More than a decade ago, a mysterious illness killed billions of sea stars, particularly along the North American Pacific coast. The sea star wasting disease caused the stars to develop lesions, their arms to fall off and their bodies to disintegrate. Now, researchers in a recent study say they have zeroed in on the cause: a bacterium called Vibrio pectenicida. The 2013-2014 outbreak caused mass die-offs of more than 20 species of sea stars. The illness still lingers at low levels today. Over the years, researchers have proposed several possible causes, including a virus, but none were proven to be definitive. To find definitive proof, scientists conducted experiments between 2021 and 2024 on the sunflower sea star (Pycnopodia helianthoides), a species that’s particularly vulnerable to the wasting disease. Once ranging widely from Baja California in Mexico to Alaska in the U.S., the disease wiped it out from much of its southern range in the continental U.S. It’s now listed as critically endangered on the IUCN Red List. For the experiments, the researchers housed both healthy looking and diseased sunflower sea stars separately in quarantined laboratory conditions. They found that even immersing the healthy sea stars in water from a diseased star’s tank made the former ill. The researchers also created slurries of both the diseased stars’ tissues, and their coelomic fluid, essentially their “blood.” When they injected either of those into healthy stars, the latter became sick. As a control, when they heated up the slurries to kill any potential…This article was originally published on Mongabay
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