• Causes unknown but biologists eliminated three likely suspects found often at the root of environmental troubles today
By Naomi Klouda
Sea stars along Kachemak Bay are found missing limbs, their flesh decayed to such a degree some observers are describing the sight as “melting sea stars.”
When this new mystery disease hits, suction cups on sea star tube feet fail them becoming too weak to cling 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, a problem documented on the Pacific Coast not yet pinned to Alaska’s northern coasts.
“I came in May and September 2013 and took a lot of photos in the ultra low tides,” said Traphagen, the 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 furthest 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 starfish 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. They began to call it “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 latest 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),” according to 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.
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).”
Another suspect, climate change, might be a cause. Although climate change is warming the ocean overall, the ocean along the West Coast has been in a cool period, said Scientist Pete Raimondi, since the 1997-98 El Nino. The water’s been cool. “There may be local warming areas, but in general it’s been a cool phase and so it doesn’t appear that this (die-off) is related.”
Scientists don’t know how many sea stars have died so far. Raimondi, chair of the Department of Ecology and Evolutionary Biology at University of California, Santa Cruz, says it could be in the millions. One particularly hard-hit species, the sunflower sea star, 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 the ‘90s, but never before at this magnitude and over such a wide geographic area.
Kachemak Bay, for example, stretches a good distance from south east Alaska beaches and British Columbia where the disease is more documented.
Researchers are leaning toward the theory that “it may 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 is willing to stake a claim on a singular theory, scientists say.
Eye on Kachemak Bay
Traphagen made her first trip to Alaska in May 2013 to see Glacier Bay. After researching destinations, she added an excursion to Kachemak Bay for its double-feature of sea coast 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, titled Stay Curious, is meant to pique people’s interest in the science of their everyday lives. She intends to share her travels and ecological information on the website. “I like to do micro-photography 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.
As a science communicator, 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 coasts of California and north. But no one had mentioned sea stars as far north southcentral Alaska.
“It was sad to see it had impacted this very special place. So, I 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 very 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, perfectly 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 dieoffs 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 MARINe researchers from Olympic National Park. These gorgeous specimens are deep purple or bright orange or sunny yellow and can sit in the open air of an exposed tide for more than eight hours of a time. Their demise has been documented from California to Alaska.
Most early observations were made in tidepools so the early reports were for ochre stars. Others 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 (Pycnopodia helianthoides) just north of Vancouver, BC. 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, Calif., with another die-off of sunflower and ochre stars around Seattle, with 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 MARINe sites from Alaska to San Diego sampled since that summer. In the summer of 2014 it has 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.
What you can do
Beach combers interested in helping to document sea stars in distress – or in health – can contribute with this precaution: do not pick sea stars 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 NOAA Kasitsna Bay Laboratory director Kris Holderied. This link provides guidelines for submitting photos, location of noted sea stars, dates and times.
A link to guide citizen scientists is at http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/index.html
“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 local 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. “
One benefit of the Kasitsna Bay Laboratory intertidal biodiversity monitoring program, now over 10 years old, is that it now has baseline information to identify and assess the spatial extent of events like the current outbreak of sea star wasting disease, she said.
The Sea Star wasting website provides a way for citizen scientists to report their observations of suspected sea star wasting. which greatly expands the ability to detect how widespread a problem it is. Pictures provide valuable information, and it is helpful to estimate the total number of sea stars and how many appear to be affected. Sea star wasting strikes quickly and affects a large percentage of sea stars in the affected region.
For Karyn Traphagen’s Tutka Bay photos and information, go to http://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 ultra low tides in September.
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