On January 14 and 15, the Seattle Aquarium convened a gathering of experts from around the country to discuss the latest findings about sea star wasting disease (SSWD). The disease causes sea stars to waste away, giving the impression of “melting.” First observed in Washington waters in June of 2013, it has impacted 20 sea star species along the west coast of North America. SSWD has killed millions and millions of sea stars is being called the largest wildlife die-off ever recorded. Says Seattle Aquarium staff veterinarian Dr. Lesanna Lahner, “In just a few years, sunflower sea stars have gone from being one of the most common species in Puget Sound to being incredibly hard to find.”
Sea stars are keystone species—which means their presence and role within an ecosystem has a disproportionate effect on other species within the same ecosystem. Sea stars, for example, prey on sea urchins. With the loss of sea stars in the wild, there are observations that sea urchin populations are increasing and expanding their ranges.
The Seattle Aquarium has been involved in the effort to understand SSWD from the start, collaborating with institutions including the Vancouver Aquarium, SeaDoc Society, Cornell University, USGS Wildlife Conservation Society and many others, to determine the cause of this unusual mortality event.
Some questions about the disease have been answered but many others remain. “Determining the cause of die-offs in wildlife is always challenging but even more so when it’s happening underwater,” comments Dr. Lahner. A virus has been found that is associated with the disease in some species, but its definitive cause remains to be determined. Current thinking says it could be toxins in the environment or changes in the sea stars’ immune function due to changing water temperatures and ocean acidification.
We’ll update our blog with developments regarding this disturbing die-off as they occur. In the meantime, click here for media coverage of the summit, and visit our website for an overview of SSWD and our previous blog posts on the topic.