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引用本文:卢慧斌,陈光杰,蔡燕凤,王教元,陈小林,段立曾,张虎才.近百年来枝角类群落响应洱海营养水平、外来鱼类引入以及水生植被变化的特征.湖泊科学,2016,28(1):132-140. DOI:10.18307/2016.0115
LU Huibin,CHEN Guangjie,CAI Yanfeng,WANG Jiaoyuan,CHEN Xiaolin,DUAN Lizeng,ZHANG Hucai.Cladoceran community responses to eutrophication, fish introduction and macrophyte degradation over the past century in Lake Erhai. J. Lake Sci.2016,28(1):132-140. DOI:10.18307/2016.0115
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近百年来枝角类群落响应洱海营养水平、外来鱼类引入以及水生植被变化的特征
卢慧斌, 陈光杰, 蔡燕凤, 王教元, 陈小林, 段立曾, 张虎才
云南师范大学旅游与地理科学学院高原湖泊生态与全球变化重点实验室, 昆明 650500
摘要:
近几十年来,以大型湖泊为代表的云南部分湖泊受人类活动的持续影响出现了生态环境的明显变化.洱海作为云南面积第2大淡水湖泊,经历了多重环境压力(富营养化、外来鱼类引入、水生植被退化等)的影响.在湖泊现代监测数据面临时段较短、缺乏连续记录的背景下,湖泊沉积物的连续记录可以提供湖泊生态环境变化的长期历史并可用于生态响应模式的识别.以目前处于富营养水平的洱海为研究对象,应用湖泊沉积物记录进行多指标分析,探讨多重环境压力影响下洱海枝角类群落的长期变化特征以及影响因素,并与已有研究成果和现代监测数据进行对比,探讨了枝角类群落对环境压力响应的空间差异性.通过分析沉积物枝角类记录,重建了近百年来洱海枝角类群落的变化历史,结果表明过去100年来,枝角类的生物量总体呈增加趋势,尤其从1990年左右开始,象鼻溞生物量显著增加,物种相对组成出现明显变化(如Bosmina longispinaB. longirostris取代).同时象鼻溞的生物量、壳长与触角长度在1990s初期有明显降低的趋势,与同期外来鱼类(如银鱼)引种成功的时间一致.限制性聚类分析结果表明,枝角类群落结构的变化有3个主要阶段:1990s以前,底栖枝角类为群落的主要组成;19902000年左右,浮游枝角类(以象鼻溞为主)在枝角类群落结构中的比例迅速增加;从2000年以后,枝角类群落组成以浮游枝角类为主.同时,枝角类数据的主成分(PCA)分析显示,仅有PCA主轴1呈现显著的变化且解释了群落结构变化的61.64%,进一步分析表明水生植被变化可能是驱动枝角类变化的主要环境梯度,如底栖枝角类生物量减少响应了湖泊水生植被的退化.与已有研究对比表明,浅水湖区沉积物记录的枝角类生物量在1970s急剧增加与1980s急剧降低等现象并没有被深水区的沉积物记录所反映,指示了洱海生态系统的变化模式存在空间差异性.同时象鼻溞个体大小的变化模式反映了外来鱼类引入导致的鱼类捕食压力的变化.总之,本文揭示了枝角类群落结构与生物量的长期变化,反映了洱海富营养化过程、水生植被的退化与外来鱼类引入的长期驱动影响,因此对洱海的生态管理与修复工作应考虑多个环境压力的影响并加强对湖泊生态系统的评价.
关键词:  古湖沼学  洱海  枝角类  群落结构  富营养化
DOI:10.18307/2016.0115
分类号:
基金项目:国家自然科学基金项目(U1133601,41171048)、教育部科学技术研究项目(213034A)、云南省中青年学术技术带头人培养计划项目(2012HB012)、云南省创新团队项目(2011C1)和云南省高端人才项目(2010CI111)联合资助.
Cladoceran community responses to eutrophication, fish introduction and macrophyte degradation over the past century in Lake Erhai
LU Huibin, CHEN Guangjie, CAI Yanfeng, WANG Jiaoyuan, CHEN Xiaolin, DUAN Lizeng, ZHANG Hucai
Key Laboratory of Plateau Lake Ecology and Global Change, School of Tourism & Geography, Yunnan Normal University, Kunming 650500, P. R. China
Abstract:
Obvious environment changes have occurred in some lakes of Yunnan Province due to intensifying human impacts over the past decades, especially in large lakes. Lake Erhai is the second largest lake in the Yunnan by surface area, which experienced the pressures of multiple environmental stressors (e.g. eutrophication, fish invasion and macrophyte degradation). The application of lake sediment records enables us to reconstruct the long-term changes of lake environment and ecosystem dynamics in situation of less monitoring data. Here multi-proxy analyses of lake sediments were conducted from a short sediment core in the south and shallow basin of Lake Erhai, which are currently eutrophic. We aimed to recognize the long-term variations and driving factors of cladoceran community, and to test for whether spatial heterogeneity exists in community responses through a comparison with monitoring data and previous results from the deep basin of Lake Erhai. Our results showed that cladoceran production showed an overall increasing trend in the past century, and since 1990s bosminid production increased significantly with a general trend of the oligotrophic taxon of Bosmina longispina replaced by B. longirostris. In addition, bosminid production and the body size (i.e. carapace and antennule length) displayed a decrease during early 1990s, were in good correspondence with the period when the population of the exotic noodlefish was well established. Based on the constrained cluster analysis, the historical changes of cladoceran community were characterized by three distinct phases:littoral cladocerans were dominant before the 1990s and the relative abundance of pelagic cladocerans increased rapidly from the 1990s before the pelagic cladocerans became predominant during early 2000s. The principal component analysis showed that the environmental gradient associated with macrophyte coverage accounted for 61.64% of the total variance in the cladoceran community. Compared with previous studies, we observed that the increased production of cladocerans during the 1970s and an abrupt decrease during the 1980s recorded in shallow basin of Lake Erhai were not reflected in the core from the deep basin, indicating that spatial heterogeneity exists in ecosystem changes of Lake Erhai. We also found the obvious shift of bosminid body sizes in response to fish introduction. Overall, our results revealed the long-term changes of cladoceran production and community structure mainly as a consequence of lake eutrophication and macrophyte degradation, while fish introduction also played a role in structuring zooplankton community through changing predation pressure. Therefore the environmental stressors which could be identified through sedimentary records should be taken into account for sustainable management and ecological restoration of Lake Erhai through facilitating lake ecosystem assessment.
Key words:  Paleolimnology  Lake Erhai  cladoceran  community structure  eutrophication
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