Comparison of spring dominant zooplankton species in Chinese estuaries with different latitudes

Based on the investigations in the Guanhe Estuary, Changjiang (Yangtze River) Estuary, Oujiang Estuary, Jiaojiang Estuary, Jiulongjiang Estuary and Beilun Estuary (covering 14 latitudes) in April or May of 2010 to 2012, the ecological features of dominant species of the zooplankton assembles in each estuary and underlying mechanisms were analyzed. The result indicated that Calanus sinicus was predominant in all the estuaries. Labidocera euchaeta was the dominant species in the Guhe, Changjiang and Jiaojiang estuaries. Sagitta crassa was the dominant species of Guanhe Estuary, and Tortanus vermiculus was only limited to the Changjiang Estuary. Both S. enflata and Penilia avirostris were the dominant species in the Beilun Estuary. The zooplankton communities of the estuaries were dominated by the warm temperate species in spring. In addition, temperate species such as S. crassa was also the dominant species in the north (Guanhe Estuary). Warm water species including S. enflata and P. avirostris were the dominant species in the south (Beilun Estuary). All the dominant species are euryhaline.