Tiny Organism Holds the Key to Ocean Carbon Cycling: Climate Change

Ocean carbon cycling is important to understand as our climate changes and as temperatures warm. Now, scientists have made a breakthrough when it comes to understanding the microscopic underpinnings of carbon cycling in the ocean.

When phytoplankton use carbon dioxide to create new cells, a portion of the material is released into the sea as molecules collectively called "dissolved organic carbon." Most of these molecules are eventually eaten by marine bacteria and then recycled back into the ocean as carbon dioxide as the bacteria exhale. These "recycling" bacteria in particular play a huge role in regulating how much of the planet's carbon dioxide is stored in the oceans.

In order to examine these bacteria a bit more closely, the scientists took a look at a particular bacterium that appears to play an important role in carbon consumption. This bacterium, called Alteromonas, can consume as much dissolved organic carbon as a diverse community of organisms.

"This was a surprising result," said Byron Pedler, one of the researchers, in a news release. "Because this pool of carbon is composed of an extremely diverse set of molecules, we believed that many different microbes with complementary abilities would be required to breakdown this material, but it appears that individual species may be pulling more weight than others when it comes to carbon cycling."

This finding, in particular, is important for understanding carbon cycling. By demonstrating that key species can play a disproportionately large role in the process, the scientists can better understand the function these microbes play in larger questions of climate warming and ocean acidity.

"In order to predict how ecosystems will react when you heat up the planet or acidify the ocean, we first need to understand the mechanisms of everyday carbon cycling-who's involved and how are they doing it?" said Pedler in a news release. "Now that we have this model organism that we know contributes to ocean carbon cycling, and a model experimental system to study the process, we can probe further to understand the biochemical and genetic requirements for the breakdown of this carbon pool in the ocean."

The findings are published in the journal Proceedings of the National Academy of Sciences.