Marine scientists are scrambling to determine the extent and cause of a disease that is killing starfish along the West Coast, including Sonoma County.
The affliction, called sea star wasting disease, has killed up to 95 percent of the stars in some tide pool populations ranging from southeast Alaska to Santa Barbara in a manner similar to scenes from a horror movie.
"They essentially melt in front of you," said Pete Raimondi, chairman of the Department of Ecology and Evolutionary Biology at UC Santa Cruz's Long Marine Lab.
Stricken starfish develop white lesions that expand and sometimes turn ulcerous, then the stars start losing arms and finally — all in a matter of days or weeks — disintegrate into what some observers have described as "goo."
In September, starfish in an aquarium at the Gulf of the Farallones National Marine Sanctuary visitor center at the San Francisco Presidio turned sickly and perished in water pumped from the ocean.
The aquarium's other occupants — including eels, sculpin and anemones — were unaffected.
The disease has struck localized coastal areas before, most notably in Southern California in 1983-84, but is already far more widespread, and its full extent is unknown.
"We've never seen it at this scale up and down the coast," Raimondi said.
Two scientists from his staff are launching a blitz this week, intent on "sweeping the coast" of California, Oregon and Washington to quantify the outbreak over the next three to five months.
At the same time, UC Santa Cruz is conducting its annual sampling of tide pool conditions at 80 sites along the West Coast.
Meanwhile, Raimondi's lab is taking starfish disease reports from scientists and citizens along the coast and plotting them on a map that includes two sites in Sonoma County: the Doran Beach jetty, sampled in mid-September, and Schoolhouse Beach north of Bodega Bay, sampled Oct. 3.
Steven Morgan, an environmental science professor at the Bodega Marine Laboratory, said he observed some emaciated sea stars on the rocks at Schoolhouse Beach two months ago, but he didn't take samples and couldn't confirm if they had the wasting syndrome.
"It was a strange anomaly," Morgan said. "None of us had ever seen anything like this before."
Larger clusters of the disease were reported near Santa Cruz, Monterey and Santa Barbara, but Raimondi said the data so far is "opportunistic" and likely under-represents the extent of the disease, which was first detected in June in Washington.
Sea star wasting primarily affects one species, Pisaster ochraceus, the orange and purple starfish that abounds in tide pools and plays a key role in their biological diversity.
Designated a "keystone species," the Pisaster — up to 20 inches wide as an adult — feasts on mussels, another common tide pool denizen. If the Pisaster are decimated, mussels will spread and crowd out other species, Raimondi said.
Plotting the disease's presence will help scientists determine its likely future course and possibly help identify the cause, which may be related to warmer-than-usual ocean water, he said.
A Southern California outbreak in the early 1980s, which virtually demolished the region's starfish, occurred in warmer waters of an El Ni? phenomenon.
Starfish are susceptible to bacterial infection, and warmer water boosts bacteria growth, Raimondi said.
How to participate
Sonoma Developmental Center Community Workshop
Saturday, June 23, 10 a.m. to 1 p.m.
Hanna Boys Center, Auditorium
17000 Arnold Dr. in Sonoma