Mystery disease killing millions of West Coast starfish.
Summertime is beach time but all is not well on the coast.
I recently visited my favourite rocky beach, on the southern coast of a Gulf island, in the midst of the Salish Sea. Turquoise blue water sparkled under a cloudless sky and a warm glow lit the encircling bluffs. An otter pulled up on shore, its glossy pelt glistening with salt and sea foam. It held a large rock crab in its claws and chewed on it with relish. The current swirls around the rocks here, carrying cold, oxygen-rich waters into shore, where clusters of mussels, clams, and starfish await the nutrients it brings.
Yet, on this day, something was wrong. The thick clumps of purple ochre stars that normally crammed into every rock gully along the beach were missing. Not one starfish remained. Only empty black crevices remained, devoid of life.
This scene is repeated up and down the West Coast of North America this year. Starfish of many species have suddenly disappeared, in a vast die-off event that has scientists puzzled.
They have succumbed to starfish wasting disease (also known as starfish wasting syndrome), but whether the cause is a virus, fungus, bacteria, or a combination of factors is not known. The starfish may be picking up the pathogen from mussels or other shellfish they consume.
So far researchers have failed to find any one definitive causal agent, although warm water temperatures appear to be linked to the high mortality events.
The term “wasting disease” is descriptive. The animals suddenly develop an unnatural, twisted appearance, followed by their arms falling off, and their bodies dissolve quickly into a jellied mass. Divers report piles of white goo and pieces of starfish arms on the ocean floor, where thousands used to live.
Starfish wasting syndrome is being tracked by the Pacific Rocky Intertidal Monitoring group at the University of California at Santa Cruz. Their interactive map shows that the syndrome reaches from Baja California to the Alaska panhandle.
According to the Vancouver Aquarium, dead and dying starfish were first observed on the B.C. coast in early September 2013, at locations such as Bamfield and Ucluelet on the west coast of Vancouver Island.