Modeling the Growth of Sugar Kelp (Saccharina latissima) in Aquaculture Systems using Dynamic Energy Budget Theory

Aquaculture is an industry with the capacity for further growth that can contribute to sustainable food systems to feed an increasing global population. Sugar kelp (Saccharina latissima) is of particular interest for farmers as a fast-growing species that benefits ecosystems as a primary producer. 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 field-based growth experiments in Rhode Island (U.S.A.). Environmental variables forcing model dynamics include temperature, irradiance, dissolved inorganic carbon concentration, and nitrate and nitrite concentration. The modeled estimates for field S. latissima blade length were accurate despite underestimation of early season growth. In some simulations, winter growth was limited by the rate at which the light-dependent reaction of photosynthesis, the first step of carbon assimilation, was performed. Nitrogen (N) reserves were also an important limiting factor especially later in the spring season as irradiance increased, although the low resolution of N forcing concentrations might restrict the model accuracy. Since this model is focused on S. latissima grown in an aquaculture setting with winter and spring growth, no specific assumptions were made to include summer growth patterns such as tissue loss or reproduction. The results indicate that this 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 S. latissima aquaculture production across a range of environmental conditions and locations. The model could be a particularly useful tool for further development of sustainable ocean food production systems involving seaweed.