Diversity-informed carbon conversion factors for open-ocean phytoplankton

Phytoplankton are integral to the ocean's carbon cycling, and the fate of their fixed carbon has implications for atmospheric carbon dioxide levels. Here, we examined phytoplankton communities in the Bay of Bengal to identify key ecotypes of Prochlorococcus, Synechococcus, and photosynthetic eukaryotes using analysis of V1-V2 16S rRNA gene amplicons. We compared these communities at the ASV level to those collected from the Bermuda Atlantic Time-series Study (BATS) site in order to delineate ecotypes spanning tropical and subtropical regions. For a subset of samples, we used V1-V2 16S rRNA gene amplicon-based taxonomy to refine estimations of carbon per-cell and overall carbon contributions derived from flow cytometry bulk cell abundances. Estimates of phytoplakton carbon content are important to understanding carbon flow through the marine food web. While it is common practice to assign one carbon value to all cells in a broad category (e.g, picophytoplankton), this approach can mask relevant nuances in carbon content. Our analyses collectively provided deeper insights into both the diversity and carbon contributions of Prochlorococcus, Synechococcus, and photosynthetic eukaryotes including prasinophytes, pelagophytes, prymnesiophytes, and diatoms. The results should improve estimates of biomass from photosynthetic communities under current conditions and aid future modelling work.

Presentation Preference: Either

Primary Presenter: Charlotte Eckmann, Marine Biological Laboratory (caeckmann@gmail.com)

Authors:

Huiwen Deng, School of Marine Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China  (denghw6@mail2.sysu.edu.cn)

Camille Poirier, Department of Biology, University of Oxford  (camille.poirier@biology.ox.ac.uk)

Fabian Wittmers, Marine Biological Laboratory  (fwittmers@mbl.edu)

Rachele Spezzano, University of Chicago  (rspeuchicago@gmail.com)

Jonathan Grone, Center for Space and Habitability, University of Bern  (jonathan.grone@unibe.ch)

Amala Mahadevan, Woods Hole Oceanographic Institution  (amala@whoi.edu)

Rachel Parsons, Bermuda Institute of Ocean Sciences  (rparso11@bios.asu.edu)

Craig Carlson, Ecology, Evolution, and Marine Biology, Univesity of California Santa Barbara  (craig_carlson@ucsb.edu)

Alexandra Worden, Marine Biological Laboratory  (azworden@mbl.edu)