Recent oceanographic research is challenging a central principle that has been the basis of scientists’ understanding of ocean productivity in the surface ocean for over 75 years, including the amount of carbon dioxide that may be consumed by marine plankton.

Bigelow Laboratory Senior Research Scientist Dr. Mike Lomas is a co-author of a new study published online in “Nature Geoscience” last week (Martiny, A.C., Pham, C., Primeau, F., Vrugt, J., Levin, S., Lomas, M.W. 2013. Strong latitudinal patterns in elemental composition of marine plankton and organic matter. “Nature Geoscience.” DOI: 10.1038/NGEO1757).

This study shows that the elemental ratios of marine plankton and organic matter exhibit a clear latitudinal trend, with large spatial differences and a global average that can vary substantially from a standard formula, known as the Redfield Ratio, that has traditionally described the relative proportions of carbon, nitrogen, and phosphorus in plankton.

A research team including scientists from the University of California-Irvine, Princeton University, and Bigelow Laboratory collected and analyzed the chemical composition of marine plankton from thousands of ocean samples across the globe, including the waters of the North Atlantic, the Caribbean, and the Bering Sea.

The team, whose work was funded by the National Science Foundation, found that the chemical composition in marine plankton communities was significantly influenced by latitude and temperature, and related to changes in the abundance of different plankton groups.

According to the paper’s lead author Dr. Adam Martiny, Associate Professor of Earth System Science and Ecology and Evolutionary Biology at University of California-Irvine, "The Redfield Concept remains a central tenet in ocean biology and chemistry,” but the team’s research shows that elemental ratios in plankton follow a strong latitudinal pattern that differs from the Redfield Ratio.

These findings suggest that the coupling between oceanic carbon, nitrogen, and phosphorus cycles via plankton varies systematically by ecosystem, “with subtropical and tropical ecosystems, regions hypothesized to expand in a future ocean and dominated by smaller plankton, potentially taking up more carbon dioxide than previously thought,” said Lomas.