Phytoplankton are photosynthetic microbes that are responsible for virtually all marine primary productivity. Over most of the surface ocean the availability of nutrients is a primary control on the abundance, activity and types of phytoplankton. In this talk I will briefly introduce the patterns of nutrients identified as limiting productivity; at a global scale these appear to be either fixed nitrogen or iron. I will then focus on experimental results I have collected from recent cruises occupying multiple biogeochemical provinces in the Atlantic Ocean. These new data add complexity to the broad-scale patterns of limitation by either nitrogen or iron; specifically, I will present experimental evidence for nutrient co-limitation. Under conditions of co-limitation the supply of multiple nutrients independently or interactively control phytoplankton productivity. These new findings are important for understanding marine biogeochemistry and microbial ecology in the ocean.
Thomas Browning's interest in oceanography started at the University of Bristol (UK) where during his Master's degree he worked on projects with Prof. Derek Vance and Dr Mark Siddall on ocean and lake chemistry. He then moved to Oxford University for a PhD with Dr. Heather Bouman and Prof. Gideon Henderson working on (micro)nutrient regulation of phytoplankton in the South Atlantic as part of the UK GEOTRACES programme. In 2015 he moved to GEOMAR in Germany as a Marie Curie Fellow and is now a postdoctoral scientist in Eric Achterberg’s research group. He is interested in the controls on phytoplankton in the ocean and mostly uses a combination of observations and experiments at sea, remote sensing, and simple numerical analyses for his research.