Project: The biogeography of primary producers in the subpolar North Atlantic

Description from the NSF award abstract:
Diatoms and dinoflagellates are both diverse and biogeochemically significant groups of plankton. The former have fast growth rates, dominate blooms and their mineral silicate components help drive significant export. The latter encompass diverse trophic strategies including mixotrophy and play a complex role in the cycling of carbon and nutrients. Current marine ecosystem models typically represent a single diatom "functional type" and do not explicitly reflect dinoflagellates or mixotrophy at all. This project will investigate and model the regional biogeography, seasonal succession, and inter-annual variability of the assemblages of diatoms and dinoflagellates in the subpolar North Atlantic, where the Continuous Plankton Recorder (CPR) survey has documented the abundance of more than 100 species of these organisms over several decades. The PIs will characterize the temporal and spatial variations of diatom and dinoflagellate assemblages and their key traits, including cell size and trophic strategy, in the CPR survey. They will use cluster analysis deduce biogeographic provinces in the subpolar North Atlantic based on the variations in species and trait assemblages of these two key groups of primary producers. To interpret how the interplay of environment and physiology regulates these spatial and temporal trends, they will develop and employ numerical simulations of the supolar North Atlantic which includes an ecosystem component where hundreds of potentially viable microbial physiologies are seeded and "survival of the fittest" in silico organizes ecosystem structure and function. Simulations will be used to seek mechanistic explanations for the previously noted interannual and decadal shifts in diatom and dinoflagellate abundance in the North Atlantic.

Data:
No new empirical data were collected in this project. However, data compilations from the Continuous Plankton Recorder survey, Joint Global Ocean Flux Study, and Atlantic Meridional Transect were analyzed. Sources for these data are as follows:

Data from the Atlantic Meridional Transect (AMT) Consortium (NER/0/5/2001/00680) were provided by the British Oceanographic Data Centre and supported by the Natural Environment Research Council. http://www.bodc.ac.uk/projects/uk/amt/

The JGOFS time-series data were provided by the Data Support Section of the Computational and Information Systems Laboratory at the National Center for Atmospheric Research. NCAR is supported by grants from the National Science Foundation. See:
Kleypas, J., and S. Doney. 2001. JGOFS Biogeochemical Properties in the Ocean Mixed Layer. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. http://rda.ucar.edu/datasets/ds259.0/.

Continuous Plankton Recorder survey data were kindly made available by the Sir Alister Hardy Foundation for Ocean Science. http://www.sahfos.ac.uk/cpr-data/introduction.aspx

Project related web pages and MIT model code:
Information regarding the efforts of this particular project is posted at http://darwinproject.mit.edu/category/research/trait-based-approaches-research/.

The MITgcm ocean model is freely available at http://mitgcm.org.

Publications produced as a result of this research:
Ward, B., S. Dutkiewicz, A.D. Barton and M.J. Follows. "Biophysical aspects of mixotrophic resource acquisition and competition," The American Naturalist, 2011, p.98. doi: 10.1086/660284

Monteiro, F., S. Dutkiewicz and M.J. Follows. "Biogeographical controls on the marine nitrogen fixers," Global Biogeochemical Cycles, v.25, 2011. doi: 10.1029/2010GB003902

Prowe, A.E.F., M. Pahlow, S. Dutkiewicz, M.J. Follows, A. Oschlies. "Top-down control of marine phytoplankton diversity in a global ecosystem model.," Progress in Oceanography, 2011. doi: 10.1016/j.pocean.2011.11.016

Monteiro, FM; Follows, MJ. "On nitrogen fixation and preferential remineralization of phosphorus," GEOPHYSICAL RESEARCH LETTERS, v.39, 2012. doi: 10.1029/2012GL050897

Ward, B.A., A.P. Martin, M. Schartau, A. Oschlies, M.J. Follows, and T.R. Anderson. "When is a biogeochemical model too complex? Objective model reduction for North Atlantic time-series sites," Progress in Oceanography, 2012. doi: 10.1016/j.pocean.2013.06.002

Fiksen, O., M.J. Follows and D. Aksnes. "A mechanistic theory of nutrient uptake from functional traits in microbes.," Limnol. Oceanogr. Reviews., v.58, 2012, p. 193. doi: 10.4319/lo.2013.58.1.0193

Barton, A.D., Z.V. Finkel, B.A. Ward, D.G. Johns and M.J. Follows. "The roles of cell size and trophic strategy in North Atlantic diatom and dinoflagellate communities.," Limnol. Oceanogr.,, v.58, 2013, p. 254. doi: 10.4319/lo.2013.58.1.0254