Power of a Multi-Year Monitoring Program to Detect Potential Change in Shoreline Fish Communities Adjacent to a Nuclear Power Plant

An expansion is underway of a nuclear power plant on the shoreline of Biscayne Bay, Florida, USA; the effects of its construction and operation on surrounding marine habitats and fishes are unknown. Consideration of spatial and temporal aspects of monitoring design their influence on statistical power are critical to the design of meaningful environmental assessments.  The present study examined data gathered as part of an ongoing monitoring survey of fish communities associated with mangrove habitats directly adjacent to the power plant. Our objective was to determine the adequacy of the survey to detect fish community changes, should they occur, at three spatial scales. Using seasonally-resolved data recorded during 477 fish surveys over 5-year period, power analyses were performed for three mangrove fish metrics (fish diversity, fish density and the occurrence of two ecologically-important fish species (Lutjanus griseus and Floridichthys carpio). Seasonal, spatial, and temporal aspects of the dataset are examined for ways to optimize power and sampling efficiency. We discuss the importance of adequate spatial coverage in monitoring design and the utility of drawing from ongoing monitoring programs for use as pilot studies, or opportunistic baselines, to evaluate sampling intensity necessary to detect a meaningful effect with adequate statistical power.