Despite an eerie epidemic, starfish stocks may be rebounding in the Strait of Georgia.
At least one local scuba diver said he’s feeling “optimistic” after spotting one of the largest sea stars he’s seen in the last two years at a popular dive site in Nanoose Bay at the tip of Madrona Point in recent weeks.
“I hope they’re coming back,” divemaster Matt Beckett told The NEWS Tuesday. “I’ve seen a number of smaller ones too.”
Beckett, a dive enthusiast, takes to the ocean every weekend observing the wonders of the marine world.
“There used to be tons of them (starfish), walls were crawling with them and then all of a sudden they just started dying off, they just sort of disappeared; disintegrated,” he said.
Beckett recalls watching the once-bountiful, beautiful sea stars melt right before his eyes.
“They’d turn white and their legs just fell off — they disintegrated into this white mush,” he said. “It was literally like watching a movie; you’d just find them in various stages of dissolving.”
Since 2013 millions of sea stars native to the Pacific coast of North America from Baja California to southern Alaska have succumbed to a mysterious wasting disease in which their limbs pull away from their bodies and their organs exude through their skin.
Researchers say the disease could trigger an unprecedented ecological upheaval under the waves.
Just before the disease hit, sea stars appeared to be over-abundant in the Strait of Georgia, but divers soon started noticing sick and dying starfish. The mass marine mortality event seemed to attack sunflower stars the hardest with dense aggregations disappearing in weeks. Purple stars, pink stars, mottled stars and several others were also affected by the disease.
But now a researcher in the Cornell University’s College of Agriculture and Life Sciences has identified the deadly culprit as the Sea Star Associated Densovirus (SSaDV), a type of parvovirus commonly found in invertebrates.
In a study published Nov. 17 in the Proceedings of the National Academy of Sciences, Ian Hewson and colleagues present a genomic analysis of the newly discovered virus prevalent in symptomatic sea stars.
“There are 10 million viruses in a drop of seawater, so discovering the virus associated with a marine disease can be like looking for a needle in a haystack,” said lead author Hewson, a professor of microbiology at Cornell.
“Not only is this an important discovery of a virus involved in a mass mortality of marine invertebrates, but this is also the first virus described in a sea star.”
Dr. Jeff Marliave, vice-president of marine science at the Vancouver Aquarium, remembers when the virus — which is commonly referred to as Sea Star Wasting Disease — first surfaced near the Burrard Inlet and Howe Sound region.
“It was Labour Day weekend of 2013 and we were hit so hard and fast around Vancouver,” Marliave told The NEWS. “We started seeing it and photographing it…and by the time we checked places back it was progressing so rapidly we weren’t fast enough to document its speed.”
Shortly after, Vancouver Island was hit and the virus was observed in parts of Nanoose Bay and Nanaimo.
“They would melt in front of your eyes, literally they’d just fall apart,” said Marliave. “It was so disgusting.”
But he believes this may not be a new phenomena.
“It’s going to prove, as we pay closer attention, this has always been an issue,” said Marliave.
Researchers at Cornell suggest the virus may have been smoldering at low levels for many years.
It was present in museum samples of sea stars collected in 1942, 1980, 1987 and 1991, and may have risen to epidemic levels in the last few years due to sea star overpopulation, environmental changes, or mutation of the virus. Sea water, plankton, sediments and water filters from public aquariums, sea urchins and brittle stars also harbored the virus.
“I think it’s part of nature,” said Marliave. “Sea stars are famous for going through population explosions…yes, this is the most extraordinary disease process documented by human beings but we’re just people.”
VIU Deep Bay Marine Field Station manager Brian Kingzett said the epidemic is puzzling.
“It appears in some areas it hasn’t wiped out the whole population but it still seems active in some regions,” said Kingzett. “We’ve noticed more (starfish) out but I don’t think there are nearly the amount of sunflower stars as there were before.”
Kingzett said it could be cyclical.
“It’s still very much a mystery,” he said. “It could be climate change, it could be all sorts of things…We do know it’s not related to Fukushima radiation.”
Cornell’s research lays the groundwork for understanding how the virus kills sea stars and what triggers outbreaks.
“It’s the experiment of the century for marine ecologists,” said Drew Harvell, a professor of ecology and evolutionary biology at Cornell. “It is happening at such a large scale to the most important predators of the tidal and sub-tidal zones. Their disappearance is an experiment in ecological upheaval the likes of which we’ve never seen.”
