Latest news with #wasting disease

National Post

Scientists have solved the mystery of what killed more than 5 billion sea stars

WASHINGTON — Scientists say they have at last solved the mystery of what killed more than 5 billion sea stars off the Pacific coast of North America in a decade-long epidemic. Article content Sea stars — often known as starfish — typically have five arms, and some species sport up to 24 arms. They range in colour from solid orange to tapestries of orange, purple, brown and green. Article content Starting in 2013, a mysterious sea star wasting disease sparked a mass die-off from Mexico to Alaska. The epidemic has devastated more than 20 species and continues today. Worst hit was a species called the sunflower sea star, which lost around 90 per cent of its population in the outbreak's first five years. Article content Article content 'It's really quite gruesome,' said marine disease ecologist Alyssa Gehman at the Hakai Institute in British Columbia, who helped pinpoint the cause. Article content Healthy sea stars have 'puffy arms sticking straight out,' she said. But the wasting disease causes them to grow lesions and 'then their arms actually fall off.' Article content The culprit? Bacteria that has also infected shellfish, according to a study published Monday in the journal Nature Ecology and Evolution. Article content The findings 'solve a long-standing question about a very serious disease in the ocean,' said Rebecca Vega Thurber, a marine microbiologist at University of California, Santa Barbara, who was not involved in the study. Article content Article content It took more than a decade for researchers to identify the cause of the disease, with many false leads and twists and turns along the way. Article content Article content Early research hinted the cause might be a virus, but it turned out the densovirus that scientists initially focused on was actually a normal resident inside healthy sea stars and not associated with disease, said Melanie Prentice of the Hakai Institute, co-author of the new study. Article content Other efforts missed the real killer because researchers studied tissue samples of dead sea stars that no longer contained the bodily fluid that surrounds the organs. Article content But the latest study includes detailed analysis of this fluid, called coelomic fluid, where the bacteria Vibrio pectenicida were found. Article content 'It's 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 the research. He said the detective work by this team was 'really smart and significant.'