Science & Technology

New research delves into the fate of marine carbon

This study investigates how marine bacteria adapt to consume the carbon produced by two major types of photosynthetic phytoplankton (diatoms and cyanobacteria) in the ocean. This affects our understanding of carbon sequestration in the ocean now and in the future. Credit: Michelle Zatcoff

Marine-dissolved organic matter from phytoplankton retains the same amount of carbon as the Earth’s atmosphere, but the biological processes that govern its fate are primarily under ideal laboratory conditions or genomic sequencing. It is studied through indirect means such as.

In a new study by scientists and collaborators at Lawrence Livermore National Laboratory (LLNL) at Oregon State University and Oak Ridge National Laboratory, the team uses relatively new technology to supply two major marine organic carbon supplies. We directly quantified the uptake of complex carbon pools from the source (diatoms and cyanobacteria from natural microbial communities).Works will be displayed in Minutes of the National Academy of Sciences.

This study is an important step in finally predicting how much carbon will eventually leave the ocean and be released into the atmosphere and how much will be buried in marine sediments.

“We provide functional insights into microbial activity during marine phytoplankton outbreaks,” said Xavier Mayali, a scientist and co-author of the study at LLNL.

“According to our research, different types of microbes in the ocean are very specific, but predictable in food sources that prefer to consume,” said Ryan, an associate professor and research leader in the Faculty of Microbiology at OSU. Mueller says. “As global climate change continues to change the marine environment rapidly, the availability of microbial food sources also changes, ultimately prioritizing certain species over others.”

Phytoplankton is a microorganism that underlies the marine food chain and is an important component of important biological carbon pumps. Most of them float in the upper part of the sea, and sunlight can easily reach them.

Small plants have a significant effect on the level of carbon dioxide in the atmosphere by sucking it up during photosynthesis. It is a natural sink and one of the main ways to remove CO2, the most abundant greenhouse gas, from the atmosphere. Since the dawn of the industrial era, atmospheric CO2 has increased by 40%, contributing significantly to global warming.

The surface ocean stores about the same amount of carbon in the atmosphere as carbon dioxide. When the ocean draws in atmospheric carbon dioxide, phytoplankton uses CO2 and sunlight for photosynthesis. These are converted into sugars that cells can use as energy and produce oxygen in the process. This carbon is ultimately used by other microbes and higher organisms in the marine food web, where it can eventually be converted to atmospheric CO2 by respiration or, when dead, sink to the bottom of the ocean.

The team used stable isotope labeling to track carbon when it invaded the organic matter produced by phytoplankton, and ultimately the microorganisms that consumed it.

The team used these isotopes to find out which organisms eat diatoms and which organisms consume cyanobacteria. Researchers were also able to find out when consumption occurred. For example, when phytoplankton cells are slowly excreting carbon (through a process called leaching) or when they rupture and open (a process called cytolysis).

“Our findings show how marine microbes and photosynthetic algae work to affect the global carbon cycle, and how this marine food network responds to continuous environmental changes. It has important implications for understanding, “says Brandon Keeft, now a Mueller graduate student at the University of British Columbia. .. “This helps us predict how much carbon will return to the atmosphere and how much will be buried in seafloor sediments for centuries.”

See: “Phytoplankton exudates and lysates support a separate microbial consortium with special metabolic and ecophysiological properties,” Brandon Kieft, Zhou Li, Samuel Bryson, Robert L. Hettich, Chongle Pan, Xavier Mayali, Ryan S. Mueller, October 7, 2021 Minutes of the National Academy of Sciences..
DOI: 10.1073 / pnas.2101178118
This study was funded by the Gordon and Betty Moore Foundation Marine Biology Initiative.

New research delves into the fate of marine carbon New research delves into the fate of marine carbon

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