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Huge crater discovered in Greenland ice sheet

Huge crater discovered in Greenland ice sheet

Yahoo5 days ago
A massive flood that breached the Greenland ice sheet in 2014 created a huge crater that is now being researched, the European Space Agency (ESA) announced on Wednesday.
Approximately 90 million cubic metres of water from an underground lake are said to have shot out of the ground within 10 days, which roughly corresponds to the volume of water that flows over Niagara Falls in nine hours.
The ESA referred to the findings of an international research team, which have now been published in the journal Nature Geoscience.
Satellite data, including from the ESA, were studied under the leadership of scientists from Lancaster University and the Centre for Polar Observation and Modelling in the United Kingdom.
The water that emerged is meltwater, and its formation could have been encouraged by climate change and the higher temperatures it has caused, the researchers said. The result of the flood is a massive crater - 2 square kilometres in size and 85 metres deep - in the uninhabited north of the island.
Researchers could hardly believe the results
In addition to the sudden water outflow, the researchers documented significant damage to the ice sheet: Ice blocks up to 25 metres high were torn out, deep cracks ran through the ice, and the surface was eroded by the force of the water.
The region was previously considered frozen according to existing models, where water rising through the ice was deemed hardly possible.
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Billions of starfish have died in a decade-long epidemic. Scientists say they now know why.
Billions of starfish have died in a decade-long epidemic. Scientists say they now know why.

CBS News

time4 hours ago

  • 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."

A Mystery Killer Wiped Out Billions of Sea Stars. Biologists Just Solved the Case.
A Mystery Killer Wiped Out Billions of Sea Stars. Biologists Just Solved the Case.

Gizmodo

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A Mystery Killer Wiped Out Billions of Sea Stars. Biologists Just Solved the Case.

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After a decade of death, Canadian scientists say they've found the sea star killer
After a decade of death, Canadian scientists say they've found the sea star killer

Yahoo

time6 hours ago

  • Yahoo

After a decade of death, Canadian scientists say they've found the sea star killer

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."

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