From California to Alaska, large populations of sea stars, or starfish, are developing mysterious lesions on their bodies and rapidly disintegrating—sometimes in a matter of hours—and turning into what scientists are describing as "white goo."
The cause of the disease, dubbed sea star wasting syndrome, has flummoxed scientists, who have not been able to ascertain if it is triggered by a virus, a bacterial infection, or a combination of influences exacerbated by environmental stressors such as increased water temperature.
“The observation is that we see them dying in the ocean, in the lab, under controlled conditions, even dying when we're trying to give them the best environment possible,” said Gary Wessel, a molecular biologist at Brown University. “It's a big concern for us that shows that it's infectious, that it works in very low amounts, and that it crosses starfish species.”
The die-off is mostly affecting the purple seastar (Pisaster ochraeceus), a predatory species that populates West Coast tide pools. The Pisaster is considered a keystone species; scientists worry its reduced numbers could trigger a ripple effect through the food chain in these tide pools. If enough Pisasters were to die off, their primary sustenance, mussels, would likely multiply unchecked and crowd out other species.
The outbreak came to light in September when Jonathan Martin, an avid diver and marine biologist, spotted abnormal numbers of sunflower sea stars (Pycnopodia helianthoides) with missing limbs at Whytecliff Park in West Vancouver, British Columbia.
Curious, he took photographs and videos and sent them to Christopher Mah, a researcher at the Smithsonian Institution in Washington, D.C., who also runs Echnioblog, a website dedicated to marine invertebrates. In a subsequent blog post, Mah outlined the widespread die-off and speculated about possible causes, including disease, natural causes from a starfish population explosion several years ago, and a link to what had been occurring on the East Coast with starfish in the same family as those Martin encountered.
“These observations kind of synergistically combined, and people began taking notice,” said Mah.
Simultaneously, researchers at the University of California, Santa Cruz, began noticing the wasting syndrome in purple seastars. “If it’s as extensive as it looks like it is, then we’re talking about a loss of millions and millions,” Pete Raimondi, a professor of biology at UC Santa Cruz, said to Time. In one Santa Cruz tide pool home to hundreds of purple seastars, the puzzling disease killed up to 95 percent of them. Scientists estimate millions of starfish live in Pacific coast tide pools.
While experts explore the root cause of the die-off, the advent of social has made the daunting task of tracking the issue a little easier. “It's completely changed the way we've looked at things; everybody has a digital camera, even if it's the one on their phone,” Martin said.
The UC Santa Cruz team has set up a tracking map on which starfish health trends can be monitored. And Rebecca Johnson, a coordinator of citizen science at the California Academy of Sciences, has also set up a site to encourage “citizen scientists” to contribute with photos and sightings.
While the environmental implications of the die-off are alarming, the potential disappearance of starfish is a huge cultural loss too, said Mah, who referred to John Steinbeck's classic Cannery Row as solidifying the iconic status of the starfish, at least in California.
“Some of these animals are endemic to the coast; they're not found anywhere else in the world,” he said. “They're just as big a part of California's history as anything else.”