Scientists at Cornell University have recently published a study that found the mysterious plague that has been killing thousands of sea stars along the Western coasts of America, from Mexico to Alaska. The epidemic has affected close to 20 species, and has been called the “sea star wasting syndrome” because of the gruesome deterioration it causes. The eerie video below from the Vancouver Aquarium shows how the disease slowly wastes away the sea stars’ limbs, until they eventually all fall off. "It's probably the largest epidemic in marine wildlife that we know of," Cornell researcher Drew Harvell said.
The scientists found “sea star associated densovirus” to be the disease responsible. The virus weakens a sea star’s immune system, which makes the organism more susceptible to infections and ultimately leads to lesions, limbs breaking off and the stars melting into what looks like piles of mush.
The research process to figure out what was causing the disease was extensive and meticulous. "In every drop of seawater, there's 10 million viruses, that we've basically had to sort through to try and find the virus responsible for this disease" said Ian Hewson, the lead scientist on the study in a recent interview.
Sea stars are “keystone species” - their place in the ecosystem has a crucial impact on other species. They are important predators of mussels and other shellfish and their abundance affects the biodiversity of the rocky intertidal communities they inhabit.
Interestingly, mass die-offs of sea stars have occurred in the past but never to this extent. In an interview with Earthfix, scientists expressed concern that projections for a warm El Niño year ahead, things will only get worse for sea stars on the west coast. Some scientists are also looking at connections between warmer temperatures due to climate change and ocean acidification for possible links to the disease. The next steps are to figure out what factors make sea stars more susceptible to the virus and if some sea stars are developing resistance to the outbreak.