Two years ago, a marine illness decimated the West Coast’s sea star population. The first animals found to be affected by an unidentified virus that causes a condition called sea star wasting syndrome were observed on the Oregon Coast in April of 2014. By summertime, this disease had spread from Alaska to Baja, California. Approximately 63 to 84% of adult sea stars in the area succumbed to the virus, which caused the animals to develop lesions, deflate, lose their arms, and finally disintegrate until they were nothing but slime and bones.
A May 4 report from a team of OSU scientists who’ve been studying the marine disease since 2015 describes an optimistic improvement in the situation. Since last winter, unprecedented numbers of baby sea stars have reemerged and appear to be both strong and healthy. Larval and juvenile members of species like the purple ochre sea star, whose population had been reduced by 80 to 99% since the disease struck, have increased to numbers up to 300 times of those recorded in previous years.
Scientists are still searching for the reasons behind both the die-off and recent uptick in the starfish population. Though originally thought to be a result of warm waters reaching record temperatures, the wasting disease was found to be unrelated to any temperature increase, due to the fact that the virus spread during cold months and was present in both warm and freezing waters.
The virus can still be found in some fully grown starfish, especially those residing in deeper waters. Research shows that the baby survivors of the illness have a distinct advantage in their new lack of competition with adults over food. In addition, the amount of food available to these tough little echinoderms has increased since the death of their elders, leaving the animals that starfish normally prey on—small barnacles and mussels—to multiply in great numbers.
Marine biologists stress that the starfish comeback is deeply significant, due to the species’ important place in the ecosystem and food chain present in Pacific waters.
By Kiki Genoa