Exporting a phytoplankton bloom

Copious amounts of particulate organic matter are produced during the spring phytoplankton bloom in the subpolar North Atlantic. This seminar will discuss and contrast mechanisms that contribute to exporting this carbon to depth. Particulate organic carbon is comprised of a wide spectrum of particle sizes, which play an important role in determining the pathways for export. While large particles sink out of the water column, smaller, non-sinking particles are transported laterally and downward at the edges of eddies. Glider profiles (collected autonomously) of oxygen, backscatter, and chlorophyll obtained a few days after the start of a spring bloom show signatures of surface water intertwined within the eddy field at depth. A numerical ocean model reveals how eddies subduct waters rich in carbon and oxygen during the phase of mixed layer stratification in the spring. The advective export of small particles is compared with the particle sinking flux and found to make a sizable contribution to the export of carbon and oxygen from the high-latitude oceans.

Speaker: Amala Mahadevan, Woods Hole Oceanographic Institution