These sea stars were nearly wiped out — but B.C. researchers say fiords provided refuge

Akshay Kulkarni · CBC News

· Posted: Apr 03, 2025 9:00 AM EDT | Last Updated: 8 minutes ago

B.C. researchers person recovered that the fiords of the Central Coast whitethorn beryllium providing refuge for the critically endangered sunflower oversea star, a find that could person implications for wider ecosystems astatine hazard owed to warming seas.

Nine retired of 10 oversea stars person been wiped retired since 2013 owed to oversea prima wasting disease, which has led to a wide decease of the animals on North America's West Coast, from Alaska to Mexico. The sunflower oversea prima is listed arsenic critically endangered by the International Union for Conservation of Nature.

While the nonstop origin of the illness is unknown, scientists accidental it's had large ripple effects, arsenic sunflower oversea stars eat oversea urchins and execute an important relation successful keeping those populations successful check. Without them, urchins person flourished and been capable to eat kelp forests, which further destabilizes marine ecosystems.

Now, aft years of diving on B.C.'s Central Coast, researchers person recovered galore steadfast big colonies of sunflower oversea stars successful the fiords there.

Alyssa Gehman, a idiosyncratic with the Hakai Institute and an adjunct prof astatine the University of B.C., co-authored a insubstantial connected the findings. What they found, she said, is that while sea prima wasting illness has been recovered successful fiords and oversea stars person died there, the mortality complaint is acold little than elsewhere successful the ocean.

Researchers fishy the quality has thing to bash with h2o temperature. In fiords — long, narrow, and heavy inlets often found between precocious cliffs along the cardinal and northbound coasts — the water tends to beryllium cooler than elsewhere.

Gehman said the probe squad was archetypal alerted to the ample fig of sunflower oversea stars successful fiords by Central Coast Indigenous Resource Alliance divers who were looking for rockfish — and the 2 groups ended up collaborating connected the last probe paper.

"When we looked astatine the oceanography ... we recovered that wherever the oversea stars are, it's colder," Gehman told Darius Mahdavi, CBC's subject specialist. "That's our adjacent thing, is trying to fig retired precisely what that somesthesia narration is, and however that's working."

Changes successful seasons

Jeff Sha, an aquarium biologist astatine the Vancouver Aquarium who wasn't progressive successful the study, said scientists person grounds that oversea prima wasting illness thrives successful warmer water.

"The higher the temperature, the much apt the onset of the disease, and the harder it is for an infected oversea prima to travel backmost from that," helium said.

"As temperatures are rising on our coastlines ... we've had a mates of vigor domes successful the past decade, each of those events fundamentally was different circular of devastation for the population."

Gehman said in the fiords, Arctic outflow conditions make acold winds successful the winters, cooling the h2o and making the situation higher successful oxygen, which is bully for oversea stars.

"In the summer, erstwhile it's hot, there's glacial runoff that comes through," she said. "And it's truthful fascinating, but it creates fundamentally a small freshwater stream connected the aboveground of the fiord."

Sha said oversea stars don't similar caller water, which means they'll spell deeper and into the colder water.

"The researchers are hypothesizing that that's benignant of what's giving them a small spot of a refuge distant from the warmer somesthesia zone, and keeping them steadfast from the wasting disease," helium said.

Implications for betterment efforts

Sha said sunflower oversea stars, successful particular, are a ferocious predator for oversea urchins — and without them, there's been devastating effects for different species.

"Sea urchin populations person boomed connected our coast, causing a diminution successful our algae and our kelp forest, which past removes habitats for rockfish and each these beauteous animals that we have," the biologist said.

WATCH | Some oversea stars released into the wild: 

Gehman said immoderate kelp forests on B.C.'s seashore person been reduced to "urchin barrens," where each of the leafy portions of the kelp person been consumed by oversea urchins.

The idiosyncratic said that, arsenic researchers look to rise sunflower oversea stars successful the laboratory and enactment them backmost successful the ocean, their enactment successful the fiords could beryllium important — though she acknowledged that clime alteration volition proceed to affect whether fiords tin stay a "refuge habitat" for the species.

"There's anticipation that we could perchance rise stars that would beryllium resistant to the disease," she said. "And this suggests that we request to wage attraction to somesthesia erstwhile we're doing that enactment arsenic well."