Coral Reefs: Ever Closer to Cliff's Edge

Nov 01, 2007

A study in the Nov. 1 issue of the journal Nature uses a novel analytical approach to assess the health of failing Caribbean coral reefs and offer suggestions for saving them.

The authors are UC Davis theoretical ecologist Alan Hastings, an international leader in using mathematical models (sets of equations) to understand natural systems, and ecologists Peter Mumby and Helen Edwards of the University of Exeter.

Mumby, Hastings and Edwards studied Caribbean reefs that are being overrun by seaweed (also called macroalgae) after a plague in 1983 killed virtually all the plant's natural grazers, a sea urchin named Diadema antillarum. With the sea urchins gone, the only line of defense against the algae is parrotfish. But parrotfish numbers are falling fast because of overfishing.

The researchers created a mathematical model of the reef, and then looked at what the future holds if human practices don't change. In particular, they examined a process known as hysteresis -- the lagging of an effect behind its cause.

"The idea of hysteresis is that you go over a cliff, then find the cliff has moved," Hastings said. "Going back is harder than getting there.

"In this case, the loss of sea urchins sent the reef off the road, and now the only guardrail is the parrotfish. Our model showed that if we overfish parrotfish, and the reef goes off the cliff, we would need four times the fish we have now to bring the reef back."

Mumby said the local authorities should act now to reduce parrotfish deaths, including changing existing policies that allow the fish to be caught in fish traps. "We also call on anyone who visits the Caribbean and sees parrotfish on a restaurant menu to voice their concern to the management," Mumby said.

This research was funded by the U.S. Environmental Protection Agency and the National Science Foundation, and the U.K. Natural Environment Research Council and the Royal Society. The paper is titled: "Thresholds and the resilience of Caribbean coral reefs."

Source: UC Davis

Explore further: Leave that iguana in the jungle, expert tells Costa Rica

add to favorites email to friend print save as pdf

Related Stories

Study: Carib reefs need parrotfish, sea urchins (Update)

Jul 02, 2014

Colorful parrotfish and spindly sea urchins are the key to saving the Caribbean's coral reefs, which may disappear in two decades if no action is taken, a report by several international organizations said ...

Caribbean wins the seaweed Olympics

Jun 07, 2012

A new study finds that Caribbean seaweeds are far better competitors than their equivalents in the Indian and Pacific Oceans. But this triumph is bad news for Caribbean coral reefs.

Recommended for you

Team defines new biodiversity metric

Aug 29, 2014

To understand how the repeated climatic shifts over the last 120,000 years may have influenced today's patterns of genetic diversity, a team of researchers led by City College of New York biologist Dr. Ana ...

Danish museum discovers unique gift from Charles Darwin

Aug 29, 2014

The Natural History Museum of Denmark recently discovered a unique gift from one of the greatest-ever scientists. In 1854, Charles Darwin – father of the theory of evolution – sent a gift to his Danish ...

User comments : 0