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引用本文:王银平,谷孝鸿,曾庆飞,毛志刚,谷先坤,李旭光.食微囊藻干粉鱼类对水环境的影响及氮素迁移转化规律.湖泊科学,2015,27(3):475-485. DOI:10.18307/2015.0315
WANG Yinping,GU Xiaohong,ZENG Qingfei,MAO Zhigang,GU Xiankun,LI Xuguang.Impacts of faeces from microcystis-dietary silver carp (Hypophthalmichthys molitrix) and tilapia (Oreochromis niloticus) on the aquatic environments and the transferring of faeces-sourced nitrogen. J. Lake Sci.2015,27(3):475-485. DOI:10.18307/2015.0315
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食微囊藻干粉鱼类对水环境的影响及氮素迁移转化规律
王银平1,2, 谷孝鸿1, 曾庆飞1, 毛志刚1, 谷先坤1,2, 李旭光1,2,3
1.中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室, 南京 210008;2.中国科学院大学, 北京 100049;3.江苏省淡水水产研究所, 南京 210017
摘要:
利用稳定同位素示踪技术研究鲢(Hypophthalmichthys molitrix)、罗非鱼(Oreochromis niloticus) 摄食微囊藻(Microcystis)干粉后排泄氮在水中的迁移转化规律,同时对营养盐浓度、浮游生物群落结构等进行测定.营养盐数据分析结果显示:罗非鱼组水体营养盐浓度后期急剧升高,而鲢鱼组营养盐浓度变化较小,后期部分浓度低于对照组.营养盐浓度变化主要是鱼类排泄和牧食等活动综合作用的结果.鲢鱼组、罗非鱼组悬浮颗粒物浓度、叶绿素a浓度和细胞密度总体高于对照组,罗非鱼组悬浮颗粒物浓度、叶绿素a浓度和细胞密度中期显著高于鲢鱼组和对照组.浮游生物统计数据显示,鲢鱼组、罗非鱼组藻类总生物量显著增加,各自最大总生物量分别为对照组的4.5、7.4倍,且主要贡献藻类为蓝藻和绿藻.浮游动物密度随鱼类滤食显著降低,罗非鱼组浮游动物密度末期趋近零.同位素分析结果显示,15N稳定同位素在鲢、罗非鱼中的迁移转化过程稍有差异,各物质δ15N比值第1 d均显著高于对照组,δ15N(NH4+)、δ15N(浮游藻类)和δ15N(浮游动物)达到最大值,但鲢鱼组和罗非鱼组δ15N(沉积腐质)和δ15N(螺)值分别于第5 d和10 d达到最大.另外,鲢鱼、罗非鱼对微囊藻干粉吸收效率差别较大,鱼背部肌肉最大δ15N值分别为36.22‰、151.53‰,总体相差4.2倍.通过同位素示踪技术,得出干粉微囊藻经鱼摄食后,排泄物氮直接参与水体营养盐循环,为藻类增殖做出直接贡献的结论.
关键词:  微囊藻  稳定同位素    罗非鱼  排泄物氮  迁移转化
DOI:10.18307/2015.0315
分类号:
基金项目:"十二五"农村领域国家科技计划课题项目(2012BAD25B06/07)和国家自然科学基金项目(31372569,31270506)联合资助.
Impacts of faeces from microcystis-dietary silver carp (Hypophthalmichthys molitrix) and tilapia (Oreochromis niloticus) on the aquatic environments and the transferring of faeces-sourced nitrogen
WANG Yinping1,2, GU Xiaohong1, ZENG Qingfei1, MAO Zhigang1, GU Xiankun1,2, LI Xuguang1,2,3
1.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P.R.China;2.University of Chinese Academy of Sciences, Beijing 100049, P.R.China;3.Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, P.R.China
Abstract:
Stable isotope tracer technique was employed to study faeces-sourced nitrogen transferring from silver carp (Hypophthalmichthys molitrix) and tilapia (Oreochromis niloticus) after feeding on Microcystis in aquatic ecosystem, when nutrients concentrations and plankton biomass were determined by the tracers.Nutrients analysis indicated that nutrients contents in tilapia group increased rapidly at the end of the experiment, while there was no obvious difference between silver carp group and control group.Some nutrient contents in silver carp group were even less than those in control group.What's more, generally concentrations of suspended solid, chlorophyll-a content and phytoplankton cell density in fish group were higher than those in control group.The three parameters mentioned above of tilapia group became significantly higher than those of the rest groups in the mid-stage of the experiment.Phytoplankton biomass showed a slight decrease after the introduction of fish, and then phytoplankton biomass increased rapidly.The maximum biomass of tilapia and silver carp were 7.4 and 4.5 times higher than those of control group when cyanobacteria and green algae were the main food.With filter behavior prolonged, the biomass of zooplankton in both fish groups reduced sharply.At the end of the experiment, zooplankton became scarce in the tilapia group.Stable isotope analysis indicated that, after microcystis-feeding, 15N stable isotope ratio increased significantly in fish muscle, dissolved NH4+, phytoplankton, zooplankton, sedimentary debris and snail (Bellamya aeruginosa) on the first day.During the experiment, 15N isotope ratio of tilapia muscle was consistently higher than that of silver carp, and 15N isotope ratios of above parameters in fish group were invariably higher than those in control group.15N stable isotope ratio of dissolved NH4+, phytoplankton and zooplankton in both fish groups reached their maximum values at the beginning of the experiment, while 15N isotope ratios of sedimentary debris and snail reached their peak point on day 5 and day 10, respectively.Significant difference was found in absorption efficiency of microcystis-feed between two types of fish.The maximum 15N isotope ratios of silver carp appeared in day 5 with the value of 36.22‰, while tilapia reached its peak value of 151.53‰ in day 15 and the peak value is 4.2 times higher than that of silver carp group.The result of the experiment indicated that faeces-sourced nitrogen went directly into water column after feeding on microcystis, taking part in nutrition cycle, finally stimulated the bloom of algae.
Key words:  Microcystis  stable isotope  silver carp  tilapia  faeces-sourced nitrogen  transformation
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