Diel cycle in lipids and carbohydrates is central to global marine metabolism

Every day, phytoplankton in the ocean fix carbon dioxide into energy storage molecules like carbohydrates and lipids, then respire most of that carbon back to carbon dioxide at night, making up the central metabolism of the global ocean. However, the magnitude of the oscillation of these energy storage pools is not well constrained. Using a combination of mass spectrometry and ion chromatography, we quantified the contribution of lipids and carbohydrates to total particulate organic matter over a diel cycle in the euphotic zone in four diverse oceanographic locations—the oligotrophic North Pacific Subtropical Gyre and Sargasso Sea, the coastal Pacific near Oregon, and the Gulf of Maine. Microbial communities in these locations exhibit a dynamic daily cycle in both lipids and carbohydrates—both reservoirs reach maxima at sunset and decline to minima by sunrise—and the magnitude of this oscillation accounts for as much as 75% of daily primary production. Differences in this cycle emerge between sampling location, influenced by light level, photic zone depth, day length, and microbial community composition. The timing and magnitude of the oscillation has implications for the structure and lability of marine organic matter at global scales, as the size of these pools relative to total particulate organic matter fundamentally changes the macromolecular composition of carbon in the surface ocean throughout each day.

Presentation Preference: Oral

Primary Presenter: Daniel Lowenstein, MIT/WHOI Joint Program in Chemical Oceanography (patton.lowenstein@gmail.com)

Authors:

Daniel Lowenstein, Massachusetts Institute of Technology - Woods Hole Oceanographic Institution - Joint Program in Oceanography  (patton.lowenstein@gmail.com)

Benjamin Van Mooy, Woods Hole Oceanographic Institution  (bvanmooy@whoi.edu)

Sallie Chisholm, Massachusetts Institute of Technology  (chisholm@mit.edu)

Allison Coe, Massachusetts Institute of Technology  (a_coe@mit.edu)

Helen Fredricks, Woods Hole Oceanographic Institution  (hfredricks@whoi.edu)