Impact Of A Reduced Water Salinity On The Composition Ofvibriospp. In Recirculating Aquaculture Systems For Pacific White Shrimp (Litopenaeus Vannamei) And Its Possible Risks For Shrimp Health And Food Safety

Tropical shrimp, likeLitopenaeus vannamei, in land-based recirculating aquaculture systems (RAS) are often kept at low water salinities to reduce costs for artificial sea salt and the amount of salty wastewater. Although these shrimp are tolerant against low salinities, innate immunity suppression and changes in the microbial composition in the water can occur. As especiallyVibriospp. are relevant for shrimp health, alterations in the species composition of theVibriocommunity were analysed in water from six RAS, run at 15 parts per thousand or 30 parts per thousand. Additionally, pathogenicity factors includingpirA/B,VPI,toxR,toxS,vhh,vfh,tdh,trh,flagellingenes andT6SS1/2ofV. parahaemolyticuswere analysed. TheVibriocomposition differed significantly depending on water salinity. In RAS at 15 parts per thousand, higher numbers of the potentially pathogenic speciesV. parahaemolyticus,V. owensiiandV. campbelliiwere detected, and especially inV. parahaemolyticus, various pathogenicity factors were present. A reduced salinity may therefore pose a higher risk of disease outbreaks in shrimp RAS. Because some of the detected pathogenicity factors are relevant for human health, this might also affect food safety. In order to produce healthy shrimp as a safe food for human consumption, maintaining high water salinities seems to be recommendable.