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Ocean acidification threatens Bering Sea crabs But can they adapt

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first_imgAn adult male red king crab in Bob Foy’s Kodiak laboratory. (Photo by Eric Keto / Alaska’s Energy Desk)Ocean acidification could threaten some of Alaska’s most important fisheries. Researchers warn that populations of red king crab in the Bering Sea – made famous by the show The Deadliest Catch – could collapse by the end of the century.But it’s possible the crabs might be able to evolve and adapt to the changing oceans. The big question is – will they have enough time?Listen nowRobert Foy directs the Alaska Fisheries Science Center’s Kodiak Laboratory. (Photo by Eric Keto / Alaska’s Energy Desk)Biologist Robert Foy reaches into a tank in his Kodiak lab, as about 20 red king crabs move around on the bottom. They are giant. They are spiny. They are kind of terrifying. But not to Foy. He scoops one out by the back leg.“As long as you stay away from the first two, the pincers, you’re just fine,” Foy said.Foy directs the Alaska Fisheries Science Center’s Kodiak Laboratory. His seawater lab is wall-to-wall crabs, in tanks and re-purposed containers: baby tanner crabs no bigger than a quarter and adult king crabs the size of my torso; crabs in tupperware, crabs in laundry baskets, crabs stacked in what Foy calls the “crab condominium.” A tangle of pipes and wires feed seawater into the different tanks, each one carefully calibrated by temperature and pH.This lab offers a peek into the future. The tanks represent the oceans around Alaska decades from now. And Foy says that future is alarming.“The expectation in change in pH over the next five decades in Alaska is fairly dramatic,” Foy said.The change in pH is a measure of how acidic the ocean is becoming. In simple terms, the more carbon dioxide is dissolved in the water, the more acidic it becomes.Ocean acidification is the less-well-understood fellow-traveler to climate change, the other impact of pumping CO2 into the atmosphere. And like climate change, it’s expected to happen faster at high latitudes — like the waters around Alaska — than in the rest of the world.Foy began this work about a decade ago, and his lab has been able to run long-term experiments, over years. It’s some of the first concrete evidence we have of what ocean acidification might mean for marine species.Eggs in a female red king crab. The laboratory studies the impacts of ocean acidification on crabs from the earliest life stages. (Photo by Eric Keto / Alaska’s Energy Desk)And Foy’s first results are discouraging – at least for red king crabs. Under conditions similar to what researchers are eventually predicting for Alaska, pretty much all the young red king crabs died.“If the results in the laboratory are accurate, and there’s no acclimation, you would see stock failure about 100 years from now,” Foy said.That’s in part because it’s harder for many crabs to make and maintain shells in more acidic water: the chemistry isn’t right. But Foy’s team found that a bigger problem may be the sheer energy required for crabs to keep their internal pH right, when the external pH is wrong.In very acidic water, most red king crabs didn’t make it past their early life stages.But some did. And that’s giving researchers like Foy hope. Because if the survivors have some trait, something in their genetic make-up that helps them cope with more acidic waters, it’s possible they could pass that on to their offspring and the species could evolve.But with oceans changing so fast – is there time for that?“That’s the question,” Foy said. “Even if they could acclimate in a short period of time, or even adapt over a longer period of time, what kind of abilities will they have to do that physiologically if it happens over the scale of 50 years? That’s only a handful of generations for a crab species.”Crabs are housed in tanks with varying pH and temperature, to mimic the conditions researchers predict will prevail in Alaska waters decades from now. (Photo by Eric Keto / Alaska’s Energy Desk)This question is something crab fishermen are very aware of.Edward Poulsen is a partner on two Bering Sea crab vessels. He grew up in the industry; he says his dad was one of its pioneers.“It’s one of those things where you don’t want to think about it too much,” Poulsen said. “Because if you think about it too much, it’s pretty depressing.”Poulsen knows the science. So do his fellow vessel-owners. He says everyone is concerned. But the potential problems are far enough in the future, and it’s not clear there’s anything fishermen can do about it.“A lot of us, this is all we know, this is what we do,” Poulsen said. “And now the government’s telling us, ‘Your future might be at risk.’ I think it’s a little bit like you want to put your head in the sand and ignore what could be coming down the path.”Poulsen says fishermen basically have two choices: they can try to diversify their business, and branch out into other fisheries.Or they can hope the crabs adapt.last_img read more

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Gut microbes linked to eye disease

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Countrycenter_img Some microbes that naturally dwell in our intestines might be bad for our eyes, triggering autoimmune uveitis, one of the leading causes of blindness. A new study suggests that certain gut residents produce proteins that enable destructive immune cells to enter the eyes.The idea that gut microbes might promote autoimmune uveitis “has been there in the back of our minds,” says ocular immunologist Andrew Taylor of the Boston University School of Medicine, who wasn’t connected to the research. “This is the first time that it’s been shown that the gut flora seems to be part of the process.”As many as 400,000 people in the United States have autoimmune uveitis, in which T cells—the commanders of the immune system—invade the eye and damage its middle layer. All T cells are triggered by specific molecules called antigens, and for T cells that cause autoimmune uveitis, certain eye proteins are the antigens. Even healthy people carry these T cells, yet they don’t usually swarm the eyes and unleash the disease. That’s because they first have to be triggered by their matching antigen. However, those proteins don’t normally leave the eye. So what could stimulate the T cells? One possible explanation is microbes in the gut. In the new study, immunologist Rachel Caspi of the National Eye Institute in Bethesda, Maryland, and colleagues genetically engineered mice so their T cells recognized one of the same eye proteins targeted in autoimmune uveitis. The rodents developed the disease around the time they were weaned. But dosing the animals with four antibiotics that killed off most of their gut microbes delayed the onset and reduced the severity of the disease. The researchers saw the same effects in so-called germ-free mice, which lack gut bacteria.To test whether gut microbes were stimulating these T cells, Caspi and colleagues added the intestinal contents of the diseased mice to T cell cultures. This gut goop switched on the cells, priming them for eye infiltration. The team wondered whether a protein released by the intestinal microbes was triggering the T cells, so they then added a protein-destroying enzyme to the intestinal mixture. The T cell response was weaker, suggesting they were responding to a protein. In another experiment, the scientists injected T cells from the genetically altered mice into control mice that were not prone to autoimmune uveitis. If these T cells haven’t been exposed to intestinal material, they don’t cause uveitis. But 86% of the animals developed autoimmune uveitis if they received a large dose of T cells that had been exposed to intestinal contents of diseased mice, the researchers report online today in Immunity.The results suggest that certain bacteria in the intestines produce proteins that closely resemble those in the eye—and can switch on some T cells in the intestines. “We can prove that activation is occurring in the gut,” Caspi says. The activated cells then presumably travel to the eyes, which they enter and start to destroy.“It’s a very rigorous approach, and it really adds to our knowledge” about the origins of autoimmune uveitis, says ocular immunologist Russell Read of the University of Alabama, Birmingham, who was not involved in the study. One question researchers now need to answer is why we don’t all have these autoimmune reactions in our retinas, says ocular immunologist James Rosenbaum of the Oregon Health & Science University in Portland. It’s possible, he says, that only some people have the bacteria that stimulate the T cells or that certain genes could leave some individuals vulnerable to the disease.Caspi and colleagues are still trying to find out which gut proteins the T cells recognize and which bacteria produce them. “I don’t want to suggest that popping an antibiotic pill or taking a probiotic is going to be a solution for the disease,” she says. But identifying these molecular mimics of the eye proteins, along with the bacteria that spawn them, could help researchers develop new ways to treat or prevent autoimmune uveitis.last_img read more

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