Biochemical and nutritional profiling of Tetraselmis chuii and Nannochloropsis oculata cultivated in conventional F/2 and modified F/2-NPK media for aquafeed applications

The pursuit of sustainable aquafeed ingredients is increasingly vital as global aquaculture demands continue to rise, placing significant pressure on traditional feed sources. Marine microalgae, with their inherent nutritional richness and potential for controlled cultivation, represent a compelling solution. However, the economic viability of large-scale microalgae production for aquafeed has historically been hampered by the cost and complexity of nutrient formulations. This recent study, evaluating *Tetraselmis chuii* and *Nannochloropsis oculata* cultivated in both conventional F/2 medium and a modified F/2-NPK formulation, offers a promising step towards addressing this constraint. The findings demonstrate that replacing select macronutrients in F/2 with a commercially available NPK fertilizer doesn't negatively impact biomass production or key biochemical characteristics, and in some cases, even improves them—specifically, carbohydrate content in *N. oculata* and lipid content in *T. chuii*. This echoes insights from related research, such as “Surviving the long fast: biochemical and photosynthetic acclimation of *Synechocystis sp. CCNM 2501* to chronic nitrogen and phosphorus starvation,” which highlights how microalgae can adapt and accumulate valuable compounds under nutrient limitation. Furthermore, the study’s focus on controlled cultivation aligns with efforts detailed in “Comparative effects of 405 nm and 450 nm blue light on *Halomonas pacifica* biofilms: implications for marine antifouling,” where optimizing environmental conditions is crucial for maximizing biomass output and desirable traits.

The observed sustained growth and comparable biochemical profiles across both cultivation conditions are particularly encouraging. While the preliminary Artemia feeding assay provides initial evidence of nutritional suitability, the authors appropriately caution against interpreting these results as definitive validation of aquafeed efficacy. This acknowledgement of limitations underscores the rigorous scientific approach underpinning the study. The data clearly indicate that the modified F/2-NPK medium can effectively support the cultivation of both microalgal species, maintaining a balance between biomass yield and the presence of key nutrients like protein, lipids, and carbohydrates. The fact that these species exhibited peak cell densities exceeding 21 × 106 cells mL-1 across all treatments is a testament to their resilience and adaptability, which is crucial for scalability. This research contributes to the growing body of evidence suggesting that nutrient optimization is a key lever for improving the economic viability of microalgae-based aquafeeds.

The broader significance of this work extends beyond simply identifying a potentially cheaper nutrient formulation. It points towards a more nuanced understanding of microalgal physiology and the potential for tailoring cultivation conditions to maximize specific biochemical outputs. This aligns with the increasing focus on "ocean intelligence"—the ability to harness data and technology to understand and manage ocean resources more effectively. The study’s emphasis on measurable, empirical data, and the authors’ call for further investigation into nutritional characterization, controlled feeding trials, scale-up evaluation, and techno-economic assessment, reinforces the commitment to scientific rigor that is essential for translating laboratory findings into real-world applications. Such comprehensive validation is critical, especially given the complexity of marine ecosystems and the need to ensure that aquaculture practices are environmentally sustainable. The approach taken here also complements the spatial modeling techniques explored in “Assessment of the protection of coastal reef-fish habitat across an isolated oceanic archipelago using spatial distribution models,” demonstrating the importance of integrating various data sources and analytical tools for effective ocean management.

Looking ahead, the key question becomes: can these findings be replicated and scaled up to meet the demands of the global aquaculture industry? The techno-economic assessment will be crucial in determining the true cost-effectiveness of the modified F/2-NPK formulation and identifying potential barriers to adoption. Furthermore, exploring the impact of this optimized cultivation on the fatty acid profiles of the microalgae, and subsequently on the nutritional value of the resulting aquafeed, warrants further investigation. The success of this approach could unlock a more sustainable and economically viable pathway for producing high-quality aquafeed ingredients, contributing significantly to the long-term health of both our oceans and the communities that depend on them.