| Sanggou Bay, Rongcheng Bay and Laizhou Bay were selected as the typical study area in Shandong coast. Based on the field survey data in six bimonthly cruises in 2009-2010 in the Sanggou Bay and four seasonal cruises in 2009 in the Rongcheng Bay, the spatio-temporal distribution and seasonal variability of the zooplankton species composition, dominant species, biomass and diversity were studied in both the bays, and the factors affecting their distributions (including aquaculture activities) were discussed. Combined with the data from historical surveys and recent ecological monitoring since 1980s in the Sanggou Bay and Laizhou Bay, the long-term variation of the zooplankton species composition, abundance, biomass and diversity were studied, and their impact factors were discussed. The results have shown that:1) A total of 61 zooplankton species (21 pelagic larvae included) were identified in the six cruises in 2009-2010 in the Sanggou Bay, and copepods had the most species (21 species). There were relatively more species in summer and autumn (more than 30 species in June, August and October), and relatively fewer species in spring (28 species in April) and winter (22 and 25 species in December and February, respectively). Aidanosagitta crassa, Calanus sinicus, Paracalanus parvus, Acartia hongi and Oithona similes were the main dominant species in the Sanggou Bay, and their spatial and seasonal distributions varied very much. The zooplankton biomass showed a declining trend from February (272.1 mg/m3) to December (92.8 mg/m3). The diversity index H’of zooplankton community averaged 2.40 in this study, and the evenness index J’averaged 0.67. The results showed that diversity and evenness were highest in August and lowest in April.2) A total of 59 zooplankton species (pelagic larvae included) were identified in the four cruises in 2009 in the Rongcheng Bay contiguous waters. There were more than 30 species in the autumn, summer and spring, with 38,35 and 32 species respectively, which were much more than that in winter (22 species). Aidanosagitta crassa, Calanus sinicus, Paracalanus parvus and Oithona similes were the main dominant species in the Rongcheng Bay, and their spatial and seasonal distributions varied very much. The zooplankton biomass (wet weight) averaged 433.8 mg/m3 in winter (highest),220.7 mg/m3 in spring,162.4 mg/m3 in autumn and 52.5 mg/m3 in summer (lowest). The diversity index H’of zooplankton community averaged 2.50 in this study, and the evenness index J’averaged 0.65. The results showed that diversity and evenness were higher in summer and lower in spring, suggesting that the zooplankton community in summer were more stable than that in spring. Further analysis concluded that the raft aquaculture in the coastal waters had significant impacts on the distribution of the zooplankton community in the Rongcheng Bay contiguous waters.3) The zooplankton species numbers varied widely during different surveys in a long term in the Sanggou Bay and Laizhou Bay. However, the dominant species composition was relatively stable (e.g. Aidanosagitta crassa and Calanus sinicus). The reasons for the long-term variability of zooplankton species number included not only the natural variability of the community, but also the sampling error and identification error from anthropogenic factor. The relatively stable dominant species composition indicated that the long-term variability of the zooplankton community in both the bays was not intense. The long-term variability of the zooplankton abundance and biomass showed no consistent pattern in the Sanggou Bay and Laizhou Bay. And the comparison results of Jiaozhou Bay also showed that there was a big regional difference in the long-term changes of zooplankton community among different bays. In addition, the inter-annual comparison of the diversity index showed that the zooplankton community had a relatively stable diversity status in the Laizhou Bay, and it appeared not to be an obvious declining trend at the long-term variability. |
PDF Full Text Request