Study: Fossil reefs give clue to future

MIAMI, April 7 (UPI) -- U.S. researchers say studies of the geological record of ancient marine reefs could provide insight into how reefs may respond to climate change.

Scientists at the University of Miami studied the fossil records of coral reefs in the Caribbean to characterize the nature of these ecosystems during the Pliocene epoch more than 2.5 million years ago.

Estimates of carbon dioxide and global temperatures of that period are close to the environmental conditions predicted for the next 100 years, James Klaus, UM assistant professor of geology, said.

"If the coming century truly is a return to the Pliocene conditions, corals will likely survive, while well-developed reefs may not," he said. "This could be detrimental to the fish and marine species that rely on the reef structure for their habitat."

The Pliocene epoch was characterized by a great diversity of free-living corals that lived unattached to the seafloor, he said.

While these free-living corals would have been well suited to ocean conditions projected for this century, modern reef-building coral fauna, which must colonize the ocean floor and then build up into reefs, may not, UM researcher Donald McNeill said.

"Like the Pliocene, we might expect shallow reefs to be increasingly patchy with lower topographic relief," he said. "Rising levels of carbon dioxide will lower the pH in the oceans, a process known as ocean acidification, and will make it difficult for corals to build their limestone skeletons."