The objective of this project is to determine if observed decreases in the antifouling performance of biocidal paints are due to environmental effects (e.g., sunlight, temperature, salinity) or biology altering biocide release.

It is hypothesized that decreases in the efficacy of antifouling marine paints are due an increased presence of metal resistance genes (MRG) in adhered biofilms, limiting the release of bioactive compounds, rather than environmental factors (e.g., temperature, salinity, ultra violet exposure) altering biocide release kinetics. The project team will perform laboratory and field evaluations of the antifouling performance of biocidal coatings (copper/zinc pyrithione), in comparison to biocide-free coatings. Microbial biofilms formed on the target substrates will undergo genomic profiling to determine their organismal composition and relative abundance of MRG. X-ray photoelectron spectroscopy and mass/optical spectrometry will be used to determine if biocides are sequestered and/or modified by adhered biofilms, as well as identify leachates and quantify their release rates. Target substrates will undergo mechanical and chemical characterization to elucidate changes in coating properties that may contribute to reduced efficacy. Lastly, the impact of environmental conditions will be determined by pre-conditioning coatings to simulate aging and cleaning, prior to the exposure to fouling communities.

This project aims to determine mechanisms by which the antifouling performance of marine coatings diminishes over time. Knowledge of these mechanisms will allow for the development of targeted approaches to improve coating performance, rather than merely increasing the loading of biocides. This will reduce costs associated with underwater hull coating cleaning, repair, and replacement as well as it will reduce drag on ships, thereby improving speed and range. (Anticipated Project Completion - 2026)