Starfish along much of the North American Pacific coast are dying in huge numbers from a mysterious wasting syndrome. Similar die-offs have occurred before in the 1970s, 80s, and the 90s, but the magnitude of this die-off greatly exceeds previous.
After months of research, scientists have published that they have now identified the pathogen that is causing the wasting disease that has been killing the starfish by the millions.
The cause is different from all other known viruses infecting marine organisms and has been named “sea star associated densovirus”. The virus causes the sea star to rapidly deteriorate in the matter of days. The three photos below were taken in three consecutive days, demonstrating how quickly the disease progresses.
To find the correct virus, a team of researchers from more than a dozen universities, aquariums, government agencies, and other organizations worked together with the help of the National Science Foundation’s coordination network for marine infectious disease.
Tissue sample from sick and healthy starfish were analyzed for all the possible pathogens associated with diseased starfish. Then using DNA sequencing of the viruses, they compared them all of the other known viruses. Once they had identified a leading candidate, they testing by injecting the densovirus in a healthy starfish in an aquarium to see if the virus would infect the starfish.
The results were positive as the starfish quickly betrayed the same deteriorating behaviors.
Interestingly, when the virus was boiled and then injected into the starfish, the starfish showed no sign of being infected. When they the scientists did not boil the virus and injected, the starfish would then show the symptoms of death and decay.
To the surprise of researchers, they were able to learn that the starfish have been living with the virus for decades as the virus was detected from preserved specimens from as far back as the 1940s.
The Pacific Northwest use to be full to the brim with star fish and the researchers believe that played a huge role in the virus transforming to be so lethal. With the overabundance in starfish, contact was very high between specimens, which also give viruses the opportunity to mutate and become more lethal.
The researchers believe that the virus doesn’t actually kill the host but is weakening their immune system. That makes the starfish more susceptible to bacterial infections, which ultimately leads to the decay of the invertebrate.
The hope is that antibiotics will be able to be used to help the starfish fight off the bacterial infections although, it is not a solution for the entire ocean. As more is learned about the virus and how it impacts starfish, researchers will be keeping a close eye on the starfish to see if they will be able to develop a resistance to the outbreak which will hopefully lead to further answers.