Comparative community structure of surf-zone fishes in the Chesapeake Bight and southern Brazil

The structure of surf-zone fish communities at Cassino (western South Atlantic, WSA) and the Chesapeake Bight (western North Atlantic, WNA) is described using historical beach seine data, to examine similarities between geographically isolated fish communities. Numerical classification, ANCOVA, Shanon-Wiener diversity and its components, and species rarefaction are used to describe fish community structure: (a) within habitat (Cassino); (b) within region (Chesapeake Bight); (c) within the western Atlantic (comparison between Cassino and the Chesapeake Bight). The surf-zone fish community at Cassino had a low diversity and was dominated by a few species. Seasonal periods identified by cluster analysis correlated well with seasonal environmental changes. The seasonal occurrence, abundance and diversity of fish species reflected recruitment patterns of juveniles, and seasonal variation in the marine and estuarine circulation patterns. Fish species associations usually fitted into three broad categories: year-round surf-zone residents; (b) spring to fall, estuarine related, pelagic planktivores or shallow water omnivores; (c) summer to fall coastal marine occasionals. Faunal similarity between Cassino and other selected locations of the WSA, decreased towards lower latitudes due to faunal replacements. In the Chesapeake Bight community structure was determined by differences between the two sampled localities. The community at Sandbridge was characterized by estuarine related species associated with the Chesapeake Bay. Sub-tropical coastal marine species at Cape Hatteras indicated influence of Gulf Stream waters. The seasonal species occurrence, abundance and diversity was determined by an enhanced seasonal migration along the coast, juvenile recruitment, and the thermal regime of the Chesapeake Bight. Ubiquitous surf-zone residents were replaced by a wintering group in the colder months. The diversity of estuarine related species at Sandbridge indicated that locally the surf-zone acted as a peripheral habitat for those species. Faunal similarities between the Chesapeake Bight and other WNA localities decreased both northward and southward due to faunal replacements. Similarities between surf-zone fish communities within the western Atlantic (Cassino x Chesapeake Bight) were correlated with the temperature range and habitat structure