Understanding how some small pockets of coral reefs are thriving even as the vast majority of their kin is suffering could offer a recipe for preserving coral populations worldwide.

Image credits: Milos Prelevic.

It’s no secret that corals are in big trouble all over the world. Climate change, ocean acidification, and human activity have driven many reefs past the point of no return, with some of the planet’s biggest largest reefs being gravely threatened. Since they’re so vital to marine ecosystems (and also provide great environmental services to us), it’s understandable that scientists are scrambling for solutions to protect the reefs.

Now, an international team of academics has developed a framework identifying small communities of corals that are flourishing against the odds. Focusing on small, key areas in the Pacific and Caribbean, they identified 38 coral “oases” that have escaped, resisted, or rebounded from threats.

The underdog story

It’s not clear why these areas thrive and others don’t — that’s exactly the point. Identifying the reasons for their success and then attempting to replicate them in other areas is a classical approach, which has previously proven successful in some cases, both in biology and in human health.

“There are a number of reasons why one coral reef might survive while its neighbour dies,” said Dr James Guest, a coral reef researcher at Newcastle University who led the study.

“It could be that the location is simply better for survival – deeper water that is outside the storm tracks, for example. The coral communities could possess biological or ecological characteristics that make them more resilient and able to resist damage. Or there may be ecological processes at play which means that the reef community is able to rebound more quickly after a disturbance.”

Study co-author Peter Edmunds, from California State University Northridge, says he was “blown away” by the capacity of the reefs in Moorea, French Polynesia, to rebound following devastation.

“We started working there in 2005, and almost immediately encountered hordes of coral-eating sea stars that quickly consumed the tissue of the corals,” he said.

“By 2010, there was as close to zero coral on the outer reefs as I have seen in my entire career. And yet, within eight years, that coral has regrown. In places, about 80 percent of the sea floor is now covered by live coral. It is a remarkable example of an oasis.”

A glimmer of hope

However, researchers warn, this won’t solve the problems of corals. The identification of these oases doesn’t mean that corals aren’t threatened, or that there is a clear-cut solution that can be applied worldwide. At most, we should be cautiously optimistic — but looking at the greater picture, the dire realism is clear to the eye.

“Coral reefs are in rapid, global decline but the severity of degradation is not uniform across the board and what we have identified are coral reefs that are doing better than their neighbours against the worst effects of climate change and local impacts,” says Guest.

“This glimmer of hope does not mean we can be complacent about the severity of the crisis facing most of the world’s coral reefs. But it does give us a starting point from which to understand why some ecosystems might be more resistant than others and to identify areas that warrant stronger protection or specific management strategies, such as restoration or mitigation.”

The same idea is underlined by Edmunds, who says that the overall situation is very bleak, even with a few very bright spots.

“This does not contradict reports of coral reefs suffering huge losses across the world and that the overall situation is very bad.”

“However, there are kernels of hope in places where corals are doing better, or where they are doing less badly than elsewhere and these places provide us with a focus of attention that might be used to enhance coral conservation efforts.”

Hopefully, these findings can help researchers and conservationists develop successful coral health strategies, but ultimately, it will be up to the policymakers to implement these strategies.

We cannot get complacent and underestimate the environmental crisis we are going through — and we are causing.

Journal References: “A framework for identifying and characterising coral reef ‘oases’ against a backdrop of degradation”, Journal of Applied Ecology (2018). DOI: 10.1111/1365-2664.13179.