About the project
Phytoplankton primary production (PhytoPP) underpins the marine foodweb and is a key component of the oceanic carbon cycle. This project will investigate the variable coupling of photosynthetic electron transport estimated using active chlorophyll fluorescence techniques, with carbon fixation, in order to facilitate autonomous wide spatio-temporal scale measurements of the latter.
Measurement of PhytoPP has enormous potential for developing our understanding of ocean productivity and validation of biogeochemical models. Historically, direct measurement of PhytoPP has been dominated by incubation-based measurement of 14C assimilation over several hours. However, as this method cannot be directly applied on meaningful spatial and temporal scales, there is extreme undersampling of the oceanic productivity.
A long-term collaboration between Chelsea Technologies Ltd and the University of Southampton has led to the development of a new generation of Single Turnover Active chlorophyll Fluorometer (STAF) systems for the assessment of photosynthetic electron transport. However the coupling of electron transport to carbon fixation is variable as a result of multiple physiological, ecological and associated environmental drivers.
This PhD project aims to undertake a comprehensive assessment of the potential for STAF to accurately estimate carbon fixation and investigate drivers of variability in electron to carbon coupling. Measurements with phytoplankton cultures grown under defined conditions in the laboratory, including variability in light and nutrients, will be combined with similar measurements on natural phytoplankton communities in the field, including the opportunity to go to sea in the Southern Ocean.
You will be trained in the use of active chlorophyll fluorometry for the assessment of phytoplankton physiology and electron transport, and the use of radiotracer techniques for microbial rate measurements. Additionally, you'll be trained in multi-variate data analysis techniques, supporting the development of a mechanistic understanding of variability in electron transport coupling to carbon fixation in the oceans.