Composition and seasonal fluctuation of zooplankton in the surf zones of Yangtze River estuary

Abstract:

To clarify the species composition and distribution of zooplankton in the surf zones of Yangtze River estuary, zooplankton was collected monthly along the 13 stations by a zooplankton net (diameter: 30 cm, 0.2 mm meshaperture) from April 2006 to June 2007, respectively. Totally 156 seine hauls were made, 74 species and 10 kind of planktonic larvae were observed during the study period. It included 63 crustacean species (43 copepod species, 15 cladoceran species and other 5 species), 5 insect species, 3 rotifers, 2 medusa species, 1 chaetognath species. Sinocalanus sinensis was the most dominant species with 0.52 dominance index; Schmackeria poplesia was the second dominant species with 0.22 dominance index. The results indicate that the zooplankton community in the surf zone of Yangtze River estuary was mainly composed of brackish estuarine species during the investigation. Influenced by environmental factors such as river runoff, ocean current, temperature and salinity, the abundance of fresh and coastal species displays seasonal variations. And the community structure of zooplankton varied widely in different sites.