By Peter Firmite, SFgate, December 9, 2013
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| At the Monterey Bay Aquarium, a bat star is suspected of suffering from wasting disease. Photo: Russell Yip, The San Francisco Chronicle |
A mysterious pathogen is wiping out starfish along the Pacific coast, a potential catastrophe that has flummoxed marine biologists who are joining forces to find the culprit.
The uncontested star of tide pools is disappearing from large areas along the coast, including Monterey, where the marine invertebrates have been withering and dying by the thousands.
Nobody knows what is causing the die-off, but the killer - most likely some kind of virus, bacteria or pollutant - is widespread and extremely virulent. It has ravaged a variety of starfish species in tide pools and in deeper water along the coast from Mexico to Alaska.
Pete Raimondi, a marine biologist and lead researcher on a team of scientists, laboratory technicians and geneticists, said he has seen 90 percent of the sea stars, as the multi-armed animals are also known, die within in an infected area in just two weeks.
"Where it has hit, it has been pretty lethal," said Raimondi, a professor in the Department of Ecology and Evolutionary Biology at UC Santa Cruz. "This is going on up and down the coast. ... It's going to change what's out there pretty fundamentally."
Syndrome discovered
The disease, which has been dubbed sea star wasting disease, was first detected last summer in tide pool areas along the coast of Monterey. Raimondi, who teaches a class in kelp forest ecology, soon began noticing dead and dying starfish further underwater during dives with his students.
Researchers in Sonoma County and in Washington state also detected the syndrome, which causes the starfish to become mushy and deteriorate until body parts begin falling off.
Raimondi said there seems to be a progression, or sequence, of infection in which different starfish species get the disease at different times.
The Ochre star, the purple or orange starfish most commonly seen in intertidal regions, is typically the first to get hit, he said.
"It's dying in huge numbers," Raimondi said of the species. "We've seen them go from a lot to zero fast."
The disease has spread from the shoreline into deeper water, ravaging the population of sunflower stars, the largest sea stars in the world. Short spined sea stars and giant sea stars have also been hit hard.
"The ones that get it first are all predators," Raimondi said of the starfish, which have very few predators and feed on a variety of invertebrates, including mussels, sea urchins, clams and snails.
Monterey Aquarium hit
The disease has even found its way through the filtration system of the Monterey Bay Aquarium, which uses sea water in its tanks. Michael Murray, the director of veterinary services, said the aquarium carefully controls temperatures and other factors like salinity, but cannot keep out natural impurities.
"There is something going on in the water," Murray said. "Unfortunately, we're not really sure what it is, so we really don't have the ability to say what it isn't."
Raimondi said he believes the starfish are succumbing mainly to a secondary bacterial infection caused by the disease, which spreads in the water almost like the common cold among the dense, often interwoven, populations of starfish.
UC Santa Cruz biologists are collecting samples up and down the coast from Washington to California while scientists from Western Washington, Cornell and Brown universities are trying to isolate the pathogen in the laboratory. They are looking for marine biotoxins and viruses and exploring a variety of possible sources, including radiation from the debris that washed across the Pacific Ocean after the Fukushima disaster.
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