In this study we present the prokaryotic community dynamics in a hatchery recirculating aquaculture system (RAS) of sole (Solea senegalensis).. Recirculating aquaculture system prokaryotic community

Recirculating aquaculture systems (RAS) allow to reduce water usage and to improve waste management and nutrient recycling in fish production, making intensive aquaculture compatible with environmental sustainability. The main challenge of this approach is to manage disease outbreaks, since in these systems a healthy microbial community contributes to water purification and water quality. The interaction of the different factors that can influence the fish and the various treatment steps, is still poorly understood. The main objective of this study is to monitor and model the water quality and microbial communities of a seawater-based RAS, taking a closer look at the biofilter, enabling the control of the water quality and bacterial infections throughout the production cycle. The work is being developed in partnership with a sole hatchery where a comprehensive characterization of the microbial communities from all RAS compartments, including the prokaryotic community of the biofilters, water, biofilms and the physicochemical parameters was conducted. Total DNA was isolated from the different matrices and the V4-V5 region of the 16S rRNA gene was sequenced using Illumina MiSeq® platform and the output analysed in the DADA2 pipeline and annotated using SILVA reference database. This study showed a highly dynamic prokaryotic community in the RAS, separate compartments developed different taxonomic profiles, even with the same water supply. The prokaryotic community shifts were found to be modelled by water parameters such as salinity, temperature, pH and nutrient load. Presently we are examining the microbiome data sets to extract knowledge on microbial interactions within this RAS unit.