MEPS 222:209-216 (2001)  -  doi:10.3354/meps222209

Cloudy weather may have saved Society Island reef corals during the 1998 ENSO event

Peter J. Mumby1,*, John R. M. Chisholm2, Alasdair J. Edwards1, Serge Andrefouet3, Jean Jaubert2,4

1Centre for Tropical Coastal Management Studies, Department of Marine Sciences and Coastal Management, Ridley Building, The University, Newcastle upon Tyne NE1 7RU, United Kingdom
2Observatoire Océanologique Européen, Centre Scientifique de Monaco, Avenue Saint-Martin, MC 98000, Principality of Monaco
3Department of Marine Science, University of South Florida, 140 7th Avenue South, St Petersburg, Florida 33701, USA
4Université de Nice, Faculté des Sciences, Campus Calrose, 06108 Nice, France

ABSTRACT: During the 1998 El Niño-Southern Oscillation (ENSO) event, mass coral bleaching in French Polynesia was patchy at a scale of 100s of km. Bleaching was extensive in parts of the Tuamotu archipelago (creating up to 99% coral mortality) but extremely mild in the Society Islands (Tahiti, Moorea), ca 350 km to the south-west, despite sea surface temperature (SST) anomalies being of similar magnitude to previous years in which mass bleaching occurred. We examine whether environmental variables account for this unexpected paucity of bleaching using a 50 yr record of SST, a 17 yr record of daily wind and cloud cover, and a 17 yr record of monthly sun hours. Records from Tahiti reveal that exceptionally high cloud cover significantly reduced the number of sun hours during the summer of 1998. Quadratic discriminant analyses of annual bleaching occurrence based on up to 3 predictors (cumulative degree heating months, wind speed, and cloud cover during periods of elevated summer SST) only predicted the correct bleaching scenario for 1998 when cloud cover was added to the function. The results demonstrate that the interactive effect of cloud cover can reverse the bleaching predictions of such statistical models. We suggest that reduced radiative stress, resulting from high cloud cover, may have prevented large-scale coral bleaching in 1998.


KEY WORDS: El Niño-Southern Oscillation · Coral bleaching · Climate change · Sea surface temperature anomaly


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