Primary production dynamics during the decline phase of the North Atlantic annual spring bloom
Meredith Meyer, University of North Carolina, mgmeyer9@email.unc.edu (Presenter)
Melanie Cohn, University of North Carolina at Chapel Hill, mcohn@live.unc.edu
Nicola Paul, University of California Santa Barbara, nicolapaul@umail.ucsb.edu
Mark Brzezinksi, University of California Santa Barbara, markbrzezinski@ucsb.edu
Sasha Jane Kramer, MBARI, sjkramer@ucsb.edu
Sharpe Garrett, University of North Carolina at Chapel Hill, gcs@email.unc.edu
Niebergall Alexandria, Duke University, alexandria.niebergall@duke.edu
Scott Gifford, University of North Carolina at Chapel Hill, sgifford@email.unc.edu
Nicolas Cassar, Duke University, nicolas.cassar@duke.edu
Adrian Marchetti, University of North Carolina at Chapel Hill, amarchetti@unc.edu
The second field campaign of the NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) program was conducted in the late spring of 2021 within the vicinity of the Porcupine Abyssal Plain (49.0ºN, 16.5ºW) in the North Atlantic Ocean. Observations collected support previous characterization of this system as highly productive and rich in organic matter with the majority of primary production occurring in large cells (? 5 µm) such as diatoms that are primarily utilizing nitrate. Daily rates of total euphotic zone depth-integrated net primary production ranged from 36.4 to 146.6 mmol C m-2 d-1 with a cruise wide average f-ratio of 0.74, indicating predominantly new production. Substantial variability in the contribution of small (<5 µm) and large cells occurred over the observation period, coinciding with the end of the annual North Atlantic spring phytoplankton bloom. Changes to the mixed layer caused by storms appear to have impacted the integrated production rates substantially, enhancing them by ~10%, and changing the balance between contributions of the different phytoplankton size fractions, and thus reiterating the important role mixed layer variability plays in nutrient entrainment into the upper water column and production-export dynamics. This second field campaign serves as the high productivity endmember within the EXPORTS research program and as such, elucidates the relative importance of a differing suite of controls on primary production dynamics than was observed in the low productivity endmember system in the Northeast Pacific during the 2018 field campaign. Our results highlight the critical role that nutrient concentrations and a turbulent physical environment play in controlling primary production and phytoplankton community composition during bloom decline and the associated carbon export dynamics.
Poster: Poster_Meyer_3-30_83_35.pdf
Poster Location ID: 3-30
Presentation Type: Poster
Session: Poster Session 3
Session Date: Thu (May 11) 3:00-5:00 PM
CCE Program: OBB