Bleaching in Hot Water

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Science  16 Sep 2005:
Vol. 309, Issue 5742, pp. 1791
DOI: 10.1126/science.309.5742.1791a

When corals lose their symbiotic algae, they bleach. Coral bleaching is known to be caused by a number of factors such as increased salinity, disease, or increased sea surface temperature (SST). The relationship with SST, in particular, has raised concerns that global warming could trigger more frequent and widespread episodes of bleaching. Because of its potentially serious effects on the productivity of reef systems and the biota they support, this relationship has been researched closely in a number of tropical reef systems. Despite clear evidence that increased SST can trigger bleaching, it has proven hard to predict from individual reef-based or laboratory studies how SST influences bleaching at the regional scale.

McWilliams et al. have assembled coral bleaching data from two decades of research in the Caribbean, at the scale of cells of 1° of latitude and longitude, and examined their relation with SST anomalies over the period. They find an exponential increase in the extent and intensity of bleaching episodes with increasing frequency of SST anomalies, such that 100% bleaching is reached with SST increases of slightly less than 1°C—well within the predicted temperature rise for the rest of this century. — AMS

Ecology 86, 2055 (2005).

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