Since 2013, marine biologists could only witness the mass mortality of starfish all along the Pacific coast. A large number of starfish from over 20 species were virtually melting all across the Northeast Pacific coast and scientists finally believe they have identified the culprit.
The journal Proceedings of the National Academy of Sciences includes a recent study suggesting that a densovirus may be responsible for the mass-melting of the wonderful sea creatures. Densovirus designates the taxonomic group including the smallest identified virus particles.
What scientists have dubbed the sea-star “wasting disease” isn’t at all new: in fact, such die-offs have been often described by marine ecologists for over thirty years. However, 2013’s outbreak made it clear that there is a grave need to identify the illness because of its uncontrolled geographical spread. Until now, scientists estimate that starfish from Baja California and up to Southern Alaska have died by the millions.
And this disease is by no means pretty: sea stars infected with the virus become lethargic. After a short while, lesions begin developing causing the sea star to lose elasticity and autonomy in its limbs. For observers, it seems as though the starfish were tearing themselves apart.
Ian Hewson led the team of scientists attempting to identify the deadly virus. Over 300 starfish from over 12 species were investigated for signs of infection (the starfish here divided into two groups: those residing in public aquariums and those stemming from natural habitats).
Researchers used filters that would not permit bacteria to cross through to pass tissue from infected specimens to healthy sea stars. Virus particles were able to cross the filter and infect the healthy specimens.
It took 10 days for the sea stars to show signs of the disease after coming in contact with the material. Scientists then identified the densovirus in more ailing sea-stars than healthy ones. Curiously, the sea-star wasting disease is believed to have been around for longer than initially believed. Museum specimens preserved in ethanol showed that the virus had been present in specimens as early as 1942.
“At this point we have no idea why something that seems have been present [in the past] has all of a sudden become so lethal.”
Peter Raimondi, co-author of the study said.
It is going to be very difficult for marine biologists to figure out precisely why this outbreak has become so devastating. In the meantime, the disease continue to spread, threatening countless marine ecosystems dependent on starfish (as they keel bivalve populations in check).