Aquaculture is one of the fastest- growing sectors in the global food industry . Cultured aquatic organisms are already more than those captured by the fishing industry. Closed aquaculture systems, such as recirculatory aquaculture systems (RAS), are gaining traction as an interesting alternative to open-sea production. Yet, the intensification of the aquaculture industry, characterized by higher stocking densities, reduced water turnover, and high nutrient input, comes with several challenges. These include high pathogen prevalence, often leading to disease outbreak s, and high mortality rates, especially during larval and early development stages. Current solutions and research are hyperfocused on fish-centric approaches and often overlook the interconnections between microbial communities inhabiting different compartments of the production system, neglecting how the se communities contribute to the overall health and stability of the entire system.
Here, we propose an innovative approach that conceptualizes the system as a holobiont, utilizing new technology to modulate the microbiome of biofilms (tank surfaces and biofilters), water, and cultured organisms in RAS at any animal developmental stage. This patent-pending technology involves the development of tailored porous mesh designed for the controlled release of biologically active beneficial substances. In this study, we present the results of our proof of concept for this innovative technology . Two validation trials with European seabass (Dicentrarchus labrax) in a lab-scale RAS and one trial in pilot RAS demonstrated that this mesh, loaded with humic substances, effectively manipulates the RAS microbiome (biofilms, bacterioplankton, and fish skin mucus ), increasing the relative abundance of potentially beneficial bacteria, and suppressing putative pathogens, improved nitrite removal, exhibited immuno-modulatory effects and increased survival rates following a exposure to a Tenacibaculum maritimum infection.
The newly developed technology evaluated here offers a high degree of customization, with a diverse range of microbiome modulators tailored to specific needs. This innovation has the potential to shift the paradigm from a fish-centered microbiome modulation approach in aquaculture systems while requiring minimal changes to current system designs.
We acknowledge the support of BlueComposite (PdC nº 08.207, SAICT-45-2021-02), funded by Centro 2020 - Portugal2020, the European Regional Development Fund (ERDF), to CESAM (UIDP/50017/2020+UIDB/50017/2020+ LA/P/0094/2020) and CIIMAR (UIDB/04423/2020 and UIDP/04423/2020) funded by the Portuguese Foundation for Science and Technology (FCT/MCTES). Davide A. Machado e Silva was supported by a PhD grant (2020.05774.BD) funded by FTC/MCTES , and the European Social Fund POPH-QREN programme.