[Spatiotemporal changes of fish community in Yangtze estuary intertidal zone]

Based on the 36 fish samplings at 4 stations in the intertidal zone of Yangtze estuary from March to November 2006, the spatial and temporal changes of the fish community were analyzed. A total of 55 fish species belonging to 20 families were collected. Cyprinid had the largest species number (18 species), followed by Gobiidae (8 species), and Sciaenidae (4 species). The intertidal fish community was classified into brackish water and freshwater groups. Brackish water group had somewhat lower diversity than freshwater group. In the estuary mouth, the dominant species were of brackish-water fishes, including Acanthogobius ommaturus, Mugil cephalus and Collichthys lucidus, etc.; in the inner estuary, freshwater fishes were dominant, including Hemiculter bleeleri, Pseudobrama simony, and Parabramis pekinensis. The average dissimilarity between the two groups reached 80.75%, and the accumulative contribution of 23 fish species was more than 90%, mainly coming from Hemiculter bleeleri, Acanthogobius ommaturus, Mugil cephalus, Collichthys lucidus, Pseudobrama simony, Parabramis pekinensis, Saurogobio dumerili, and Odontamblyopus rubicundus. The abundance of fish assemblages in spring differed from that in summer and autumn to certain extent, but the abundance in summer and autumn had little differences. For each of the two groups, the abundance was more affected by water temperature than by water salinity; for the whole fish community, opposite situation was observed.