Turbulence, mixing, and nutrient fluxes in kelp farms

Marcelo Chamecki, University of California, Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, Yan Chao, University of California Los Angeles, Los Angeles, United States and James C. McWilliams, University of California Los Angeles, Los Angeles, CA, United States
The deployment of large-scale offshore macroalgae farms is currently under consideration as an alternative to land-based biofuel crops. The viability of this enterprise depends, among many other factors, on the hydrodynamical conditions that develop as ocean mixed layer (OML) flows interact with macroalgae farms. In particular, the forces exerted by the flow field on the farm and nutrient depletion within large-scale farms are critical issues that must be addressed. We employed large-eddy simulation of the Craik-Leibovich equations to study the modifications of OML turbulence induced by the presence of a model farm of giant kelp. Kelp fronds are represented in the model via drag forces in the dynamical equations and a nutrient sink based on a simple model for uptake. Results showing the strong modulation of Langmuir turbulence by the drag force associated with kelp fronds will be presented and discussed, and implications for nutrient availability within farm will be explored.