Distribution Features and Relation of Phytoplankton with Environment Factors in the Coastal Water of Guangxi in Summer 2010

We investigated the abundance and species composition of phytoplankton community in the coastal water of Guangxi(21.35-21.90′N,118.00-119.70′E) during 4 to 26 June,2010.A total of 149 species belonging to 70 genera of 6 classes were identified.Diatoms contributed to 71.1% of the total phytoplankton species number and 95.81% of the total phytoplankton cell abundance;followed by dinoflage1lates,which accounted for 21.48% of total phytoplankton species number and 1.44%of the total phytoplankton cell abundance.The average density was 61.10×104 cell/L,was 58.54×104 cell/L and 0.88×104 cell/L for phytoplankton,diatom and dinoflagellate,respectively.Phytoplankton abundance had a lower value in Maowei sea and the coastal zone of Qinzhou port,in addition to the two areas,the quantitative distributions of phytoplankton presented a trend of being higher in the inner bay than in the outer bay.The dominant species were Pseudo-nitzschia pungens,Skeletonema costatum,Chaetoceros pseudocurvisetus,Thalassionema nitzschioides,Leptocylindrus danicus.P.pungens and C.pseudocurvisetus gathered in Fangchenggang sea area,while S.costatum gathered in the adjacent waters of Beihai.There were no significant relationships between phytoplankton abundance and temperature,salinity,nitrate,nitrite,ammonia salt and silicate.A positive relationship was found between phytoplankton abundance and phosphate in Beihai sea area and Fangchenggang sea area.Phosphorus was the limiting factor of phytoplankton in the above two sea areas.