The influence of phytoplankton productivity and molecular physiology on biogeochemical dynamics of two contrasting ocean environments

Understanding the controls on oceanic primary production is crucial to elucidating it’s influence on global biogeochemical cycling, ocean health, and climate regulation under current and future climate scenarios. The NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) program aims to investigate and constrain the mechanisms controlling oceanic primary production and the proportion of this fixed carbon that is exported from the surface to the deep ocean (i.e., sequestered on the human time scale). Field campaigns were conducted in summer of 2018 to Ocean Station PAPA in the Subarctic North Pacific and in spring of 2021 to the Porcupine Abyssal Plain in the North Atlantic. These two systems represent the lows and highs of open ocean primary production, foodweb dynamics, and carbon export in the open ocean. My dissertation focuses on these field campaigns by quantifying the rates of primary production, the types of macronutrient utilization associated with this primary production with a particular focus on nitrogen, the environmental controls on primary production, and the physiology of the primary producers (i.e., phytoplankton). I will approach this analysis at multiple levels and uses traditional and novel approaches, ranging from stable isotope incubations, laboratory culture experiments, to metatranscriptomics and statistical probing.

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