Latest news with #Alyssa Gehman
National Post
06-08-2025
- Health
- National Post
Scientists have solved the mystery of what killed more than 5 billion sea stars
WASHINGTON — Scientists say they have at last solved the mystery of what killed more than 5 billion sea stars off the Pacific coast of North America in a decade-long epidemic. Article content Sea stars — often known as starfish — typically have five arms, and some species sport up to 24 arms. They range in colour from solid orange to tapestries of orange, purple, brown and green. Article content Starting in 2013, a mysterious sea star wasting disease sparked a mass die-off from Mexico to Alaska. The epidemic has devastated more than 20 species and continues today. Worst hit was a species called the sunflower sea star, which lost around 90 per cent of its population in the outbreak's first five years. Article content Article content 'It's really quite gruesome,' said marine disease ecologist Alyssa Gehman at the Hakai Institute in British Columbia, who helped pinpoint the cause. Article content Healthy sea stars have 'puffy arms sticking straight out,' she said. But the wasting disease causes them to grow lesions and 'then their arms actually fall off.' Article content The culprit? Bacteria that has also infected shellfish, according to a study published Monday in the journal Nature Ecology and Evolution. Article content The findings 'solve a long-standing question about a very serious disease in the ocean,' said Rebecca Vega Thurber, a marine microbiologist at University of California, Santa Barbara, who was not involved in the study. Article content Article content It took more than a decade for researchers to identify the cause of the disease, with many false leads and twists and turns along the way. Article content Article content Early research hinted the cause might be a virus, but it turned out the densovirus that scientists initially focused on was actually a normal resident inside healthy sea stars and not associated with disease, said Melanie Prentice of the Hakai Institute, co-author of the new study. Article content Other efforts missed the real killer because researchers studied tissue samples of dead sea stars that no longer contained the bodily fluid that surrounds the organs. Article content But the latest study includes detailed analysis of this fluid, called coelomic fluid, where the bacteria Vibrio pectenicida were found. Article content 'It's incredibly difficult to trace the source of so many environmental diseases, especially underwater,' said microbiologist Blake Ushijima of the University of North Carolina, Wilmington, who was not involved in the research. He said the detective work by this team was 'really smart and significant.'
Sky News
05-08-2025
- Science
- Sky News
Mystery of what killed billions of starfish solved, say scientists
More than a decade after a mysterious killer devastated sea star populations along the Pacific coast of North America, scientists believe they have finally found the culprit. The mass die-off, which began in 2013, wiped out an estimated five billion sea stars from Mexico to Alaska, and continues to affect over 20 species. "It's really quite gruesome," said Alyssa Gehman, marine disease ecologist at the Hakai Institute in British Columbia, Canada, who helped identify the cause. She said healthy sea stars - also known as starfish - have "puffy arms sticking straight out". But the wasting disease that set in more than a decade ago caused them to grow lesions and "then their arms actually fall off". Worst hit was the sunflower sea star species, which lost around 90% of its population in the outbreak's first five years. After following numerous wrong turns and red herrings, scientists are now confident the killer was a bacterium that also infected shellfish. The breakthrough, published in the journal Nature Ecology and Evolution, solves "a long-standing question about a very serious disease in the ocean," said Rebecca Vega Thurber, a marine microbiologist at the University of California, Santa Barbara, who was not involved in the study. Previous efforts missed the real killer because they focused on the wrong type of virus or investigated samples of dead sea stars which no longer contained the bodily fluid that surrounds the organs. But the latest study involved careful analysis of this so-called coelomic fluid, and found the pathogenic bacteria Vibrio pectenicida. 1:57 The death of sea stars triggered a cascade of effects through coastal ecosystems. Without predators like sunflower sea stars, which eat almost everything on the seabed, sea urchin populations exploded. In Northern California, this has led to the destruction of roughly 95% of kelp forests over the past decade - important underwater habitats often described as the "rainforests of the ocean". Scientists hope their discovery could help with work to save sea stars. Researchers are investigating whether to relocate the animals, or breed them in captivity to later transport them to areas that have lost most of the population. They can also test whether treatments like probiotics could boost immunity to the disease.
The Independent
04-08-2025
- Health
- The Independent
Scientists believe they have solved the mystery of what killed more than 5 billion sea stars
Scientists have finally unravelled the decade-long mystery behind the devastating epidemic that has killed more than five billion sea stars off the Pacific coast of North America. The breakthrough identifies a specific bacterium as the culprit, offering a crucial step towards saving the iconic marine creatures. Since 2013, a mysterious sea star wasting disease has caused a mass die-off from Mexico to Alaska, affecting over 20 species and continuing its destructive path today. The sunflower sea star was particularly hard hit, losing approximately 90 per cent of its population within the first five years of the outbreak. "It's really quite gruesome," said marine disease ecologist Alyssa Gehman at the Hakai Institute in British Columbia, Canada, who contributed to pinpointing the cause. She described how healthy sea stars typically have "puffy arms sticking straight out," but the disease causes them to develop lesions before "their arms actually fall off." The long-sought answer, published in the journal Nature Ecology and Evolution, points to a bacterium that has also been found to infect shellfish. The findings "solve a long-standing question about a very serious disease in the ocean," commented Rebecca Vega Thurber, a marine microbiologist at the University of California, Santa Barbara, who was not involved in the study. Identifying the cause proved to be a complex, decade-long endeavour, fraught with false leads. Early research mistakenly focused on a densovirus, which was later found to be a normal resident within healthy sea stars, not linked to the disease, according to Melanie Prentice of the Hakai Institute, a co-author of the new study. Previous attempts also failed because researchers studied tissue samples from dead sea stars that no longer contained the vital bodily fluid surrounding their organs. The latest study, however, meticulously analysed this fluid, known as coelomic fluid, where the bacterium Vibrio pectenicida was ultimately discovered. Microbiologist Blake Ushijima of the University of North Carolina, Wilmington, who was not involved in the research, praised the team's "really smart and significant" detective work, noting the immense difficulty in tracing environmental disease sources, especially underwater. Scientists say they have solved the mystery of what killed more than 5 billion sea stars Show all 5 With the cause now identified, scientists are better positioned to intervene. Ms Prentice suggested that researchers could now test the remaining sea stars for health, considering relocation or captive breeding programmes to reintroduce them to areas where sunflower sea stars have been decimated. They may also investigate if certain populations possess natural immunity or if treatments like probiotics could boost resistance to the disease. The recovery of sea star populations is not merely about saving a single species; it is vital for the entire Pacific ecosystem. Healthy sea stars play a crucial role in controlling sea urchin populations. "They're voracious eaters," Ms Gehman explained about the Sunflower sea stars, despite their seemingly innocent appearance, as they consume almost everything on the ocean floor. The dramatic decline in sea stars led to an explosion in sea urchin numbers, which in turn devoured approximately 95 per cent of Northern California 's kelp forests within a decade. These kelp forests are critical habitats, providing food and shelter for a diverse array of marine life, including fish, sea otters, and seals. Researchers are hopeful that these new findings will enable them to restore sea star populations and, consequently, regrow the kelp forests that Ms Thurber aptly compares to "the rainforests of the ocean." ___ The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
CBS News
04-08-2025
- Health
- CBS News
Billions of starfish have died in a decade-long epidemic. Scientists say they now know why.
Scientists say they have at last solved the mystery of what killed more than 5 billion sea stars – often known as starfish – off the Pacific coast of North America in a decade-long epidemic. Starting in 2013, a mysterious sea star wasting disease sparked a mass die-off from Mexico to Alaska. The epidemic has devastated more than 20 species and continues today. Worst hit was a species called the sunflower sea star, which lost around 90% of its population in the outbreak's first five years. "It's really quite gruesome," said marine disease ecologist Alyssa Gehman at the Hakai Institute in British Columbia, Canada, who helped pinpoint the cause. Healthy sea stars have "puffy arms sticking straight out," she said. But the wasting disease causes them to grow lesions and "then their arms actually fall off." The culprit? Bacteria that has also infected shellfish, according to a study published Monday in the journal Nature Ecology and Evolution. The findings "solve a long-standing question about a very serious disease in the ocean," said Rebecca Vega Thurber, a marine microbiologist at University of California, Santa Barbara, who was not involved in the study. Sea stars typically have five arms and some species sport up to 24 arms. They range in color from solid orange to tapestries of orange, purple, brown and green. "Symptoms of sea star wasting syndrome include abnormally twisted arms, white lesions, deflation of arms and body, arm loss, and body disintegration," the National Park Service says. "They die over the course of days or weeks." It took more than a decade for researchers to identify the cause of the disease, with many false leads and twists and turns along the way. Early research hinted the cause might be a virus, but it turned out the densovirus that scientists initially focused on was actually a normal resident inside healthy sea stars and not associated with disease, said Melanie Prentice of the Hakai Institute, co-author of the new study. Other efforts missed the real killer because researchers studied tissue samples of dead sea stars that no longer contained the bodily fluid that surrounds the organs. But the latest study includes detailed analysis of this fluid, called coelomic fluid, where the bacteria Vibrio pectenicida were found. "It's incredibly difficult to trace the source of so many environmental diseases, especially underwater," said microbiologist Blake Ushijima of the University of North Carolina, Wilmington, who was not involved in the research. He said the detective work by this team was "really smart and significant." Now that scientists know the cause, they have a better shot at intervening to help sea stars. The International Union for Conservation of Nature has listed the sunflower sea star as critically endangered. Prentice said that scientists could potentially now test which of the remaining sea stars are still healthy — and consider whether to relocate them, or breed them in captivity to later transplant them to areas that have lost almost all their sunflower sea stars. Scientists may also test if some populations have natural immunity, and if treatments like probiotics may help boost immunity to the disease. Such recovery work is not only important for sea stars, but for entire Pacific ecosystems because healthy starfish gobble up excess sea urchins, researchers say. Sunflower sea stars "look sort of innocent when you see them, but they eat almost everything that lives on the bottom of the ocean," said Gehman. "They're voracious eaters." With many fewer sea stars, the sea urchins that they usually munch on exploded in population — and in turn gobbled up around 95% of the kelp forest s in Northern California within a decade. These kelp forests provide food and habitat for a wide variety of animals including fish, sea otters and seals. Researchers hope the new findings will allow them to restore sea star populations — and regrow the kelp forests that Thurber compares to "the rainforests of the ocean."
Globe and Mail
04-08-2025
- Health
- 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.'
