摘要
稳定同位素示踪方法是研究生态系统组成与功能的重要手段,有助于认识湖泊食物网的基本组成与生物地球化学循环的主要过程.本研究选择了云南省东部地区营养水平不同的10个湖泊,开展了高等水生植物(沉水植物、漂浮植物)、浮游植物与浮游动物的空间调查,分析了不同生物在碳、氮稳定同位素信号与元素组成上的分布模式.在碳稳定同位素信号的分布上,漂浮植物在4种生物类型中最为偏负且变化幅度最小,为-28.99‰±0.86‰;浮游动物碳稳定同位素(-20.85‰±2.70‰)的分布特征与浮游植物(-21.88‰±2.97‰)显著相似;而沉水植物的碳稳定同位素显著偏正且变化范围较大,平均值为-12.04‰±4.57‰.结果表明,碳源及其传输途径的差异是导致湖泊生物体内碳同位素信号不同的主要驱动过程.在氮稳定同位素信号上,同为初级生产者的沉水植物(5.43‰±5.84‰)、漂浮植物(5.58‰±7.38‰)与浮游植物(7.26‰±3.83‰)较为相似,而浮游动物氮同位素信号(11.02‰±3.18‰)显著高于浮游植物且平均富集约3.46‰,反映了湖泊生物随着营养级的增加出现较为明显的同位素分馏效应.在空间分布上,湖泊生物碳同位素信号受到水温、水深等因素的明显影响,氮同位素信号则随湖泊营养水平的增加而逐渐偏正.与长江中下游等地区相比,云南湖泊生物的碳、氮元素含量总体偏高;同时,代表内源有机质组分的水生植物和浮游生物C/N质量比值都小于20.因此,本研究揭示的生物碳、氮同位素信号与元素组成特征可为评价高原湖泊食物网组成与生物地球化学循环提供重要的科学依据.
Stable isotope method serves as an important means to uncover the ecosystem structure and functioning,and to reveal the composition of lake food webs and the processes for biogeochemical cycling. In this study,a spatial survey of ten lakes with different nutrient levels in Eastern Yunnan was conducted through analyzing the carbon and nitrogen stable isotopes and elemental composition for aquatic plants（ submerged macrophyte,floating plant）,phytoplankton and zooplankton,respectively. The result shows that,among the four groups of lake organisms,floating plant has the most negative signal of stable carbon isotope,with a mean value（ ±SD） of-28.99‰±0.86‰. While phytoplankton（-21.88‰±2.97‰） and zooplankton（-20.85‰±2.70‰） are characterized by similar carbon isotope values,the submerged macrophyte has a large variation with significantly more positive δ13 C value（-12.04‰±4.57‰）. This indicates that the difference in carbon sources absorbed or utilized has caused the deviation in stable carbon isotope composition among these four organisms. In terms of stable nitrogen isotope,the primary producers,including submerged macrophyte（ 5.43‰±5.84‰）,floating plant（ 5.58‰±7.38‰） and phytoplankton（ 7.26‰±3.83‰）,showsignificantly similar δ15 N values. While the δ15 N value of primary consumer,zooplankton（ 11.02‰±3.18‰）,is significantly higher with a averaged enrichment factor by 3.46‰,indicating the effect of nitrogen isotope fractionation across trophic levels in our lakes. Furthermore,the carbon isotope signal of lake organisms are also affected by factors such as water temperature and water depth. The varia-tion in the nitrogen isotope signal is dominated by lake eutrophication,which leads to a gradual enrichment in the organismal signal of δ15 N. In addition,the carbon and nitrogen content of aquatic organisms from Yunnan lakes are higher than those in lakes from the middle and lower reaches of the Yangtze River. There existed a threshold C/N ratio of primary producers and primary consumers in defining the shift between autochtonous and allothonous sources of organic matter in our lakes. This spatial survey provided important data for understanding the food web composition and biochemical cycling for plateau lakes.
作者
梁红
黄林培
陈光杰
康文刚
刘园园
王教元
朱庆生
刘术
邓颖
LIANG Hong;HUANG Linpei;CHEN Guangjie;KANG Wengang;LIU Yuanyuan;WANG Jiaoyuan;ZHU Qingsheng;LIU Shu;DENG Ying(Yunnan Province Key Laboratory of Plateau Geographical Processes and Environmental Change,School of Tourism and Geography,Yunnan Normal University,Kunming 650500,P.R.China)
出处
《湖泊科学》
EI
CAS
CSCD
北大核心
2018年第5期1400-1412,共13页
Journal of Lake Sciences
基金
国家自然科学基金项目(41302151
41771239
31460131
U1133601)资助
关键词
碳、氮稳定同位素
水生生物
营养级
富营养化
云南湖泊
Carbon and nitrogen stable isotopes
aquatic organism
trophic level
eutrophication
Yunnan lakes
