Analysis of a 41-year data set : Environmental influences on the fish assemblages of Albemarle Sound, North Carolina

Abstract

North Carolina both historically and currently maintains one of the most productive fishery resource basins in the nation. However, fish stocks are spatially and temporally variable in abundance and distribution in estuarine ecosystems and the influence of changing environmental factors on the inhabiting fish community of Albemarle Sound, North Carolina has not been studied. Sites within Albemarle Sound were sampled (trawls and seines) monthly by the North Carolina Division of Marine Fisheries from 1972 to 2012. A total of 56 families representing 132 fish species including freshwater, estuarine, and marine species were represented in sampling Anchoa mitchilli, Menidia beryllina, Micropogonias undulates, Leiostomus xanthurus, Alosa aestivalis and Morone Americana were the most abundant species in sampling. Two gear types were utilized during sampling, and the composition of fish assemblages collected between the two gears were significantly different (ANOSIM R=0.759, p=0.001). 1) Spatial analysis: Salinity and wind direction were significantly correlated with for the seine samples spatially (R=0.754, p=0.01), cumulatively describing 51.9% of the total variation in species assemblage. For trawl samples, salinity and dissolved oxygen were significantly correlated with differences in species assemblages (R=0.683, p=0.001), which cumulatively described 38.3% of the variation in the biological patterns. 2) Temporal analysis: Temporal correlations were weaker than spatial correlations, with depth, temperature, salinity, dissolved oxygen and wind speed only weakly correlated with species assemblage (R=0.28, p=0.01) for the seine samples, and cumulatively described 14.5% of the variation. For the trawl samples, depth and salinity were weakly correlated with biological patterns (R=0.299, p=0.01), cumulatively describing 15.5% of the variation in the biological patterns. These results suggest that spatial variability in fish assemblage and biological patterns in Albemarle Sound are best described by salinity, with northeast and southwest winds indirectly influencing these patterns through wind driven tides. Temporally, correlations were weak and the amount of variability described was moderate, indicating there are other major factors influencing these patterns and fish assemblages through time.