Comparison of Fish and Invertebrate Assemblages Among Variably Altered Tidal Creeks in a Coastal Landscape

Salt marsh creeks are important sources of biological production but have become increasingly disturbed by human activities along the rapidly developing U.S. Atlantic coast.  We sampled six variably altered salt marsh creeks in coastal North Carolina USA monthly from spring through fall 2012 and 2013 with an actively fished 1 m² throw trap and passively fished wire mesh minnow traps.  Throw trapping (in five creeks) was used to estimate density of smaller and juvenile individuals while minnow trapping (in six creeks) was used to estimate the relative abundance of larger, more mobile fishes.  Non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) were used to compare nekton communities among creeks.  Principal components analysis was used to reduce dimensionality of environmental data and incorporate principal components (PCs) as potential explanatory factors in predicting the density of common species.  We found differences in relative abundance and community composition among creeks; mummichogs were most abundant and dominated the community in tidal creeks with less watershed imperviousness and larger Spartina marsh.  The opposite was true for amphipods.   Our results suggest that abundances of mummichogs, the dominant fish species in this study, will decline in salt marsh creeks as urbanization within tidal creek watersheds continues.