Fish assemblages spatially structure along a multi-scale wave energy gradient

Elucidating how ecological systems structure along environmental gradients to form barriers is important for improving the understanding of community ecology and the management of human-nature interactions (fisheries). Principal Component Analysis was used to create new variables from species abundance data collected in a seine survey on the Maine coast. The new variables were related to wave-energy values created for each site from available wind speed and fetch data. The results show a strong relationship between potential wave energy experienced and the species composition at a location. There were two scales of importance in determining species assemblages. First is at the regional scale where wave energy and the resulting coastal geomorphology create barriers to certain species and act to maintain different species groups. Second is at the local scale where wave energy interacts with species traits to create differences in species assemblages within a specific bay. The structure in fish communities delineated through this analysis provides a biodiversity indicator and the relationship between this indicator and an easily estimated physical quantity allows area-based management concepts to be better designed. For example, essential habitats of one or many species may be inferred through analysis of available environmental data, rather than depending on costly and time-consuming surveys of entire regions.