Sea stars along Kachemak Bay are being found with found missing limbs, their flesh decayed to such a degree some observers are describing the sight as “melting.”
When this new mystery disease hits, suction cups on sea stars’ tube feet fail them as they are too weak for clinging to dock pilings. Their cups don’t adhere to rocks in their habitat tidal pools.
A scientist visiting Alaska, Karyn Traphagen, said she hoped she wouldn’t find the mysterious ailment so pervasive when she visited Tutka Bay in July. The problem had been documented on the Pacific Coast and not yet pinned to Alaska’s northern coasts.
“I came in May and September 2013 and took a lot of photos in the ultralow tides,” said Traphagen, executive director of the blog, “Science Online: Stay Curious.” “I saw signs of it then, but it was much more pronounced when I returned last month. I saw even more signs of the sea star wasting disease — lesions on some of the arms, some were missing one or more arms. The tissue decays, mushy flesh, the inability to even hold itself against the piling or rock.”
Traphagen sent photos to biologists collecting sea star research at the University of California Santa Cruz. The biology/ecology department there is on the forefront of documenting the problem and finding the cause.
“They confirmed that the sea stars I observed exhibited the sea star wasting syndrome and that the location observed was the farthest north field reported incidence of the disease,” Traphagen said Friday. “I then went back to my 2013 photos (May and September in Kachemak Bay) and found some evidence of the disease as early as May 2013.”
Since last summer, scientists and tide-poolers up and down the Pacific Coast have noticed sea stars dying in startling numbers. Observers documented sea star bodies turning to mush. Others described the creatures disintegrating, while others found stars that had lost their limbs and color. The phenomenon was termed sea star wasting disease.
That’s a name for the problem, but there’s no firm understanding yet of what causes it. Biologists do know what’s not causing it, Traphagen said. On its website, UCSC’s Department of Ecology and Biology gives a report that shows the usual suspects are being ruled out.
It’s not plastic pollution.
“We’re talking about completely pristine areas to completely degraded areas, and we don’t see any pattern that is suggestive of (plastics),” states the report, “Pacific Rocky Intertidal Monitoring: Trends and Synthesis.”
It’s not ocean acidification.
“What we’ve seen with respect to ocean acidification is that there are local areas which can be affected, but we don’t see any broad pattern of it,” the report states.
And it’s not the Fukushima radiation.
“The trajectory that has been proposed with respect to the distribution of any of the debris really doesn’t come very far south. And with respect to the radiation, that wouldn’t have arrived here yet. Also, just the distribution of the disease and apparent lack of the disease in other areas, really doesn’t lend itself to (a Fukushima link),” the report continues.
Another suspect, climate change, might account for some of the problem. Although climate change is warming the ocean overall, the ocean along the West Coast has been in a cool period since the 1997-98 El Niño, said Pete Raimondi, chair of the Department of Ecology and Evolutionary Biology at University of California, Santa Cruz. “There may be local warming areas but in general it’s been a cool phase and so it doesn’t appear that this is related,” he said.
Scientists don’t know how many sea stars have died so far. Raimondi says it could be in the millions. One particularly hard-hit species, the sunflower starfish, has “pretty much disappeared,” Raimondi said.
Raimondi and Benjamin Miner, professor of marine biology at Western Washington University, made their remarks on a recent National Public Radio Forum about the latest outbreak of this mysterious disease. While similar die-offs have happened before, scientists are befuddled about this more-pervasive bout.
“The patterns that we’re seeing make it especially perplexing, because we’ve seen major die-offs in regions that are geographically separated,” Raimondi said. Similar die-offs occurred in the 1970s, ’80s and’90s, but never before at this magnitude and over such a wide geographic area.
Kachemak Bay, for example, is a far distance from Southeast Alaska beaches and British Columbia where the disease is more documented.
Researchers are leaning toward the theory that it might be a pathogen of some sort that is distributed through ocean currents or other oceanographic forcing. Still, there is no scientific consensus on that, and neither Raimondi nor Miner are willing to stake a claim on a singular theory, they said.
Traphagen made her first trip to Alaska in May 2013 to visit Glacier Bay. After researching destinations, she added an excursion to Kachemak Bay for its double feature of coastline in a mountainous-forest region. “It was the perfect mix for me, an amazing place. It became a personal oasis, a place to reflect and rejuvenate.”
Work on her science blog is meant not so much to explain as to pique people’s interest in the science of their everyday lives. She intended to share her travels and ecological information on the website.
“I like to do microphotography and had planned to photograph the sea anemones under the docks — the beautiful things that maybe people do not get to see, and share those with audiences,” she said.
Traphagen is involved in education as well as explaining science for environmental issues that impact public policy from her base at Durham, North Carolina. She was aware in the beginning stages that biologists were identifying the sea star wasting disease on the West Coast in California and farther north. But no one had mentioned sea stars being affected as far north as Southcentral Alaska.
It was sad to see it had impacted this very special place. So when I returned to Tutka Bay in July 2014, I wanted to see if I would notice any difference in the hundreds of sea stars that I had observed and photographed in 2013. The short answer — yes,” she said.
Two things were evident — many sea stars exhibited the lesions and decay of tissue that are symptomatic of sea star wasting, and the population of the five-armed Pisaster ochraceus was dramatically diminished.
When people think of sea stars, they’re probably envisioning the photogenic five-armed Pisaster. It’s the striking burnished pink specimen, with symmetrical arms extending from a center. In Kachemak Bay, it is these stars most evident in Traphagen’s documentation.
The five-armed specimens may be the most common, but 2,000 or so different sea star species can have anywhere from four to 50 arms. The sunflower star, for example, a common West Coast sea star, has 24 arms. That is the sea star causing greatest alarm in its massive die-offs along the West Coast, the one Raimondi said is disappearing.
The current bout of ailing sea stars was first noted in the five-limbed ochre stars in June 2013 along the coast of Washington State during monitoring surveys conducted by researchers from Olympic National Park. These specimens are deep purple, bright orange or sunny yellow and can sit in the open air of an exposed tide for more than eight hours at a time. Their demise has been documented from California to Alaska.
Most early observations were made in tide pools, so the early reports were for ochre stars. Other species affected include the mottled star (Evasterias troschelii), leather star (Dermasterias imbricata) and six-armed stars (Leptasterias), the UCSC biologists explain in their reports.
In August 2013, divers investigating subtidal habitats reported massive die-offs of sunflower stars just north of Vancouver, British Columbia. Shortly afterward, other subtidal sea star species in the region began showing signs of wasting. During October and November 2013, a similar mass death of sea stars occurred in Monterey, California, with another die-off of sunflower and ochre stars around Seattle and the syndrome spreading throughout Puget Sound.
In mid-December 2013, substantial numbers of wasting stars were spotted around southern California. By the turn of the year it had been reported in 45 of the 84 Multi-Agency Rocky Intertidal Network sites from Alaska to San Diego sampled since that summer. In the summer of 2014, it was noted as having spread to Mexico and parts of Oregon, which had previously been unaffected. It is also intensifying in places already reported as impacted by the wasting.
Beachcombers interested in helping to document sea stars in distress — or in good health — can contribute observations, but are cautioned to not pick sea stars up out of their tidal pools. Local biologists are referring to the University of California Santa Clara program as currently the best reference for information on sea star wasting disease, said Kris Holderied, NOAA Kasitsna Bay Laboratory director.
“The (University of Alaska Fairbanks) researchers, Drs. Brenda Konar and Katrin Iken, working out of our NOAA Kasitsna Bay Laboratory, have not seen signs of the disease at their annual monitoring sites in Kachemak Bay,” Holderied wrote in an email response to inquiries. “But the disease does have patchy distribution, according to information listed on the website, so it would not be surprising to see it in one place and not another.”
Anyone interested in submitting observations of sea stars can do so online at www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/index.html
Karyn Traphagen’s Tutka Bay photos and information are available online at www.stay-curious.com/sea-star-wasting-in-tutka-bay-alaska/.
She invites comments and questions, and plans on a return to Kachemak Bay during the ultralow tides in September.