SSaDV or Sea Star Associated Densovirus hasn’t been widespread since the early 1940’s, but scientists recently confirmed that a mutated form of SSaDV is back, and it’s deadlier than ever.
The realization that SSaDV was back came when scientists looked into the reasons why scores of starfish were disappearing from North America’s Pacific Coast. The usual culprits were first investigated, including protozoans, fungi and bacteria, but it soon became clear that SSaDV was the cause of millions and millions of dead sea animals. The virus is raging through over 20 different species of starfish – also called sea stars – from the coastline of Southern Alaska all the way down to the coast of Baja California.
Dying from SSaDV leaves little hope for the animals. The starfish develops white lesions on its body, before it finally sags, ruptures and eventually spills out its internal organs. The animal effectively “melts” or experiences “rapid dengeneration,” according to a study chronicled in the Proceedings of the National Academy of Sciences of the United States of America.
Researchers conducting the study found that starfish samples from 1942 also contained SSaDV, but those animals weren’t devastated the way the current epidemic is devastating the sea star species off the western coast of North America.
Why SSaDV has reemerged now, after almost 75 years, as well as the question of how the virus liquifies body tissue, is currently a mystery. One theory is that overpopulation of the sea star species may have contributed to the problem. Pollution being dumped into the ocean off the United States West Coast may be feeding tiny plankton floating in the water. Smaller animals like sea urchins eat the plankton which in turn are prey for the starfish, which enables them to grow their numbers. However, more research is needed to fully flesh out that theory.
Another theory for the rapid reemergence of SSaDV is warmer weather. However, experts say that despite global warming, the water off the western coast of North America has actually been cooler than normal of late. Amanda E. Bates, an ocean researcher at the University of Southhampton whose past research has found connections between higher water temperatures and starfish mortality, commented on applying that logic to the current SSaDV outbreak.
“I don’t think the present outbreak has been connected to warming. However, we know that if animals are exposed to temperatures that are warmer than what they are used to – such as a very hot spring – they have reduced ability to fight off the disease.”
Cornell ecologist Drew Harvell also commented to Uncover California on the current outbreak and the possibility of a SSaDV mutation.
“That’s the million-dollar question in all this: why now? What is it that changed that created the conditions for this outbreak? And we don’t have the answer to that. But certainly a viral mutation could be one explanation.”
The research into the causes of SSaDV, the starfish melting disease, continues.
[Images via Crosscut and Tatiacha]