mermaidskey:todropscience:Ocean acidification leads to “unprecedented” evolutionary change in import

mermaidskey:todropscience:Ocean acidification leads to “unprecedented” evolutionary change in important marine bacteriaMany people are aware that anthropogenic greenhouse gasses are causing average global temperatures to rise. Fewer people are as aware of ocean acidification, the result of the oceans absorbing greenhouse gasses from the atmosphere. Marine researchers have identified many problems resulting from this dangerous phenomenon: marine organisms’ protective shells dissolve, coral reefs cannot grow, and fish cannot find their food or evade predators. Researchers from the University of Southern California and the Woods Hole Oceanographic Institution have discovered an additional, and potentially very dangerous, consequence of ocean acidification: a key marine bacteria, called Trichodesmium, undergoes an apparently irreversible evolutionary change that could cause huge sections of the marine food web to collapse.Trichodesmium, called “Tricho” for short, plays an extremely important role in the marine food web by “fixing” nitrogen gas – that is, making nitrogen available for other organisms to consume. All life needs nitrogen to grow, so nitrogen fixation is something that the marine food web cannot do without. Tricho itself depends on carbon dioxide to grow, and produces more nitrogen the more carbon it consumes.Because ocean acidification leads to more carbon in the oceans, researchers have studied the effects of acidification on many marine microorganisms and have found that marine cyanobacteria (including Tricho) will likely produce a great deal more nitrogen as the oceans become more acidic over time, which will cause huge changes to the global nitrogen cycle. Until now, most research on this topic has focused only on the short-term effects of acidification.USC and WHOI researchers decided to look into ocean acidifications’ long-term impact on Tricho. They grew six different lines of Trichodesmium erythraeum for almost five years to examine how the bacteria would react to changing acidity levels. Importantly, they also examined how these bacteria would react when returned to normal acidity levels.The Tricho lines did, as expected, consume more and more carbon and generate more and more nitrogen. When taken out of the high-acidity environments and placed back in normal conditions, however, the overconsumption of carbon and overproduction of nitrogen did not stop. Most unexpectedly, overconsumption and overproduction did not stop even in future generations of the bacteria. The lines had lost their ability to regulate their own growth – an evolutionary change that the study’s authors say they have never seen before.This means that, even if carbon levels in the ocean return to lower levels as the result of conservation movements or smarter energy policies, Tricho may not be able to return to its usual levels of carbon consumption. This would cause Tricho populations to burn through all their resources too quickly and then die of starvation, which will in turn lead to mass die-offs of the many species that depend on Tricho.The team has begun looking through Tricho’s DNA – which was recently discovered to inexplicably feature elements normally seen only in higher life forms – to understand why this irreversible evolutionary change occurs. These findings point to an increasingly urgent need to understand how climate change will impact marine microorganisms and the critical roles they play in the marine food web.Based on materials originally provided by the University of Southern CaliforniaImage credit: Abby Heithoff, MIT / WHOIJournal reference: David A. Hutchins, Nathan G. Walworth, Eric A. Webb, Mak A. Saito, Dawn Moran, Matthew R. McIlvin, Jasmine Gale, Fei-Xue Fu.Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide. Nature Communications, 2015; 6: 8155 DOI: 10.1038/ncomms9155Submitted by volk-moryaNot to mention that ocean acidification will probably make all the coccolithophores melt. WILL NO ONE THINK OF THE PLANKTON? -- source link

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