WASHINGTON — Scientists are struggling to find the cause of a gruesome disease that is killing off numerous species of starfish on both the Pacific and Atlantic coasts of North America.
Researchers said on Thursday that they have ruled out some of the possible culprits, including fungi, some parasites and certain types of microbes. Now they're considering whether viruses or bacteria may be to blame.
The starfish, also called sea stars, are being obliterated by an unexplained wasting disease that causes white lesions to appear before the animal's body sags and ruptures and it spills out its internal organs. "There's the potential that some of these species could actually go extinct," said Cornell University ecologist Drew Harvell, one of the scientists involved in the loosely organized search for a cause.
Harvell said she is concerned because the mysterious pathogen is affecting 18 different West Coast species along their entire range. The disease appeared last year and is showing no indication of abating.
"What is it that has caused this? Where did it come from? If it's exotic, how did it get here? Is it something that's likely to be repeated?" asked Pete Raimondi, a biologist at the University of California at Santa Cruz.
Raimondi is worried that the disease, whatever it is, could be a harbinger of bad things to come for other marine species. He said scientists are wondering whether the starfish have been infected by a virus, bacterium or something else unwittingly imported to the region, or whether a pre-existing pathogen somehow has became more dangerous.
Scientists prefer to call the animals sea stars rather than starfish, because they're not actually fish. Instead, they're echinoderms, the cousins of sand dollars, sea cucumbers and sea urchins. They are significant predators in their ecosystems.
"If they do go extinct ... there undoubtedly would be some really huge impacts on the ecosystems that they live in," said Bruce Menge, a marine community ecologist at Oregon State University.