枯水期钦州湾浮游植物群落结构组成与分布特征

The structure and distribution of phytoplankton community in the Qinzhou Bay during dry season

应用浮游植物特征光合色素的分析方法，研究了2011年枯水期钦州湾浮游植物的结构组成与分布特征。结果表明：枯水期含量较高的浮游植物光合色素按含量高低依次为叶绿素 a、岩藻黄素、叶绿素 b、青绿素和多甲藻素，其他特征光合色素的含量很低。经 CHEMTAX 对光合色素转化计算，枯水期普遍检出的浮游植物类群为硅藻、青绿藻和甲藻，是枯水期浮游植物的优势类群，其生物量的平均值（±标准差）分别为（2．36±2．38）μg/L、（0．87±0．53）μg/L、（0．13±0．14）μg/L，变化范围为0．18～7．45μg/L、0．10～1．80μg/L 和0．02～0．60μg/L。硅藻、青绿藻和甲藻占枯水期浮游植物生物量比例的平均值（±标准差）分别为59％±21％、30％±16％、6％±4％，占比变化范围为29％～96％、1％～53％和0．4％～14％，其他藻类所占比例很低。河口和外湾靠外海域两个区域以硅藻为优势类群，内湾及外湾近岸硅藻和青绿藻共同为优势类群。河流营养盐输入量和比例的不同决定了钦州湾河口海区浮游植物群落结构的差异，大面积贝类养殖导致了内湾至外湾近岸海区硅藻比例的降低，而外湾水温的增加引起暖水性硅藻大量增长成为优势类群，在温度进一步增加和营养盐持续输入等条件下存在会发生硅藻赤潮的风险。

Photosynthetic pigment analysis method was used to analyze the structure and distribution of phytoplank-ton community in the Qinzhou Bay in the dry season of 2011.Data showed that the major phytoplankton pigments were chlorophyll a,fucoxanthin,chlorophyll b,prasinoxanthin and peridinin,while the levels of other photosyn-thetic pigments were very low.Bacillariophyta,Prasinophyceae and Dinoflagellates were detected as dominant phy-toplankton groups during the dry season by converting signal changes into phytoplankton spectra-dynamics with CHEMTAX software.The mean biomass of three groups phytoplankton were （2.36±2.38）μg/L,（0.87±0.53）μg/L,and （0.13±0.14）μg/L,ranging from 0.18 μg/L to 7.45 μg/L,from 0.10 μg/L to 1.80 μg/L,and from 0.02 μg/L to 0.60 μg/L,respectively.The Bacillariophyta,Prasinophyceae and Dinoflagellates occupied the total biomass of phytoplankton by 59%±21%,30%±16% and 6%±4%,ranging from 29% to 96%,1% to 53%and 0.4% to 53%,respectively.Bacillariophyta dominated in the Maolingjiang Estuary and its adjacent areas, while both Bacillariophyta and Prasinophyceae dominated in the inner and outer bay areas.The community struc-ture and distribution of the phytoplankton were influenced by river floods,salinity,and nutrients.Large-scale oys-ter aquaculture might lead to decrease of Bacillariophyta ratio in inner and outer bay areas,while increased water temperature in the outer bay might make Bacillariophyta largely grow and be the dominant group.The diatom red tide might occur under the condition of further increase in temperature and nutrient input.