Global Warming Threatens Possible Cancer-Fighting Agents in Antarctica

James McClintock

Compounds that have shown potential for fighting cancer in humans are facing a major threat in Antarctica. The culprit? Global warming.

That's the word from James McClintock, a marine biologist at the University of Alabama at Birmingham (UAB) and an international expert on the Antarctic ecosystem. An army of king crabs that live deep in the ocean is moving up an underwater slope toward the continental shelf of Antarctica, in an area where McClintock has conducted research for 28 years.

The crabs are invaders that threaten a number of native species, such as Antarctic clams, snails, and brittle stars. And that could have a profound impact on animal and human welfare. Reports The Birmingham News:

"The risk?" McClintock said. "The ecosystem could be devastated. They could eat everything in their path."

If that happens, there's a potential human cost, McClintock said. In its Antarctic research, McClintock's research team has found marine species that produce compounds that are ac­tive against skin cancer or influenza.

McClintock is helping analyze photographic evidence of the king crab invasion. The newcomers are a South American species, one that typically has steered clear of the Antarctic ecosystem:

Antarctica has long been an isolated marine ecosystem, protected by its intensely cold waters, McClintock said. Clams and snails elsewhere in the world developed thick shells to protect themselves from the crushing strength of crabs and other crustaceans, or the powerful jaws of creatures like the parrot fish.

But those predators are absent from Antarctica, and there the clams and other shelled creatures have only a thin protection, which leaves them defenseless against crabs.

"You can crush an Antarctic clam between two fingers," McClintock said.

Shell-crushing crabs have been gone from Antarctica for as long as 40 million years, the fossil record shows. The ecosystem "is like stepping back into the Paleozoic Era," more than 250 million years ago, McClintock said. "No sharks, no skates (rays), no fish with crushing jaws."

Why have the shell crushers returned? The evidence points in one direction:

McClintock said the crabs that are invading today cannot survive intensely cold water. But it appears that a 1.8-degree warming of the ocean temperature at Antarctica since the 1950s--likely caused by human-induced climate change, he said--may have opened the curtain to invasion by crabs.

"They're there in large numbers," McClintock said. "They're poised to move onto the shelf."

In a UAB press release, McClintock puts the situation in perspective:

Loss of unique mollusks could jeopardize organisms with disease-fighting compounds, McClintock said. Sea squirts, for example, produce an agent that fights skin cancer. If the crabs eat them, it could bring McClintock’s research with that organism to a halt.

McClintock’s chemical ecology program has published more than 100 papers on species researchers have discovered, including the compound that combats skin cancer and one to treat flu, that are being explored by drug companies.

“I am very concerned that species could disappear, and we could lose a cure to a disease,” he said.

[Photo: uab.edu]