Photosynthetic activity of phytoplankton in Lake Gehu and Lake Luoma in spring

Abstract

本研究应用Phyto-PAM荧光仪测定滆湖和骆马湖春季浮游植物的光合活性,包括浮游植物最大光量子产量Fv/Fm(可变荧光与最大荧光之比)、有效光量子产量Φ_PSII(实际光合作用效率)和快速光响应曲线(RLC);同时,采用显微镜对浮游植物进行镜检和计数.结果表明:滆湖蓝藻和硅藻的最大光量子产量分别为0.36~0.52和0.27~0.53,实际光量子产量分别为0.25~0.37和0.25~0.36,没有检测到绿藻的光合活性,RLC曲线表明蓝藻有较高的光合作用效率,更易形成优势种群;骆马湖绿藻和硅藻的最大光量子产量分别为0.45~0.65和0.41~0.49,实际光量子产量分别为0.25~0.32和0.19~0.25,没有检测到蓝藻的光合活性;滆湖浮游植物丰度在530×10⁴~4200×10⁴cells/L之间,平均值为2918×10⁴cells/L,群落组成以蓝藻门、硅藻门、隐藻门和裸藻门为主;骆马湖浮游植物丰度在260×10⁴~510×10⁴cells/L之间,平均值为379×10⁴cells/L,群落组成以硅藻门和绿藻门为主.综合滆湖和骆马湖水体的营养水平、浮游植物丰度和光合作用活性表明,湖泊富营养化能提高浮游植物种群丰度和蓝藻的光合作用活性,进而有利于蓝藻在浮游植物群落中占有竞争优势.;In the present study,Phyto-PAM was applied to measure maximal photochemical quantum yield of PSII (Fv/Fm), actual photochemical efficiency of PSII (Φ_PSII),and rapid light response curve (RLC) of phytoplankton samples collected from Lake Gehu and Lake Luoma in spring.Meanwhile,the cell numbers of phytoplankton were counted by microscopy.The results showed that values of Fv/Fm and Φ_PSII of cyanobacteria in Lake Gehu varied from 0.36 to 0.52 and from 0.27 to 0.53,and Bacillariophyta, from 0.25 to 0.37 and from 0.25 to 0.36,respectively,but there was no photochemical vitality of Chlorophyta.RLC has indicated that cyanobacteria has higher photochemical vitality and are prone to form advantage populations in Lake Gehu.On the other hand,the values of Fv/Fm and Φ_PSII of Chlorophyta and Bacillariophyta in Lake Luoma ranged from 0.45 to 0.65, from 0.41 to 0.49,from 0.25 to 0.32,and from 0.19 to 0.25,respectively,and no photochemical vitality were found for cyanobacteria.The density of phytoplankton in Lake Gehu ranged from 530×10⁴ to 4200×10⁴ cells/L,with an average of 2918×10⁴ cells/L.Cyanophyta,Bacillariophyta,Cryptophyta and Euglenophyta were dominant in the phytoplankton community.The density of phytoplankton in Lake Luoma varied from 260×10⁴ to 510×10⁴ cells/L,with an average of 379×10⁴ cells/L,Bacillaryophyta and Chlorophyta were dominant in the phytoplankton community.According to the comparison between nutritional level,the abundance and photochemical vitality of phytoplankton assemblages in the two lakes,the lake eutrophication can increase the abundance of phytoplankton and photosynthetic activity of cyanobacteria,and become in favor of gaining advantages in phytoplankton assemblages.