Fate of Gulf's Deep-Water Corals Unknown

* Corals live deep underwater in the Gulf of Mexico, near the oil spill.
* Scientists are revealing new details about how corals deal with stress.
* It's not yet clear what the future holds for the Gulf's corals.

Gulf deep-water corals

A close-up of the coral Lophelia pertusa from an undersea canyon in the Gulf of Mexico at approximately 450 meters (1,476 feet) depth in a photo taken by a deep-sea rover in Sept., 2008. Click to enlarge this image.
Lophelia II 2009: Deepwater Coral Expedition: Reefs, Rigs, and Wrecks
Unlike the well-publicized turmoil of pelicans, turtles, fish and other obvious animal victims of the Gulf oil spill, the fate of corals more than 1,000 feet below the surface remains unknown.

While scientists haven't been able to visit the Gulf's deep-water coral since oil started gushing under water in April, research elsewhere is revealing new details about how the corals respond to environmental stresses. One of the latest studies out of Australia found that, much like people, some corals have stronger immune systems that help them resist stress and fight diseases.

Along with other ongoing research in the Gulf, the findings should help scientists predict what's going to happen to the corals that now lie beneath massive plumes of oil. For now, the experts are left to worry.

"There are increasing reports from some colleagues out at sea right now who are finding subsurface oil plumes at depth that are moving around," said Erik Cordes, a marine ecologist at Temple University in Philadelphia. "Those are the things that are starting to scare us."

Coral live in deep, dark and frigid waters around the world, where they make reefs that stretch for miles and provide homes for animals that live nowhere else. Unlike the colorful corals that live near the surface in tropical waters, though, deep-water corals have only recently begun to get attention from scientists.

"Every time we find new sites, we find new species," Cordes said. "We know so little about these deep-water corals, we don't even know where they are."

On an expedition to the Gulf of Mexico last summer, Cordes and colleagues found a huge deep-water reef, made up mostly of a coral species called Lophelia pertusa.

Before the spill, the researchers put gear on the seafloor at the site (more than 1,000 feet down) to measure current patterns, collect sediment and take pictures. They hope to get back to the site soon to retrieve information from the instruments, which unintentionally recorded a catastrophe.

At the same time, the scientists are conducting lab experiments, hoping to answer a whole slew of basic biological questions about how deep-water corals live, reproduce and defend themselves against stresses, including oil. One major difference is they don't have symbiotic algae that make food for them, like shallow-water corals do.

"If this had happened on a shallow-water reef, there would be a lot more data to evaluate the impact," Cordes said. "We're kind of playing catch-up. We're trying to come up to speed very quickly on this."

The new Australian study might help. In samples of more than 15 families of coral that live in the Great Barrier Reef, some closely related to Lophelia pertusa, the researcher team pinpointed three ways that corals fight back against diseases and other stresses.

Their results showed both that some types of coral invested more in immune systems, and that corals with stronger immunity were less likely to suffer from disease and bleaching -- the loss of color that happens when shallow-water corals lose their life-sustaining symbiotic algae.

"For the first time, they've shown there's a relationship between bleaching and immunity," said Gerald Weissmann, director of the Biotechnology Study Center at the New York University School of Medicine and editor of the FASEB Journal, which published the new study. "They found that the kind of stuff the spill has produced in the Gulf interferes with that immunity."

"No one has ever studied this in coral," he added. "It's a major finding. This is very exciting."

There are plenty of ways that the oil spill might threaten corals in the Gulf. Besides simply coating them in oil, Weissmann said, the spill could deprive the corals of oxygen, because air doesn't dissolve in oil. The dispersants being used to clean up the oil threaten to damage the reefs, too.

Even if they do survive the ongoing oil assault, Cordes said, deep-water corals grow very slowly, and it's not clear how long it would take them to bounce back. He is eagerly awaiting the chance to see how the corals look now, compared to how they looked last year.

"My greatest hope is that we find nothing," he said. "I would love to go down there and find no impact whatsoever. That's what I'm holding on to."