鲢鳙放养对水体微生物碳源利用影响的围隔试验

Effects of stocked silver carp and bighead carp on carbon sources utilized by microbes in enclosures in Lake Gehu

利用Biolog技术就滆湖原位围隔内鲢鳙放养密度和比例对水体微生物碳源利用的影响进行了研究。结果显示,在试验阶段后期不同围隔内水体微生物对碳源总量的利用相对于试验中期有较明显的变化。未放养鲢鳙的对照组(A0)在试验后期对于碳源总量的利用低于各实验组(A_1:鱼密度40 g/m^3、鲢鳙比7∶3;A_2∶40 g/m^3、3∶7、A_3∶80 g/m^3、7∶3和A_4∶80 g/m^3、3∶7)。试验中期和后期,利用比例较高的碳源类型均为聚合物。主成分分析表明,试验后期不同围隔水体微生物群落碳代谢方式具有显著差异。其中,与主成分1显著相关的碳源主要有16种,分别属于聚合物、糖类、羧酸、氨基酸。实验中期和后期围隔水体微生物碳代谢多样性指数Shannon物种多样性指数、丰富度指数和Pielou均匀度指数均存在显著差异,代谢多样性指数最高的是实验组A1,实验组A4碳代谢多样性指数相对较低。根据鳙的绝对生物量、多样性指标以及对碳源的总量利用,可以得出以鲢鳙主导的微型生态系统中,鳙的绝对生物量对于水体微生物影响更加显著。

Using Biolog technique,the effect of stocking density and ratio of silver carp（ Hypophthalmichthys molitrix） and bighead carp（ Aristichthys nobilis） on carbon sources utilized by aquatic microbial communities was studied in Lake Gehu.The results showed that total amount of carbon sources utilized by microbes in the last phase of experiment obviously varied compared with that in the middle phase of experiment. In the middle phase of experiment,the total amount of carbon sources utilized by microbes of control group（ A0） was lower than that of the other experimental group（ A1： stocking biomass of 40 g/m^3 and stocking ratio of silver carp to bighead carp of 7∶ 3; A2： 40 g/m^3,3∶ 7; A3∶ 80 g/m^3,7∶ 3; A4∶ 80 g /m^3,3∶ 7）. Polymers were the main type of carbon sources both in the middle and last phase of experiment. Principal component analysis（ PCA） revealed that the carbon metabolism way of the microbial communities differed significantly among different experiment treatments in the last phase of experiment. A total of 16 categories of carbon sources were significantly related to the first principal component,which were belonged to polymers,carbohydrates,carboxylic acids and amino acids. There were significant differences among different experiment treatments in carbon utilization diversity indices of the microbial communities,including Shannon diversity,richess and Pielou evenness,with the highest and lowest metabolism diversity for A1 and A4,respectively. According to the relationship of biomass of bighead carp and diversity indices and total amount of carbon sources,absolute biomass of bighead carp had more impacts on the functional diversity of aquatic microbial communities in the microcosms dominated by silver and bighead carp.