Marine Protected Areas do little to protect coral reef ecosystems from ocean warming and global climate change
Arlington, VA – A paper published today in the journal
Global Change Biology showed that corals that are found living within the
boundaries of Marine Protected Areas (MPAs) appear to be just as susceptible to
ocean warming as corals found in unprotected areas. The study was conducted by
scientists from Conservation International, the University of North Carolina at
Chapel Hill and the National Oceanic and Atmospheric Administration.
To determine whether coral deaths caused by ocean warming were lower inside
marine protected areas, researchers combined more than 8,000 coral reef surveys
performed by divers with satellite measurements of ocean surface
“Marine protected areas can protect coral reefs from localized problems,
particularly overfishing and terrestrial run-off,” said Elizabeth Selig,
conservation scientist with Conservation International and the study’s lead
author. “However, the magnitude of losses from increased ocean temperatures as a
result of climate change seems to be overwhelming these positive effects. This
paper suggests that we need to rethink our current planning for MPAs in order to
maximize the benefits they can provide.”
Globally, corals reefs are being degraded by a number of factors including
overfishing, sedimentation and rising ocean temperatures due to greenhouse gas
emissions, Selig said.
MPAs provide many direct benefits to fisheries and coral reefs, however such
zones appear to offer limited help to corals in their battle against global
warming, according to the new study. The researchers on the study concluded that
to protect coral reefs from climate change, marine protected areas need to be
complemented with policies that can meaningfully reduce greenhouse gas
“Although marine protected areas could help coral populations recover from
temperature-induced mortality in particular situations, this does not appear to
be an effective general solution,” said study author John Bruno, Ph.D.,
associate professor of biology in the UNC College of Arts and Sciences.
A rise of just 1 degree to 2 degrees Fahrenheit (about 0.5 degrees to 1
degree Centigrade) above normal summertime highs can kill coral polyps, which
Given the difficulty of slowing or reversing the rate of greenhouse gas
emissions, coral reef scientists, managers and conservationists had pinned their
hopes on a different, more localized strategy: saving corals by restricting
fishing in marine protected areas. The reasoning is that fishing depletes
herbivorous fishes, which can lead to more seaweed on the seafloor; that can
harm baby corals, so restricting the taking of fish that trim back seaweed
should help coral populations recover.
Previous research has shown that under optimal conditions, reefs in marine
protected areas saw increases in coral cover of 1 percent or 2 percent per
But those gains might not be enough to mitigate the impact of thermal stress
events. For example, the new study found that when water temperatures were more
than 1 degree Centigrade above summertime averages for eight weeks (recognized
as the threshold that generally results in widespread bleaching and significant
coral death), it correlated with coral cover loss of 3.9 percent annually.
“Reducing overfishing, although clearly a very good thing, will not
meaningfully limit the damage being done to the world’s coral reefs by
greenhouse gas emissions,” Bruno added.
Richard B. Aronson, Ph.D., professor and head of the biological sciences
department at the Florida Institute of Technology, said the study clearly showed
that marine protected areas cannot by themselves save coral reefs.
“We have to reverse climate change by stopping runaway greenhouse gas
emissions,” said Aronson, who did not participate in the study. “That is a lot
harder than protecting a reef against local problems like fishing pressure,
because it requires international cooperation. But it can be done — and it must
be done if we are going to save the coral reefs and the rest of the planet.”
Along with Selig and Bruno, the other author of the study was Kenneth S.
Casey, Ph.D., a satellite oceanographer and technical director of NOAA’s
National Oceanographic Data Center.
Study link: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02658.x/abstract
For a photo gallery of images of UNC researchers conducting coral reef
surveys in Belize in 2009, go to http://uncnews.unc.edu/content/view/3339/74/
Video: To see underwater video from the Belize surveys, go to http://www.youtube.com/user/UNCChapelHill#p/f/0/0iIz4tnj_1k
UNC News Services contact: Patric Lane, (919) 962-8596, email@example.com