基于环境容纳量的区域性养殖容量评估

针对淡水养殖池塘养殖水体及周边水域水质日趋恶化的现状,为了保证水产养殖业的可持续发展,亟需开展养殖容量相关方面的研究,将主要养殖品种面积和密度控制在最佳的范围内。以浙江南浔区为研究区域,通过调查该区域水环境现状和6种主要养殖模式养殖特点,计算了该区域水体总磷的环境容纳量,再根据单位养殖模式排污量初步评估了该区域主要养殖品种的养殖容量。结果显示:(1)南浔区水环境的磷为限制因子;(2)常规鱼、大口黑鲈(Micropterus salmoides)、乌鳢(Ophiocephalus argus)、翘嘴鲌(Culter alburnus)、中华鳖(Trionyx Sinensis)和青鱼(Mylopharyngodon piceus)单位产磷量分别为0.26、0.70、0.73、0.17、0.33和0.22 g/kg;(3)在II类水质前提下,常规鱼、大口黑鲈、乌鳢、翘嘴鲌、中华鳖、青鱼养殖塘可接受的最大磷负荷为7.38、5.79、2.36、1.82、1.51、2.52 t,其对应养殖容量分别为28 370、8 271、3 236、10 698、11 648、9 685 t;(4)养殖容量模型参数敏感性分析表明,磷滞留系数、换水系数和外河磷浓度敏感度系数分别为0.365、0.364和-0.271;区域养殖容量的合理评估可为生态渔业的发展提供科学依据。

Regional Aquaculture Carrying Capacity Based on Environmental Capacity

Evaluation of regional aquaculture capacity, based on environmental capacity, is necessary to achieve optimal densities for primary breeding species, reduce pollution from aquaculture and support sustainable develop in aquaculture. The Nanxun district of Huzhou city in Zhejiang Province was selected as the research area, where there is an aquacultural area of 5946.71 hm2 with an annual yield of 90,000 t. In May, August and November 2015, ten monitoring sites were established to investigate the condition of aquaculture and the water environment at Nanxun District and determine the pollution discharge per unit production of six primary aquaculture modes. Based on the results, an aquaculture capacity model was constructed, taking phosphorus loads and Grade II water quality standards as the restricting condition. The model was then used to calculate the optimal ecological capacity of the six aquaculture modes. Results show (1) phosphorus limits water quality in Nanxun district; (2) the phosphorus discharge per unit production for the six primary aquaculture modes (the four major Chinese carps; Micropterus salmoides; Ophiocephalus argus Cantor; Culter alburnus Basilewsky; Trionyx Sinensi and Mylopharyngodon piceus ) were 0.26 g?kg-1, 0.70 g?kg-1, 0.73 g?kg-1, 0.17 g?kg-1, 0.33 g?kg-1 and 0.22 g?kg-1, respectively; (3) The corresponding maximum acceptable P-loading (Pmac) for the six primary aquaculture modes were 7.38 t, 5.79 t, 2.36 t, 1.82 t, 1.51 t and 2.52 t and the corresponding aquaculture capacities were 28370 t, 8271 t, 3236 t, 10698 t, 11648 t and 9685 t. Parameter sensitivity analysis of the aquaculture capacity model was carried out using Markov Chain Monte Carlo (MCMC) methods and the sensitivity coefficients for the phosphorus retention rate, water exchange coefficient and phosphorus concentration in the river were, respectively, 0.365, 0.364 and -0.271. These values indicate that the regional aquaculture capacity estimates, based on TP meeting Grade II water quality standards, are reasonable and provide a scientific reference for decision making in relevant administrative departments.