Study On The Ecology Of Zooplankton In The Yangshan Port

The seasonal variation of zooplankton community, diversity, spatialdistribution and the correlation with environmental factors were studiedbased on the researched on March2009to March2010and January toDecember2011. The results showed:1. To understand the seasonal variation of the copepod community structure,abundance, dominant species and diversity in the Yangshan Port, sampleswere collected monthly from March in2009to February in2010. Theresults showed that there were32species in the nearshore of Yangshan Port.The dominant species were Limnoithona tetraspina, Acartia pacifica,Labidocera euchaeta, Paracalanus aculeatus, Acartia bifilosa,Microsetella norvegica, Paracalanus gracilis and Paracalanus parvus. Theseasonal variation in the mean abundance was remarkabl（eF=2.11，p<0.05）,and the order from high to low is spring (14.01±3.53ind./L), summer(11.93±9.73ind./L), autumn (7.44±2.36ind./L), and winter (5.47±1.15ind./L). The variation of copepod abundance showed single peak in oneyear. The results of multivariate analysis showed that the variation ofdominant species made a great contribution to the variation of copepodcommunity. Now, Xiaoyang is the main shipping docks, and it has a biggerthe ship flux than Dayang. The copepod community has already appeared difference between Dayang and Xiaoyang. The Shannon Weaver index ofXiaoyang was higher than Dayang in spring and winter. But the Pielouindex of Xiaoyang was higher than Dayang in spring, summer and winter.2.52species of zooplankton were monitored in the Yangshan Port,2011.The number of species has no significant difference in four seasons. It hasthe lowest number of species in spring and highest in Summer, including26species in spring,29species in summer,27species in autumn and27species in winter. The average annual density of zooplankton was11.50ind./L in Yangshan Port, the seasonal fluctuations was obvious. Thespecific trends were: spring(22.64to24.05ind./L; a mean of25.04±1.74ind./L)> sunmer(5.34to14.94ind./L, a mean of11.31±3.01ind./L)>autumn(0.40to9.27ind./L, a mean of6.25±2.93ind./L)> winter(0.74to4.95ind./L, a mean of3.42±1.34ind./L).There were a significantdifference (p<0.01) in spring and no significant difference(p>0.05) in thethree seasons. The spatial distribution of zooplankton in Yangshan Portwere: S1(11.16ind./L)> S2(9.46ind./L)> S3(8.12ind./L)>S4(7.03ind./L)>S5(6.94ind./L). The changing of Shannon-Wiener index inthe four seasons were: Summer (1.59)>Autumn (1.49)>Spring (1.27)>Winter (1.07), and the evenness index of four seasons were: spring (0.46);summer (0.55); autumn (0.54); winter (0.40). With the combined influenceof monsoon, yellow sea cold water mass, changjiang diluted water, coastal current of Jiangsu and Zhejiang, Taiwan Warm water and so on, theYangshan Port has a unique characteristics, which caused the zooplanktondiversity changing irregularly.3. The results of CLUSTER analyses and MDS showed the obviouslyseasonal difference of the zooplankton community inYangshan port. Thereis significant difference between summer with autumn and spring withwinter (p<0.05). The zooplankton communities can be divided into sixgroups in spring, and the community similarity was65%. The zooplanktoncommunities can be divided into six groups in summer, and the communitysimilarity was70%. The zooplankton communities can be divided into sixgroups in autumn, and the community similarity was60%. But thezooplankton communities can be divided into three groups in winter, andthe community similarity was70%. For the spatial distribution ofzooplankton in Yangshan port, the differences between section S1to S3andsection S4with S5were significantly (p<0.05). And the sampling sites atchannel were also different with xiaoyangshan side and dayangshan side(p<0.05). According to the features of zooplankton community, wesuggested it should be set three monitoring sections from east to west ofYangshan port, the east, the middle and the west in respectively. Eachsection has three parallels. This is the best and optimized design now.4. The result of Principal Component Analysis (PCA) on the environmental factors showed that there were significant differences samplings. To thefurther analysis, RELATE showed there were significant correlation withenvironmental factors and zooplankton community(spring, ρ=0.49，p=0.001; summer, ρ=0.51，p=0.001; autumn, ρ=0.43，p=0.001; winter,ρ=0.26，p=0.001). The zooplankton community of four seasons relied ondifferent environmental factors combination. Different species had differentadaptability to environmental factors. The correlation coefficients fordissolved oxygen with temperature and zooplankton community was0.658in spring. The correlation coefficients for temperature with salinity, pH,suspended solids and zooplankton community was0.562in summer. Thecorrelation coefficients for temperature and zooplankton community was0.756in autumn. The correlation coefficients for temperature with totalnitrogen and zooplankton community was0.662in winter. Temperaturewas the common impact factor for four seasons.