The case of the disintegrating starfish

In September 2013 a marine biologist found dozens of dead sea stars while on a diving trip near Whytecliffe Park, located near West Vancouver’s Horseshoe Bay neighbourhood. He wasn’t sure what was causing these deaths so he reached out to other marine biologists. UBC professor Chris Harley (Yes, our very own professor!) blamed the increase in rainfall that had been seen during that period for the deaths. The increase in rainfall meant that there was a larger amount of freshwater blending into the seawater, which he says the sea stars are not able to live well in.

Here’s a link to a video posted by the biologist who discovered the sea stars, showing dead sea stars that he later found in another location in Vancouver:

In the past year scientists have been doing a lot of research to figure out what may be causing these deaths. What they have discovered is that the deaths aren’t just in the waters located near Vancouver, they are in the waters from British Columbia all the way down the Mexico! And the numbers have grown from a few hundred sea stars to finding MILLIIONS of them dead in the ocean. The Vancouver Aquarium nicknamed this problem as the “Sea Star Wasting Syndrome” since the number of these sea stars that were just disintegrating at the bottom of the ocean floor was staggering.

An explanation of how these sea stars have been observed to die is quiet unbelievable. The researchers described that the body of the sea star begins to look deflated, white cuts emerge on the arms of the sea stars, and then quite quickly their arms fall off. Finally, the body disintegrates into what has been called “goo.” Researchers explained how in some situations it was difficult for them to collect samples because once the arms fell off, the body of the sea stars disappeared into the water so quickly. Here is a photo of a sea star which can be seen mid-way between starting to lose its arms:

Sunflower sea star (Image taken from Google)

No one still knows what the exact cause of this mass fatality is, but one recent study suggests that it may be a bacteria or virus which is causing the deaths. Once the bacteria or virus appear in the waters, it is hard to eliminate and begins to affect all of the sea stars that are exposed to it, making it hard to maintain a population. Other studies have suggested that it may have to do with climate change its effect on the temperature or salinity of the ocean. It is possible that the warming of the ocean is allowing certain bacteria to live, when they previously were unable to.



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