Will Corals Survive The Stormy Future?

Science Daily 29 Apr 08;

Hurricanes and storms limit the ability of corals in Belize to “recruit” new coral into their communities, according to an Earthwatch-supported study published in Marine Environmental Research.

“Increasing evidence now shows that storms are becoming more intense due to climate change,” said lead author and Earthwatch scientist Dr. James Crabbe from the University of Bedfordshire in the United Kingdom.

Coral reefs—which can grow to be thousands of years old—form and grow when free-swimming coral larvae in the ocean attach to rocks or other hard surfaces and begin to develop. Intense storms can wipe out this “recruitment” process.

“Storms threaten the survival of the entire reef itself,” said Crabbe, who found similar results in another Earthwatch-supported study in Jamaica a few years ago. The new study will appear in the May issue of Marine Environmental Research.

“If the storms don’t destroy corals outright, they render them more susceptible to disease, and that is certainly apparent on the Belize reefs,” said Crabbe, who is doing a lecture tour related to this work throughout 2008—deemed the International Year of the Reef by the International Coral Reef Initiative (ICRI).

The study holds implications for marine park managers, Crabbe said. “They may need to assist coral recruitment and settlement [in hurricane years] by establishing coral nurseries and then placing the baby corals (larvae) in the reef at discrete locations” or by setting up artificial reef blocks to help the corals survive.

Crabbe conducted the research in 2006 and 2007 with Edwin Martinez, Earthwatch Field Director in Belize and co-author, as well as with the help of young local scientists. Earthwatch, the world’s largest environmental volunteer organization, has conducted a coral research program in Belize for the last three years.

The team measured the size of more than 520 non-branching corals in two major coral reef areas in southern Belize: the Sapodilla Cayes Marine Reserve, a world heritage site in the second largest barrier reef in the world, and the Port Honduras Marine Reserve. In addition to providing habitat for an array of marine life, non-branching massive corals—robust and shaped like mounds, and sometimes called ‘brain corals’—buffer coastal zones from erosive wave energy.

Crabbe’s team determined the surface area covered by the corals and entered the growth rates of the corals into a computer model to determine when in history the coral colonies first settled. They compared numbers of corals that started life in each year with hurricane and storm data, and as suggested by data from fringing reefs of Jamaica, the coral recruitment was much lower during storm years, Crabbe said.

“The rapid growth of the tourism industry in Belize over the past five years tops the list of threats to the corals,” and agricultural runoff is a close second, Martinez said.

“Climate change is coming up the list very quickly,” Crabbe said.