Efficiency of a new RAS in the removal of microplastics

Plastics are a ubiquitous source of marine pollution, especially in the form of microplastics (MP). Exposure and contamination of fish and other seafood products by MP is a major concern worldwide and brings two types of risks to fish culture: 1) disruption of fish growth and reproduction thereby impacting operational capacity and 2) possible adverse health effects on consumers of fish products contaminated by MP. Culturing of fish in onshore recirculating aquaculture systems (RAS) can on the one hand potentially reduce exogenous MP contamination, i.e., from seawater, via water filtration, but on the other hand may expose fish to endogenously generated MP, i.e., from within the RAS plastic components, or even be contaminated through fish feeds derived from marine sources. Aiming for two major objectives: 1) knowing whether MP contamination in RAS-cultured fish is higher, lower, or equivalent to fish grown in open sea cages or wild-captured fish, and 2) knowing if MP characteristics (particle size and chemical composition, including plasticisers and other additives) are different for RAS-grown fish in comparison to fish obtained from other sources; a consortium formed by SEAentia (RAS meagre producer) and 2 research institutes, IPMA and SINTEF, implemented the project “Minimizing microplastic contamination in onshore (RAS) meagre farming” – MP-RAS, funded by EEA Grants. The aim of this study was to investigate if the RAS water contains differences in the quantity and characteristics of MP content when compared to seawater used to fill up the system.