Unraveling the Mystery: Why Billions of Sea Stars Are Struggling to Survive

Mysterious Sea Star Illness Uncovered

In recent years, a shocking number of sea stars have perished due to a condition called sea star wasting disease. This illness has turned their vibrant bodies into a gooey mess, and for years, no one could pinpoint the cause. However, after four years of innovative research, scientists have identified the villain: a bacterium named Vibrio pectenicida.

This outbreak began in November 2013 and has impacted ecosystems all along the west coast of North America. Sadly, it’s not just a local problem; over 40 species worldwide have been affected, signaling a broader crisis in marine health.

The disease starts with lesions on the sea stars, which are typically covered in bumpy skin. As the illness progresses, their bodies break down. The once-thriving sunflower sea stars, known for their beautiful arms and colors, have faced a devastating decline of over 90%. By 2015, they nearly disappeared from the West Coast, prompting conservation groups like the International Union for Conservation of Nature to label them critically endangered by 2020.

So, why do these starfish matter? They play a key role in their ecosystems by controlling sea urchin populations. Without sea stars, urchins thrive and can obliterate kelp forests. These underwater forests are crucial habitats for many species and play a significant role in absorbing carbon dioxide.

Vibrio pectenicida is in the same family as bacteria that cause cholera and coral bleaching. As marine ecologist Drew Harvell from the University of Washington explains, this bacterium is tricky to study because it doesn’t show up easily in tests. Initially, researchers thought the culprit might be a virus. But their work revealed it was a bacteria all along.

Leading the investigation, evolutionary ecologist Melanie Prentice conducted experiments with captive sea stars to see how healthy ones reacted to infected tissue. The results confirmed that under the right conditions, the healthy stars would succumb to the bacteria, causing the familiar decay.

Interestingly, climate change might be at play here. Warmer waters help Vibrio bacteria thrive. However, some sunflower sea stars are found in cold-water fjords in British Columbia, where temperatures may inhibit the bacteria’s growth. This indicates that temperature could be a significant factor in this unfolding crisis.

The findings bring a glimmer of hope. By understanding the cause of this disease, scientists can work toward solutions that may save not just the sunflower sea star, but also the vital kelp forests that depend on them.

This research was published in Nature Ecology & Evolution and highlights the importance of protecting these unique marine creatures. After all, the ocean would lose a bit of its magic without its stars.

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