CAJ | 학술논문

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( Micro-cystis)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,15 N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δ15 N比值第1 d均显著高于对照组,δ15 N(NH+4)、δ15 N(浮游藻类)和δ15 N(浮游动物)达到最大值,但鲢鱼组和罗非鱼组δ15 N(沉积腐质)和δ15 N(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δ15 N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.
이용은정동위소시종기술연구련( Hypophthalmichthys molitrix)、라비어( Oreochromis niloticus)섭식미낭조( Micro-cystis)간분후배설담재수중적천이전화규률,동시대영양염농도、부유생물군락결구등진행측정.영양염수거분석결과현시：라비어조수체영양염농도후기급극승고,이련어조영양염농도변화교소,후기부분농도저우대조조.영양염농도변화주요시어류배설화목식등활동종합작용적결과.련어조、라비어조현부과립물농도、협록소a농도화세포밀도총체고우대조조,라비어조현부과립물농도、협록소a농도화세포밀도중기현저고우련어조화대조조.부유생물통계수거현시,련어조、라비어조조류총생물량현저증가,각자최대총생물량분별위대조조적4.5、7.4배,차주요공헌조류위람조화록조.부유동물밀도수어류려식현저강저,라비어조부유동물밀도말기추근령.동위소분석결과현시,15 N은정동위소재련、라비어중적천이전화과정초유차이,각물질δ15 N비치제1 d균현저고우대조조,δ15 N(NH+4)、δ15 N(부유조류)화δ15 N(부유동물)체도최대치,단련어조화라비어조δ15 N(침적부질)화δ15 N(라)치분별우제5 d화10 d체도최대.령외,련어、라비어대미낭조간분흡수효솔차별교대,어배부기육최대δ15 N치분별위36.22‰、151.53‰,총체상차4.2배.통과동위소시종기술,득출간분미낭조경어섭식후,배설물담직접삼여수체영양염순배,위조류증식주출직접공헌적결론.
Stable isotope tracer technique was employed to study faeces-sourced nitrogen transferring from silver carp ( Hypophthal-michthys molitrix) and tilapia ( Oreochromis niloticus) after feeding on Microcystis in aquatic ecosystem, when nutrients concentra-tions and plankton biomass were determined by the tracers. Nutrients analysis indicated that nutrients contents in tilapia group in-creased 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 in-creased 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, 15 N stable isotope ratio increased significantly in fish muscle, dissolved NH4+, phytoplankton, zoo-plankton, sedimentary debris and snail ( Bellamya aeruginosa) on the first day. During the experiment, 15 N isotope ratio of tilapia muscle was consistently higher than that of silver carp, and 15 N isotope ratios of above parameters in fish group were invariably higher than those in control group. 15 N stable isotope ratio of dissolved NH4+, phytoplankton and zooplankton in both fish groups reached their maximum values at the beginning of the experiment, while 15 N 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 be-tween two types of fish. The maximum 15 N 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 nu-trition cycle, finally stimulated the bloom of algae.