclones, seven major bleaching events, and several outbreaks since the 1980s. In order to document the effects of these perturbations on coral assemblages, we initiated a long-term monitoring program that extended over both local and regional scales. Coral cover was quantified at 20 sites situated on the outer reef slope of 13 islands. The results from the first decade (1992-2002) are analyzed and the adequacy of our approach is discussed in the context of identifying potential indicators of coral reef health. Among 13 islands in French Polynesia, only two were unaffected by natural disturbances. We found important local and regional variation in the impacts of coral bleaching and cyclones, and three major temporal trends were distinguished: 1) 10 sites where coral cover decreased in relation to the occurrence of major disturbances; 2) nine sites where coral cover increased, despite the occurrence of disturbances affecting seven of them; and 3) a site where no significant variation in coral cover was found. The responses to perturbations were different among coral genera: species were particularly susceptible to bleaching events, whereas physical damages induced by cyclones concerned mainly branching species of and . Thus, monitoring surveys could be improved by selecting different and complementary indicators (one on the variation in diversity, one estimating changes in the abundance/cover, and one estimating the potential for recovery), by integrating several spatial scales, and by including at least the most informative species. High frequency recordings of environmental parameters (e.g. sea surface temperature) may be also a complementary tools for identifying causal relationships between changes in coral reef community structure and the factors causing the changes.