Mass die-off of starfish in ocean
VANCOUVER—Last month, a diver alerted Vancouver Aquarium staff that he had found a number of dead and decaying sunflower sea stars in the cold Pacific waters of a popular dive spot just off the shore of West Vancouver.
Within weeks, the tentacled orange sea stars had all but disappeared in Howe Sound and Vancouver Harbour—disintegrating where they sat on the ocean floor.
“They’re gone. It’s amazing,” said Donna Gibbs, a research diver and taxonomist on the aquarium’s Howe Sound Research and Conservation group.
“Whatever hit them, it was like wildfire and just wiped them out.”
The sunflower sea star population inexplicably had exploded in recent years. In some areas, they were stacked several stars deep—and those conditions may have been ripe for disease, Gibbs noted.
“We are seeing some babies, so we’re wondering if they will survive,” she added.
“We’re hoping we get the natural abundance back without this overabundance.”
Other species of sea star—commonly called starfish—also are affected.
Jeff Marliave, the aquarium’s vice-president of marine science, said the collapse has been confirmed around the Defence Islands, north of Vancouver, and off the south shore of Bowen Island, where there is no longer any evidence of what was a huge over-population of the voracious cousins of the sea urchin.
“Where the population density had been highest in summer of 2012, on the western shore of Hutt Island, all the sunflower sea stars are gone from that area, with rivers of ossicles [a hard body part] filling ledges and crevices,” Marliave wrote in his blog.
The aquarium has dubbed the epidemic Sea Star Wasting Syndrome.
Aquarium staff don’t know the cause because they have had trouble gathering specimens for testing as starfish that looked healthy in the ocean turned up as goo at the lab.
The epidemic has killed thousands of the marine invertebrates, which can weigh up to five kg and live up to 35 years.
The Howe Sound research team have heard from veterinarians and other marine experts that similar die-offs have taken place in Florida and California.
“We’re just not sure yet if it’s all the same thing,” Gibbs admitted.
“They’re dying so fast.”
In July, researchers at the University of Rhode Island reported sea stars were dying in a similar way from New Jersey to Maine, and the university was working with colleagues at Brown and Roger Williams universities to figure out the cause.
The collaboration came about after a graduate student collected starfish for a research project and then watched as they “appeared to melt” in her tank.