Tiny Cyanobacteria May Be Key to Ocean Carbon Sequestration

10:03 AM ETDeveloping

Science Desk

In Short: A new study reveals that cyanobacteria, not previously considered efficient, play a larger role in carbon sequestration than larger phytoplankton.

Tiny cyanobacteria, often overlooked in carbon sequestration studies, are now recognized as significant contributors to ocean carbon storage, according to a new study. By analyzing amino acid carbon isotope signatures, researchers found that about two-thirds of the carbon sequestered in the ocean comes from these tiny, often unicellular prokaryotic phytoplankton, rather than from larger eukaryotic microalgae.

The biological carbon pump (BCP), which moves organic carbon from the surface to the deep ocean, is a primary mechanism for long-term carbon sequestration. Cyanobacteria's carbon is less prone to loss during this process due to efficient aggregation and ballasting, which helps reduce microbial degradation and enhances carbon sinking.

This finding challenges previous assumptions that larger phytoplankton are more efficient at exporting carbon to the deep ocean. The study, which used sediment traps in the South China Sea, also shows that the efficiency and origin of carbon collected deeper down do not significantly vary by season.

The implications of this research extend beyond just understanding ocean carbon dynamics. It could lead to revised models of ocean carbon sequestration and provide insights into how the BCP might respond to climate change.

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That carbon often stays there for hundreds or thousands of years, making the BCP a primary source of carbon sequestration in the oceans.
These tiny, often unicellular prokaryotic phytoplankton are so named because of the blue-green color seen when they grow in large colonies.

Sources

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