Washington – Scientists say that they finally resolved the mystery of what killed more than 5 billion star of the Côte du Pacific in North America in a decade.
Starfish – often known as star of the sea – generally have five arms and certain species wear up to 24 arms. They vary in color from solid orange to orange, purple, brown and green tapestries.
From 2013, a mysterious disease wasted with the sea star sparked a mass death from Mexico to Alaska. The epidemic has devastated more than 20 species and continues today. The worst blow was a species called The Sunflower Sea Star, which lost around 90% of its population in the first five years of the epidemic.
“It’s really horrible,” said the ecologist of marine diseases Alyssa Gehman at the Hakai Institute in British Columbia, Canada, who helped identify the cause.
Healthy starfish have “swollen arms that keep up straight,” she said. But wasted disease leads them to cultivate lesions and “then their arms fall”.
The culprit? Bacteria that also infected crustaceans, according to a study published Monday in the journal Nature Ecology and Evolution.
The results “resolve a long -standing question about a very serious disease in the ocean,” said Rebecca Vega Thurber, marine microbiologist at the University of California in Santa Barbara, who was not involved in the study.
Researchers took more than a decade to identify the cause of the disease, with many false tracks and twists and turns along the way.
The first research suggested that the cause could be a virus, but it turned out that the densovirus on which scientists were initially concentrated was in fact a normal resident inside the healthy starfish and not associated with the disease, said Melanie Prentice of the Hakai Institute, co-author of the new study.
Other efforts have missed the real killer because the researchers studied samples of Dead Sea Star fabrics which no longer contained the body fluid that surrounds the organs.
But the latest study includes a detailed analysis of this fluid, called coelomic fluid, where Vibrio Pectenicida bacteria were found.
“It is incredibly difficult to trace the source of so many environmental diseases, especially underwater,” said Microbiologist Blake Ushijima of the University of North Carolina, Wilmington, who was not involved in research. He said that this team’s detective work was “really intelligent and significant”.
Now that scientists know the cause, they have a better chance of intervening to help stars of the sea.
Prentice said scientists could potentially test which remaining seas of sea are always in good health – and reflect on the opportunity to move them, or raise them in captivity to transplant them later in areas that have lost almost all of their sunflower star.
Scientists can also test whether certain populations have natural immunity and if treatments such as probiotics can help stimulate immunity to disease.
Such recovery work is not only important for starfish, but for whole ecosystems of the Pacific, because the healthy starfish engulfs in excess of urchins, according to researchers.
Sunflower Sea Stars “looks somehow innocent when you see them, but they eat almost everything that lives at the bottom of the ocean,” said Gehman. “They are voracious eaters.”
With far fewer seas of sea, the sea urchins on which they usually nibbled exploded in the population – and in turn passing around 95% of Varech forests in northern California in a decade. These Varech forests offer food and habitat for a wide variety of animals, including fish, otters and seals.
The researchers hope that the new discoveries will allow them to restore the populations of Sea Star – and to repel the forests of Varech that Thurber compares to “tropical forests of the ocean”.
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