Kennedy, C. G., M. E, Mather, and J. M. Smith. 2017. Quantifying integrated, spatially-explicit, ecologically-relevant, physical heterogeneity within an estuarine seascape. Estuaries and Coasts, 40(5): 1385-1397; https://doi.org/10.1007/s12237-016-0207-9; https://link.springer.com/article/10.1007/s12237-016-0207-9
Abstract In marine and estuarine ecosystems, quantifying spatially explicit patterns of physical heterogeneity is essential for meaningful ecological research and effective resource management. To identify site specific patterns of ecologically relevant heterogeneity, we asked three research questions for which we measured 23 geomorphic metrics at 40 sites within Plum Island Estuary (PIE), MA. Quantifying spatial patterns for complex physical features (e.g., confluences, bathymetric variation, channel networks, land features) provided several insights about seascape scale physical heterogeneity. First, individual metrics that described a single complex physical feature (e.g. confluence) showed different geographic patterns. When we used a cluster analysis to combine metrics from the same individual feature, we identified five patterns of confluences and three patterns of drop-offs throughout PIE. Second, because different types of physical features also varied in their geographic patterns, we developed and tested two indicators of overall physical heterogeneity. These overall heterogeneity indices combined physical features at specific sites via either a cluster analysis or an additive index. Third, these spatial patterns of overall physical heterogeneity were related to concentrations of striped bass (Morone saxatilis) within Plum Island Estuary. Specifically, more of these structure-oriented fish predators occurred at geographic locations with high overall heterogeneity (i.e., within a single heterogeneity cluster and at sites with the highest additive heterogeneity index values). With the creation and analysis of new metrics for individual and combined physical features, we have provided insights into spatially explicit patterns of physical heterogeneity that are relevant to seascape scale predator research and management.