人类活动是我国湖泊富营养化发展的主要驱动力，湖泊富营养化则引起浮游植物群落演替并可能导致水华现象。云贵高原第二大淡水湖洱海虽然水质为II-III类，但已发生有毒蓝藻水华，且近30年水华蓝藻优势种发生了从束丝藻-鱼腥藻-微囊藻的演替。目前这类富营养初期湖泊的蓝藻水华发生规律尚未明了。本项目将以洱海为对象，在210Pb/137Cs测年基础上，采用沉积物的蓝藻DNA分析检测新技术和藻类色素高分辨分析检测技术，结合卫星遥感历史数据，重建近百年洱海的蓝藻群落演替过程和蓝藻水华规模变化过程；以沉积物人类活动相关标志物分析，结合流域社会经济数据，重建近百年流域人类活动干扰过程；通过蓝藻演替和人为干扰之间的关系研究，解析蓝藻水华发生和演替的驱动因子。同时本研究还将结合流域气象变化历史数据，分析当地气候变化对蓝藻水华的影响强度。本研究结果将为洱海以及其他富营养初期湖泊的蓝藻水华防治提供基础理论依据。

Anthropogenic activities are the main driving forces for the lake eutrophication of China. Eutrophication causes succession of phytoplankton community and may induce algal bloom. Algal bloom occurred in many lakes in China has already posed threats on water resources and aquatic ecosystem. Toxic cyanobaterial bloom also occurred in Erhai lake, the second largest freshwater lake of Yunnan-Guizhou plateau, although the water quality of Erhai lake still remained at class II to III. The dominant bloom-forming cyanobateria showed succession from Aphanizomenon to Anabeana and to Microcystis presently during the last 30 years. The mechanism of the occurrence and succession of cyanobacterial bloom in mesotrophic lake is not well understood. Therefore in this project we plan to collect the sediment cores of Erhai lake, constructing the chronology by 210Pb/137Cs dating, to reconstruct the succession process over the last 100 years of cyanobaterial communities by sediment pigment analysis and qPCR/DGGE analysis, as well as the change of algal bloom scale in last 30 years by retrieval of Chl-a values from remote sensing data. The paleolimnological proxies for human activities will also be determined with the sediment cores, to reconstruct the anthropogenic disturbance process over the last 100 years with the supplement of local socio-economic data. The main driving factors will be identified by relationship analysis between the cyanbaterial community succession and the human activities. The influence of local climate change on the cyanobacterial community succession will be evaluated. The results of this project will be of benefit to the prevention of cyanobacterial bloom in Erhai lake as well as in other mesotrophic lakes.