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Nutrient Replenishment by Turbulent Mixing in Suspended Macroalgal Farms
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  • Tong Bo,
  • James C. McWilliams,
  • Christina A. Frieder,
  • Kristen A. Davis,
  • Marcelo Chamecki
Tong Bo
University of California Los Angeles

Corresponding Author:[email protected]

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James C. McWilliams
University of California Los Angeles
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Christina A. Frieder
Southern California Coastal Water Research Project
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Kristen A. Davis
University of California, Irvine
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Marcelo Chamecki
University of California, Los Angeles
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Abstract

This study uses large eddy simulations to investigate nutrient transport and uptake in suspended macroalgal farms. Various farm configurations and oceanic forcing conditions are examined, with the farm base located near the nutricline depth. We introduce the Damkohler number Da to quantify the balance between nutrient consumption by macroalgae uptake and supply by farm-enhanced nutrient transport. Most cases exhibit Da<1, indicating that farm-generated turbulence sufficiently contributes to upward nutrient fluxes, supporting macroalgae growth. High Da and starvation may occur in fully grown farm blocks, a configuration that generates weakest turbulence, particularly when combined with densely planted macroalgae or under weak flow conditions. Flow stagnation within the farm due to macroalgae drag may constrain the uptake efficiency and further increase the starvation risk. Mitigation strategies involve timely harvesting, avoiding dense macroalgae canopies, and selecting farm locations with robust ocean currents and waves. This study provides insights for sustainable macroalgal farm planning.
09 Mar 2024Submitted to ESS Open Archive
11 Mar 2024Published in ESS Open Archive