Divergent Patterns of Metabolite Expression in Red Seaweeds (Devaleraea mollis and Palmaria hecatensis) Following Nitrate and Ammonium Supplementation

This study explores species-specific metabolic responses to different nitrogen-rich formulations in Devaleraea mollis and Palmaria hecatensis, highlighting distinct adaptive strategies. We evaluated the effects of Von Stosch Enrichment (VSE, nitrate-only), F/2 (nitrate-only), and Jack’s Special (JS, nitrate and ammonium) on metabolic profiles. D. mollis exhibited elevated energy storage and growth-related me-tabolites, with JS enhancing creatine production for energy storage and regeneration, alongside increased DNA/RNA synthesis and cell division activity. This suggests D. mollis prioritizes rapid growth and energy demands, supporting broader ecological adaptability. Conversely, P. hecatensis showed higher expression of metabolites linked to amino acid metabolism and protein synthesis, indicating a focus on efficient nitrogen use for protein production, likely advantageous in low-light, high-turbidity conditions. Nitrogen sources significantly influence amino acid metabolism, with JS promoting broader amino acid production and VSE and F/2 stimulating specific metabolites. These species-specific metabolic patterns underscore the flexibility of D. mollis in energy use versus adaptations of P. hecatensis to protein synthesis pathways. These findings highlight species-specific nutrient formulations as essential for optimizing seaweed growth and metabolic traits in aquaculture.