This study, examines seasonal patterns and year-to-year variation in the community makeup of fouling organisms in three US bays: Chesapeake Bay, San Francisco Bay and Tampa Bay. Interactions of exotic species with native species are a key part of this study. Non-indigenous species may have considerable impact on the succession of organisms and final makeup of the community that forms on fresh substrates as they become available. Standardized PVC (polyvinyl chloride) settling plates are deployed in the bay for varying lengths of time (monthly, quarterly, annually) and then retrieved. The plates are brought to the lab where biomass is estimated, patterns of coverage are measured and each taxon present is identified and vouchered. Study sites are selected in the areas of the three bays where salinities are 20 ppt and higher. Most sites are selected for their proximity to concentrations of naval and commercial shipping activity. These activities may inoculate port waters with invaders.