June 10, 2009

Climate Change Contributes To Caribbean Coral Destruction

A recent study shows that a change in climate has assisted in advancing the leveling of the complex, multi-layered construct of Caribbean coral reefs. This jeopardizes their ability to provide a buffer against tropical storms and be a nursery for fish stocks.

The analysis of 500 surveys of 200 reefs, conducted between 1969 and 2008, revealed that the most complex types of coral reef had been virtually destroyed throughout the entire Caribbean.

These reefs, which are characterized by table corals of over 1 yard across and huge antler-shaped staghorn corals, provide a safe-haven for local fish stocks and a hunting ground for larger, commercially fished species.

Many of these reefs have been substituted with the flattest types of rubble-strewn reef that are now spread over approximately three quarters of the Caribbean's reef area. This number has increased from about one- fifth in the 1970s, according to the study published in the Royal Society journal Biology Letters.

The report by researchers from Britain's University of East Anglia and Canada's Simon Fraser University says that the greatest impact has occurred in the last decade.

"Lack of ... refuges for species with commercial importance, such as lobsters and large fishes may compromise the long-term sustainability of fisheries and fishing communities," the report stated.

These flatter reefs are also not as effective in providing protection for coastal homes and villages from storm swells and tidal surges.

"The importance of this is going to increase," said leader of the study Lorenzo Alvarez of the University of East Anglia. "Many scientists think there will be more hurricanes in the future."

The deterioration of Caribbean reefs cannot be blamed entirely on climate change. Disease is responsible for killing about 90% of Elkhorn and Staghorn Corals in the 1970s, but now second period of coral destruction is underway.

This second wave of damage is the result of "coral bleaching," which is the loss of color of corals due to stress-induced expulsion of the tiny coral building organisms from their colonies.

"We suggest that the last period of decline is partly due to climate change, but also due to several other human impacts such as over-fishing and coastal development," said Alvarez.. "In future, we'll need to change our behavior and reduce the stress on the reefs."


On the Net: