Quantifying bacterial assemblages associated with both farmed and wild populations of Saccharina latissima across the aquaculture growing season in SW EnglandReef-associated Biodiversity

Jasmine Ramshaw^1,2

¹The Marine Biological Association of the UK, UK - ² University of Plymouth, UK

Seaweed farming is the world’s fastest growing aquaculture sector and understanding the mechanisms that promote seaweed health and limit wider ecosystem impacts will be fundamental for its expansion. Bacteria associated with seaweed hosts play fundamental roles for host health and development but the impacts of farming on these relationships is poorly understood. Here, we describe the bacteria-kelp relationships for farmed Saccharina latissima (Sugar Kelp) and compare it to a local wild population throughout the aquaculture growing season (February - June) in SW England to determine the impact, if any, farming has on these communities.
Kelp-associated bacterial communities were quantified, using 16s amplicon sequencing, at two farms and one wild population in SW England at three timepoints (early, mid, and late growing season). Kelp-associated bacterial community structures were significantly differentiated from the surrounding seawater, as well as from each other across both site and timepoint. Only timepoint influenced community diversity (alpha diversity) with all sites having more diverse bacterial communities at the late timepoint. This could potentially be due to increased time for bacterial colonisation or to increased fouling as the season developed.
Studying the influence of aquaculture on kelp-associated bacterial communities during the growing season is a vital step towards understanding wider impacts on biodiversity, water quality (i.e. recreation and fishing in farmed areas) and on kelp health and yield, which has potential commercial importance. This work facilitates the further exploration of these potential future benefits and issues in order to enable sustainable industry development and expansion.