Understanding oceanic photosynthesis

Oceanic photosynthesis can be responsible for ~50% of carbon fixed globally. However, predictions of how future oceanic primary production may change are uncertain as we lack a mechanistic understanding of how photosynthesis operates under different growth conditions such as nutrient limitation and light stress. This project will provide important new insights into the use of solar energy to sustain life on Earth.  

 In this project, the student will couple in situ and experimental approaches to develop a mechanistic understanding and characterise the resources required for photosynthesis specifically:  

1. Existing datasets collected from a recent NERC-funded research cruise, on which both physiological and molecular data were collected, will be used to develop a mechanistic understanding of how genes related to photosynthesis change over gradients of light and nutrients.  
2. A laboratory test system, including phytoplankton isolated from diverse marine environments, including some of the smallest (Prochlorococcus) and largest (Diatoms), will be grown under a range of experimental and laboratory conditions. A suite of physiological (FRRf) and molecular approaches will be used to determine how photosynthetic resources are allocated.  
3. A related NERC-funded cruise to the Southern Ocean provides an opportunity to collect more data and/or samples to empirically test hypotheses generated in this project.    

The above approach will:  

• Generate data from which the energetic ‘costs and benefits’ of photosynthesis can be constrained.   

• Identify marker genes for diagnosing how photosynthesis is operating in situ.   

Together, these outputs will reveal how the fundamental process of photosynthesis has evolved and will adapt in a future ocean.      

You will also be supervised by organisations other than the University of Southampton, including Julie Robidart and Richard Puxty.