Community structure of zooplankton near lvsi ocean port area and its environmental assessment

Changes in the species assemblage or abundance of zooplankton have a direct impact on both primary productivity and the biomass of fish and other marine animal resources. Species composition, biomass, abundance and community structure of zooplankton have a close relationship with the dynamics of hydrologic environment. Zooplankton is a key member of marine food webs, so they are the focus of a number of studies in the Changjiang estuary. The majority of these studies have evaluated zooplankton population dynamics at a large scale. Herein, we evaluated the species composition, quantitative distribution, dominant species, and community structural characteristics of zooplankton at 20 inshore sites near the Lvsi Ocean Port (32.04°~32.20°N, 121.56°~121.80°E) in April 2010. We identified 14 species belonging to 6 groups, including 9 species of Copepoda, 1 species of Protozoa, 1 Chaetognath, 1 Cumacea, 1 Euphausiacea and 1 Mysidacea. The abundance of zooplankton ranged from 16 to 1193 ind./m3 (mean: 422 ind./m3). The most abundant group was the Copepoda. Eight species had a dominance index ranking of >0.02 within the study area. Among these, Acartia clausi, Schmackeria poplesia, Labidocera euchaeta, Calanus sinicus and Paracalanus parvus were the primary dominant species (dominance index: 0.876, 0.477, 0.299, 0.271 and 0.255, respectively). The amplitude of the index varied significantly (species: 5 to 10, richness: 0.471~1.507, diversity index: 0.847~2.130, evenness index: 0.282~–0.759) suggesting the community structure was instable. The mean diversity index of zooplankton was 1.485, the mean richness index was 0.530, and the mean evenness index was 0.587. The correlation analysis shows that the abundance of zooplankton and COD and PO4-P were significantly correlated (correlation coefficients: 0.528 and 0.502, respectively; P<0.05). The abundance of zooplankton and water depth were significantly negative correlated (P<0.05) (correlation coefficients:–0.586;P<0.01). We observed a significant negative relationship between the number of species and the content of the suspended substance (correlation coefficients:?0.509, P<0.01). We found a significant correlation between the evenness indices of zooplankton and the content of the suspended substance. We observed a significant negative correlation between the evenness indices and the content of Zn. The Species richness index of zooplankton and COD and the content of the suspended substance were significantly negative correlated (correlation coefficients:?0.523 and ?0.473, respectively; P<0.05). Diversity Index and the content of Zn were significantly negative correlated (correlation coefficients: ?0.524; P<0.05). The zooplankton diversity index has since been adopted to assess water quality near the Lvsi Ocean Port in Jiangsu province. Monitoring results indicate that the quality of seawater is under intermediate pollution.