Composition and seasonal changes of zooplankton in the surf zone of sandy beach at Sijiao Island, Zhejiang

Abstract:

In order to find out the composition and seasonal changes of zooplankton in the surf zone of sandy beach in Sijiao Island,zooplankton were collected at the 8 stations by a zooplankton net (0.3 cm mouth-diameter,0.2 mm mesh-aperture) each month during the spring tide from August 2010 to August 2011. During the study period,67 species and 10 kinds of planktonic larvae were collected. They included 56 crustacean species(43 copepod species,3 cladoceran species and 10 other species),4 chaetognath species,7 medusa species. There were 13 dominant species in total,such as Paracalanus parvus,Paracalanus crassirostris and Centropages dorsispinatus. The zooplankton in the surf zone of sandy beach in Sijiao Island could be divided into four ecotypes:estuarine low salinity group(2 species),offshore warm temperate group(2 species), offshore warm water group(52 species), and eurytopic group(5 species). The results indicated that zooplankton community in surf zone of sandy beach were mostly offshore warm water group. Affected by salinity,water temperature,ocean current and other environmental factors,seasonal changes were obvious. In spring,the mean density of zooplankton was the highest,while it was the lowest in winter.