A Modeling Platform to Evaluate Offshore Macroalgal Farming

Christina Frieder, University of California Irvine, Irvine, United States, Kristen A Davis, University of California Irvine, Civil and Environmental Engineering Department, Irvine, CA, United States, Marcelo Chamecki, University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, James C. McWilliams, University of California, Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, United States, Martha Sutula, Southern California Coastal Water Research Project, Costa Mesa, CA, United States, Raphael Martin Kudela, University of California Santa Cruz, Santa Cruz, United States, Javier Infante, Ocean Rainforest, Inc., Santa Barbara, Chile, Chao Yan, University of California Los Angeles, Los Angeles, CA, United States, Faycal Kessouri, Southern California Coastal Water Research Project, Costa Mesa, United States, Daniel Dauhajre, University of California, Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States and Meredith L McPHERSON, University of California Santa Cruz, Santa Cruz, CA, United States
Abstract:
Offshore macroalgal farming is being evaluated for its potential as a thriving marine biomass industry. Such farms could produce food, feed, chemicals and fuel while also offering ecosystem services such as nutrient and acidification bioremediation. Yet, scalability and ecosystem interactions are uncertain given the industry’s nascency. We have developed a modeling framework to evaluate offshore macroalgal farms. This tool not only simulates farm growth from oceanographic inputs and a dynamic macroalgal growth model, but also incorporates effects of farm-environment interactions through (1) a fine-scale hydrodynamic model (large eddy simulation) of modified flow due to macroalgal-induced drag and (2) changes to within-farm light and chemical fields. Simulation of an offshore farm of giant kelp, Macrocystis pyrifera, in the Southern California Bight reveals the relative importance of modifying these within-farm fields on farm growth. Further, integration of the simulated farm back into a regional model with a coarsening of the representation of farm drag, algal uptake and chemical fields allows for test of a suite of ecosystem effects. This new modelling tool can be used to locate optimal farm sites, survey farm designs, assess best cultivation practices, and evaluate ecosystem services and impacts.
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