At the bottom of the sea … things are not very good, at least not for starfish. It is possible that you are not aware of it, also because if you are talking less about what should be, but at the moment, and for 12 years, a terrible epidemic has been underway that affects dozens of different species of marine stars in all the oceans in the world. The disease is called SSWD, and now, after a decade of research, we have finally identified the cause: it is a bacterium, as shown by a study published on Nature Ecology & Evolution.
Denied the hypothesis of the virus
SSWD stands for Sea Star Wasting Disease, starfish deterioration syndrome. It is a terrible disease, which begins with the “block” of the animal’s ability to feed. His skin begins at this point to develop whitish injuries, and when the pathology reaches the aquifer system, which allows the victim to move, the marine star falls. There is worse: at this point, his arms begin to detach himself from the body (sometimes he is also seen leaving after having separated). What remains of the animal begins to melt, and in the end he dies.
Observed for the first time in 2013, along the coasts of the North American Pacific, SSWD affects more than 20 different species of starfish, spread to all latitudes and temperatures, killing billions of specimens. The most damaged is the STAR SIGNASOLE STAR: within just ten years he has lost 90% of his population, and has passed from “No danger” to “In critical danger according to the IUCN”. The first hypotheses on SSWD claimed that it was caused by a virus, an idea definitively denied by a study from 2018. Now, the study of the University of British Columbia finally identifies the pathogen that causes SSWD.
The name of the culprit is Pectenicide vibrioa bacterium that we already knew because it is an infestant of the Atlantic capitant, one of the most used crossroads in aquaculture. The bacterium attacks the larvae of the scales and, apparently, is able to do the same with the starfish. It was not easy to find out because SSWD is a very rapid course disease, but breeding starfish in the laboratory and subjecting them to a series of pathogens, the team has managed to exclude all the other causes and identify Pectenicide vibrio as the only guilty of the epidemic.
The impact on coastal ecosystems
The massacre of starfish is not only a problem for them, but also for their neighbors.
Along the coasts of the northern Pacific, for example, their disappearance has led to a boom of sea urchins, which are animals that “burn” the seabed and that, in large numbers, can damage or destroy the Kelp forests that characterize the local ecosystem. Knowing the name of the star killer, therefore, is a turning point: now, at least, we know who we are fighting against.
