The biogeography of primary producers in the subpolar North Atlantic

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Intellectual Merit: 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. Broader Impacts: The proposed work is fundamentally interdisciplinary in nature. It fosters international collaborations through the EU/North American BASIN program. The tools developed will have potential applications in models of the global change and the carbon cycle, as well as studies of climate change and microbial evolution rooted in the paleo-record of these two groups. The project involves the development and training of a graduate student and post-doctoral scientist.