Bacterial diversity within and outside the premises of a South Norwegian salmon fish farm

Abstract

Norwegian salmon farming is a rapidly expanding sector and the Norwegian Government have a set goal to facilitate a five-fold growth towards 2050. Organic enrichment of the surrounding waters and the sediment below the cages due to the inputs of organic matter from uneaten food, tissue and faecal matter etc., affect the macro -and microfauna. To monitor the effect of these organic inputs, fish breeding companies must perform periodic controls. Traditionally, these periodic controls are based on time-consuming and expensive methods, and the necessary taxonomic knowledge is declining. In this study, we evaluated the usefulness of marine bacterial communities as bioindicators. Benthic samples were collected from within the premises of a fish breeding facility and compared with samples from outside the facility based on metabarcoding of the 16S rRNA gene. Water samples were also collected from the same sites, and from different depths representing different water layers. The bacterioplankton composition in both benthic and water samples showed significant shifts from within the facility compared to stations outside the fish farm. The bacterial composition also varied greatly between the different water layers. Our results demonstrate the potential for bacterioplankton composition diversity as bioindicators, and that this methodology could be a useful asset in the periodic monitoring controls.