Infectious wasting disease is killing sea stars along the Pacific Coast of North America and scientists believe, global warming is to blame.
A new report reveals that the rising ocean temperature has made sea stars more susceptible to the disease. In just a few years, it has devastated what once was a large population of sunflower sea stars in the area.
"At one time plentiful in nearshore waters, the sunflower sea stars right now cannot be found off the California coast and are rare into Alaska," stated Drew Harvell, a professor of ecology and evolutionary biology at Cornell University and co-lead author of the report published in the journal Science Advances. "Numbers of the sea stars have stayed so low in the past three years, we consider them endangered in the southern part of their range, and we don't have data for northern Alaska."
Wasting Sea Stars
Harvell and his team said that the wasting disease has caused mass mortality of multiple sea stars species from Mexico to Alaska since 2013. Sea star populations in the East Coast were also affected.
The sea star wasting syndrome is a general description for symptoms that are found in sea stars. When a sea star is infected, lesions appear in the ectoderm. This is followed by the decay of tissue surrounding the lesions, eventually leading to fragmentation of the body and then death.
According to researchers, the disease progresses rapidly. The infected sea star can die within only a few days.
"The heat wave in the oceans — a product of increasing atmospheric temperatures — is exacerbating the sea star wasting disease," added Harvell. "It's a lethal disease, and when you add a higher temperature to that, it kills faster, causing a bigger impact."
Bigger Impact On The Ocean's Ecosystem
Pycnopodia helianthoides, most commonly known as sunflower sea stars, can grow to about 39 inches or 1 meter from arm tip to arm tip. They are some of the largest sea stars in the North Pacific.
They survive in a diet of crabs, snails, sea cucumbers, dead or dying squid, and sea urchins. With the disappearance of sunflower sea stars in the Pacific Coast, scientists see a boom in the population of sea urchins, which eat kelp.
The disappearance of kelp forests, which house a variety of underwater species, can vastly affect biodiversity in the region. Joseph Gaydos, director of the SeaDoc Society at University of California, Davis and a senior author of the study, added that California, Washington, and parts of British Columbia in Canada rely on the sunflower sea stars to keep the sea urchin population.