主养草鱼高密度池塘溶氧收支平衡的研究

采用原位生态学的方法测定广东省中山市9口主养草鱼高密度池塘中浮游植物光合作用产氧量、水柱呼吸耗氧量、底泥呼吸耗氧量和鱼呼吸耗氧量, 并用数学模型计算增氧机增氧量及用差减法计算大气扩散作用引起的得氧或失氧, 对高密度养殖池塘中溶氧收支平衡状况进行了研究。结果显示: 在水深为1.5-2.0 m的主养草鱼高密度池塘中, 光合作用产氧量随着水深的增加而显著降低(P0.05), 底层出现负值呈现氧债现象。水呼吸耗氧量在表层、中层和底层之间没有显著差异(P0.05)。表层水光合作用产氧量显著大于水呼吸耗氧量(P0.05), 而中层和底层水光合作用产氧量却显著小于水呼吸耗氧量(P0.05)。在主养草鱼高密度池塘溶氧的收入中, 浮游植物光合作用产氧量、增氧机增氧量和大气扩散溶入氧量分别占总溶氧来源的44.7%、42.3%和13.0%, 机械增氧作用已接近光合作用, 成为溶氧来源的主要贡献者; 在池塘溶氧的支出中, 水呼吸、鱼呼吸和底泥呼吸耗氧量分别占总耗氧量的45.9%、45.0%和9.1%, 鱼呼吸耗氧与水呼吸耗氧相当, 成为水体中氧气的主要消耗者。结果表明在草鱼高密度养殖过程中, 合理使用机械增氧是池塘溶氧管理的有效措施。  

THE BUDGET OF DISSOLVED OXYGEN IN HIGH DENSITY PONDS MAINLY STOCKED WITH CTENOPHARYNGODON IDELLA

To increase the efficiency of dissolved oxygen (DO) management in high density ponds mainly stocked with grass carp (Ctenopharyngodon idella), the present research aimed to characterize the budget of dissolved oxygen in nine fish ponds in Zhongshan, Guangdong province, China. The water depth was 1.5-2.0 m. Photosynthesis of phytoplankton and water respiration rate (WR) were determined by the clear and dark bottles method. The sediment respiration rate (SR) was measured by in situ respirometry. The fish respiration rate was determined by the respiratory chamber method. The mechanical aeration was calculated by predicting models. Atmosphere diffusion was estimated by the subtraction method. The results showed the gross oxygen production (GOP) of photosynthesis showed a decreasing trend as the water depth increased, and the value in the bottom was negative, which was the common oxygen debt phenomenon. There was no significant difference between the WR under the surface, middle layer and bottom (P0.05). The GOP of photosynthesis in the surface was significantly higher than the WR (P0.05), but the GOP of photosynthesis was significantly lower than the WR both in the middle layer and in the bottom (P0.05). The photosynthesis of phytoplankton and the mechanical aeration were the main contributors to the total oxygen production in high density ponds mainly stocked with C. idella, which accounted for 44.7% and 42.3% of the total oxygen production, respectively, but the contribution of atmosphere diffusion was the lowest and accounted for 13.0%. Among the oxygen consuming factors, the WR was the largest oxygen consumer, which accounted for 45.9% of the total oxygen consumption of water column, followed by fish respiration rate which accounted for 45.0% of the total oxygen consumption, and the proportion of SR was the lowest which accounted for 9.1%.