淡水池塘虾蚌混养对浮游甲壳动物群落结构的影响

以浙江省海盐县百步镇6口罗氏沼虾养殖池塘为对象,比较了罗氏沼虾单养与罗氏沼虾、三角帆蚌混养两种养殖模式池塘中浮游甲壳动物的种类组成、密度和生物量及养殖水化因子的差异。结果表明:混养池塘中TN、TP、NO3--N与DO均显著低于单养池塘,而其它水化因子无显著性差异;养殖期间共鉴定出浮游甲壳动物22种,其中枝角类13种,占总种类数的59.09%;桡足类9种,占40.91%。混养池塘浮游甲壳动物Shannon-Wiener多样性指数显著高于单养池塘,而Pielou均匀度指数无显著差异。单养池塘浮游甲壳动物密度和生物量均显著高于混养池塘。经逐步回归分析表明,水温和总磷是影响浮游甲壳动物密度和生物量的主要因子。典型对应分析(CCA)显示,浮游甲壳动物的时空分布主要受水温的影响。混养池塘罗氏沼虾产量(866.70±214.92kg/m2)极显著高于单养池塘(533.30±104.24 kg/m2)。结果表明,虾蚌混养对池塘中水质指标有一定的改善,虽然对浮游甲壳动物物种组成不造成影响,但明显地降低了浮游甲壳动物的多样性、密度和生物量,并且虾蚌混养可提高虾类产量。

Effect of prawn and pearl mussel polyculture on crustacean plankton community in freshwater ponds

The crustacean plankton community structure and water quality were compared between freshwater prawn (Macrobrachium rosenbergi) monoculture ponds and prawn+pearl mussel (M. rosenbergi+Hyriopsis cumingii) polyculture ponds located in Baibu Town, Haiyan County, Zhejiang Province from June to October in 2011. This study aimed at understanding the ecological effects of prawn + pearl mussel polycuture. TN, TP, NO₃-N and DO were significantly lower in polyculture ponds than those in monoculture ponds, and no differences in other parameters of water chemistry between two culturing modes were found. A total of 22 crustacean plankton species were identified, including 13 Cladoceran species and 9 Copepod species, accounting for 59.09% and 49.91% of the total species number of crustacean plankton, respectively. Significant difference between culture modes in Shannon-wiener diversity index of the crustacean plankton was found, but not detected in Pielou evenness index. Density and biomass in monoculture ponds were significantly higher than those in polyculture ponds. Stepwise regression analysis showed that water temperature and total phosphorus from 12 environmental factors were the main factors affecting density and biomass of crustacean plankton. Canonical correspondence analysis (CCA) indicated that water temperature was the key factor influencing the temporal and spatial distribution of crustacean plankton. The output of M. rosenbergii (533.30±104.24 kg/m²) was significantly lower in monoculture ponds than that in polyculture ponds (866.70±214.92 kg/m²) (P<0.01). Results suggest that prawn and pearl mussel polyculture can improve the water quality of the aquaculture ponds. Although the polyculture can't significantly change the species composition of crustacean plankton, it can significantly decrease the diversity, density and biomass of crustacean plankton. Meanwhile, prawn and mussel polyculture can also raise the output of prawn.