| According to the monitoring results of zooplankton and phytoplankton and environmental factors in three sites(Dayang(DY), Xaoyang(XY) and Zuantouzui(ZZ)) of Yangshan port nearshore area from September 2014 to August 2015. The spatial distribution characteristics of nearshore environmental factors, plankton communities and the correlation of biological and environmental in Yangshan port was analysised. The long-term ecological research of plankton in Yangshan port from 2011 to 2015 was also analysisied in this study. Then compared to the historical data that was plankton community structure characteristics in 1980 s, 1990 s and 2000 s, aimed to analysis the long-term variation of the plankton community in Yangshan port.The results show that:1. After researching the spatial distribution characteristics of environmental factors in Yangshan port nearshore(XY, DY and ZZ), the results of temperature, p H, dissolved oxygen, salinity, suspended solids, total nitrogen, total phosphorus, and silicate were showed. From september 2014 to august 2015, the range of temperature is 6.80 ~ 27.10℃, 27.10 ~ 26.60℃ and 6.90 ~ 28.70℃ respectively in XY, DY and ZZ. The monthly temperature of three sites changed unconspicuously and had similar annual variation with obvious seasonal change. Average p H value was respectively 8.13(XY), 8.14(DY) and 8.12(ZZ). Maximum value of salinity was in spring(march) in each site, and little bit mouth salinity minimum of XY and ZZ appeared in summer, minimum of DY appeared in autumn. Each point annual average value of suspended solids with obvious differences respectively was 1015mg/L(XY) > 877mg/L(ZZ) > 863mg/L(DY). Seasonal variation of total nitrogen was obvious, the concentration of spring and summer rised. From april to august, total nitrogen in DY and XY was higher., decreased in autumn and winter, total nitrogen of DY in December dramaticly rised phenomenon. In winter, DY’s total nitrogen is higher than the other two sites. The total phosphorus annual concentration had fluctuating change, DY’s change was the largest, between the maximum and the minimum was 0.28 mg/L, the second was in XY, the change was the smallest in ZZ. Seasonal change of silicate concentrations in each site was obvious, become lower in fall. XY’s change was the largest, between the maximum and the minimum was 0.49 mg/L, the second was in DY, the change was the smallest in ZZ.2. From 2014 to 2015, there were four taxon 18 genus, a total of 146 species collected in phytoplankton, the total number of phytoplankton species in three sites(DY, XY and ZZ) was 87, 79 and 90 respectively. There were most species of bacillariophyta, of which was 79(DY), 61(XY) and 83(ZZ), that with the total number of species of 87%, 92% and 91% respectively. Followed by pyrrhophyta, that species number was five, six and six respectively, with the percent of 6%, 9% and 7%. Chlorophyta species was less, there were respectively 2, 2 and 1, with the percent of 2%, 3% and 1%. Euglenophyta was only collected in DY and XY, the species number was 1 with one percent. Skeletonema costatum was the absolute dominant species in 2014~2015. Dominance was 0.72(DY), 0.56(XY) and 0.55(ZZ) respectively, most of the dominant species were included in diatom in three sites. The dominant species composition of DY and XY is relatively similar, but ZZ‘s dominant species composition is different with peculiar dominant species, such as Achnanthes tropics, Melosira moniliformis, Melosira nummuloide and Achnanthes brevipes. Analysis of Variance(ANOVA) showed that the difference of phytoplankton diversity index in three sites was significant(P<0.01). The species richness in DY was the highest, followed by ZZ and XY. But ZZ‘s evenness and Shannon Wiener index was higher than DY‘s, XY‘s was lowest. Average density monthly of phytoplankton was 7.19×104 cells/L(DY), 6.42×104 cells/L(XY) and 6.78×104 cells/L(ZZ) respectively in 2014~2015. One-way ANOVA showed that there was no significant difference between phytoplankton annual densities in three sites(P>0.5), but each season of average density showed significant difference(P<0.01). The mouthly trends of density in three sites were similar.3. In this study, there were five taxon of zooplankton consisted of enterocoely, plankton Crustacean, larvae, chaetognath and protozoa from September in 2014 to August in 2015. The percentage of planktonic crustaceans and larvae as the main group was 45% and 54% respectively in the density of zooplankton. Most planktonic crustaceans were found in XY with the density of 4.94 ind./L, followed by DY and ZZ with the density of 2.57 ind./L and 0.42 ind./L. Planktonic larvae density was 2.37 ind./L(DY), 6.03 ind./L(XY) and 1.72 ind./L(ZZ) respectively, thus highest density in XY. Zooplankton comminity was more richness with more abundance in XY and DY, but it‘s worse in composition and density of ZZ. There were 32 species of zooplankton in Yangshan port, 26 species in DY, 21 species in XY, 20 species in ZZ. The same dominant species of three sites were Acrocalanus monachus, Lubbockia marukawai, Limnoithona tetraspina, Copepodid larva, Cephalopods,Nauplius larva, Sabellariidae and Sagitta sp., the dominance of Acrocalanus monachus is largest with the dominance of 0.49(DY), 0.37(XY) and 0.17(ZZ), the followings were larvas and Limnoithona tetraspina. Analysis of Multidimensional Scaling(MDS) and CLUSTER showed that zooplanktonic community was obvious different between ZZ and DY&XY in summer. In 2014 ~ 2015, average density of zooplankton were 4.97 ind./L(DY), 11.03 ind./L(XY) and 1.63 ind./L(ZZ), the minimum of zooplankton density was in ZZ. The range of evenness index(J) was respectively 0.4 ~ 1(DY), 0.4 ~ 0.9(ZZ) and 0.5 ~ 0.8(XY). The range of Shannon-Wiener index(H) was 1.08 ~ 1.75(DY), and 1.03 ~ 1.7(XY) and 0.84 ~ 1.84(ZZ). The biggest change of Shannon-Wiener throughout the year was in ZZ.4. From 2011 to 2015, the range of average phytoplankton density in Yangshan port was from 7.92×103 to 4.36×105 cells/L. Phytoplankton density change was not stable and had no obviously regular change. There were more dominant species in winter, with a species number of 10, whereas those were less in summer and fall with a species number of 2~6. The seasonal variation of total nitrogen and total phosphorus concentration was significant with a higher level in summer and lower level in winter. Results indicated there was a significant difference in phytoplankton density(P<0.05) due to the tidal changes in harbor. Pearson correlation analysis showed that there was a significant positive correlation between diatom density and suspended solids and total phosphorus(P<0.01). Phytoplankton density was affected by phosphorus greatly. Since the 1980 s, the density of phytoplankton increased significantly. The increasing rate of phytoplankton density was up to 103, 102 and 10 in 1980 s, 1990 s and after 2000 s, respectively. The number of dominant species in dinoflagellates was increased and the composition was also changed. The size of dominant species in diatom was decreased minimized gradually.5. From 2011 to 2015, the range of average zooplankton density in Yangshan port was from 0.81 to 9.27 ind./L. The winter was the season of zooplankton density minimum, followed by spring and autumn, the highest density was in summer. The main taxon of zooplankton were larvae and plankton crustacean with the total zooplankton density of 22%~66% and 34%~61% respectively. About 31 species were found in Yangshan port during five years. The composition of dominant species from 2011 to 2015 was in extremely significant difference(P < 0.01). Yangshan port zooplankton density was a dramatic rising in the 1890 s, but the density was decresing in 2009~2010. Zooplankton biomass had dramatic changes in 1980 s~2000 s. During the period of 1982 ~ 2001, there was no significant change in the zooplankton biomass, which was sharply increasing in 2009.During the study of environmental factors and plankton community spatial distribution in Yangshan port nearshore, there were certain differences of aquatic environment between three sites because of human disturbance factors. Many years of research showed that water environment in Yangshan port had unique characteristics due to the influence of the Yellow sea cold water, Changjiang diluted water, Jiangsu and Zhejiang coastal current and Taiwan warm current, etc. Compared to the historical data, the abundance of phytoplankton and zooplankton in Yangshan port were rising sharply during past 30 years. The increment of phytoplankton density and the change of community structure were affected by eutrophication, imbalance of nutrient structure in Yangshan port. |
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