Microalgae Grown in Aquaculture Effluents and Their Effects on Mussels

Global seafood consumption is rising, increasing the need for sustainable feed sources in aquaculture. Microalgae, such as Tetradesmus obliquus (To) and Microchloropsis salina (Ms), offer a promising nutritional profile for animal feed, including mussels. This study evaluated the potential of these microalgae, cultivated in synthetic medium and aquaculture effluent, as feed for the saltwater mussel Mytilus edulis . The microalgae achieved productivity rates of 194.3 mg L −1 day −1 (To) and 156.4 mg L −1 day −1 (Ms), removing 100% of nitrogen and phosphorus and up to 91% of the chemical oxygen demand. Mussels were fed with microalgae grown in aquaculture effluent or in synthetic medium as their diet for 45 days. These mussels showed increases in protein (54.3–58.3%) and lipid (4.1–5.2%) content, with no significant differences between the microalgal diets. However, mussels fed microalgae cultivated in aquaculture effluent exhibited significantly greater gains in weight and shell length than those fed with microalgae grown in synthetic medium. These findings highlight the potential of effluent-grown microalgae to enhance the growth and nutritional value of mussels while contributing to sustainable practices in aquaculture by using aquaculture effluent as a growth medium. This approach supports circular economy strategies, offering an innovative and environmentally friendly alternative for bivalve feed.