Cecilia Pascelli1, Nicholas Paul1, Madeleine Smith 1, Tasmin Steele 1, Nicole Dare1 & Alex Campbell1
1 Seaweed Research Group, University of the Sunshine Coast, 90 Sippy Downs drive, QLD, Australia
Seaweeds are distinguished biofilters which can be successfully grown in Integrated multitrophic aquaculture (IMTA) systems, absorbing nutrient waste, while promoting nature bioremediation. Although the benefits of integrating seaweed to IMTA is indisputable, its role towards its microbial community is still poorly understood. Therefore, a study has been conducted in a tropical prawn farm effluent water treatment system to investigate the microbial dynamics in three sediment pond stages and in a slow sand filter (SSF) located in one of the stages. Amplicon sequencing approach was used to characterize the microbial community associated with the ponds water (n=39), sediment (n=18), SSF (n=20) and seaweed (n=30). Additionally, seaweed composition and abundance were characterised for each stage. The results indicated that SSF promotes microbial biodiversity and evenness increase, while reducing populations of bloom-forming Cyanobacteria. Actinobacteria, Proteobacteria, Cyanobacteria and Flavobacteria were dominant microbial groups in the water, while sediment microbiome was majority composed of Gammaproteobacteria, Cyanobacteria, Deltaproteobacteria and Alphaproteobacteria. Planctomycetia and Verrucromicrobia were amongst the most abundant microbial groups associated with seaweed, encompassing functionally relevant microbes which can play key roles in ammonium oxidation, carbon, phosphorus, and nitrogen fixation. Ecological descriptors highlighted a positive correlation between microbial diversity and seaweed abundance, which negatively corelated with the occurrence of opportunistic pathogen groups and fermentative anaerobic sulphate reducing microbes. This study indicates that integrating seaweeds in IMTA systems potentially contributes towards a heathier and more functionally diverse microbial community.