Why are all the Sea Stars Dying?

Sea stars may not be everyone’s favorite animal. After all, who can compare the adorableness of a sea otter to the sedentary lifestyle of a weird looking invertebrate that never seems to move?

Still, sea stars are crucial organisms for coastal ecosystems. They act as a food source for other organisms (such as sea otters and even other sea stars) and they help keep the checks and balances of an ecosystem in place.

Unfortunately, for the past year and a half, sea star populations living along the west coast of the United States have been greatly affected by a virus. Referred to as sea star wasting disease (or SSWD for short), the virus forces the body of a sea star to go limp before they form lesions. Eventually, sea star arms will detach on their own and leave the central part of the sea star to disintegrate.

Researchers recently published the news in Proceedings of the National Academy of Sciences and have discovered that the disease is damaging about 20 species of sea stars.

According to the study, “the incursion of SSWD in aquaria with sand-filtered intake suggests a microscopic infectious stage, rather than a disease that spread only via contact with an infected host or vector. Overall, these patterns suggest a microscopic, water-borne, infectious disease agent, rather than environmental pollutants.”

Although SSWD has been known to damage sea stars for over a decade, the problem is that the disease is now spreading widely across the west coast. Currently, sea stars ranging from Baja, California all the way to Alaska are feeling the heavy blows of the virus.

The die off of sea stars is already causing some major changes in coastal food chains. Without sea stars, islands near the state of Washington are noticing booming populations of green sea urchins. These urchins are overtaking kelp forests, and will ultimately cause chaos in the food chain. Researchers are currently looking to answer more questions such as how the infection actually kills sea stars and why the virus has recently become an epidemic.

Image source: Elizabeth Cherny-Chipman/ABC News