Study On Phytoplankton Community Structure And Seasonal Variation In Ningbo-Zhoushan Port Water

In this study the phytoplankton community in Ningbo Water, Zhoushan Sea and YushanIsland were investigated from Oct.2009to Jul.2012. Which were mainly composed of speciescomposition, quantity change, dominant species, community structure as well as horizontaldistribution characteristic parameters such as seasonal change. The main contents are as follows:There were five stations in Ningbo Water (Meishan, Guoju, Daxie, Xiepu, Zhenhai). A totalof97species were identified, belonging to four phyla. The diatoms species were dominant, up to71.25percent of total taxa. Coscinodiscus subtilis Ehrenberg were the absolutely dominant speciesin very season and respectively. Annual average cell abundance was3.75×10~6cell/L. The cellabundance reached the peaks in spring and summer, nearly up to5.3×10~3cell/L,4.5×10~3cell/L andtheir highest richness occurred in the Daxie water.In autumn and winter, their richness centersshifted to the Meishan waters (6.3×10~3cell/L,6.6×10~3cell/L). The biotic index being the highest (H′is3.73, d1.17) in autumn and the lowest (H’3.08, d0.67) in spring. Pielou index the highest(J′1.32) in summer and the lowest (J′1.32) in spring and auytmn, which index changed muchthroughout the year. The degree of water quality was Meishan>Guoju>Daxie>Xiepu>Zhenhai.There were five stations in Zhoushan Sea (Gouqi, Sijiao, Dongji, Zhujiajian, Taohuadao). Theresults showed that4classes, including45genuses and102species were found. The diatomsspecies were dominant, up to87.3percent of total taxa. The cell abundance was an average of3.04×10~4cell/L. The maximum cell abundance appeared in the spring (May), followed insummer(August).The Common species were Coscinodiscus asteromphalus Ehrenberg, Biddulphiasinensis Greville, Noctiluca scientillans (Macartney) Kofoid et Swezy, Chaetoceros decipiensCleve and Thalassiothrix frauenfeldii (Grun.)Grunow. The cell abundance of Noctiluca scientillans(Macartney) Kofoid et Swezy was4.9×10~3cell/L, and Thalassiothrix frauenfeldii (Grun.)Grunowwas2.7×10~3cell/L. The biotic index being the highest (H’is3.48, d1.18) in summer and the lowest(H’3.00, d0.81) in autumn. Pielou index the highest (J′1.40) in winter and the lowest (J′1.19) insummer. The degree of water quality was Gouqi>Sijiao>Dongji>Zhujiajian>Taohuadao.There were eught stations in Yushan Island(Ximatou, Daao, Dongao, Dengta, Xianrenqiao,Dabaijiao, Baijiaowei, Baijiaowan). A total of133species of43genera of4phyla were identified,among which,93species belonged to32genera of diatoms,35species belonged to8genera ofdinoflagellates,3species belonged to2genera of chlorophyta, and2species belonged to1generachrysophyta. The main dominant species were Skeletonema costatum (Greville)Cleve and Chaetoceros curvisetus Cleve.The dominance of C. s curvisetus Cleve in spring was hightest inthis survey, which reached0.37. The cell abundance and biomass being the highest (185×10~3cell/L,2.76mg/L) in spring. The biotic index being the highest (H’4.79, d2.18, J1.31) in autumn and thelowest (H’2.82, d1.40, J0.87) in spring. Correlation analysis demonstrated that the distribution ofphytoplankton community had definite correlations with water nutrient content, temperature andsalinity C. s curvisetus cells in summer could greatly reproduce, even result in high probability ofred tide.Principal component analysis showed that water temperature, salinity, pH, dissolvedoxygen, transparency, total phosphorus, total nitrogen, ammonia nitrogen and nitrite salt waterquality can be a very good response. Through biodiversity comparing the degree of waterquality was:yushan islands>ningbo water>zhoushan sea. Although the three sea water qualityis good, but should be timely to monitoring the red tide species, to prevent the deterioration ofwater quality.