Oysters will tell if oil reaches Georgia coast

By Ty Tagami

The Atlanta Journal-Constitution

In the unlikely event that the BP oil slick sullies Georgia's coast, Jeb Byers will be ready.

The University of Georgia researcher is part of a team documenting the condition of oyster reefs that dot the U.S. coastline from the Atlantic Ocean to the Gulf of Mexico.

The fragile reefs are an essential habitat for a menagerie of sea creatures and the oysters themselves appear to be an ideal barometer of change, the scientists say.

Oysters are immobile, so they can be used to monitor specific locations. And they feed by filtering nutrients from the water, absorbing whatever pollution may be swirling around them.

Their bodies, if one looks with the right equipment, can say whether some food sources have disappeared, or whether new contaminants have come along, such as oil from the Deepwater Horizon spill, said Byers, an associate professor at UGA's Odum School of Ecology.

"We can look at how the oil changes the food web structure," Byers said. "It's sort of based on this notion of you are what you eat."

On June 1, Byers and colleagues at Florida State University in Tallahassee and the University of North Carolina at Chapel Hill began a 3-year project to document the state of oyster reefs in a dozen estuaries from Virginia to the Florida Gulf coast. Byers is monitoring two Georgia sites, one off Sapelo Island and the other off Skidaway Island.

The project received an $850,000 grant from the National Science Foundation. It was planned long before the oil spill with the goal of cataloging and comparing the species present at each of the reefs. But the research has taken on added significance in the wake of the disaster.

Now, the data could provide crucial evidence about the state of the reefs before, and after, any intrusion of oil.

The scientists will collect reef samples and study them with mass spectrometers. The devices can detect isotopes that indicate the presence of various species in oyster diets, Byers said. They also could identify the presence of the unique  "isotope fingerprint" from the Deepwater Horizon oil spill, he said.

"Oil is ultimately an organic substance, so it has an isotopic signature," he said. "You can actually fingerprint an exact plume of oil."

A couple reefs off the northwest Florida coast are likely targets of the BP spill, Byers said. It's far less likely to reach Georgia's coast, but that's not an impossible prospect.

"I presume that it would be pretty diffuse by the time it got here," said Dana Savidge, an oceanographer at the Skidaway Institute of Oceanography. She lays the odds of the spill reaching Georgia's coast in significant quantity at "highly unlikely."

It could get here by way of two major currents.

The unpredictable Loop Current swirls around the bottom of Florida and could swing a finger of the oil plume around the tip of that state, into the Atlantic Ocean. From there, the powerful Gulf Stream would take over, carrying the oil up the coast at about 1 mph, Savidge said.

At that speed, it would reach Georgia in three weeks.

Some oil was spotted in the Loop Current in mid-May, but apparently never made it into the Atlantic, Savidge said.

Even if oil from the spill reached Georgia's latitude, it would have to hurdle a couple big barriers to reach the coastal reefs.

The Georgia coastline is buffered by an exceptionally wide and shallow continental shelf that projects about 75 miles into the ocean. At 200 feet deep, it's like a river bank against the Gulf Stream, which runs parallel to the coast in the half-mile-deep ocean beyond.

Wind or minor currents and tides could push any oil toward shore, but probably not in large quantities, Savidge said. Meanwhile, sunlight and hydrocarbon-eating microbes would break down the oil, further diffusing it.

But there are a lot unpredictable things that could influence the outcome. For instance, said Savidge, a hurricane could slam into Georgia, pushing oil ashore.

If the oil were to come, Byers' data could prove invaluable. It could be like a home inventory before a fire: documentation of what was destroyed.

Oysters are crucial because they sit somewhere in the middle of the food chain, filtering phytoplankton from the water while serving as a meal for crabs and other predators. Their razor-sharp shells help create the protective reefs that shelter many species of fish.

Should oil round the tip of Florida, those other creatures might move on or die, but the oysters would have to stay behind. With Byers' help, they would document what happened.

"Because oysters have to sit there and take it and they can't run away," he said, "they're a very good canary in the coal mine."