The cause of the sea star wasting syndrome is still a mystery, but reports from citizen scientists continue to pour into the Aquarium’s database, giving researchers a better idea of where this is happening. Last year, the sunflower star (Pycnopodia helianthoides) seemed to be the hardest hit species. This year, the purple star (Pisaster ochraceus) may be on its way to getting this dubious distinction.
Andy Lamb, author of Marine Life of the Pacific Northwest, lives on Thetis Island. Six weeks ago, while exploring the marina-end of “the cut,” as this channel is known, he counted 605 purple stars that were “goopy and falling apart.” Two weeks later, in the same place only 12 of these sea stars were left.
It was a similar story at a rocky point near Clam Bay, where at first he saw 950 purple stars, 600 during his next visit and then 300 after that. Andy says that this phenomenon is not unique to Thetis Island and that people on other Gulf Islands have also been reporting the loss of purple stars.
“Nobody’s seen anything like this before.”
While he’s “heartened” by the sight of sunflower star juveniles this year, “There’s definitely something happening again this summer.”
Dr. Jeff Marliave, vice president of marine science at the Vancouver Aquarium, confirms what Andy says about the other Gulf Islands with sightings of “disintegrating” purple stars on Valdes Island. He says a majority of the purple stars exposed to the sun were affected, but also notes that there were “repeated instances of healthy purple stars clustered on the undersides of large slabs of sandstone, which usually overlaid a shaded puddle of seawater.” This evidence plays into what investigators are thinking: temperature is a factor causing this syndrome to reach a lethal level.
Doug Biffard is an Aquatic Ecologist with BC Parks. He reports that “pretty much 100 per cent” of the purple stars at Henderson Point and Mackenzie Bite have been affected. He says all of the purple stars he saw had at least one lesion, with some of them being in full-blown disintegration mode.
Last year at this time, Doug says the purple stars were healthy. In fact, he didn’t notice anything amiss until suddenly this past May. It’s something he says BC Parks will continue to monitor in local areas and at remote sites along the coast.
We’ll check in again with Andy and Doug at the end of the summer. In the meantime, you can add to the data that they, and others, have been collecting by logging your sightings on the Aquarium’s Sea Star Wasting Syndrome page.
Written by Karen Horak, writer-editor, content and digital experience at the Vancouver Aquarium.