Cost-effective nutrient supplementation strategies for land-based cultivation 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 traditionally used enrichment media are a limitation of land-based cultivation of D. mollis and P. hecatensis. This study explores ways 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) von Stosch enrichment medium (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. Growth rates, pigment, and protein content of D. mollis and P. hecatensis were measured. D. mollis showed faster growth rates than P. hecatensis, indicating that the former is more economically suitable for land-based cultivation based on this parameter alone. Growth and protein content of D. mollis exposed to VSE decreased due to insufficient nitrogen in the tissue. However, the protein content of D. mollis exposed to JS and JSV significantly increased without a decrease in growth. Palmaria hecatensis showed similar growth, pigment, and protein content regardless of the treatment, except in AS. 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 linked to nutrient supplementation.