Coral reefs, among Earth's richest ecosystems, traditionally teem with an abundance of life. But in recent years, corals have been dying in droves. Scientists suspect a variety of factors, ranging from accidental damage from fishing activity to the effects of polluted runoff from land. One threat that appears to be growing dramatically in Australia's famed Great Barrier Reef is white syndrome, a disease that is spreading rapidly, leaving stripes of dead corals like ribbons of death in its wake. In a new study published by PLoS Biology, John Bruno, Amy Melendy, and colleagues show that the interaction between anomalously high ocean temperatures and the extent of coral cover is likely to account for the occurrence of the disease.

Global warming has seemed a likely suspect for several reasons. Past epidemiological studiesacross a broad range of life formshave shown that stress, including the stress of changing environmental conditions, often increases disease susceptibility. As temperatures rise, pathogens can reproduce more quickly. The fact that coral diseases seem to spread faster in summer also provides support for the notion that warmer temperatures may be involved. The authors conducted a regional-scale longitudinal study of the hypothesized link between warm temperature deviations and the presence of white syndrome, considering the density of coral cover as an additional variable of interest. To quantify temperature fluctuations, the researchers used a high resolution dataset on ocean surface temperature provided by the United States National Oceanic and Atmospheric Association and the University of Miami. They used the dataset to calculate w eekly sea surface temperature anomalies (WSSTAs), instances in which temperature was higher by 1C or more from mean records for that week, for 48 reefs within the Great Barrier Reef. To evaluate the extent of white syndrome and coral cover, the researchers used data collected by the Australian Institute of Mari
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Contact: Natalie Bouaravong
press@plos.org
415-568-3445
Public Library of Science
7-May-2007