Samenvatting

With a growing world population and simultaneously degrading ecosystems due to unsustainable agricultural practices, and due to a limited available space and resources, sustainable food sources are increasing in demand. Seaweed has emerged as a promising nutritious and protein rich alternative of low environmental impact. However, cultivation methods are limited for many seaweed species. Seaweeds have a dynamic physiology resulting in changing biochemical composition reflective of environmental factors. Therefore, this study explored different factors to optimize growth and protein content in the red seaweed Gracilaria sp. Through a range of experiments, stocking density (0.5, 1 and 1.5 g/500 mL), fragmentation size (1.5-3.5 cm), water movement (still water, aerated or shaken), water source (autoclaved or only filtered) and nitrate concentration (0 - 400 μmol/L) were investigated to improve current cultivation practices. Results showed no difference between the tested densities or water sources assessed. Highest growth (5.8 % day-1) was observed in the 3.5 cm fragment size. There were no significant differences in protein content between seaweeds grown for 2 weeks in nitrate concentrations of 0 to 400 μmol L-1. These findings indicate that more research is needed for the optimization of Gracilaria sp. cultivation using larger fragment sizes (at least 3.5 cm) with different types of water movement. Future research should utilize longer experimental periods to clarify nutrient-protein relation, in addition to establishing optimal stocking density for cultivation and translating those findings into an outdoor upscaling.