Studies On The Distribution Of Zooplankton Community And The Effects Of Environmental Factors In Longyuan Offshore Wind Farm Area Of Rudong

Some studies indicated that the establishment of offshore wind farm might change tide motion characteristics including waters flow field,erosion and deposition of sediment,and then produced the vertical movement of upwelling and eddy currents.Under the effect of these currents,the phenomenon of sediment resuspension can be caused,which released the nutrients in sediment into water.These changes of suspended solids concentration might impact the growth and feeding activity of zooplankton directly and indirectly,and eventually influenced zooplankton commity.In general,high suspended solids concentration within a certain range can lead to a reduction of marcozooplankton abundance.The impact of mircozooplankton abundance varies based on the suspended solids concentration,lastly might show miniaturization of zooplankton community.This paper investigated the zooplankton and the main environmental factors obtained from three cruises in May.,Aug.,and Nov.of 2015 on Longyuan off wind farm waters in Rudong.We analyzed the spatio-temporal distribution of zooplankton,combining the data before the construction of the wind farm.We concluded the influence of wind farm on the zooplankton community.Moreover,we identified how the zooplankton influnced by the wind farm through Canonical Correlation Analysis(CCA),Redundancy Analysis(RDA)and Multiple Regression Analysis.The main results are as follows:We identified 9 categories and 27 species of macrozooplankton during the three cruises,including Copepod(14 species),Chaetognatha(3 species),and Jellyfish(3 species),Decapod(2 species),Mysidacea(1 species),Tunicata(1 species),Euphausiacea(1 species)and Amphipoda(1 species),respectively.We also identified 8 categories and 39 species of microzooplankton,including Copepod(16 species),Chaetognatha(7 species),Jellyfish(7 species),Mysidacea(3 species),Amphipoda(2 species),Ostracoda(2 species),Euphausiacea(1 species)and Tunicata(1 species)respectively.Decapod included 2 species,Mysidacea,Tunicata,Euphausiacea and Amphipoda included 1 species respectively.Copepod is the dominant group of Crustacea,and pelagic larvae accounts for large proportion in our investigate.The biomass of marcozooplankton in the area of wind farm was higher than that outside the wind farm.The marcozooplankton abundance were no significant difference between inside and outside the wind farm,so as the microzooplankton.The Shannon-wiener index of marcozooplankton and microzooplankton has significant difference between inside and outside the wind farm.The Shannon-wiener index of marcozooplankton in the area of wind farm was higher than that outside the wind farm.Conversely,The Shannon-wiener index of microzooplankton has a opposite spatial distribution.Compared with the pre-construction of wind farm,in spring,the abundance of marcozooplankton declined slightly and the biomass obviously increased.In autumn,the biomass and abundance of marcozooplankton and mircozooplankton sharply decreased,especially the former.And the Shannon-wiener index also showed an marked drop trend.In general,the dominance of Acartiidae in the marcozooplankton was obviously decreased,but the dominance of Copepods larva in the mircozooplankton increased significantly.Harpacticoida Cyclopoidea changed to the common species of all zooplankton after the construction of wind farm.Moreover,the water showed a trend of eutrophication in our study area.Based on the survey data of 2008,by using the method of CCA and RDA,this paper studied the relationship between the marcozooplankton,mircozooplankton species and its envionmental factors.The result showed that water temperature,dissolved oxygen,pH and suspended matter cocentration were the most important factors influencing the zooplankton community.The suspended matter cocentration had an opposite effect on the marcozooplankton and mircozooplankton community,zooplankton community might show miniaturization of zooplankton community.As for the zooplankton community characteristic data,which had the great est change,we did the correlation analysis with the envionmental factors.Our results suggest that NO3--N,suspended matter cocentration,species quantity and abundance of phytoplankton are significantly correlated to marcozooplankton a nd mircozooplankton abundance.The regression equation between marcozooplan-kton abundance and its envionmental factors was LnD=0.96-1.6791n(SS)-1.4781 n(NO3--N)+1.3011n(abu_phy)+1.279ln(NO2--N).And the regression equation betw een the mircozooplankton abundance and its envionmental factors was lnDi=0.078-1.4261n(NO3--N)+1.2071n(abu_phy)-1.1631n(SS)+0.763(NO2--N).The analysis a-bove indicated that the suspended matter cocentration played a major role in t he change of the abundance of zooplankton.In the RDA and Multiple Regression Analysis above,the suspended matter cocentration played a reverse role in the abundance of microzooplankton.This is because that suspended matter concentration had different effects on different species of zooplankton and that it had different effects within different conc-entration range.As a result,the suspended matter cocentration had a different impact on the total microzooplankton abundance.