MICROBIAL COMMUNITY COMPOSITION OF MARINE BIOFILMS IN A NORTHERN TEMPERATE

Abstract

Marine biofilms are microbial aggregates that ubiquitously develop on substrates in seawater. Biofilms are not simple layers of microorganisms adhering to a surface followed by new organisms growing on top, but they instead have a complex developmental process making biofilms dynamic, diverse and functional communities. The negative effects of biofilms on ships, underwater cables and pipelines have spawned research in antifouling approaches; however, little is known about their development in a northern temperate estuary, such as Narragansett Bay. The goal of this study was to investigate the first steps in biofouling in this area by assessing biofilm biomass through chlorophyll, carbon, nitrogen, total DNA extractions and percent biomass coverage, as well as bacterial biofilm community composition through the use of a molecular technique, the automated ribosomal intergenic spacer analysis (ARISA). Comparisons were made between biofilms on control surfaces and surfaces treated with a commercial foul-release coating, between biofilms grown in the summer and winter seasons, as well as over a 90-day immersion time. Biofilm biomass data revealed no overall significant differences between seasons or across surface types; however, immersion time had a significant effect as biomass tended to accumulate over time. Bacterial community composition obtained from ARISA profiles was influenced by immersion time, as communities separated out into ‘early,’ ‘mid,’ and ‘late’ groupings. It was also influenced by season as well as surface type.