• 关键词：千岛湖  沉积物色素  浮游植物丰度  人类活动  气候变化

• 基金项目：浙江省基础公益研究计划项目（No.LY20D010003）；国家自然科学青年基金（No.42007284）

• 黄汇豪
• 浙江师范大学生命科学学院， 金华 321004

• 林琪
• 中国科学院南京地理与湖泊研究所， 南京 210008

• 倪健
• 浙江师范大学生命科学学院， 金华 321004

• 廖梦娜
• 浙江师范大学生命科学学院， 金华 321004

• 摘要：千岛湖是浙江省第一大水库，近二十年来藻类异常增殖现象频发，正面临着生态脆弱性增加的风险.目前，针对千岛湖初级生产力和藻类群落长期演替缺乏研究，为水库生态环境保护及区域饮用水安全管理带来了一定困难.本研究基于千岛湖东南部沉积物短岩芯，综合分析沉积物年代学、色素及营养盐等地球化学指标，并结合流域社会经济和气候数据，重建了千岛湖建库以来的浮游植物变化历史，并探讨其主要影响因素.结果表明，千岛湖浮游植物色素生产量总体经历了3个主要阶段：1960—1975年的低生产量阶段，1976—2002年的缓慢增长阶段，2003—2021年的快速增长阶段.尽管该水库初级生产力在2003年达到峰值后出现下降趋势，但仍维持在偏离自然基线的较高水平.多元统计分析显示人类活动导致的水体营养富集，以及增温为代表的气候变化，是影响千岛湖初级生产力长期变化的主要因素.水体营养盐的年际及年代际尺度变化对千岛湖浮游植物丰度能够产生显著影响，蓝藻色素生产量主要响应于温度的年代际、年际和季节尺度变化.此外，降水量对浮游植物丰度的季节性变化影响显著，但对长期变化的影响很小.2000年以来基于鲢、鳙鱼的生物操纵技术对千岛湖浮游植物生长起到一定控制作用，但并未根除异常增殖问题，因此有关部门仍需加强对外源营养盐输入的控制.本研究为认识千岛湖水生态环境的长期变化提供了新视角，对水库生态环境保护政策的制定和实施提供了参考.

• Abstract：Qiandao Lake， known as Xin’anjiang Reservoir， is the largest reservoir in Zhejiang Province. Over the past two decades， abnormal algae proliferation happened frequently in the lake， which has increased the risk of ecological vulnerability. The long-term changes in the phytoplankton community and its driving factors in Qiandao Lake are lack of knowledge， which has brought difficulties to the reservoir’s ecological protection and threatened the regional drinking water safety management. This study reconstructed the history of phytoplankton abundance based on a sedimentary pigment record from the southeast part of the lake， and explored the key factors driving the change process by combining geochemical proxies， regional meteorological data， and indices reflecting human activities. Cluster analysis indicated three main stages of pigment concentration since the reservoir’s impoundment： the low production stage （1960—1975 A.D.）， the slow increasing stage （1976—2002 A.D.）， and the rapid increasing stage （2003—2021 A.D.）. The primary productivity of the lake reached its peak around 2003. Despite a decreasing trend after 2003， the primary productivity remained high deviating from the natural baseline. Increased nutrient concentration in water caused by human activities， and temperature rising were the main factors affecting the long-term changes in phytoplankton abundance in Qiandao Lake. Inter-annual and inter-decadal changes in nutrient concentration had significant effects on phytoplankton abundance. Inter-decadal， inter-annual and seasonal temperature variations significantly affected the abundance of cyanobacteria. Precipitation had little effect on the long-term phytoplankton abundance change but strongly affected the seasonal phytoplankton abundance. The biomanipulation had been applied in Qiandao Lake since 2000 A.D.， which resulted a reduction in phytoplankton abundance. However， the phytoplankton abundance was still high after 2000 A.D.， indicating that the biomanipulation technique is not the absolute solution for abnormal algal proliferation in Qiandao Lake. Therefore， the control of nutrient input should be given priority in water management. This study provides a new understanding of the long-term changes in the ecological environment in Qiandao Lake， and provides a reference for the formulation and implementation of protection strategies for the reservoir ecological environment.

• Key words：Qiandao Lake  sediment pigment  phytoplankton abundance  human activities  climate change

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