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Death of sea stars in Howe Sound reveals ecological domino effect

In this July 30, 2015 file photo, a healthy sea star is seen under a magnifying glass during a survey to determine the health of local sea star populations at Camano Island State Park in Washington state. A mass die-off off of sea stars in British Columbia's Howe Sound appears to be causing a significant change in the ecology of the waterway north of Vancouver.
Image Credit: THE CANADIAN PRESS/ AP-Ian Terry/The Herald via AP, File
June 24, 2016 - 7:00 AM

VANCOUVER - The mass death of sea stars in British Columbia's Howe Sound has created a trickle-down effect that a researcher says should be a warning about the depletion of any species in the ocean.

Sea stars began dying by the millions in waters from Alaska to Mexico in the summer of 2013.

Experts still don't have a conclusive cause, but have linked some deaths to a virus and others to fluctuating water temperatures, said Jessica Schultz, a master's student at Simon Fraser University and the Vancouver Aquarium's Howe Sound research program manager.

"It's difficult to prevent further disturbances like this when you don't fully understand what the cause was," she said in an interview Wednesday.

Schultz and fellow marine ecologists Ryan Cloutier and Isabelle Cote from Simon Fraser discovered that the deaths in the Howe Sound, just north of Vancouver, triggered a rapid rise in the number of green sea urchins and a depletion of the kelp they like eat.

The sunflower star, one of the star fish most affected by the wasting disease, was a voracious predator of the urchins. At the same time, kelp has declined by 80 per cent.

Cote says the upheavals in the food chain are a sign of an ecological domino effect.

"It's a stark reminder that everything is connected to everything else. In this case, the knock-on consequences were predictable, but sometimes they are not," she said in a news release.

Schultz said there is still no sign of recovery for Howe Sound's sea stars. In fact, they are still dying.

There has been talk of listing some of the star fish as endangered, she said, including the sunflower sea star, among the largest sea stars in the world.

The loss of that predator put things out of whack, Schultz said.

"The more we can try to maintain ecosystem integrity in whatever system it is, the better systems will be able to recover from things like this," Schultz said. "Everything is connected."

News from © The Canadian Press, 2016
The Canadian Press

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