[Shrimp community structure and its influential factors in the Jiaojiang River estuary during spring and autumn]

Based on the data from two oceanographic surveys during April and October 2010, the spatial and seasonal variations in composition, dominance, and diversity of shrimp communities, as well as the influential factors in the Jiaojiang River estuary were analyzed. A total of 16 species of shrimp were found, which belonged to 12 families under 8 genera. 14 species of shrimp were found in spring (April) and 12 species in autumn (October). With the employment of index of relative importance (IRI), in spring 6 dominant species were identified, as Acetes chinensis, Alpheus distinguendus, Parapenaeopsis hardwickii, Leptochela gracilis, Alpheus juponicus and Palaemon gravieri, and in autumn 3 dominant species were found as Solenocera crassicornis, Parapenaeopsis hardwickii and Metapenaeus joyneri. Eurythermal and eurysaline shrimp community prevailed in the Jiaojiang River estuary, followed by eurythermal and hyposaline shrimp community. Margalef index (D), Shannon index (H) and Pielou's evenness index were used to evaluate the diversity of shrimp community in the studied area. The stations with higher value of D and H were mainly located in the west of the Dachen Island, whereas the Pielou's evenness index was stable all across the Jiaojiang River estuary. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) method, the results indicated that shrimp communities had significant seasonal and spatial variations. Depth was the most important factor that affected variations in the shrimp community structure in the Jiaojiang River estuary.