广西北海凡纳滨对虾养殖池塘叶绿素a和微藻的变化研究

于不同养殖时间,采集广西北海市3口凡纳滨对虾（Litopenaeus vannamei）养殖池塘水样,调查养殖水中叶绿素a浓度和微藻组成。叶绿素a浓度用分光光度三波长法测定,微藻分类计数用镜检法进行,微藻多样性分析用Shannon-Wiener多样性指数、Pielou种类均匀度指数和种类优势度指数进行。结果表明,3口池塘叶绿素a的浓度养殖前期低,在10.0μg/L以内,养殖中期增长迅速,养殖后期达到150.0μg/L;微藻细胞密度在养殖前期低于20×106cells/L,养殖后期高于100×106cells/L;微藻多样性指数和均匀度指数皆为养殖前期高,养殖中后期逐渐降低,多样性指数0.98～3.15,均匀度指数0.28～0.82;在养殖前期,微藻的种类较多,优势种是硅藻和绿藻,养殖中后期种类减少,优势种是绿藻、蓝藻和甲藻。

Variation of Chlorophyll a Concentration and Microalgae Composition in Litopenaeus vannamei Culture Ponds in Beihai,Guangxi

Variation of chlorophyll a(Chl.a) concentration and microalgae composition was studied in 3 culture ponds of Litopenaeus vannamei in Beihai City.The results indicated that there was a distinct change of Chl.a concentration during the culture period.In the early stage,Chl.a concentration was lower than 10.0μg/L,then it increased rapidly and reached about 150.0μg/L in the late stage.Similar to Chl.a concentration,cell density of microalgae was lower than 20×106 cells/L in the early stage and higher than 100×106 cells/L in the late stage.On the contrary,diversity index and evenness of microalgae were high in the early stage and low in the late stage.The diversity index fluctuated from 0.98 to 3.15,and the eveness index from 0.28 to 0.82.There were more microalgae species in the early stage than that in the late stage.In the early stage,the dominant species belonged to Bacillariophyta and Chlorophyta,and that belonged to Chlorophyta,Cyanophyta and Pyrophyta in the late stage.There were some little differences on the variation of Chl.a concentration and microalgae composition in the three culture ponds.