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A New Study Shows Warmer Water Temperatures Are Linked To Sea Star Die-Offs

Elaine Thompson
/
AP
In this photo taken April 9, 2015, a volunteer reaches over to measure two tiny baby sea stars as a mature one clings nearby to a concrete piling on Washington’s Hood Canal near Poulsbo, Wash. ";

 

A massive die-off of sea stars a few years ago was caused by a virus. But a study published this week shows that higher water temperatures also played a big role.

 

The peak of sea star wasting disease was in 2014. It turns the often colorful invertebrates into shrunken masses with white patches. After that, “The arms can fall off and eventually they just waste away and they stay in one place and just melt,” said Joel Elliot, a biology professor at University of Puget Sound.

 

Elliot is one of the authors of the study published in the Royal Society. It shows, for the first time, that the mortality rate in infected sea stars increases in warmer water.

 

“It appears that warm water is either causing the virus to have a better ability to infect a host or to replicate — or somehow it’s compromising the immune system, or what we’d consider to be an immune system, in these invertebrates, to protect themselves from the infiltration of the virus,” Elliot said.

 

The study focused on sea stars in the San Juan Islands. It also found that larger sea stars were more likely to die from the virus.

 

“And we suspect it’s going to have very significant influences on the populations and biology of these sea stars, because the large sea stars are the ones that are reproductive, and if you don’t have reproductive individuals in your populations, they’re not going to be able to replenish themselves,” said Elliot.

 

During the height of the die off,  water temperatures there were two to three degrees higher than usual. The ochre sea star population in the San Juans was reduced by nearly 75 percent. Researchers want to study the surviving sea stars to see if they’ve developed an immunity to the virus.

Jennifer Wing is a former KNKX reporter and producer who worked on the show Sound Effect and Transmission podcast.