放牧干扰对若尔盖高寒湿地不同水生生物δ^(13)C、δ^(15)N的影响

Effect of Along Grazing Gradients on the Stable Carbon and Nitrogen Isotopes of Organisms in the Zoige Apline Wetland of China

为了解畜牧业发展对若尔盖湿地水生生物类群的影响,本试验设置了A(对照组),B(影响组I),C(影响组II)3个样点,应用稳定同位素技术并结合多维尺度(MDS)等方法研究了若尔盖湿地影响组与对照组之间不同水生生物类群δ^(13)C、δ^(15)N值。结果表明,初级生产者POM(颗粒有机物)样品(主要成分为藻类)δ^(13)C、δ^(15)N值分别为-26.39‰^-21.17‰,3.68‰~6.61‰;浮游动物(枝角类)δ^(13)C、δ^(15)N值分别为-25.69‰^-23.43‰、3.19‰~9.53‰;软体动物泉膀胱螺δ^(13)C、δ^(15)N值分别-28.00‰^-22.30‰、5.19‰~9.27‰,钩虾为-28.57‰^-26.87‰、7.36‰~8.06‰;鱼类样品中高原鳅δ^(13)C、δ^(15)N值分别-30.83‰^-27.01‰、6.41‰~10.02‰,黄河裸裂尻为-26.89‰^-25.95‰、10.24‰~10.89‰。其中不同组间POM样品和浮游动物δ^(13)C值变化不明显,而其δ^(15)N值变化极显著。因此,若尔盖湿地食物网中,氮稳定性同位素信号能较灵敏地反映放牧干扰信息,与软体动物、鱼类相比,POM、浮游动物更适合作为该区域环境评价的指示物种。放牧干扰已经对若尔盖湿地POM、浮游动物等产生了一定的影响,因此,控制若尔盖湿地放牧规模和减少动物粪便的流入量,对于保护若尔盖湿地生态系统的稳定性具有重要意义。

To study the effect of graziery on the aquatic organisms community in the Zoige Apline wetland, three sites named as control group A, impact group B I and impact group C II were set, and the stable isotope technique, multidimensional scaling and variance analysis methods were applied to compare theδ13C and δ15Nvalues of aquatic organisms among the impact groups and control group. The results showed that the carbon and nitrogen stable isotope were -26.39‰ - -21. 17‰ and 3.68‰ -6.61‰ for POM （the main component of particle organic matter is algae）, - 25.69‰ - - 23.43‰ （δ15N） and 3. 19%v - 9.53‰ （ δ15N） for zooplankton, - 28.00‰ - - 22.30‰ （ δ13C） and 5.19‰ -9.27‰ （δ15N） for snail （Physafontinalis）, -28.57‰ - -26.87‰ （δ13C） and 7.36%o - 8.06‰ （δ15N） for shrimp （gammarid） , - 30.83 ‰ - - 27.01‰ （ δ13C ） and 6.41‰ - 10.02‰ （δ15N） for fish （ Triplophysa sp） , - 26.89‰ - -25.95‰ （δ13C） and 10.24‰ - 10. 89‰ （δ15N） for fish （Schizopygopsis pylzovi）, of which the 813C value was changed very little in POM group and zooplankton group, while their δ15N values were significantly different （P 〈 0. 001 ）. Therefore, the nitrogen stable isotope signature is sensitive enough to be used as an indicator for grazing interference in Zoige Apline wetland, and the POM and zooplankton was much better being the indicator species than other organisms （e. g. macroinvertebrate and fish） assessing the quality of environment. Moreover, our findings showed that the grazing had influenced the δ15N values of primary producer and zooplankton, as well as the top predator （fish）. It suggested that the strengthen of husbandry management in Zoige Apline wetland, control of Grazing scale and the of animal waste had an important significance for the production of Zoige Apline wetland ecosystem.