New marine ecology tool corrects effects of fossil fuel emissions

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While much about the lives of ancient animals remains a mystery, paleoecologists are able to learn much about the food webs that existed thousands of years ago by studying the carbon isotopes found in bones and animal teeth.

But the continued burning of fossil fuels by mankind has made this analysis of carbon isotopes tricky. By burning fossil fuels, said Casey Clark, a marine biologist with the Washington Department of Fisheries and Wildlife, humans are actually changing the isotopic signature of the atmosphere and, subsequently, the oceans.

This human-induced change is called the Suess effect, named after the physical chemist Hans Suess, who first noted this effect in work published in 1955. Scientists must take this effect into account. they want to analyze old isotopes with precision. But, said Clark, there isn’t necessarily a lot of agreement on how best to perform this correction, and different techniques can be used in different subdomains, which can make it difficult to compare the results of different. studies.

That’s why Clark and a team of researchers from the University of Alaska Fairbanks, University of Washington, University of Minnesota, and Idaho State University collaborated to create SuessR, a free, customizable tool. which will allow researchers to easily and consistently make specific corrections for the Suess effect. An article presenting the new tool was published earlier this year in the journal Methods in ecology and evolution.

Eric Guiry, a biomolecular archaeologist at the University of Leicester, said the tool could make data analysis easier for many scientists. “What I find interesting about the program is that it should be a user-friendly way of doing [the Suess correction], which was a bit of a hindrance. I think there is a pretty steep learning curve if you want to do a more nuanced and precise Suess correction for your data. So in the past a lot of people had sort of a one-size-fits-all approach.… Doing something that is more tailor-made for your area and aware of the types of complications you should be dealing with takes a fair bit of effort and knowledge. basic, so it should help people overcome this barrier.

Modern ecology

Clark explained that correcting the Suess effect is becoming increasingly important in ecological research, in addition to paleoecological research, where it is more widely used. This is because the magnitude of the Suess effect increases exponentially over time. While the change in the magnitude of the Suess effect may have been undetectable for a 10-year data set collected in the 1970s, this is no longer the case. Clark and the research team found measurable differences in the magnitude of the Suess effect when comparing data over a period of only 8 years in a recent data set.

Clark said that being able to correctly correct the Suess effect has major implications for how we understand what’s going on in our oceans today. For example, he said there had been a long-term decline in carbon isotope ratios in some marine systems, but there had been some disagreement on how those drops should be interpreted.

“One of the conclusions drawn, particularly for the Bering Sea and the North Pacific, is that a long-term decline in carbon isotope ratios is in fact indicative of a decline in primary production,” he said. -he declares. “Some people said it was an indication that the ocean as a whole is becoming less productive here. And that has huge implications – for how many salmon we can expect to see in the future and what food web structures will look like and how much food will there be to feed those systems. “

However, after re-analyzing these datasets, Clark said that it appears that a substantial amount of this drop in carbon isotope ratios is in fact due to the Suess effect and that primary productivity is unlikely to decrease. as much as some have suggested. The Suess Effect is therefore not just an abstract concept, but a key part of our understanding as we try to answer important questions about food conservation and production.

Future directions

Clark does not consider the current iteration of SuessR to be the final version of the tool. Instead, he hopes it becomes a project shared by the scientific community, with many people from all over the world contributing data and suggestions for improvement.

SuessR currently includes built-in corrections for four regions in the North Atlantic and North Pacific, but Clark wants to add more, as the Suess effect can vary somewhat from region to region, especially at different latitudes.

—Hannah Thomasy (@HannahThomasy), science writer



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