We have seen studies on warmer ocean temperatures and the effects it has on coral disease and bleaching events but a new study shows the link between mild water temperatures during the preceding winter period with outbreaks of coral diseases. The research was conducted on Australia’s Great Barrier Reef by studying satellite measurements of unusual sea surface temperatures. The team of scientists also examined the magnitude of stress on corals from unusually warm temperatures, particularly in summer, and confirmed a strong relationship with coral disease outbreaks.
The study, a collaboration between scientists from National Oceanic and Atmospheric Administration (NOAA), the Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University and the Australian Institute of Marine Science, was published in August in the online, peer-reviewed international publication PLoS ONE.
“Previous studies examined the relationship between warm conditions throughout the year and the likelihood of disease,” said Scott Heron, Ph.D., physical scientist with NOAA’s Coral Reef Watch. “We considered the influence of summer and winter separately, taking into account both cold and warm stress, to find that winter temperatures are just as important as summer stress in determining the susceptibility of corals to disease outbreaks.”
With advance warning to the higher potential of coral diseases on reefs, managers will not be able to do much beyond reducing human-use stressors like diving, swimming, fishing and boating. Also launched and described in the paper is the new experimental Coral Disease Outbreak Risk Map available online. This regional product provides a seasonal outlook based on winter metrics and an outbreak risk assessment updated in near-real-time during summer for the Great Barrier Reef. Ongoing work will soon expand it to the Hawaiian archipelago.
“Satellite monitoring of sea surface temperature has been useful in predicting coral bleaching,” said C. Mark Eakin, Ph.D., coordinator of NOAA’s Coral Reef Watch. “Now we’ve used satellite measurements to find links between disease and temperature stress. Our new product should allow us to predict the risk of potential disease outbreaks in Australia, providing reef managers with vital information and enabling rapid management response. We look forward to expanding it to other areas as well.”
Also noted were some outbreaks of coral disease being observed following bleaching events when the resistance of corals is reduced. Severe coral bleaching has been reported throughout Southeast Asia, the Indian Ocean and the Pacific since May. NOAA Coral Reef Watch is currently predicting a high potential for bleaching throughout the Caribbean this year. NOAA also recently reported that the combined global land and ocean surface temperature made this past July the second warmest on record and the warmest averaged January-July on record. This warming is expected to increase the incidents of coral bleaching worldwide.