A mysterious wasting syndrome that started killing countless sea stars along Canadian coastlines last June — suddenly infecting whole populations of the usually hardy creatures then turning them into piles of mush within days or hours — has crept its way south in recent months and has now taken hold in Santa Barbara waters.
While a few infected specimens were spotted off S.B. beaches as early as September, the incident rate began to spike in January. UCSB research biologist Carol Blanchette said her team’s latest survey of five intertidal sites between Point Conception and Coal Oil Point failed to turn up a single living sea star. Subtidal areas have been hit hard as well, she said, and further out into the ocean, more sick animals are being found. While it’s hard to predict how many Santa Barbara sea stars have withered away so far, Blanchette said it’s likely in the hundreds to thousands.
The disease spread appears to be moving from north to south, west to east, Blanchette went on, noting how the west end of Santa Cruz Island is littered with the dead animals, but the east end remains relatively untouched for the time being. Infected sea stars have also been discovered at Goleta Beach and near Stearns Wharf, and the specimens that occupy UCSB touch tanks — which pump water directly from the ocean — are now on their way to a disintegrative demise.
Blanchette said Santa Barbara scientists and beyond haven’t been able to pinpoint the disease’s trigger, unsure whether it’s caused by environmental factors, a virus, a bacterial infection, or some combination. “Nobody’s gotten a handle on the cause yet, but a couple of researchers at Cornell [University] have been funded to really attack it as a big problem,” she said, noting that while Cornell’s team suspects the disease is viral, UCSB researchers are working with the theory it may in fact be bacterial and have had some success testing antibiotics on lab samples.
Whatever it is, the disease typically starts as lesions on the animals’ bodies followed by the decay of surrounding tissue. And while sea stars are normally able to re-grow limbs should they lose one or more to injury or predation, the wasting syndrome’s wounds don’t heal and creep into the animals’ vital areas. The disease doesn’t discriminate by sea star species, attacking ochres, pinks, giants, and others.
Blanchette and other scientists up and down California aren’t sounding any massive alarms over the unexplained phenomenon, but they’re certainly keeping their eyes on it. “The thing that’s very interesting is that it’s nothing we’ve ever seen before, and we don’t understand the environmental triggers,” she said. “It’s so outside the scope of diseases we’ve normally seen.”
Large amounts of Pacific Ocean sea stars have succumbed to a similar kind of wasting syndrome before, Blanchette said, but that happened during the 1997-98 El Niño years when the disease originated in southern waters and was carried north by warm currents. The geographic trend has been flipped this time around, the area of impact is significantly larger, and the time scale is dramatically longer, Blanchette said.
Speculation that the wholesale die-offs are being caused by radioactive fallout from the Fukushima nuclear power plant meltdown has been brought up a number of times by those outside the scientific community, but there appears to be no basis for that hypothesis, Blanchette explained. “It’s safe to say that’s not a concern at this point,” she said.
Inexplicably, the disease is not attacking other echinoderms, a phylum of marine animals that also includes sea urchins or sea cucumbers. And as the sea stars continue to fall, the delicate balance of their ecosystems will begin to tip as their prey — especially barnacles, mussels, and other invertebrates — find themselves without a direct predator. “We’re very interested in consequences if a keystone predator goes extinct locally,” Blanchette explained.
While there’s no indication the disease is a threat to humans, Blancette said she’s nevertheless advising people to not touch diseased animals without gloves.
- Sea Star Wasting Syndrome Reaches Santa Barbara County [ November 11, 2013 ]