【作者】 杨建雷；

【导师】 董双林；

【作者基本信息】 中国海洋大学 ， 水产养殖， 2011， 硕士

【摘要】 本研究于2009-2010年在山东省淡水养殖研究所进行,实验采用围隔将淡水养殖池塘进行分隔,在不同围隔中按照不同比例混养草鱼（Ctenopharyngodon idellus）、鲢鱼（Hypophthalmichthys molitrix）和鲤鱼（Cyprinus carpio Linnaeus）,应用传统的显微镜计数法与生化标志法,即色素分析与脂肪酸谱分析,相结合的方法,比较了不同混养模式的围隔内浮游植物群落结构的变动和不同,从而对淡水鱼类混养池塘中,鲢鱼的滤食作用对浮游植物群落结构的影响进行了分析研究。显微镜计数结果表明,鲢鱼混养组中隐藻门的隐藻与硅藻门的小环藻、冠盘藻或针杆藻等为优势种,鲢鱼的滤食作用导致浮游植物的粒级趋于小型化,<5μm、5²0μm和>20μm的浮游植物分别占浮游植物生物量的69%、24%和7%;同时浮游动物也趋于小型化,个体较小的原生动物和轮虫生物量占有相对优势,导致浮游动物生物量降低;无鲢鱼混养的草鱼单养及草-鲤混养组色球藻和螺旋藻大量发生,导致蓝藻水华的暴发,草-鲤混养组中<5μm、5²0μm和>20μm的各粒级对浮游植物生物量的贡献率分别在30%左右,个体较大的枝角类和桡足类占相对优势。实验中悬浮颗粒物（SPM）范围为18.89¹16.27 mg/L,平均值为52.49 mg/L,颗粒有机物（POM）与SPM含量之比的平均值为50.08%,POM与SPM呈显著正相关（R²=0.188,P<0.01）,较好地评价了池塘悬浮颗粒物的性质。从浮游生物群落结构的角度看,三元混养组最好,二元混养组其次,草鱼单养组最差,三元混养组中,草鱼、鲢鱼和鲤鱼的最佳放养密度分别为0.58 ind·m^-2、0.69 ind·m^-2和0.19 ind·m^-2。高效液相色谱的方法（HPLC）成功的分离了主要微藻种群的标志性特征色素,各特征色素分别与对应的浮游植物种类生物量相关性显著,如变异花黄素（alloxanthin）与隐藻生物量、叶黄素（lutein）与绿藻生物量相关关系显著。浮游植物种类的多样性与色素种类的多样性相对应。对色素数据进行多元相似性分析显示,8月和9月各混养模式之间差异显著,而10月差异不显著。8月,鲢鱼对蓝藻水华控制能力最强,有效抑制蓝藻水华,9和10月,鲢鱼的抑制作用减弱,但鲤鱼对底泥的扰动作用一定程度上控制了蓝藻水华。整个养殖过程中,各混养组中叶绿素酸酯a （chlorophyllide a）的高含量表明了叶绿素a （chlorophyll a）的大量降解,文中详细分析了chlorophyllide a的具体来源。10月份,chlorophyllide a含量明显高于8、9月,这与10月份温度降低,说明了浮游植物的大量的衰老和死亡。叶绿素酸酯（chlorophyllide a）对组内相似性和组间差异性贡献最大,墨角藻黄素（fucoxanthin）或变异花黄素（alloxanthin）其次,而在草鱼和鲤鱼混养组中,玉米黄素（zeaxanthin）对组内相似性占一定的贡献率,说明在鲢鱼组中包含墨角藻黄素（fucoxanthin）和变异花黄素（alloxanthin）的藻类（硅藻、甲藻和隐藻）占优势,而在草鱼和鲤鱼混养组中包含玉米黄素（zeaxanthin）的蓝藻占优势。浮游植物特征脂肪酸的组成与变化较好地表征了水体中浮游植物的群落结构的月份变化以及不同养殖模式对浮游植物群落结构的影响。各月各组内和各组间浮游植物脂肪酸的差异显著,表明各围隔间浮游植物群落结构的差异性。细菌脂肪酸（BAFA）占总脂肪酸的3.40-10.23%,C13:0是主要的BAFA,G组细菌脂肪酸含量略高于GS组,说明了围隔中细菌的大量存在,G组浮游植物衰老更快,鲢鱼加快了浮游植物的演替。多不饱和脂肪酸（PUFA）占总脂肪酸的14.20-56.29%,C18:2n6、C18:3n6、C18:3n3和C20:5n3是PUFA的主要成分,反映了养殖过程中各组营养状态较好。对草鱼组和草-鲢混养组脂肪酸数据进行MDS分析显示,各月草鱼组和草-鲢组明显成簇分布。7月和8月C16:0和C18:1n9均对两组组内的相似性贡献最大,而9月和10月C16:0、C18:3n3、C18:3n6和C20:5n3均对两组组内的相似性贡献最大,各月C20:5n3、C18:3n3和C18:3n6对各组间的不相似性贡献最大,说明不同月份鲢鱼滤食作用不同,鲢鱼对包含C20:5n3、C18:3n3和C18:3n6的浮游植物种类组成影响比较显著。7～9月,草鱼单养组中,包含C18:3n3和C18:3n6的绿藻和裸藻对浮游植物生物量的贡献相对较大,鲢鱼混养组中,绿藻和裸藻对浮游植物的生物量贡献较小。10月份,草鱼单养组中,包含C18:3n3和C18:3n6的绿藻或裸藻对浮游植物生物量的贡献较小,鲢鱼混养组中,绿藻或裸藻对浮游植物的生物量贡献较大,说明鲢鱼通过改变水体浮游植物组成改变了水体的营养状态。显微镜计数、色素分析和脂肪酸谱得方法从不同的角度表征了浮游植物的群落结构。三种方法的结合使用可以弥补单一方法的不足,更加全面准确地反映鲢鱼的滤食作用对浮游植物群落结构的影响,为优化草鱼、鲢鱼和鲤鱼混养结构提供了理论依据。更多还原

【Abstract】 Experiments about polyculture of grass carp, silver carp and common carp are conducted in ponds of Freshwater Fishery Research Institute of Shandong Province from 2009 to 2010 using the enclosure approach. The dynamics of phytoplankton community structure, phytoplankton size structure and seston structure are studied by microscopy; HPLC pigment data are compared with microscopy to analyze the phytoplankton community structure and the use of HPLC pigment analysis in freshwater ponds is also discussed; the relations between phytoplankton fatty acid compositon and phytoplankton community structure, nutrition status are analyzed by using diagnostic fatty acid, respectively. Attentions are focused on the filtration effect of silver carp.Polyculture of silver carp can suppress the Cyanobacteria bloom and make phytoplankton size smaller, contributions of <5μm, 5²0μm, >20μm are about 69%, 24%, 7% to total phytoplankton biomass, respectively; Zooplankton are dominated by protozoa and rotifer and zooplankton biomass is reduced by silver carp. In group GC without silver carp, Cyanobacteria bloom occurrs, contributions of three size strcutures to total phytoplankton biomass are about 30% and zooplankton are dominated by copepods and Cladocera. Suspended particulate matter（SPM）concentration ranges from 18.89 mg/L to 116.27 mg/L and is 52.49 mg/L on average. The contribution of particulate organic matter（POM）to SPM averages 50.08%. Positive correlation（R²=0.188,P<0.001）is found between POM and SPM indicating the quality of SPM. Optimum stocking denstity is 0.58 ind·m^-2, 0.69 ind·m^-2 and 0.19 ind·m^-2 for grass carp, silver carp and common carp respectively.HPLC pigment analysis provides accurate separations of main pigment markers. class-specific phytoplankton biomass and corresponding pigment concentrations are correlated significantly such as alloxanthin with Cryptophytes biomass, lutein with Chlorophytes biomass. Significant difference is present between groups exclusively in August and September while insignificance in October. Silver carp can suppress the appearance of Cyanobacteria species in August and it takes a decreasing effect on the Cyanobacteria growth from August to October. Grass carp and common carp have failed to control phytoplankton biomass and algal bloom but common carp may play a complementary role in suppressing the growth of Cyanobactetia to a certain extent. The high content of chlorophyllide a indicates the importance of chlorophyll a degradation. Fucoxanthin-containing algal and alloxanthin-containing algal contribute most to similarity and dominate in silver carp group while contribute most to similarity zeaxanthin-containg algal dominate in group of grass carp and common carp group. The role of HPLC pigment analysis for assessing phytoplankton community structure should be considered as a strong complement to microscopic enumeration.Phytoplankton fatty acid compositon reflects the phytoplankton dynamics and the filtrate effect of silver carp. The diversity of fatty acid compositon between groups and within groups indicates the complication of phytoplankton compositon. BAFA, SFA, MUFA and PUFA represent for 3.40-10.23%, 30.06-51.32%, 10.25-34.68% and 14.20-56.29% of total fatty acid, respectively. C13:0, C16:0, C18:1n9, C16:1n7, C18:2n6, C18:3n6, C18:3n3 and C20:5n3 contribute a considerable percentage to the corresponding fatty acid taxa, respectively, which indicates the nutrient status in the ponds. Group of grass carp monoculture and group of polyculture of grass carp and silver carp cluster in the MDS ordination,respectively. C16:0 and C18:1n9 contribute most to similarities within groups in July and August while C18:3n3、C18:3n6 and C20:5n3 contribute a high percentage besides C16:0 in September and October. C20:5n3, C18:3n3 and C18:3n6 contribute most to dissimilarities between groups. Chlorophytes and Euglenophytes which contain abundant C18:3n3 and C18:3n6 contribute more relatively in group G compared with group GS from July to September, while the case is opposite in October. Nutrient status of ponds is changed by the filtration effect of silver carp.更多还原