Ecological Studies On Picoplankton In Coastal Waters Of Zhejiang

In this paper studies on the spatial and temporal distribution of Picoplankton and analyzed the correlation with environmental factors in the coastal waters of Zhejiang.Representative samples of sea water were collected in the coastal waters of Zhejiang for 4consecutive seasons in November 2014(Autumn),January 2015(winter),May 2015(spring)and July 2015(summer).The distribution of Picoplankton was studied by flow cytometry,and the correlation between the abundances of Picoplankton and environmental factors were also analyzed.The results of analysis of planktonic and heterotrophic bacteria,from the horizontal distribution,in the four seasons virioplankton and heterotrophic bacteria abundance showed low-abundance areas were the stations of Ningbo,Shenjiamen,Daishan immediate offshore area,high-abundance areas were the stations of Dongji and Gouqi offshore area.From the seasonal distribution,the abundance of the virioplankton and heterotrophic bacteria was the same as that of summer > spring > autumn > winter.The abundance of virioplankton and heterotrophic bacteria was significantly positively correlated in the 4 seasons.The abundance of virioplankton was significantly positively correlated with VBR in spring,autumn and winter.The abundance of virioplankton was significantly positively correlated with salinity in summer and autumn.The abundance of virioplankton was significantly negatively correlated with TP in spring and summer.The abundance of virioplankton was significantly positively correlated with dissolved oxygen,pH,COD in spring.The Heterotrophic bacteria was significantly positively correlated with dissolved oxygen in spring and summer and were significantly negatively correlated with dissolved oxygen in winter.The Heterotrophic bacteria was significantly negatively correlated with TP in spring and summer.The Heterotrophic bacteria was significantly positively correlated with salinity and temperature in autumn and winter.The Heterotrophic bacteria was significantly positively correlated with COD in winter and spring.The results of analysis of Picophytoplankton,from the horizontal distribution,in the four seasons,the abundance of picophytoplankton were low-abundance areas in the stations of Ningbo,Daishan,Shenjiamen immediate offshore area,high-abundance areas in the stations of Dongji and Gouqi offshore area.From seasonal distribution,the abundance of Prochlorococcus was in order of summer>autumn>winter>spring,the abundance of Synechococcus autumn>winter>spring>summer;and the abundance of Picoeukaryotes summer > autumn>spring>winter.Prochlorococcus,Synechococcus and Picoeukaryotes were significantly significantly corelated with pH in the spring.Prochlorococcus,Synechococcus and Picoeukaryotes were significantly significantly corelated with temperature in autumn.Synechococcus and Picoeukaryotes were positively correlated with salinity in winter.Prochlorococcus were significantly negatively correlated with TP and NH4+-N in spring.Picoeukaryotes was significantly negatively correlated with TP in summer,and was significantly positively correlated with NH4+-N.Synechococcus and Picoeukaryotes were significantly positively correlated with COD in winter.this research showed that the abundance of Picoplankton was generally lower in the immediate offshore area,and high abundance in the offshore area.The large amount of sediment discharge on the Yangtze River and the influence of human activities.sea water is turbid and transparency is low.All of these limit the photosynthesis of Picophytoplankton.This makes coastal primary productivity is not high.Indirectly,it also limits the growth and reproduction of virioplankton and heterotrophic bacteria.The Picoplankton was basically high in summer,and low in winter.The results of analysis showed that the water temperature rose in summer and the strong solar radiation.Terrigenous inputs bring rich nutrients.It was beneficial to the photosynthesis of Picophytoplankton,which makes Picophytoplankton increasing.Low water temperature limits the growth of Picophytoplankton in winter.