基于因子分析法的罗非鱼养殖池水质影响要素的研究

池塘养殖的水质指标众多且彼此相关,找出养殖过程中应重点监测的少量指标是养殖工作者的现实需求。因子分析是在损失较少信息的前提下,把原来多个变量转化为少数几个综合指标的一种统计方法。运用该方法对基于生物絮团技术养殖罗非鱼的池塘水质进行分析。试验分4组,其中对照组投喂正常量的商品饲料,试验组A、B和C分别投喂100%、80%和75%正常量的饲料,同时添加小麦淀粉作为水体碳源;定期对pH、DO、水温(T)、透明度(SD)、氨氮(TAN)、亚硝酸盐氮(NO2--N)、硝酸盐氮(NO3--N)、总氮(TN)、总磷(TP)、叶绿素a(Chl.a)、絮体体积(FV)、悬浮物(TSS)和异养细菌总量(THB)进行检测。结果表明:当提取3个主因子时,水温、pH、TSS和THB的共同度都低于0.5,故分析时将其排除。在溶氧充足的条件下,有3个主因子影响养殖水质,第1主因子为有机营养盐,由TP、Chl.a和TN构成;第2主因子为无机氮和透明度,由TAN、SD、NO3--N和NO2--N构成;第3主因子为絮团生成量,由FV构成。对各池的3个因子得分进行加权计算得到综合得分,C组综合得分最低且显著低于对照组,表明在不影响罗非鱼生长性状的情况下,添加碳源并减少投喂量时养殖水质最好,养殖时应重点监测水体总氮、总磷和叶绿素a的浓度,并对氨态氮和亚硝氮进行定期监测。

Study on the influential factors of the water quality in tilapia culture systems based on factor analysis approach

There are many water quality parameters in aquaculture,the relationship of which is complicated.To find a few monitoring parameters is practical demand for farmers.Factor analysis approach is a statistical method that uses a few factors to replace many original factors.Water quality in tilapia ponds based on biofloc technology was evaluated using this method in this paper.Tilapias were kept in 12 outdoor cemented ponds.The control group was fed with commercial feed normally,while group A,B and C were fed with 100%,80% and 75% of normal amount of feed and added with wheat starch as carbohydrate.Water samples were taken to measure pH,DO,T,secchi disk depth(SD),total ammonia nitrogen(TAN),nitrite nitrogen(NO2——N),nitrate nitrogen(NO3——N),total nitrogen(TN),total phosphorus(TP),chlorophyll-a(Chl.a),floc volume(FV),total suspended solids(TSS) and total heterotrophic bacterial(THB)every week.The results showed that the communalities of T,pH,TSS and THB were lower than 0.5,and removed when factor analysis was done.Three main factors affecting the water quality were extracted when dissolved oxygen was sufficient.The first main factor was composed of TP,Chl.a and TN,which reflected organic nutrients.The second main factor was composed of TAN,SD,NO3——N and NO2——N,which reflected inorganic nitrogen and SD.The third main factor was composed of FV.The component score of each pond was calculated by the weight of 3 factor scores.The component score of group C was the lowest,and lower than the control group significantly.It showed that water quality of group C was the best of all,and biofloc technology could improve water quality and promote the sustainable development of tilapia culture.TN,TP and Chl.a should be monitored emphatically in tilapia culture systems using biofloc technology and TAN,NO2-N should be monitored regularly.