Macroalgal Farming for Carbon Sequestration - Turbulence and Scalar Transport

The cultivation and harvest of macroalgae has the potential to become a sustainable strategy for biofuel production, food supply, and carbon sequestration. Given the constraints posed by the ecological carrying capacity of existing nearshore aquaculture, recent interest has thus arisen in expanding macroalgal farming offshore. These offshore macroalgal farms are usually attached to suspended structures near the ocean surface, typically within the ocean mixed layer. An essential factor affecting the performance of suspended macroalgal farms is their interaction with the hydrodynamic processes in the ocean mixed layer.

This study investigates the interactions between suspended macroalgal farms and ocean mixed layer hydrodynamics in the presence of currents and waves. We use the large eddy simulation (LES) method, where the wave effect is incorporated by solving the wave-averaged equations. Distinct Langmuir circulation patterns are generated within various suspended farm configurations. Canopy shear layer turbulence is also created at the farm edges due to drag discontinuity. The altered hydrodynamic conditions due to the presence of macroalgae can in turn determine nutrient availability, chemical transport, and salinity and temperature conditions in the farms, thereby affecting macroalgal growth.

Reference(s):

Bo, T., McWilliams, J. C., Yan, C., & Chamecki, M. (2024). Langmuir turbulence in suspended kelp farms. Journal of Fluid Mechanics

Bo, T., McWilliams, J. C., Frieder, C. A., Davis, K. A., & Chamecki, M. (under review at Geophysical Research Letters). Nutrient Replenishment by Turbulent Mixing in Suspended Macroalgal Farms.