Something is killing starfish up and down the West Coast and no one knows what.
A
mysterious illness that first appeared in June in Washington state has
now spread from Sitka, Alaska, to San Diego. Starfish first waste away
and then "turn into goo," divers say. Whatever is causing it can spread
with astonishing speed — a healthy group of starfish can die in just 24
hours.
"It's widespread, it's very virulent and it's unlike
anything we've seen in the past," said Pete Raimondi, a marine ecologist
at the University of California-Santa Cruz who is one of the lead
researchers in an international effort to track the outbreak.
The
ailment seems to hit starfish the hardest, with smaller numbers of sea
urchins and sea cucumbers reported falling to it. No one knows what
percentage of the West Coast's starfish are affected but in some areas
they've been wiped out.
So far at least 12 different starfish species are known to be at risk, Raimondi said.
Marine
biologists call starfish "sea stars" because they are not actually
fish, but invertebrates. They've dubbed the ailment "sea star wasting
syndrome."
The first case was reported in a tide pool in Washington state's Olympic NationalPark in June.
Sea stars near Sitka, Alaska, also began to fall ill.
In
September sea stars in the waters along the coast of British Columbia
in Canada were found affected by the same phenomenon, said Linda Nishida
of the Vancouver Aquarium in Vancouver, British Columbia.
The
animals first "look a little bit odd," said Mike Murray, director of
veterinary services at the Monterey Bay Aquarium in Monterey, Calif.
"Their arms may be twisted or weirdly positioned."
They then
develop what look like tiny wounds on their surface and bits of whitish
discoloration. Within days and sometimes hours, the animal begins to
waste away and fall apart. "It's almost like they're melting," he says.
"They turn into slime or goo, they just kind of disintegrate."
Scientists
are asking recreational divers to report outbreaks. Don Noviello is a
member of the Kelp Krawlers Dive Club in Olympia Wash. He and a dive
partner saw their first infected sea stars on Dec. 21.
"It's like they become zombies of the sea," Noviello said. "I saw a leg walking away by itself," he said.
Scientists
are scrambling to find the cause. The National Science Foundation gave
rapid response research grants over the summer so marine biologists
could begin intensively studying the problem. Groups far and wide are
involved, including the National Wildlife Center in Madison, Wis.,
Cornell University in Ithaca, N.Y., and various universities in Canada.
Teams
are now going up and down the West Coast looking for outbreaks so they
can develop an accurate map of affected areas. The list is ever
increasing. "We had our first report in Santa Barbara on Dec. 7,"
Raimondi said. "Last week, they found five affected areas there."
Researchers
believe the sea stars' actual disintegration and death is caused by
bacterial infection, but they have no idea what's suddenly making them
susceptible.
Raimondi put it this way: "Suppose someone's walking
down the street and they get stabbed in the arm and develop an infection
and die. So the infection killed them, but the real question is this:
Who stabbed them in the first place?"
There have been previous,
small scale sea star die-offs. While they looked similar, "there are
only certain ways starfish can look when they die. A melting starfish is
going to look like a melting starfish," Murray said.
The cause
could be a toxins, a virus, bacteria, manmade chemicals, ocean
acidification, wastewater discharge or warming oceans. "We're not ruling
anything out," Raimondi said.
The fact that the ailment is so
widespread is what's most troubling, said Benjamin Miner, a professor
of marine biology at Western Washington University in Bellingham, Wash.
"Every time you come up with what seems like a reasonable hypothesis,
it's challenged because other affected places don't match."
Whatever
is killing the sea stars is highly lethal. "We've had populations go
locally extinct overnight. Literally. Some species go from completely
fine to a mush ball in 24 hours," said Miner, who's organizing the
mapping project.
Starfish may seem fairly unimportant, but they're
actually a keystone species in many marine environments. Most live near
the shore, but some inhabit the bottom of deep seas. Few things eat
them, but they are a top predator, eating mussels, barnacles and sea
snails.
"The niche they fill is vital. If they die off, the
ecological communities they live in could change fundamentally,"
Raimondi said.
Sea stars aren't eaten by humans, and there is no
danger to people who might come into contact with them, Murray said.
However, "melting sea stars, or not, any time you handle wildlife, you
want to wash your hands."
Asked for a bright spot, Raimondi could
only think of one: "Sea stars don't feel pain," so death by dissolving
doesn't hurt them.
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