It is a strain of the bacterium Pectenicide vibrio the culprit of the epidemic that led to the death of different species of starfish from 2013 to today because of the Starfish deterioration syndrome (Sea Star Wasting Syndrome – SSWS). This is what emerged from the study published on Nature Ecology & Evolution by researchers from the University of British Columbia and the Hakai Institute. After about three years of experiments, Canadian scientists seem to have found an answer to the causes of this disease which so far of uncertain origin or erroneously attributed by some studies to a virus (SSODV densovirus). It is a series of symptoms that start with some external lesionsfollowed by the decomposition of the tissue, which can lead to the fragmentation of the body and to death in a few days. More than 20 species of starfish have been decimated on the North American peaceful coast, From Mexico to Alaska; Among the most affected are the Sunflower starfish (Pycnopody Helianthoides), whose population has decreased by 90%with important repercussions on the marine ecosystem.
What is the Sea Star Wasting Syndrome that kills the starfish
Over 20 species of starfish On the North American Pacific Costa have been affected in the last ten years by a serious epidemic called Starfish deterioration syndrome (Sea Star Wasting Syndrome – SSWS), who decimated its populations. The symptoms of this disease can be confused with the dehydration of a marine star left out of the water; Apparently “deflated” and with external lesions, these echinoderms are affected by the syndrome in their natural habitat, under water. From the lesions the disease continues to do decay or “disintegrate” the surrounding fabric leading to the death of the animal.
The deterioration syndrome affects numerous species of starfish, from Ocher Marine Star (Pisaster Ochraceus) at the Giant Rosa Marine Stella (Pisaster Brevispinus) but the most vulnerable turns out to be the STAR SIGLIOLE STAR (Pycnopody Helianthoides). This species, present in the coastal waters from Mexico to Alaska, once counted several billion individuals but from 2013 to 2017 it saw its population reduced by 90% because of this plague. Among the starfish largest in the worldis considered a key species for the balance of the marine ecosystem since, feeding on sea urchinscontrols the population by protecting the algae forestsfundamental for the storage of carbon and to host numerous marine species.
The study to discover the bacterium responsible for the death of the starfish
Although initially some studies had hypothesized that at the base of the Sea Star Wasting Syndrome It was a virus (densovirus ssadv), subsequent research made this hypothesis unlikely, up to the discovery of researchers from the University of British Columbia and the Hakai Institute who identified the FHCF-3 strain Of Pectenicide vibrio Like the direct cause of the SSWs.
To identify the origin of the disease, the researchers compared healthy and sick marine star, noting a huge amount of bacteria like that Vibrium Only in the samples of the sick stars. After isolating the specific species, V. pectenicidethe team exposed healthy starfish to this bacterium by checking that all the stars exposed, except one that received the lowest dose, died.
This procedure follows the famous Postulates of Kochthe scientific criteria used to confirm that a specific microorganism is the cause of a specific disease. In short, these conditions must be satisfied:
- The microorganism suspected of being the cause of the disease must be present in all sick individuals and absent in the healthy ones.
- It must be possible isolate the microorganism from the sick guest and make it grow in a pure crop in the laboratory.
- Once inoculated in a healthy and susceptible guest, the microorganism in pure culture must cause the same disease.
- It must be possible isolate the same microorganism again from the infected guest.
Further studies will be of fundamental importance to understand the origin of the bacterium and the reasons for its diffusion. The first hypotheses, supported by the fact that in British Columbia the most serious epidemics occur at late summer, connect the diffusion to theIncrease in the temperatures of the seas and to climate change.
