Title: Optical partitioning of phytoplankton niches and implications for carbon cycling
Supervisors: Dr Martina Doblin, Professor Peter Ralph, Dr Nagur Cherukuru (CSIRO Land and Water)
PhD conferred: 2017
Primary production generated by phytoplankton contributes 50% of the oxygen in the atmosphere. These single-celled protists exist in highly diverse environments where the availability of resources controls the type of species present and their capacity to photosynthesise and generate biomass. The light climate within the water column exhibits dynamic niche partitioning, where factors as small as the vibration of individual water molecules results in a complete shift in the quality and quantity of available light. Phytoplankton are known to alter their light harvesting and utilisation capabilities in order to optimize the use of available light for photosynthesis, however this is poorly studied in nature and needs to be linked to ocean-ecosystem models in order to improve our estimates of primary productivity. This project aims to investigate the bio-optical properties of the water column and physiological responses of phytoplankton to this particular niche partitioning of available light. Investigations of cell physiology measuring chlorophyll fluorescence, oxygen evolution, radiocarbon uptake, light absorption and photopigments contained within the light harvesting complexes will assist to determine the influence of light on the community physiology. This research will provide key knowledge required to improve ability to estimate primary productivity in the coastal and estuarine marine environment.
This project investigates the fate of light in optically complex coastal waters and the physiological implications of bio-optical niche partitioning for carbon cycling by phytoplankton.
The project will address the following objectives:
- Comparison of bio-optical properties of water column to phytoplankton physiology, light harvesting capabilities, community composition and species selection, and biomass production.
- Collection of in situ data to contribute to bio-optical knowledge database
- Determination of light absorption components, radiative transfer models and remote sensing signature
- Development of alternative estimates of primary production to improve speed and reliability primary productivity estimates in turbid waters
Charlotte is the recipient of a CSIRO top-up scholarship.