Why is Ontario seeing a spike in deadly drowning cases?
Stephanie Bakalar with the Lifesaving Society of Ontario explains what could be behind a recent rise in deadly drownings.
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CTV News
an hour ago
- CTV News
Special air quality statement remains in effect across Ontario
Playing null of undefined How poor air quality affects your short-term and long-term health Here's what you need to know as smoke continues to impact air quality across the country Special air quality statement issued for Toronto and GTA
Globe and Mail
an hour ago
- Globe and Mail
Breakthrough in mysterious sea star wasting disease offers hope for recovery of critically endangered creatures
Sunflower sea stars were once everywhere along the Pacific coast. Big, colourful and many-armed, they could be spotted at low tide clinging to rocks as if painted there by Vincent Van Gogh. Then came a devastating sickness that turned healthy sea stars into mounds of decaying mush. Known as sea star wasting disease, the mysterious syndrome is estimated to have killed billions of individuals since it emerged in 2013. More than 20 species have been affected, with sunflower sea stars among the hardest hit. Their numbers have plummeted by 90 per cent and the species is listed as critically endangered by the International Union for the Conservation of Nature. Now the cause of the contagion has been found: It is a bacterium – a member of the vibrio family – whose relatives include pathogens associated with seafood-borne illnesses and with cholera. The breakthrough, reported Monday in the journal Nature Ecology and Evolution, marks a turning point in the quest to understand why sea stars are dying. It may also aid efforts to help populations recover. 'The exciting thing about it being a bacteria is that it makes it possible for us to isolate and grow it,' said Alyssa Gehman, an adjunct professor at University of British Columbia and a marine disease ecologist at the Hakai Institute, whose lab spearheaded the work. And since the strain can be cultured, it also means that Dr. Gehman and her colleagues have been able to report their discovery with an unusually high degree of confidence. While the researchers employed the tools of modern molecular biology to arrive at their conclusion, their approach was essentially one developed by medical pioneers in the 19th century to pinpoint the cause of infectious disease. 'It's very clean work, very thorough,' said Blake Ushijima, a marine microbiologist at the University of North Carolina Wilmington who was not involved in the discovery. He said that while the disease cannot be removed from the environment, knowing its cause raises the possibility that captive populations of sea stars can be protected from it and then successfully reintroduced. The find also sheds light on a long-suspected connection between sea star disease and climate change. Because vibrio bacteria tend to be more active in warmer water, rising ocean temperatures along the Pacific coast may account for why the disease has become so rampant. The outcome has wreaked havoc on ocean ecosystems. Sea stars are voracious hunters. In their absence, sea urchin populations have exploded and led to severe overgrazing of kelp forests that provide crucial habitat for other species. Dr. Gehman said that when she first undertook the project in 2020 with funding from The Nature Conservancy of California among other sources, she felt the complexity of the disease would likely preclude finding a definitive cause. But she thought she could help to move the field forward. 'We didn't expect to get to the place we did,' she said. Much of the work was conducted at the United States Geological Survey Marrowstone Field Station, located near the entrance to Puget Sound. The station includes facilities where sea stars can be kept in quarantine without risk of contamination or of infection being released back into the ecosystem. It began by setting up a baseline group of specimens that were isolated long enough to be reliably disease free. These were subjected to a series of 'challenge experiments' to determine under what circumstance disease would spread. Dr. Gehman said that from the outset, she and her colleagues considered all possible causes, including marine viruses and contagious forms of cancer. An important step forward came when the researchers learned they could spread the disease by injecting a body fluid from a sick to a healthy sea star. Known as coelomic fluid, the material ceased to be infectious once it was heat treated, pointing to the presence of a live pathogen. Infection was also blocked when the fluid was passed through a filter that should have allowed viruses to pass through. It was by systematically combing through the genetic contents of the coelomic fluid that researchers eventually zeroed in on a bacterial cause. This was a Herculean task since sea stars, like many organisms, host a vast and diverse microbiome. They can also be colonized by secondary infections that are not responsible for the disease but are present alongside it. It was during a meeting in early 2024 that the team first noticed how the DNA of one particular bacterium among myriad of suspects was consistently appearing in their genetic readouts. It was called Vibrio pectenicida, a species known to attack scallop larva. Dr. Gehman and research scientist Melanie Prentice were on a Zoom call with Grace Crandall, a PhD student at the University of Washington who conducted the challenge experiments, when the researchers suddenly realized they might have hit upon the answer. 'It was a moment of eerie quiet as we were all looking at each other,' Dr. Prentice said. 'Part of me was thinking, can we have some streamers coming from the ceiling or something?' But to confirm their suspicions the team needed a diseased specimens to work with and transmit diseased fluid – not easy to find during the winter months. They quickly put out the call and heard back from a colleague who was dealing with an outbreak in his lab. 'It's about a four-hour drive plus ferry from the University of British Columbia where we were, so we just hopped in a car and drove straight there,' Dr. Gehman said. 'We arrived at 9 p.m. and sampled the stars in the dark with headlamps.' Using the sample material, the group conducted a battery of controlled tests which confirmed their initial suspicions. The results consistently pointed to Vibrio pectenicida as the single definitive cause. The bacteria is now cultured and available for further research. That includes studies across different species to look for differences in response to the disease and the potential for finding individuals with some innate resistance. Scientists also hope to trace the recent evolution of the bacteria by looking at preserved tissue samples. All of this can inform recovery strategies for bringing back the threatened sea stars. 'This discovery has been so critical and so important,' Dr. Prentice said, 'But the most exciting part about it is all the stuff that it's allowing us to do next.'
CBC
2 hours ago
- CBC
After a decade of death, Canadian scientists say they've found the sea star killer
Social Sharing Scientists say they have found the cause behind the disease that turns vibrant, 24-armed sea stars into puddles of goo. Melanie Prentice, a research scientist at the Hakai Institute, is part of a team that has spent years investigating the cause of this disease. Their research was published on Monday in the journal Nature Ecology and Evolution. "The agent is a bacteria. It's called Vibrio pectinicida," Prentice told CBC News. After a decade of these creatures being pushed to the brink of extinction, experts say this is the first step in a road to recovery, not just for this species, but for a critical support in humanity's defence against climate change. Twisted arms that walk away The most affected species are sunflower sea stars, which once boasted a range along the west coast of North America, from Baja California to Alaska. Then, in 2013, a mass die-off occurred from sea star wasting disease. And it's a gruesome end. "Their arms kind of twist back on themselves, so they get kind of into puzzle pieces," said Alyssa Gehman, a marine disease ecologist who is also part of the Hakai Institute research team. They then tend to lose their arms, and then, "their arms will sort of walk away from their bodies." Soon after, Gehman says that lesions form and the sea stars dissolve and die. The paper estimates that more than 87 per cent of sunflower sea stars in northern parts of the west coast have been killed. In the southern habitat ranges, the species is considered functionally extinct. "When it first happened, it was just fields and fields of puddles of dying sea star goo," said Sara Hamilton, science co-ordinator for the Oregon Kelp Alliance. Hamilton was not involved in the research. "It was like something out of a horror movie." The hunt for the star killer Multiple theories identifying the cause either didn't pan out or were disproven. What the team did in this case was take healthy sea stars into the lab and expose them to infection. They did this over several years to try and isolate the cause. Gehman explained the process: "We take body fluid or tissue from a sick star and then we put that experimentally into other sea stars that we know are healthy." The paper's result was that 92 per cent of these exposures worked in transmitting the disease to the healthy star — killing it within 20 days. These experiments also revealed that Vibrio pectinicida was the most likely culprit. Experts are impressed with the paper's diligence and effort. "They didn't just stop when they found one level of evidence — they went and found a second level of evidence and a third level of evidence," said Hamilton, from Oregon Kelp Alliance. Amanda Bates, ocean conservation professor at the University of Victoria, also said "there's a pathway — essentially that you isolate disease agents and link them to being a cause of an outbreak — and this research team followed those processes perfectly." Hope for recovery Knowing the cause provides hope for restoration efforts, experts say. "Now we can go out and actually do tests and see the actual prevalence of this pathogen in the field," said Gehman. Furthermore, any captive breeding programs that are trying to restore sea star populations can now screen and test those populations before putting them back into a risky environment. Hamilton agrees. "That's one of the things we're most worried about with some of these recovery efforts," she said. "If we do captive breeding and outplant, we certainly don't want to introduce … a new outbreak of the disease." The lost decade Bates, who has seen this disease as far back as 2009, is cautious about the rush to recovery. "While we know disease impacts us as humans, I think we often forget that it impacts wildlife," she told CBC News. "We're a decade on since that really big mass mortality event, and we still don't have pycnopodia [sunflower sea stars] recovering in many places." Hamilton said the reintroduction of sunflower sea stars will be valuable because of what their absence has meant for ecosystems. Sea urchin populations have gone up — which also means kelp forests have been decimated. "Urchins are kind of like the goats of the ocean," she said. "They'll eat anything, they just mow things down." Restoring the sea star means kelp forests might once again thrive. This will likely mean improvements to biodiversity, food, tourism as well as serve as coastline defences against erosion and storms supercharged by climate change. "It's definitely our ally in the climate crisis," Prentice said. "I think when we're talking about sea star wasting disease, we're not just talking about the sea star species — which we love in their own right — but entire marine ecosystems that have collapsed because of this epidemic."
