![]() ![]() A fossil from Morocco of a Diademaproetus, one of the trilobites that were plentiful in the world’s oceans but went extinct at the end of the Permian.Géry Parent/Flickr Before ongoing volcanic eruptions in Siberia created a greenhouse-gas planet, oceans had temperatures and oxygen levels similar to today’s’. Scientists used a climate model with Earth’s configuration during the Permian, when the land masses were combined in the supercontinent of Pangaea. John/Flickrįirst author Justin Penn, a UW doctoral student in oceanography said, “This is the first time that we have made a mechanistic prediction about what caused the extinction that can be directly tested with the fossil record, which then allows us to make predictions about the causes of extinction in the future.” The fossil is on display at the Idaho Museum of Natural History.James St. The tooth whorl was located inside the shark’s lower jaw. What happens, the group says, may depend on how quickly the disease disappears from the region and how many young sea stars can grow up and start munching on mussels.This fossilized spiraling shark tooth is from the Helicoprion, an unusual shark that lived during the Permian. If sea star wasting disease has similar effects on the Pacific intertidal food web, Menge and his colleagues write, “it would result in losses or large reductions of many species of macrophytes, anemones, limpets, chitons, sea urchins and other organisms from the low intertidal zone.” The sea stars, Paine concluded, were a “ keystone species” that kept the local food web in control. Without the starfish to prey on them, mussels were able to take over. For years, he removed starfish from one area of rock in Makah Bay at the northwestern tip of Washington and left another bit of rock alone as a control. In the 1960s, Robert Paine of the University of Washington performed what is now considered a classic experiment. What those factors are, though, is still a mystery.Īlso unclear is what long-term effects this outbreak will have on Pacific intertidal communities. “Given conflicting results on the role of temperature as a trigger of, it seems most likely that multiple factors interacted in complex ways to cause the outbreak,” they conclude. ![]() Bruce Menge and colleagues at Oregon State University took advantage of their long-term study of Oregon starfish to evaluate what happened to sea stars during the recent epidemic and found that , finds that may not be true for sea stars in Oregon. Studies of California starfish came to a similar conclusion. Warm waters may increase disease progressionĪnd rates of death. Menge et al./PLOS ONE 2016Įarlier this year, scientists studying the outbreak in Washington state reported in the Scientists are still trying to determine what set off an outbreak of this disease along the west coast that started in 2013. had completely fallen apart just four hours later. A sea star that was losing its grip on its rocky home at 6:20 a.m. ![]() ![]() So there must be some other factor at play. But the virus can’t be the only cause of the disease it’s found in both healthy and sick sea stars, and it has been around since at least 1942, the earliest year it has been found in museum specimens. One likely factor is the sea star-associated densovirus, which, in 2014, scientists reported finding in greater abundance in starfish with sea star wasting disease than in healthy sea stars. And they’re getting closer to figuring out just what happened in this latest incident. With the latest outbreak happening over such a large - and well-studied - region and period of time, marine biologists have been able to gather more data on the disease than ever before. These past incidents, though, happened fast and within smaller regions, so scientists had struggled to figure out what had happened. ![]()
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