Marine reserves are “a crucial part of the solution” if coral reefs are to be saved from a mounting range of threats to their existence, a new study suggests.
Hope that warm-water coral reefs can survive a mounting array of threats has been provided, scientists said, by their unexpected resilience.
However, with climate change adding to an already long list of man-made threats, governments need to step in to protect reefs, the paper in the journal Science urges.
Bleaching caused as climate change leads to warmer waters and acidification is regarded as the biggest threat to the survival of the reefs.
In 1998, driven by the El Niño system, bleaching caused widespread mortality among corals globally. Similarly widespread levels of bleaching are forecast by the National Oceanic and Atmospheric Administration (NOAA) this year and into 2016.
Dr Mark Spalding, of the universities of Cambridge and Siena, led the study and said that some corals made an unexpectedly strong recovery from the 1998 bleaching.
However, if they are to continue to survive El Niño warming events they need to be given a “breathing space” from the man-made threats including overfishing and pollution while the bigger problem of climate change can be tackled.
The study highlighted the recovery of corals in the Chagos Archipelago, in the Indian Ocean, which in a deal brokered by BLUE was established as the world’s largest ‘no take’ marine reserve. The recovery of coral reefs in the Seychelles where there are several smaller protected areas, was also cited.
Dr Spalding told BLUE that protected areas of the seas are vital to the future of coral reefs: “They are absolutely part of the solution, a critical part of the solution.”
He said that reefs have always faced a variety of threats which can leave them badly damaged – some natural like tsunamis and storms, others man-made such as overfishing – but have usually been able to bounce back.
Climate change, however, adds another level of threat: “That’s where marine reserves come in. They reduce the background array of threats. There are things we can do to reduce the stresses.
“But the reserves have to be big enough, in the right place and they have to be enforced. That’s a huge challenge.
“This isn’t the silver bullet that will save the coral reefs. We are talking about trying to get a breathing space to save some reefs.”
Nevertheless, he was encouraged by the resilience displayed by coral reefs over the last 15 years.
In the study published in Science he and co-author Dr Barbara Brown, of the universities of Newcastle and Thurso, spoke of their hope: “Many reefs….have a high capacity for recovery, and after a perturbation they typically return to previous levels of coral cover. After severe bleaching, coral cover can return within a decade.
“The challenge comes when severe perturbations become too frequent to allow full recovery or
when multiple perturbations occur at the same time.
“It is perhaps naïve to try and hold any ecosystem in a pre-Anthropocene state, but equally it is too early to proclaim the end of coral reefs.
“Without the stabilization of greenhouse gas concentrations, it seems inevitable that many of the world’s coral reefs will become nonaccreting habitats—they will, based on most common definitions, cease to be coral reefs.
“The main drivers of current reef decline—pollution, overfishing, sedimentation, and direct destruction—may be just as influential in the near term as climate drivers in the long term.
“Concerted efforts by governments with jurisdiction over coral reefs may be able to manage these direct threats. This could win critical time both for adaptation and, crucially, for the global community to act on stabilizing and reducing emissions.”
And in a separate blog, Dr Spalding added: “It’s hard to keep optimistic in the face of all these challenges, but it’s not the end for reefs. We still have reasons to hope, if we act now.”