Marine plankton culture and associated microbiome for aquaculture implementation

This study focuses on marine plankton, with the laboratory culture techniques of copepods Acartia tonsa and their associated microbiomes for biotechnological applications in aquaculture. Copepods are a key group in marine zooplankton, linking primary producers with higher-trophic consumers in the food chain. Due to their excellent nutritional value and adaptability, they have recently been proposed as an ideal alternative to rotifers and Artemia in live fish larvae feeds. They are also important model organisms for ecotoxicological and environmental adaptability studies. The main objectives of this paper are to optimize the laboratory culture system for A. tonsa and to evaluate the practical effectiveness of natural zooplankton, such as A. tonsa, as a replacement for traditional live feeds in fish larvae culture. The bacterial communities associated with copepod A. tonsa and mussel Mytilus coruscus planktonic larvae will be isolated and characterized. Microbial strains and their secretions will be screened for antimicrobial activity and evaluated for their in vitro inhibitory effects against pathogens of fish and zoonotic origin. This research established multiple culture systems for phytoplankton microalgae Isochrysis galbana, Rhinomonas reticulata, and Rhodomonas baltica, as well as zooplankton A. tonsa, Tigriopus fulvus, and wild zooplankton, providing techniques and methods for plankton cultivation. In the fish larvae culture experiment, using the freshwater zebrafish Danio rerio as a model organism, the effects of different combinations of feeds containing A. tonsa, Artemia, and a specialized zebrafish artificial diet zebrafeed on larvae growth and survival were evaluated. Results showed that a live feed containing 60% Copepod and 40% Artemia in addition to the artificial diet was effective in improving larvae growth. We also explored the effects of diet composition on host microbial diversity and functional gene expression. Results showed that feeding a composite algae diet increased bacterial species richness in A. tonsa, contributing to improved metabolic efficiency and adaptation to environmental stress. Studies on mussel planktonic larvae also demonstrated that different microalgae combinations can reshape their microbial landscape and influence nutrient absorption. Furthermore, the microbiome of the same mussel can vary across different geographic environments. Using traditional isolation and culture combined with high-throughput sequencing technologies, strains of Peribacillus with antimicrobial activity were successfully screened and identified from wild plankton samples. Some strains were effective against Enterococcus and Staphylococcus bacteria, common pathogens in aquatic and zoonotic organisms, demonstrating potential as natural probiotics or antibiotic alternatives. In summary, this study improves the aquaculture technology of zooplankton, and also deepens our understanding of the ecological functions of their microbiomes under different culture conditions. It explores how the microbiome of the related marine organism, mussels, varies with different diets and geographic locations. This research provides theoretical support and a technical foundation for its practical application in green, efficient, and sustainable aquaculture.