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Researchers say the near total destruction of a massive starfish is changing the ocean off the B.C. coast

A disease that has decimated sea stars from California to Alaska has all but killed off the massive sunflower sea star in the Salish Sea, off the coast of British Columbia and Washington state, says a new study.

The near disappearance of Pycnopodia helianthoides, one of the largest sea stars in the world, is changing the underwater environment in the Pacific, said Joe Gaydos, chief scientist with the UC Davis School of Veterinary Medicine’s SeaDoc Society and one of the authors of the study published Wednesday in the journal PLOS One.

“What we saw was that the sunflower sea stars basically have disappeared. You may find one here or one there but we used to see 10 or 12 on a routine dive and now people are lucky to see one. So that population has really been decimated,” Gaydos told Yahoo Canada News.

Sea star wasting disease was first noticed in 2013. Animals infected with the virus essentially disintegrate, their limbs falling off as their tissue decays.

In a matter of months, the disease was detected all along the Pacific coast of North America.

Using data from both previous research work and from 10 years-worth of monitoring by trained recreational divers, Gaydos and his colleagues were able to compare the pre-outbreak ecosystem to the current situation.

The bad news is that some species – the sunflower, spiny pink and others – have been hit hard. But some, including the leather star, are actually increasing in numbers.

“That may be because the virus doesn’t impact them as much… or that may be that they’re not being predated upon as much by these other ones or that there’s more food available to them,” Gaydos said.

The results are similar to what a team of Canadian researchers found in Howe Sound.

In a study published in June, Jessica Schultz and colleagues at Simon Fraser University and the Vancouver Aquarium found 90 per cent of sunflower sea stars have died in Howe Sound.

Their absence has caused a spike in green sea urchins, the main prey of sunflower sea stars. Urchins are herbivores that feed largely on kelp, which provides habitat for invertebrates like the spot prawn.

“Everything’s connected,” said Schultz, an SFU master’s student and Vancouver Aquarium’s Howe Sound research program manager. “There could be long-term, far-reaching impacts. We’ll have to wait and see.”

Gaydos and some of his colleagues are in discussions with the National Oceanic and Atmospheric Administration about potentially having sea stars listed as a “species of concern” in the U.S.

“We don’t really know what is going to happen with the ecosystem but to have so many changes in so many predator animals is definitely going to change the way the ecosystem looks,” he said.

In Canada, Schultz said there has been discussion among Canadian scientists about seeking some type of designation for sea stars under the federal Species At Risk Act, but there is some hesitation.

“One is that the benefits of listing sea stars are questionable,” she told Yahoo Canada News.

The animals are not harvested so there is no need for direct protection, she pointed out.

“A drawback might be that once species are listed as threatened, it’s more difficult to get permits to do research so it could actually make it trickier for research in some ways.”

The die-off is still happening, Gaydos said. Divers and researchers continue to report sightings of dying sea stars.

The ultimate effects remain to be seen.

“The virus is still out there and the die-off is still going on,” he said. “The dust hasn’t really settled on the whole thing yet.”