Offshore macroalgal farming has been proposed as a sustainable strategy for carbon sequestration, biofuel production, food supply, and bioremediation. These offshore farms are typically attached to suspended structures near the ocean surface. A crucial factor affecting the performance of these farms is their interaction with hydrodynamic processes in the ocean mixed layer, which determine turbulent mixing and nutrient supply. In this study, we conduct large eddy simulations of wave-averaged equations to understand the influence of suspended farms on ocean mixed layer turbulence and nutrient transport. Suspended farms can generate intense turbulence by enhancing shear in the ocean currents and affecting the interaction between surface gravity waves and farm-modulated currents. Farm-generated turbulence can drive upward nutrient fluxes from below the farm base and increase nutrient supply within the farm. We introduce the Damkohler number to quantify the balance between nutrient consumption by macroalgae uptake and supply by turbulent nutrient transport. Various farm configurations are examined, with most cases exhibiting a low Damkohler number, indicating that farm-generated turbulence drives sufficient upward nutrient fluxes to support macroalgae growth. Several farm configurations that generate weak turbulence show a high Damkohler number and an increased risk of starvation. To mitigate the risk of farm starvation, we propose strategies such as timely harvesting, avoiding dense macroalgae canopies, and selecting farm locations with robust ocean currents and waves.

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