In June 2013, Steve Fradkin hiked the rugged coast of Washington State’s Olympic National Park to count the stars. In the summertime, the lowest tides expose the slippery rocks of the intertidal zone from daybreak until noon. Perfect conditions for spotting Pisaster ochraceus, the five-armed purple, orange and red sea stars common to Pacific waters along the western edge of the United States.
Each summer, Fradkin, a marine ecologist for the National Park Service, returns to four plots along this 65-mile stretch of protected shoreline to take inventory. The ochre star, as Pisaster is known, is an important predator in Olympic’s coastal ecosystem. Fradkin has been monitoring the population since 2008.
The moment he arrived at the first plot that June, Fradkin knew something was off. Many of the stars had gooey-white lesions across large patches of their skin. Some were missing a limb, or two or three. Disembodied arms crawled around the rocks by themselves. Other stars had fallen apart altogether, their melted carcasses scattered about the plot.
“It looked pretty much like a horror show,” Fradkin said, describing the mess.
As he worked his way north through the remaining plots, Fradkin saw the same picture everywhere. About one in every four stars showed obvious signs of sickness.
Back at his office, Fradkin picked up the phone and began reaching out to other ecologists along the Washington coast to find out if their stars were in the same dire shape.
When Fradkin made those calls in June of 2013, none of his contacts had seen anything like what he was describing. By the end of the summer, they all had. The sickness had hit Washington’s Puget Sound and Salish Sea inlets with devastating effects. Shortly after, it was spotted up and down the California coast. In 2014, it popped up in Oregon.
Sea Star Wasting Disease, as it became known, quickly reached epidemic proportions. Afflicting over 20 species from Alaska to Baja, California, the disease reduced stars to five percent of their original population in some regions. Tide pools along California’s central coast saw ochre star communities decimated in a matter of months. And Pycnopodia helianthoides, the 16- to 24-armed iridescent sunflower star, looked poised for extinction.
Despite calling Sea Star Wasting Disease the largest marine epidemic in recorded history, scientists had no clear explanation for what was causing it. Little is known about the viruses and bacteria that inhabit ocean ecosystems, and not a single one had been identified in sea stars. Before 2013, no one had even looked.
“It’s sort of a big detective story,” Fradkin said about solving the mystery of the wasting stars. “And it’s certainly ongoing.”