草鱼不同混养系统中细菌生产力的初步研究

A Preliminary Study on Bacterial Productivity in Different Grass Carp Polyculture Systems

利用陆基实验围隔,采用原位培养法,对比研究5种草鱼(Ctenopharyngodon idellus)混养系统中细菌生产力的状况。结果表明,细菌生产力波动在(85.22±9.68)^(899.24±29.67)μg C·L-1·d-1,平均为(442.33±210.51)μg C·L-1·d-1。总体上,各处理组细菌生产力随时间呈现先升高后降低的趋势,在8月份达到最高值。其中,草鱼、鲢鱼和鲤鱼的三元混养模式中的细菌生产力显著高于其它处理组(P<0.05)。细菌生产力总体上与水体初级生产力、溶解有机碳(DOC)和颗粒有机碳(POC)含量及水温均呈显著正相关,与水体磷酸盐含量呈显著负相关。通过主成分分析(PCA)发现,养殖前期水体无机氮(DIN)、DOC和POC含量对细菌生产力的贡献率高达44.058%,养殖中期DOC和POC含量对细菌生产力贡献率降为32.693%,而养殖后期DIN、DOC和POC含量对细菌生产力的贡献率为45.921%。研究表明,在养殖前期,DIN、DOC、POC是细菌生产力的关键因素;DOC、POC的重要作用使得养殖中期细菌生产力处在较高水平,但PO4-P含量成为限制因素;低温限制了浮游植物的初级生产力,使得养殖后期较高的营养元素含量只能维持细菌较低的生产力。

Bacterial productivity （BP） in 5 different grass carp （Ctenopharyngodon idellus） potyculture systems was studied in situ in land-based enclosures. The results showed that BP of enclosures ranged from （85.22±9.68） to （899.24±29.67） μgC·L^-1·d^-1 with an average of （442.33±210. 51） μgC·L^-1·d^-1. The BP showed the same trend in general, increasing at beginning and then decreasing. The highest BP was reached in August. Grass carp-silver carp-common carp polyculture system was significant- ly higher than other systems （P〈0.05） in BP. The BP correlated significantly with the primary produc- tivity of phytoplankton （PP）, the concentration of DOC and POC, water temperature and phosphate. Principal components analysis showed that DIN, DOC and POC in water contributed 44. 058% at the early stage of culture; 32. 693% at the middle stage and 45. 921% at the later stage to BP. It was found that BP was driven by DIN, DOC and POC at the early stage of culture; DOC and POC maintained high BP, and the concentration of PO4-P was the limiting factor at the middle stage of culture. At the later stage of cul- ture, the concentration of nutrition was high, but BP was low, which may be caused by low water temper- ature.