草鱼混养生态系统能量收支的研究

An Experiment Study on the Energy Budget and Conversion Efficiency of Ecosystem in Ployculture of Ctenopharyngodon idellus

采用陆基围隔实验法,对草鱼(Ctenopharyngodon idellus)、鲢鱼(Hypophythalmichthys molitrix)和鲤鱼(Cyprinus carpio)不同混养系统的能量收支和转化效率进行了研究。实验共设置7个处理组,分别为草鱼单养(G)、草鱼和鲢鱼二元混养(GS)、草鱼和鲤鱼二元混养(GC)以及草鱼、鲢鱼和鲤鱼按照不同比例放养的三元混养(GSC1、GSC2、GSC3和GSC4)。研究结果表明,实验期间各系统接收的总太阳辐射能为4 970MJ.m-2;光能利用率在0.25%～0.33%之间,各处理组之间差异显著(P<0.05);光合能转化效率以草鱼单养组最低,且与GS、GSC2、GSC3和GSC4处理组之间差异显著(P<0.05);各混养组与草鱼单养组相比,总能量转化效率分别提高了43.51%、11.62%、30.16%、64.30%、38.49%和61.90%,其中,以GSC2为最高,GSC4次之;单位净产量耗饲料能以单养草鱼组最高,显著高于GS、GSC2和GSC4处理组(P<0.05);各处理组沉积能量在3.42～17.73MJ.m-2之间,各处理组间差异显著(P<0.05),各组沉积能量占总投入能量的比例分别为30.92%、12.18%、39.08%、29.43%、28.90%、28.87%和29.80%。本研究结果表明,不同食性鱼类混养系统能够提高光合能转化效率和总能量利用率,降低沉积能量,从而有效提高系统对输入能量的利用效率。

The energy budget and conversion efficiency of different ecosystems, in which Ctenopharyng- odon idellus, Hypophythalmichthys molitrix and Cyprinus carpio were cultured in different mono- and poly-culture treatments, were studied in land-based enclosures. There were seven treatments： grass carp treatment （G） ; grass carp and silver carp treatment （GS） ; grass carp and common carp treatment （GC） and four treatments stocked grass carp, silver carp and common carp with different proportion （GSC1, GSC2, GSC3, GSC4）. The results indicated that the solar radiation energy during the experiment was 4970 MJ m^-2. The solar energy utilization rates of phytoplankton ranged from 0. 25% to 0. 33%, the difference among each treatments was insignificant （P〉0. 05）. The photosynthetic energy efficiency of mono-culture closure was the lowest, and significantly different from GS, GSC2, GSC3 and GSC4 treat- ments （P〈0. 05）. Compared with mono-culture enclosures, the total energy conversion efficiency of polyculture enclosures increased 43.51%, 11.62%, 30. 16%, 64. 30%, 38. 49% and 61.90%, respectively. The GSC2 treatment was the highest, and the GSC4 was the second. The feeding energy consumption per unit of net yield of mono-culture treatment was the highest, and significantly higher than GS,GSC2 and GSC4 treatments （P〈0.05）. The sediment energy, which was significantly different from each treat- ment, ranged from 3.42 to 17. 73 MJ m^-2. The sediment energy of each treatment accounted for total input energy were 30. 92%, 12. 18%, 39.08%, 29.43%, 28. 90%, 28. 87% and 29.80%, respectively. This study demonstrated that poly-culture modes can improve photosynthetic energy efficiency, raise total energy utilization rate, reduce sediment energy and effectively improve energy efficiency of ecosystem.