About the project
Climate change has focused attention onto whether atmospheric carbon dioxide concentrations may be lowered by direct intervention. Sinking marine macroalgae to the sea-floor is one suggested approach to increase ocean carbon storage. But what are the consequences for the seafloor organisms when all this material is deposited?
Utilizing its rapid growth and high carbon content, the farming of macroalgae has been proposed as a marine carbon dioxide removal (mCDR) approach to increase long term storage of carbon in the ocean. The intention is that farmed macroalgae are harvested and sunk to the seafloor, trapping the carbon at depth, away from the atmosphere. In practice major uncertainties remain over the impact on the benthic organisms of these large ‘falls’ of macroalgae and how quickly the macroalgae would be respired by them (e.g. NASEM, 2022).
This project will use a benthic ecosystem model to address these questions. BORIS (Benthic Organisms Resolved In Size; Kelly Gerreyn et al., 2014; Yool et al., 2017) captures the dynamics of the full range of organism sizes from bacteria to demersal fish, allowing the different timescales of response and relative contribution to respiration of the deposited macroalgae to be assessed.
The seafloor respiration of this large flux of macroalgae may be slowed if ambient oxygen concentrations are reduced to the point of hypoxia. The project will also therefore incorporate the impact of oxygen availability into BORIS to investigate how the balance between the flux of macroalgae and its respiration controls the time before which the carbon trapped in macroalgae is released back into the water, a fundamental limitation on the efficacy of the approach as a means of mCDR.
The project will therefore provide information needed to inform the ongoing international debate on whether society should pursue mCDR and, if so, through which approach.
Supervisors
You will also be supervised by organisations other than the University of Southampton, including:
