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叶绿素a(Chl.a)是各类水体浮游植物生长状况的表征,其含量体现出水体生态系统的初级生产能力和水质环境状况。Chl.a含量的高低与诸多环境因子的变化密切相关,以通径分析的方法来研究水体环境因子变化对Chl.a的影响,能够剖分Chl.a受各环境因子的影响为直接和间接作用,解析出各因子对浮游植物生长效应的决定比例,使复杂的水体环境因子关系明了清晰化。该实验主要研究罗非鱼(Oreochromis niloticus)养殖池塘水体营养因子TN、TP、NH_4~+-N、NO_3~--N、NO_2~--N及pH变化对Chl.a的影响,通过相关性分析和多元回归分析剔除了对Chl.a影响不大的TN和NO_2~--N,并在此基础上根据偏回归系数建立罗非鱼养殖池塘Chl.a与环境因子的多元回归方程。重点进行了通径分析,计算得出pH、TP、NH_4~+-N和NO_3--N变化对叶绿素a影响的直接通径系数分别为0.416、0.325、0.404和-0.223,间接通径系数总和分别为-0.276、0.198、0.072和-0.163。分析表明,环境因子的变化其自身可以以直接敏感的方式较大比例地影响浮游植物的生长和繁殖,而通过作用其他因子间接对浮游植物的生长和繁殖产生影响的路径也十分重要,前后两者的绝对作用值和的比例分别约为65.9%和34.1%。决定系数显示TP和NH_4~+-N是对Chl.a影响最大的因子,其决定值分别达到了0.235和0.221。研究表明,通径分析能够更科学地为了解罗非鱼等养殖池塘水体系统的营养结构、更合理地为水体环境的控制和改善及健康养殖模式的寻求提供科学依据。
Chlorophyll a (Chl.a) is a manifestation of phytoplankton growth in various types of water bodies, and its content reflects the primary production capacity of aquatic ecosystems and water quality and environmental conditions. The level of Chl.a is closely related to the changes of many environmental factors, and the influence of environmental factors on Chl.a is studied by the method of path analysis. Chl.a can be divided into direct and indirect effects by various environmental factors Role, to resolve the various factors on the growth of phytoplankton the proportion of the decision-making, so that the relationship between complex water environmental factors clearly clear. The experiment mainly studied the effect of the changes of nutrition factors TN, TP, NH_4 ~ + -N, NO_3 ~ -N, NO_2 ~ -N and pH on the growth of Chl.a in the ponds of Oreochromis niloticus. Through the correlation Analysis and multiple regression analysis removed TN and NO_2 ~ --N, which had little effect on Chl.a, and on the basis of partial regression coefficients, established multiple regression equations of environmental factors and Chl.a in tilapia farming ponds. The path analysis was focused on and the direct path coefficients of chlorophyll - a, pH, TP, NH_4 ~ + -N and NO_3 - N were calculated to be 0.416, 0.325, 0.404 and -0.223 respectively. The sum of the indirect path coefficients Respectively -0.276, 0.198, 0.072 and -0.163. The analysis shows that the change of environmental factors can itself affect the growth and reproduction of phytoplankton in large proportion in a direct and sensitive way, and it is also very important to indirectly influence the growth and reproduction of phytoplankton by acting on other factors. The absolute value of the role and the proportion of about 65.9% and 34.1%. The coefficient of determination shows that TP and NH_4 ~ + -N are the most influential factors on Chl.a, and their determination values reach 0.235 and 0.221 respectively. The research shows that the path analysis can provide a scientific basis for more scientific understanding of the nutritional structure of aquaculture ponds such as tilapia and more reasonable for the control and improvement of water environment and the seeking of healthy breeding mode.