Scientists have revealed that a virus is responsible for the mysterious death of millions of sea stars or starfish on the Pacific Coast from Southern California to BC to Alaska.
The virus causes wasting disease in the starfish and leads to lesions and swelling. In the next step, the fish loses its ability to coordinate its multiple limbs and then starts to lose the limbs. And ultimately the limbs disintegrate leaving behind a lump of flesh.
Since the summer of 2013, the star fish had been disappearing and researchers were unable to understand the cause of their mass death.
A study published in journal Proceedings of the National Academy of Sciences said a variety of densovirus is the likely cause of wasting syndrome among sea stars. Varieties of densovirus are used as a biological control on cockroaches.
The team got material from animals which were dying from the disease and passed it through filters that should exclude bacteria. When the material was injected into healthy starfish, even they suffered from wasting. Treating this material with heat disabled it from causing disease. Thus, it proved that virus was the reason begind the disease.
Cornell University marine microbiologist Ian Hewson said they found greater amount of virus in sick sea stars than healthy ones and as the disease progressed, the amount of virus also increased.
Hewson said they don't know what spread the virus, which can be found in plankton, sandy ocean bottoms and sea urchins and has been found in museum specimens of sea stars dating to 1942.
Dr Martin Haulena, a veterinarian at the Vancouver Aquarium, one of the aquariums that offered samples for the study, said, 'sunflower sea stars were affected very quickly by the virus that caused such huge die-offs that may be part of the normal boom-and-bust cycle of nature'.