Natalie Cohen

My research addresses how unicellular eukaryotes (also known as protists) respond to changes in their chemical environment and the resulting implications for biogeochemical nutrient cycling in the ocean. Photosynthetic protists, in particular, play a key role in ocean biogeochemistry by converting atmospheric carbon dioxide into organic carbon, transferring energy to higher trophic levels and exporting organics to the deep ocean. Their growth is dependent on macronutrient (e.g., nitrate, phosphate) and micronutrient availability (e.g., trace metals and vitamins), the concentrations of which may vary due to their physical, biological and geochemical sources and sinks.

An open question in the field of biological oceanography is how naturally-occurring, anthropogenic and climate-induced shifts in micronutrients alter microbial ecosystems and biogeochemical cycles. I examine this over multiple spatial scales ranging from the molecular physiology of individual populations to community metabolism across expanses of the ocean. A combination of interdisciplinary approaches are used, including laboratory culture experiments, oceanographic field surveys, and transcriptomic analyses, enabling an understanding of the metabolic strategies used by protists when acclimating to variations in their geochemical environment.