刘术^1,,
陈光杰^1,,,
王教元¹,
邓颖¹,
白宁静¹,
刘园园¹,
陈小林²,
黄林培¹,
孔令阳¹
1. 云南师范大学旅游与地理科学学院, 高原地理过程与环境变化云南省重点实验室, 云南 昆明 650500
2. 玉溪师范学院地理与国土工程学院, 云南 玉溪 653100

基金项目: 国家重点研究发展计划项目（批准号：2017YFA0605202）、国家自然科学基金项目（批准号：41771239、41171048和41302151）和教育部科学技术研究项目（批准号：213034A）共同资助


详细信息

作者简介: 刘术, 男, 26岁, 硕士研究生, 自然地理学专业, E-mail:liushu9302@163.com

通讯作者: 陈光杰, E-mail:guangjiechen@gmail.com

中图分类号: Q949.27⁺1;P941.78

收稿日期:2018-03-27
修回日期:2018-05-16
刊出日期:2018-07-30

Diatom community response to long-term enviromental changes and ecological evaluation in Jianhu Lake, northwest Yunnan

Liu Shu^1,,
Chen Guangjie^1,,,
Wang Jiaoyuan¹,
Deng Ying¹,
Bai Ningjing¹,
Liu Yuanyuan¹,
Chen Xiaolin²,
Huang Linpei¹,
Kong Lingyang¹
1. Yunnan Provincial Key Laboratory of Plateau Geographical Processes and Environmental Change, School of Tourism and Geography, Yunnan Normal University, Kunming 650500, Yunnan
2. College of Geography and Territorial Engineering, Yuxi Normal University, Yuxi 653100, Yunnan


More Information

Corresponding author: Chen Guangjie,E-mail:guangjiechen@gmail.com

MSC: Q949.27⁺1;P941.78

--> Received Date: 27 March 2018
Revised Date: 16 May 2018
Publish Date: 30 July 2018


摘要
摘要:近几十年来，持续的流域开发与气候变化等环境胁迫已经对云南部分中小型湖泊生态系统产生了重要影响，古湖沼学的研究方法能有效弥补湖泊现代监测数据的不足，且有助于识别湖泊生态系统的长期演变特征并开展生态响应模式的评价。本研究以滇西北地区的剑湖31cm深度钻孔为例，结合²¹⁰Pb和¹³⁷Cs定年，通过沉积物记录的多指标（硅藻、烧失量、粒度、元素与稳定同位素）分析及流域历史资料重建了近200年来剑湖生态环境的演化过程，结果显示剑湖水动力条件持续减弱，营养水平持续上升，硅藻已从45种减少到26种，且底栖类型物种持续减少，表征了剑湖生物多样性出现了持续降低的趋势。并运用主成分分析（PCA）和冗余分析（RDA）等方法，识别出驱动硅藻群落长期变化的重要环境变量为水动力条件和营养水平，进一步的方差分解结果表明，近200年来水动力条件和营养水平分别解释了硅藻群落变化的6.3%和1.4%，两者相互作用时解释了13.1%；而1960年以来，水动力条件、营养水平及气温分别独立解释了硅藻群落变化的6.5%、1.4%和0.2%，三者相互作用时解释了10.6%，表明剑湖的水动力条件、营养水平及气候变化是造成剑湖生态环境变化的重要环境梯度。综合剑湖生态环境长期变化特征分析表明，该湖受人类活动和气候变化的持续影响，其生态系统结构已经出现了明显变化。因此，在气候变暖的长期背景下，控制流域污染物输入及合理的水文调控是维持高原浅水湖泊生态系统健康的重要前提。
关键词: 剑湖/
环境变化/
硅藻/
生态评价/
生物多样性

Abstract:Over the last few decades, small and medium-sized lakes in Yunnan have experienced increasing stressors derived from anthropogenic disturbances and regional climate change, and the deterioration of water quality and the loss of ecosystem resilience. In the context of absent or insufficient monitoring data, it is urgently needed to uncover the ecological responses to environmental changes over a decadal to centennial timescale in these lakes. Here we applied sediment records from Jianhu Lake(26°25.0'~26°31.5'N, 99°55.0'~99°59.5'E) from the northwest part of Yunnan Province, which is a medium-sized(lake area=6.23 km²) and shallow(mean depth=2.7m) system with an altitude of 2188 m a.s.l. and a catchment area about 918 km². A 31-cm long sediment core was taken from the deep basin(26°29'29.94″N, 99°56'11.15″E; water deep in 5.2 m) using a gravity corer. The top 5cm of the core was extruded at 0.5-cm intervals with the core below 5-cm depth sectioned at 1-cm intervals, resulting in a total of 36 sediment samples. The ²¹⁰Pb and ¹³⁷Cs radioactivity profiles showed that the sediment core spanned the last ca. 200 years(ca. 1830~2013A.D.). Diatom and multiple proxies(i.e. LOI₅₅₀(loss on ignition), grain size, carbon and nitrogen elements and stable isotopes) from the sediment core were analysed to reconstruct the environmental change history and to uncover the temporal pattern of diatom responses in Jianhu Lake. A total of 64 diatom species belonging to 32 genera were identified throughout the core, including 21 species with a relative abundance > 5%. The dominant species included Nitzschia angustata, Cyclostephanos tholiformis, Aulacoseira granulata, Cyclotella pseudostelligera, Gyrosigama acuminatum and Cocconeis placentula. The diatom species richness decreased steadily from 45 to 26 over time, with a long-term decline in the percentage of benthic diatoms. The sediment grain size records indicated a weakening trend of hydrodynamic conditions due to lake regulation. The increasing concentration of total nitrogen(TN) indicated a trend of nutrient enrichment during the past two centuries, with an accelerating trend observed since ca.1990. Increased lake productivity and algal production was reflected by the increased LOI₅₅₀ level and a depletion of δ¹³C_bulk signal over the last two decades. The results of Redundancy Analysis(RDA) showed that hydrodynamic conditions and the nutrient level were among the key environmental factors in driving diatom community variation over the last two centuries. Furthermore, variance partitioning analyses showed that hydrodynamic conditions and the nutrient level independently accounted for 6.3%and 1.4%of the total variance in diatom variation, respectively, with their interaction explaining 13.1%of diatom variation since ca.1830A.D. More recently, the stronger interaction among nutrient, hydrological and temperature proxies revealed an important role of regional warming in driving diatom community shift. Overall, the decrease in ecosystem health and biodiversity has been prominently caused by intensified human disturbances in the context of climate change over the last two centuries. Therefore, the control of catchment nutrient input and appropriate water regulation should be required for the maintenance of ecosystem health in plateau shallow lakes under the scenario of long-term climate change.
Key words:Jianhu Lake/
environmental change/
diatoms/
ecological assessment/
biodiversity



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