草鱼不同混养模式下养殖水体的营养元素变化研究

A PRELIMINARY STUDY OF NUTRITION ELEMENTS VARIATION OF DIFFERENT GRASS CARP POLYCUITURE SYSTEMS

碳(C)、氮(N)、磷(P)是影响水体生态系统的重要元素,其利用率和积累情况常被作为评价养殖水平、模式以及自身污染程度的重要指标.根据不同种类的生态位和习性互补的特点,以草鱼(Ctenopharyngodoni dellus)为主养品种,混养滤食性的鲢(Hypophthalmichthys molitrix)和底栖类的凡纳滨对虾(Litopenaeus vannamei),采用陆基围隔法,研究了5~10月草鱼、鲢和凡纳滨对虾不同混养模式下养殖水体的营养元素变化.每月定期采样,分别测定不同养殖模式水体C、N、P含量,分析养殖水体营养元素变化.研究发现,相同实验条件下,草鱼单养组(G组)总氨氮、硝酸氮、磷酸盐含量高于草鱼、鲢(GS组)和草鱼、鲢、凡纳滨对虾(GSL组)混养组;总氮、总磷含量随养殖周期延长呈上升趋势,养殖期内积累量G组显著高于GSL组(P<0.05);养殖期内水体溶解性有机碳(DOC)、颗粒性有机碳(POC)的含量呈上升趋势,部分月份,水体DOC、POC含量G组显著高于GSL组(P<0.05).实验初步表明,草鱼、鲢、凡纳滨对虾三元混养模式对改善养殖水体水质具有积极作用.

C、N and P are important elements affecting water ecosystem,and their utilization and accumulation are often used as important indicators to evaluate the level,pattern and degree of pollution of aquaculture.According to the different species′ecological niche and habits,the grass carp was set as the main breed,and the silver carp、Litopenaeus vannamei were fed by mixed culture.Based on enclosures,the article is mainly to research the variety of nutrition elements in mesocosm polyculture ecosystem comprising with grass carp,silver carp and Litopenaeus vannamei.From May to October,the samples were collected monthly for measurements of the variety of C、N and P in polyculture mode with different quantitative proportions.Main results are as follows.The concentration of TAN,phosphate and nitrate in group G are higher than those in group GS and group GSL.And they are also higher in group GS than group GSL.The TP and TN concentrations in water grow along with the progressing of the research,and the situation is a lot more obvious in group G than in group GLS(P<0.05).The DOC and POC concentrations in water also grow along with the progressing of the research.In some months,the DOC concentration in group G is markedly higher than that in group GSL(P<0.05).The results preliminarily indicated that the polyculture with grass carp,silver carp and Litopenaeus vannamei is positive to improve the aquaculture water quality.