Researchers explore deep sea oil seeps

By Environmental News Network staff

Researchers are looking to find out whether sea fans and other deep-sea creatures that live in colonies wherever oil and methane gas seep from the floor of the Gulf of Mexico are part of the food chain.

(ENN) -- Giant tubeworms, mussels, sea fans, brittlestars and other deep-sea creatures live in colonies wherever oil and methane gas seep or bubble from the floor of the Gulf of Mexico. Researchers at Louisiana State University are exploring the bottom of the sea this summer to find out whether fish turn to these colonies for their food supplies and whether there are any new species of fish swimming around down there.

When probing for the secrets of Gulf marine life in a mini-submarine, the only swimming animals scientists see are the ones not frightened away by the intruding vehicle and its bright lights, LSU marine biologist Bob Carney said. "We get a biased view of what's going on."

Nobody knows what might be gliding silently through the water just outside the viewing range of the submersible's portholes. Carney and his colleagues want to know what's out there and if there's any interaction between those fish and the seep colonies.

"There may be in the deep sea whole sets of as-yet undiscovered fish," he said.

"The seeps and vents were a total surprise to scientists just a few years ago. We know that large predatory animals swim to great depths, and we know that large squid wash up on the beach occasionally. We saw a pod of sperm whales in the Gulf of Mexico last summer. Nobody expected to see them there. If sperm whales are in the Gulf, then there is also an abundant food source in the Gulf to attract the whales there. We know that the greater the sea depth, the poorer is the availability of food. There is the nagging possibility that we're missing something," he said.

As principal investigator, Carney is spending the summer on a research vessel to collect large fish and crabs in deep water near oil seeps and bring them to the surface. The idea is to "grab an animal and look at what's in its stomach," he said. Carney believes they'll find evidence that the big fish are nipping and chewing at the oil seep tubeworms.

"We think it's happening because the deep sea is food starved. The animals that live on the seeps would seem like a smorgasbord to the fish," he said. By inference, if deepwater fish are eating animals that ingest oil and methane, and fish nearer the surface dine in turn on these deepwater predators, then humans may be eating fish that several links back in the food chain were eating the naturally leaking oil and methane.

"Every time people look at the Gulf of Mexico, they see more and more oil. Are these bits of chemistry or part of the whole fabric?" Carney said. "There are thousands of animals inhabiting the deep Gulf, yet none are seen near the seeps. Why aren't they at the seeps, knocking off a tubeworm or two for a snack?" They probably are, Carney replies to his own question.

Carney is conducting his research under the sponsorship of Minerals Management Service, which has the responsibility for managing oil and gas offshore.

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