Marine Antifouling Coatings Determine Biofilm Community Composition and Microbiome Development in Settling Invertebrates

Abstract

This study investigated the impact of biocidal and non-biocidal marine anti-fouling coatings on the microbial composition and functionality of associated biofilms, marine invertebrates and their larvae using 16S rRNA gene sequencing. This is complemented by exploratory shotgun sequencing which was used to identify resistance genes present within the anti-fouling treatments. Differences between biocidal and non-biocidal biofilm treatments were identified, with unique ASVs found in each treatment. Although there was a high level of community overlap between treatments, there were diversity distinctions between treatments. Predicted functional analysis also demonstrated distinct differences in their antimicrobial resistance potential between biocidal and non-biocidal treatments. Shot gun sequencing analysis identified polymyxin and multi-drug as the dominant resistance gene types. In the barnacle Semibalanus balanoides, the adult microbiome acquisition upon settlement was heavily influenced by the settling substrate, forming beta-diversity rated distinct communities, where the biggest distinction in the microbiome was between the planktonic cyprid and calcification. In established adult-stage Ciona intestinalis and Bugula neritina, the coating they were attached to impacted their associated microbial communities. C. intestinalis on biocidal coatings with booster biocides demonstrated a significant reduction in dominant taxa compared to the other treatments. Similarly, in B. neritina the dominant taxa composition was significantly different between those with booster biocides and the other treatments. The microbiome AMR potential was characterised using shotgun sequencing and lab culture. Ampicillin and ciprofloxacin resistance were reduced in biocidal coatings in bryozoan samples, whereas kanamycin resistance was more prevalent in biocidal treatments. Larval microbiomes were distinct from their parents; however, they demonstrated both trans-generational transfer and uptake from the surrounding environment. The findings from this study not only contribute to the understanding of ecological consequences of antifouling strategies, but also offer insights into the potential implications of marine microbiome change.