Marine phytoplankton are responsible for half of the photosynthesis on our planet and form the base of the marine food chain. These tiny photosynthetic cells are the conduit through which energy in the form of sunlight enters ocean ecosystems. Seasonal fluctuations in phytoplankton biomass and diversity are intimately linked to the flux of organic carbon out of the surface ocean into the mesopelagic where it can remain locked away for decades to millennia. While it is widely believed that the diversity of marine phytoplankton is crucial in the sinking of organic carbon into the ocean's interior, our understanding of the spatio-temporal variability and photosynthetic properties of key phytoplankton groups remains limited. This limitation arises from our heavy reliance on ship-based measurements that are patchy in both space and time. The launch of NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission in early 2024 will provide global hyperspectral data of ocean colour. The data stream from the PACE mission combined with the rapidly growing number of measurements of light absorption by phytoplankton cells presents us with the opportunity to develop a deeper understanding of how energy across the visible spectrum is processed by the ocean’s microflora and how the composition of phytoplankton communities is shifting in the rapidly changing waters of the subpolar North Atlantic.
This project will consolidate biogeochemical and bio-optical datasets from a region of global importance to the ocean’s carbon cycle: the subpolar North Atlantic. The student will examine the absorptive and photosynthetic characteristics of natural phytoplankton communities that have been collected during UK and international oceanographic campaigns and during two planned research cruises that are scheduled for 2024 as part of NERC’s Bio-Carbon programme (https://bio-carbon.ac.uk).