Old reserves were more effective in reducing coral loss, for yet unknown reasons. We need to think long term and act now to establish marine reserves that can better protect coral reefs from unknown future threats.
These results should sound a warning bell for reef managers believing that marine reserves will be more resilient to climate change. The biggest stresses put on coral reefs are ocean warming and disease outbreaks.
These were among the findings of a study of data on 8540 coral reefs in the Indian, Caribbean and Pacific regions over the 18 years from 1987 to 2005.
Old reef parks survive warming better
University of Carolina, ScienceAlert 2 Dec 08;
Marine reserves might help restore local fish populations but they are failing to protect fragile coral reefs from the effects of global warming.
These are the findings of Associate Professor John Bruno from the University of New Carolina, who presented at the Ecological Society of Australia's annual conference at the University of Sydney.
Professor Bruno and his former graduate student Elizabeth Selig, compared data collected from 8540 coral reefs in the Indian, Caribbean and Pacific regions over the 18 years from 1987 to 2005. They compared coral cover, sea surface temperatures and whether the reef was in a marine reserve or not.
"We found that while coral loss was reduced in marine reserves, the rate of coral decline with warmer temperatures was just the same in marine reserves as in highly fished areas," he says.
Professor Bruno believes these results should sound a warning bell for reef managers believing that marine reserves will be more resilient to climate change.
"The biggest stresses put on coral reefs are ocean warming and disease outbreaks," he says. "These stresses are regional and global in scale and local protection through marine reserves is unlikely to help these reefs resist such changes.
"Marine reserves are very important for protecting fish populations, maintaining coral reef food webs and protecting against anchor damage, but they are unlikely to reduce coral losses due to ocean warming."
But, Professor Bruno found that marine reserves that have been around for a long time - at least 15 years - were more effective in reducing coral loss then reserves that have been around for a shorter time period.
"We don't know the reason for this result, although we can speculate that it could be due to longer-term marine reserves being better managed or established," he says. "But the key thing is that we need to think long term and act now to establish marine reserves that can better protect coral reefs from unknown future threats.
"Restoring and protecting corals from climate change requires urgent implementation of regional and global strategies to deal with the root causes of climate change, including reducing carbon emissions."
Professor Bruno with colleagues from James Cook University and the Australian Institute of Marine Science also looked at data from Australia's Great Barrier Reef Marine Park, specifically comparing water temperatures with outbreaks of the devastating white syndrome disease that kills coral. They found that warmer ocean temperatures do increase the likelihood of an outbreak.
