| Liaohe River estuary is located in the top of the Liaodong Bay, it is an important Liaohe River estuary, and terrigenous nutrient inputs from Liaohe have a major impact on the Liaodong Bay of Bohai Sea and the marine ecosystem. 32 sampling sites are chosen around Liaohe River estuary waters to research zooplankton communities in August 2013(summer), October 2013(autumn) and May 2014(spring). This paper analyzes variation of zooplankton community structure, dominant species differentiation and spatial ecological environmental factors, and explores the main herbivorous copepods feeding on phytoplankton biomass feeding pressure. The results are as follows:1. Liaohe River estuary waters surrounding each season(spring, summer, autumn) three cruises were identified seven categories of zooplankton 26 species, planktonic larvae(body) 14 categories. Zooplankton abundance and biomass were highest in spring from spring to autumn decline, a large network of seasonal abundance of high value areas are mainly distributed in the upper part of the estuary, while the net abundance distribution showed a bucket from the spring to summer estuary in eastern and southern transfer characteristics, biomass distribution and abundance in the network similar distribution. Liaohe River estuary zooplankton community Shannon-Weaver diversity index and evenness showed Pielou summer> spring> autumn.2. Liaohe River estuary waters surrounding each season(spring, summer, autumn) zooplankton dominant species(class) to copepods, accounting for 66.7% of the species composition of the dominant species(class) obviously seasons, spring, summer, summer autumn dominant species(class) turnover rate was 53.33% and 46.15%. Acartia hongi, schmackeria poplesia, Sagitta crassa and paracaplanus parvus each season account for a large proportion of the dominant species for the waters. Using formulas and Petrailis Levins niche breadth index was measured and niche overlap of dominant species, dominant species of each season(class) niche breadth ranged from 0.04 to 0.73, there is a large niche breadth difference between the dominant species, species niche overlap of between 0.00 to 0.99, the average niche overlap index was 0.47. Often between often show wide niche between the type of a higher degree of overlap, narrow niche of species and other species often show a lower degree of overlap, the more niche and are subject to similar environmental factors on similar species It showed a higher degree of overlap.3. The data Pearson correlation analysis, niche breadth Liaohe River estuary waters surrounding each season(spring, summer, autumn) zooplankton dominant species(class) populations mainly affected by salinity, temperature and dissolved oxygen content influence. Liaohe River estuary salinity indicator species for the Schmackeria poplesia each season(spring, summer, autumn) are roughly divided into three environmental areas. Zooplankton community structure in each season are subject to different degrees of environmental factors, including salinity, temperature, pH and water nitrogen and phosphorus content is zooplankton community structure and play a major role in the impact of environmental factors.4. Application gut pigment method, the Liaohe River estuary waters surrounding the main herbivorous copepods feeding studies conducted to calculate the main types of feeding rate and population feeding rate, and then calculate the amount of phytoplankton grazing pressure. The results showed that each group feeding season averaged 119.56 μg·m-3·d-1, and summer>spring> autumn; each season herbivorous copepod on phytoplankton amount of grazing pressure an average of 0.94%, and the spring > summer> autumn. Acartia hongi Liaohe mouth waters surrounding the main herbivorous copepods, intestinal pigment content of between 0.04~0.71 ng·ind-1, the average content of 0.28 ng·ind-1, group feeding rate ranged from 12.89 ~77.81μg·m-3·d-1 between an average 53.62 μg·m-3·d-1, the amount of phytoplankton grazing pressure an average of 0.49%. |
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