About the project
Phytoplankton frequently experience scarce supply of multiple nutrients simultaneously in the marine environment, yet mechanisms enabling them to cope with nutrient co-limitation are poorly understood. This project seeks to better understand how a major group of phytoplankton, the diatoms, coordinate physiological adaptations to different nutrient co-limitation scenarios.
Marine phytoplankton play vital roles in regulating global climate, contributing almost half of net primary productivity. Nutrient availability is a major factor limiting phytoplankton growth in marine ecosystems, with evidence highlighting the prevalence of nutrient co-limitation, where two or more nutrients restrict phytoplankton growth simultaneously (Browning and Moore, 2023).
Despite the environmental significance of nutrient co-limitation, investigations have focused primarily on how phytoplankton cope with single nutrient limitations. Understanding of how multiple nutrient stressors shape phytoplankton eco-physiology lags far behind.
This project builds on recent work investigating how globally abundant phytoplankton, the diatoms, respond to co-limitation by nitrogen (N) and phosphorus (P). We have identified that N/P colimitation causes distinct physiological adaptations to those observed under N or P limitation alone. These findings have important implications to the use of biomarkers to accurately diagnose nutrient limitation in the field. Our evidence that N availability exerts dynamic control of P metabolism, suggests that diatoms have regulatory machinery to prioritize resource use when nutrients are scarce.
Combining molecular biology, physiology and environmental research this project will:
- Identify diatom regulatory mechanisms for coping with N/P co-limitation, mining existing proteomics datasets.
- Examine signature N and P limitation responses in natural phytoplankton populations across gradients of (co-)limitation using at sea experimentation and (meta-)transcriptomics.
- Determine impacts of co-limitation by other nutrients on typical P and N limitation responses, to deduce diatom nutrient prioritization strategies.
- Use existing global nutrient databases (World Ocean Atlas) to understand and scale-up impacts on marine diatoms in situ.
You will also be supervised by organisations other than the University of Southampton, including Dr Katherine Helliwell from Marine Biological Association and Dr Julie Robidart from National Oceanography Centre.
