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Unprecedented bleaching-induced mortality in Porites spp. at Rangiroa Atoll, French Polynesia

Lookup NU author(s): Dr Peter Mumby, Emeritus Professor Alasdair Edwards


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In April-May 1998, mass coral bleaching was observed in the lagoon of Rangiroa Atoll, Tuamotu Archipelago, French Polynesia. Six months later, the extent of bleaching-induced coral mortality was assessed at three sites. Corals in the fast-growing genus Pocillopora had experienced > 99% mortality. Many large colonies of the slow-growing genus Porites (mean horizontal cross-sectional area 5.8 m2) had also died - a phenomenon not previously observed in French Polynesia and virtually unprecedented world-wide. At one site, 25% of colonies, or 44% of the pre-bleaching cover of living Porites, experienced whole-colony mortality. At the two other sites, recently dead Porites accounted for 41% and 82% of the pre-bleaching live cover. Mortality in Porites was negatively correlated with depth between 1.5 and 5 m. Using a 50-year dataset of mean monthly sea surface temperature (SST), derived from ship- and satellite-borne instruments, we show that bleaching occurred during a period of exceptionally high summer SST. 1998 was the first year in which mean monthly SSTs exceeded the 1961-1990 upper 95% confidence limit (29.4°C) for a period of three consecutive months. We suggest that the sustained 3-month anomaly in local summer SST was a major cause of coral mortality, but do not discount the synergistic effect of solar radiation. Recovery of the size-frequency distribution of Porites colonies to pre-bleaching levels may take at least 100 years.

Publication metadata

Author(s): Edwards AJ; Mumby PJ; Chisholm JRM; Clark CD; Roark EB; Andrefouet S; Jaubert J

Publication type: Article

Publication status: Published

Journal: Marine Biology

Year: 2001

Volume: 139

Issue: 1

Pages: 183-189

Print publication date: 01/01/2001

ISSN (print): 0025-3162

ISSN (electronic): 1432-1793

Publisher: Springer


DOI: 10.1007/s002270100575


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