Coral Reef Collapse Not Inevitable: Ecosystem in Danger, Not Doomed

Coral reefs, the stunning underwater ecosystems that play home to thousands of fish, are declining rapidly. Yet researchers have now found that there is a silver lining. With local and global action, coral reef collapse could potentially be avoided.

Coral reefs are an important part of coastal ecosystems. They act as valuable nurseries for fish and can actually bolster fish populations in the surrounding area. Reefs also create natural buffer zones, protecting coastal areas from storm surge and preventing erosion. In addition, they contribute millions of dollars to the tourist industry each year, helping to bolster economies as snorklers and scuba divers view the spectacular formations.

"Structurally complex reefs provide nooks and crannies for thousands of species and provide the habitat needed to sustain productive reef fisheries," said Peter Mumby of the University of Queensland and the University of Exeter in a news release. "If we carry on the way we have been, the ability of reefs to provide benefits to people will seriously decline."

Reefs are affected by a series of factors. Practices such as dynamite fishing have helped to physically destroy reefs, while climate change has also had a major impact. Warmer ocean temperatures cause a phenomenon called bleaching, which is when corals release their zooxanthellae into the surrounding waters. Zooxanthellae allow corals to use sunlight to photosynthesize and generate food. Without them, the corals eventually starve and die off.

In addition, corals may be impacted by ocean acidification. With increased CO2 levels, seawater becomes slightly acidic. This makes the formation of calcium carbonate, which hard corals are largely made up of, to be slower than usual. This, in turn, makes it more difficult for the corals to fight off diseases that can sweep across entire reefs.

In order to examine reef decline and what could be done to prevent it, researchers spent two years constructing a computer model of how reefs work. They built on hundreds of studies conducted over the last 40 years. They then combined their reef model with climate models in order to make predictions about the balance between forces that will allow reefs to continue growing their complex calcium carbonate structures.

After examining their models, the researchers found that it's certainly possible to save coral reefs--it just won't be easy. Effective local protection and assertive action on greenhouse gases are both necessary for their survival.

"Business as usual isn't going to cut it," said Mumby in a news release. "The good news is that it does seem possible to maintain reefs--we just have to be serious about doing something. It also means that local reef management--efforts to curb pollution and overfishing--are absolutely justified. Some have claimed that the climate change problem is so great that local management is futile. We show that this viewpoint is wrongheaded."

The findings are published in the journal Current Biology.