Latest news with #AlyssaGehman
Express Tribune
02-05-2025
- Health
- Express Tribune
Scientists discover that cooler waters shield sea stars from deadly wasting disease
Listen to article A mysterious disease that has plagued sea stars for more than a decade may have met its match in the frigid waters of British Columbia's fjords. Researchers have discovered that sunflower sea stars, which are critically endangered due to sea star wasting disease (SSWD), are thriving in these cooler waters, providing valuable insight into how temperature may offer protection from the disease. The study, published in April in the Proceedings of the Royal Society B, found that the sunflower sea stars were healthier in the fjords compared to those in other areas. This discovery is significant because the species, once abundant along the Pacific coast from Baja, California to Alaska, has seen a 91% decline due to the deadly disease that causes grotesque body contortions and rapid death. The SSWD outbreak first emerged in 2013, and scientists have struggled to pinpoint the cause. While initial research pointed to a virus, subsequent studies have been inconclusive. Ian Hewson, a marine ecologist at Cornell University, says that microbial or environmental causes have also failed to provide answers. The sunflower sea star is a crucial predator in marine ecosystems, particularly in controlling sea urchin populations. Without them, sea urchins can decimate kelp forests, which provide habitats for many marine species. The discovery of sunflower sea stars thriving in cold waters may offer hope for restoring the species and its ecosystem role. The finding was made by marine ecologist Alyssa Gehman, who, along with her team, surveyed the fjords of British Columbia from 2018 to 2023. They found that while sea stars in the fjords showed signs of SSWD, the populations were healthier overall, with more adults surviving compared to populations on the outer islands. The fjords' cooler, deeper, and saltier water appeared to offer a refuge from the disease, suggesting that temperature could be a protective factor. The study also highlighted the importance of environmental conditions in shaping sea star health. Sea stars in the fjords were found in areas where snow melt created a layer of fresher, cooler water, in contrast to the warmer waters of the outer islands where the sea stars struggled to survive. The findings are a breakthrough in understanding SSWD and could provide a clue in determining the environmental conditions that either promote or prevent the disease. Researchers now believe that warmer-than-normal waters increase the likelihood of disease outbreaks, while cooler temperatures may slow or prevent its spread. Alyssa Gehman is continuing to investigate the interplay between temperature, microbial environments, and the progression of SSWD. "We've restarted the question from square one on what causes this disease," she said. This discovery offers new hope for sea star conservation and may lead to further research on how to protect vulnerable marine species from the devastating effects of climate change and disease.
CBC
03-04-2025
- Science
- CBC
These sea stars were nearly wiped out — but B.C. researchers say fiords provided refuge
Social Sharing B.C. researchers have found that the fiords of the Central Coast may be providing refuge for the critically endangered sunflower sea star, a discovery that could have implications for wider ecosystems at risk due to warming seas. Nine out of 10 sea stars have been wiped out since 2013 due to sea star wasting disease, which has led to a mass death of the animals along North America's West Coast, from Alaska to Mexico. The sunflower sea star is listed as critically endangered by the International Union for Conservation of Nature. While the exact cause of the disease is unknown, scientists say it's had major ripple effects, as sunflower sea stars eat sea urchins and perform an important role in keeping those populations in check. Without them, urchins have flourished and been able to eat kelp forests, which further destabilizes marine ecosystems. Now, after years of diving along B.C.'s Central Coast, researchers have found many healthy adult colonies of sunflower sea stars in the fiords there. Alyssa Gehman, a scientist with the Hakai Institute and an adjunct professor at the University of B.C., co-authored a paper on the findings. What they found, she said, is that while sea star wasting disease has been found in fiords and sea stars have died there, the mortality rate is far lower than elsewhere in the ocean. Researchers suspect the difference has something to do with water temperature. In fiords — long, narrow, and deep inlets often found between high cliffs along the central and north coasts — the ocean tends to be cooler than elsewhere. Gehman said the research team was first alerted to the large number of sunflower sea stars in fiords by Central Coast Indigenous Resource Alliance divers who were looking for rockfish — and the two groups ended up collaborating on the final research paper. "When we looked at the oceanography ... we found that where the sea stars are, it's colder," Gehman told Darius Mahdavi, CBC's science specialist. "That's our next thing, is trying to figure out exactly what that temperature relationship is, and how that's working." Changes in seasons Jeff Sha, an aquarium biologist at the Vancouver Aquarium who wasn't involved in the study, said scientists have evidence that sea star wasting disease thrives in warmer water. "The higher the temperature, the more likely the onset of the disease, and the harder it is for an infected sea star to come back from that," he said. "As temperatures are rising along our coastlines ... we've had a couple of heat domes in the last decade, each of those events basically was another round of devastation for the population." Gehman said in the fiords, Arctic outflow conditions create cold winds in the winters, cooling the water and making the environment higher in oxygen, which is good for sea stars. "In the summer, when it's hot, there's glacial runoff that comes through," she said. "And it's so fascinating, but it creates essentially a little freshwater river on the surface of the fiord." Sha said sea stars don't like fresh water, which means they'll go deeper and into the colder water. "The researchers are hypothesizing that that's kind of what's giving them a little bit of a refuge away from the warmer temperature zone, and keeping them healthy from the wasting disease," he said. Implications for recovery efforts Sha said sunflower sea stars, in particular, are a ferocious predator for sea urchins — and without them, there's been devastating effects for other species. "Sea urchin populations have boomed on our coast, causing a decline in our algae and our kelp forest, which then removes habitats for rockfish and all these beautiful animals that we have," the biologist said. WATCH | Some sea stars released into the wild: Sunflower sea stars released into the wild after disease stunted population 7 months ago Duration 4:13 Over the past decade, disease has killed off around five billion sunflower sea stars, disrupting underwater ecosystems from Alaska to California. Now, the starfish are being released back into the wild around the San Juan Islands in Washington State. They're the first of their kind to have been bred in captivity by researchers at the University of Washington. Jason Hosin, a University of Washington marine biologist, shares more about his research. Gehman said some kelp forests along B.C.'s coast have been reduced to "urchin barrens," where all of the leafy portions of the kelp have been consumed by sea urchins. The scientist said that, as researchers look to raise sunflower sea stars in the laboratory and put them back in the ocean, their work in the fiords could be important — though she acknowledged that climate change will continue to affect whether fiords can remain a "refuge habitat" for the species. "There's hope that we could potentially raise stars that would be resistant to the disease," she said. "And this suggests that we need to pay attention to temperature when we're doing that work as well."
