The assumption is still widely held that isolated reefs, far from human activities are better off than reefs around densely populated and heavily used areas. However, a recent study published in the journal Nature Scientific Reports found that isolated coral reefs are in fact not healthier than those in more densely populated areas.
The work, led by John Bruno, a professor of marine biology in UNC’s College of Arts and Sciences, marks the first global test of the hypothesis that isolated reefs are suffering from less damage. “We often mythologize isolated coral reefs as pristine and safe from harm,” said Bruno. “In fact, coral loss on some of our isolated reefs is just as dramatic as coral decline on reefs adjacent to more densely populated islands.”
Bruno and co-author Abel Valdivia analyzed data from 1,708 reefs around the world from the Bahamas to Australia collected from 1996 to 2006. Reef isolation was calculated as the number of people living within 50 kilometers of the reefs.
The research shows that local management efforts to mitigate impacts of things like fishing and tourism cannot alone restore coral reef populations. Although these efforts can help on a small scale, overall climate change, ocean warming and ocean acidification pose a far greater risk to the health of coral reefs.
“Widespread arguments that coral reef degradation is mostly caused by local factors are unsupported,” added Valdivia. “We found the problem is better explained by global impacts such as climate change.”
One striking example is the massive bleaching of hundreds of kilometers on the northern and central Great Barrier Reef in Australia — which is one of the world’s most isolated and well-protected reefs — that was reported earlier this year, Bruno said.
“Our work illustrates the truly far-reaching effects of global warming and the immediate need for drastic and sustained cuts in carbon emissions to help restore the health of coral reefs,” Bruno said.