Scientists Link Massive Starfish Die-Off to Warming Ocean

Source: The Seattle Times/Lynda V. Mapes - February 22, 2016 in Environment

Scientists Link Massive Starfish Die-Off to Warming Ocean
Photo: Jonathan Martin/Flickr (CC BY 2.0)

It was the starfish arms walking off on their own that alerted biologist Steven Fradkin that something was terribly wrong at Starfish Point at Olympic National Park.

Next he noticed white lesions pitting the skin of the usually colorful orange, purple and brick-red starfish that are the signature of Olympic tide pools. Worse, the starfish, usually so thick and clinging robustly to their rock, were melting into goo.

“They were just falling apart,” said Fradkin, Olympic National Park coastal ecologist. “It was a horror show.”

The observations he made and shared June 7, 2013, would turn out to be the first reported sighting of a mysterious starfish wasting disease that in 2013 and 2014 would devastate more than 20 species of starfish from Alaska to Mexico.

In its geographic scope, the number of species of starfish affected, and duration of the outbreak — still not over — the sea star wasting syndrome Fradkin first documented is now understood to be the largest observed die-off of a wild animal in the ocean. Nearly three years later, the epidemic of sea star wasting disease has left many coves, tide pools, pilings and beaches still largely bereft of starfish. Some locations saw complete mortality of sea stars.

Scientists working ever since to understand the outbreak have published the first evidence of a link between warmer ocean temperatures and the devastation of the wasting disease. Unusually warm ocean temperatures coincided with the 2014 die-off analyzed in the paper published last week in the Philosophical Transactions of the Royal Society.

“We were able to show warmer temperatures were related with the higher risk of disease,” said Drew Harvell, professor of ecology and evolutionary biology at Cornell University and a co-author of the study, along with Fradkin and others. “We suspected there was a temperature link, but we really needed to look at the field data to pull that out, and we were able to back that up with lab experiments that found that in warmer temperatures, they died faster.”

The scientists also figured out why so few sick juvenile sea stars were being seen that summer: While younger sea stars took longer to show symptoms, once they did, they died right away.

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