GROWTH OF SACCHARINA LATISSIMA IN AQUACULTURE SYSTEMS MODELED USING DYNAMIC ENERGY BUDGET THEORY

Aquaculture is an industry with the capacity for further growth that can sustainably feed an increasing human population. Sugar kelp (Saccharina latissima) is of particular interest for farmers as a fast-growing species that benefits ecosystems. However, as a new industry in the U.S., farmers interested in growing S. latissima lack data on growth dynamics. To address this gap, we calibrated a Dynamic Energy Budget (DEB) model to data from the literature and a 2-year growth experiment in Rhode Island (U.S.). Environmental variables forcing model dynamics included temperature, irradiance, dissolved inorganic carbon (DIC) concentration, and nitrate and ammonium concentration. The modeled final estimate for S. latissima blade length (cm) was reasonably accurate despite underestimation of early season growth. Carbon limited winter growth due to a low modeled specific relaxation rate (i.e. the light-dependent reactions of photosynthesis) for some model runs; other model runs displayed nitrogen limitation which occasionally led to length overestimation and underestimation due to the degree of interpolation necessary from the field data. The model usage, however, is restricted to S. latissima grown in an aquaculture setting because of assumptions made about tissue loss, summer growth patterns, and reproduction. The results indicate that our mechanistic model for S. latissima captures growth dynamics and blade length at the time of harvest, thus it could be used for spatial predictions of kelp aquaculture production across a range of environmental conditions. The model could be a particularly useful tool for further development of sustainable ocean food production systems in the U.S. involving seaweed.