As a massive oil spill threatens the Gulf Coast, seafood retailers and restaurateurs in the Charleston area are concerned about the future impact on the supply and price of seafood.

The effect on oysters is of particular concern because Lowcountry residents consume a lot of local and Gulf oysters in the winter months.

The oyster-roast season is winding down, but when demand for oysters rises again next winter, there could be fewer Gulf oysters available to meet it. That likely would increase the demand for local oysters and drive up the price.

James Richardson at Marvin's Seafood in North Charleston said that in the winter he sells about 100 bushels of Gulf oysters and 50 bushels of local oysters each week. He would lose a lot of his business if he couldn't get Gulf oysters, which grow in individual shells, unlike local oysters, which grow in clumps.

He doubts that enough local oysters would be available to pick up the slack. He also said people would be inclined to overharvest local oysters and would ruin the beds.

Frank Blum, executive director of the South Carolina Seafood Alliance, said the oil spill also might harm the shrimp in the Gulf, which could, in turn, increase the demand for Lowcountry shrimp.

And it could severely limit the supply of other fish, such as red snapper and grouper. South Carolina fisherman couldn't compensate for the decreased supply of red snapper and grouper because federal rules and regulations severely limit fishing off the state's coast, he said.

He also said he's concerned that if the local supply is depleted, even for a short time, people will turn to imported seafood. "Once the imports get a toehold," he said, "it's hard for locals to break back into it."

Robert Barber uses only local oysters at his Bowen's Island Restaurant. And he serves local shrimp and other fish whenever possible.

Barber, who is running for state comptroller general, is keeping an eye on the "potential dire consequences" to the environment and the seafood industry.

"We'll still have our oysters, but we might have to pay a little more for them," Barber said.

Reach Diane Knich at 937-5491 or dknich@postandcourier.com.