Local News

6/17/2010

Team studies oysters for clues

By SHANESSA FAKOUR The Brunswick News

Oyster reefs in the Southeast will provide an early warning to scientists should oil from the Gulf of Mexico reach the Atlantic Ocean.

It's unlikely oil from the Deepwater Horizon well spill will reach the coast here, scientists agree, but if it should happen, the first detectable traces could show up in oysters.

A team of researchers recently began studying oyster reefs along the Gulf Coast of Florida up to the Atlantic Coast of Virginia to document their changing habitat functions.

"We're interested in this because oyster reefs are one of the really important habitats in our estuaries along the entire Atlantic and Gulf Coast in the U.S.," said Jeb Byers, associate professor at the University of Georgia Odum School of Ecology. "We wanted to see how the function of the food web varies."

Oyster reefs, considered essential fish habitats, also shelter and serve as food for crabs and shrimp, creating a complex food web, at which they are the center of, he said.

The three-year project, which includes sampling 12 different oyster reefs across a 600-mile coastline, was proposed before the oil spill, but has since taken on another important aspect.

"We can look at how the food web potentially changes pre- and post-oil," Byers said.

The team of researchers is scrambling to gather data for oyster reefs situated on the Gulf Coast of Florida, their project's most vulnerable sites to be hit with oil from the Deepwater Horizon spill.

"We presently do not have any oil in our shellfish harvesting areas (in Florida)," said Leslie Sturmer, aquaculture extension agent for the University of Florida Cooperative Extension Service.

"With the oil spill, these researchers understand that it's important to get pre-impact assessment data."

Byers and his counterparts at Florida State University and the University of North Carolina will use a mass spectrometer to analyze samples of oysters and other organisms near the reefs for their isotope signatures, which will reveal what they have eaten.

"We could get a reading on the oil itself and follow it through the food web and see which organisms are accumulating it," Byers said. "One of the reasons oysters are good for this work is they're immobile and will tell us what happens to a given place. They are like canaries in the coal mine."

Oil is toxic to small organisms and their larvae that spend time in the water column. If the oil residue is heavy enough, it could kill adult oysters.

"It could cause a couple of years of recruitment failure, and the population can crash because there would be no new replacements to replace those that are dying off," Byers said. "They would eventually recover, but it could get knocked back to where it would take several years to recover to full health."

The chance of the oil reaching Georgia's estuaries is low, Byers said.

"There's some pretty good protection, based on our distance and the shape of our continental shelf," he said, noting that over time, floating oil becomes degraded by the sun and diluted by the salt water.

The oil would have to enter the Loop Current from the Gulf of Mexico and be carried around Florida and into the Gulf Stream. Oil in the Gulf Stream travels about 1 mph, so it would take two to three weeks for oil to reach Georgia, according to the Skidaway Institute of Oceanography.

The Gulf Stream runs about 75 miles off the coast of Georgia and is a half mile deep, so it does not flow near shore.

However, extreme events, such as a hurricane, could push oil in the Gulf Stream onto the continental shelf or the coast.

* BP promises to pay $20 billion, 7A