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Oceans are still sucking up carbon – Maybe more than we thought – Flooding because of that?


From EOS under CC . license HT / Tom BOOM

Recent studies of carbon sequestration bacteria show that we still have a lot to learn about the ocean’s biological carbon pump.

Via Nancy Averett May 3, 2022

A newly discovered marine microorganism has a “mucosphere” that chemically traps other microorganisms and their nutrients — including carbon. Credit: Nature Communications, CC BY 4.0

The ocean plays an important role in carbon sequestration. Phytoplankton, living on warm, well-lit surfaces, suck carbon dioxide out of the atmosphere for food. They also need nutrients like phosphorus and nitrogen from colder, heavier, saltier water come alive into warmer layers. When the phytoplankton die, they sink, carrying some of the carbon and other nutrients they’ve consumed back into the ocean depths.

The key to this circular process, known as the ocean bio carbon pump, is the longitudinal mixing of surface and deeper layers of water, occurring through mechanisms such as currents, winds, and tides. However, because higher ocean temperatures cause greater stratification of these layers, traditional scientific models have long predicted that as the planet warms, this process will be disrupted. Plankton would not be able to grow and the ocean would sequester less carbon.

Now, two studies have shown the limitation of such models. One piece of evidence suggests that phytoplankton can become more efficient as the oceans warm. Another report reports the discovery of a new, widely distributed ocean microbial species that also has the potential to sequester carbon.

“We normally view the ocean carbon cycle’s response to global warming as an on-off switch, but these results suggest it’s a dimmer and has some flexibility. active for self-care”. Mike Lomasa senior research scientist at the Bigelow Laboratory for Ocean Science in Maine and lead author of the first study, published in Nature Communications.

Better methods on the horizon

Lomas and his colleagues analyzed 30 years of data of the Sargasso Sea through Bermuda Atlantic time series study, in which scientists have been sampling the ocean every month since 1988 to examine nutrients, carbon, salinity, temperature, and other properties of ocean water. Lomas and his co-authors found that even when fewer nutrients come up from the depths of the ocean, phytoplankton are still taking carbon from the atmosphere. They suggest that one reason for this phenomenon may be that the distribution of phytoplankton favors species that need fewer nutrients from the depths of the ocean.

Some species “can actually continue to fix carbon at present rates 2 or 3 times higher than the Redfield rate, basically they can still absorb carbon dioxide, even if it’s there.” [are] reduce nitrogen and phosphorus input. ”

One of the key points of the paper, says Lomas, is the idea that the ratio of carbon to nitrogen and phosphorus in phytoplankton (called Redfield ratio) used by traditional climate change models may not apply to certain phytoplankton species. Some species, says Lomas, “can actually continue to fix carbon at a rate that’s currently two or three times higher than the Redfield rate, basically, they can still absorb carbon dioxide, even when in there [are] the input of nitrogen and phosphorus decreases because the ratio they combine them is much higher. “

Steven Emerson, professor emeritus of chemical oceanography at the University of Washington, who was not involved in the study, said the data collection from the Bermuda Atlantic Time Series Study was remarkable and important. However, he said, the station uses an older technique called sediment trapping to measure carbon particle flow (the rate at which carbon sinks into the deep ocean). “This particular method (sediment trapping) makes no sense in determining this flow when you compare it with other methods,” says Emerson.

There are newer, more reliable methods for measuring the flow of ocean carbon particles, says Emerson, that use high-powered optical instruments that are mounted on buoys and can measure particles with high precision. Sensitivity higher than regular every 5 days. “Soon to be across the ocean,” he said. “And them and the data from [them] going to check if this sediment trapping flux (in the Lomas paper) is indeed correct.… So, you know, to be continued. ”

Traps new marine bacteria its prey

“It takes this straw-like appendage and sucks up the insides of the bacteria it gets trapped in. And then it allows the whole thing. ”

In another study, also published in Nature Communications, Martina Doblinan oceanographer from the University of Technology Sydney in Australia, and colleagues described a species of marine microorganism called Prorocentrum cf. balticum. This species is a mixed organism, which means it can perform photosynthesis like phytoplankton but can also consume other microorganisms, which allows it to live in the deeper layers of the ocean. . More, Prorocentrum cf. balticum uses the carbon it obtains from photosynthesis to build a structure out of mucus, which the researchers call a “mucosphere,” which chemically attracts and traps other bacteria, some Prorocentrum cf. balticum then consume.

“It takes this straw-like appendage and sucks up the insides of the bacteria it’s trapped in,” Doblin said. “And then it allows the whole thing.” Inside the mucous membrane, she says, is a variety of microorganisms (including carbon), and because the mucous membrane “floats negatively” it sinks.

The unique mucospheres of Prorocentrum cf. balticum could allow it to transport carbon to the deep ocean. Credit: Nature Communications, CC BY 4.0. Click image to view larger image.

Doblin said the study started with the premise that if the ocean becomes increasingly more unpredictable, it could favor mixed organisms. She and her team took a sample of ocean water from an oceanographic station 30 kilometers southeast of Sydney. Michaela Larssona postdoc in Doblin’s lab, then put the sample in low light so any bacteria would need more than photosynthesis to survive.

A week later, Doblin said, Larsson noticed that they were full of creatures, and she started feeding them different foods and exposing them to different light conditions. The team matched the organism’s DNA with samples from Tara’s Ocean project, in which an interdisciplinary team of scientists traveled around the world and sampled ocean microorganisms at 210 different locations.

Having access to those data, says Doblin, allows her team to demonstrate that their findings are crucial. “It allowed us to really confirm that this organism is indeed quite abundant and widely distributed.”

—Nancy Averett (@nancyaverett), Science Writer

Quote: Averett, N. (2022), The oceans are still sucking up carbon — maybe more than we think, Eos, 103, https://doi.org/10.1029/2022EO220220. Published on May 3, 2022.
Text © 2022. Authors. CC BY-NC-ND 3.0
Unless otherwise noted, images are copyrighted. Any reuse without the express permission of the copyright owner is prohibited.





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