Exploring Nutrient Supplements for Enhanced Growth and Quality of Devaleraea mollis and Palmaria hecatensis

Devaleraea mollis and Palmaria hecatensis have emerged as potential species for land-based cultivation of red seaweeds in the Pacific Northwest of the United States. Land-based cultivation has the advantage of customization of high-quality biomass production. However, the high material and preparation costs of the von Stosch enrichment medium (VSE) are a limitation of land-based cultivation of D. mollis and P. hecatensis . This study aims to reduce operational and management costs associated with controlling the culturing conditions of D. mollis and P. hecatensis without compromising biomass growth and quality in land-based tank cultivation systems. Five experimental treatments, 1) ambient seawater (AS); 2) VSE; 3) Guillard's f/2 medium (f/2); 4) commercial fertilizer, Jack's Special (JS); 5) JS with vitamin (JSV), were used in the present study. The growth, pigment, and protein content of D. mollis and P. hecatensis were measured. Except for AS, Palmaria hecatensis showed similar growth, pigment, and protein content at all experimental treatments. The growth and protein content of D. mollis exposed to VSE were decreased by nitrogen limitation. However, the protein content of D. mollis exposed to JS and JSV significantly increased without a decrease in growth. Therefore, the commercial fertilizer, Jack's Special (25-5-15), can replace the VSE for D. mollis and P. hecatensis , reducing operational and management costs link to nutrient supplementation.