鲢鳙在长寿湖水生态系统氮磷循环中的作用

为探究长寿湖鲢、鳙在水体生态系统氮(N)磷(P)循环中的作用,研究测定了季节性水体总氮(TN)、总磷(TP)的变化,进行了原位鲢、鳙排泄率的测定。通过N、P排泄对比分析了鲢、鳙对水体N、P的贡献率。通过长寿湖鲢、鳙鱼体N、P含量测定,估算水体中N、P去除量。结果显示:鲢、鳙N、P排泄率夏季最高,冬季最低,季节性温度变化对其排泄率有一定影响;2016—2017在长寿湖平均水温为19.88℃条件下,鲢的N、P排泄率分别为0.973 1μg L-1d-1和0.242 2μg L-1d-1;鳙的N、P排泄率分别为0.642 5μg L-1d-1和0.174 9μg L-1d-1,鲢、鳙N、P排泄量分别占长寿湖藻类初级生产所需N含量的1.19%和0.79%,P含量的9.57%和6.91%;2016—2017长寿湖通过捕捞鲢、鳙产品带走的N、P含量分别为60.61 t和23.31 t。结果表明,长寿湖开展生态养殖对水体N、P贡献较小,不会引起水体富营养化。

Role of silver carp and bighead on nitrogen and phosphorus cycle of aquatic ecosystem in Changshou Lake

In order to explore the role of silver carp and bighead on nitrogen and phosphorus cycle of aquatic ecosystem in Changshou Lake, the preset study seasonal change of total nitrogen(TN) and total phosphorus(TP) in water, excretion quantities of N and P in silver carp and bighead were determined.Contribution rates of silver carp and bighead N/P excre-tions in water were obtained by comparative analysis.N/P retention of silver carp and bighead were estimated through deter-mined the fish body N/P contents.The result showed that the N and P excretion rates of silver carp and bighead were the highest in summer and lowest in winter, the seasonal temperature influenced on the excretion rates.Under average water temperature 19.88 ℃ in Changshou Lake during 2016—2017, the N/P excretion rates of silver carp were 0.973 1 μg L-1 d-1and 0.242 2 μg L-1d-1, and bighead were 0.642 5 μg L-1d-1and 0.174 9 μg L-1d-1respectively.N and P excre-tions of silver carp and bighead account for 1.19%, 0.79% of N amount, and 9.57%, 6.91% of P amount required by algae primary production in Changshou Lake.The amount of N/P taken out by silver carp and bighead catch to market was up to 60.61 t and 23.31 t in Changshou Lake during 2016—2017.The present investigation suggested that the practice of ecological stocking silver carp and bighead fisheries will have a small contribution to N and P in the water and will not cause eutrophication.