[Long-term pattern of lake ecosystem in response to eutrophication and water regulation in Chenghai Lake, Yunnan, China]. / äº‘å—ç¨‹æµ·æ¹–æ³Šç³»ç»Ÿå“åº”å¯Œè¥å »åŒ–ä¸Žæ°´æ–‡è°ƒæŽ§çš„é•¿æœŸæ¨¡å¼.

In the context of catchment development and climate change, anthropogenic activities have significantly altered the succession and functioning of freshwater ecosystems. Combining the sedimentary records and modern survey data, we reconstructed a 250-year history of ecological changes in Chenghai Lake, aiming to assess the long-term ecological changes in Changhai Lake in response to multiple environmental stresses, such as eutrophication and hydrological fluctuation.Three stages were identified for the process of nutrient enrichment leading to a long-term increase in primary production. Nutrient level was relatively low before 1970, increased gradually between 1970 and 2000, with an accelerating increase after 2000. The water regulation project enhanced water turbulence and river flux during 1993-2000, which promoted the growth of turbulence-tolerant Aulacoseira and influx of benthic Nitzschia. The organic carbon cycling in Chenghai Lake was mainly driven by the autogenetic inputs. The eutrophication process dominated the long-term shifts of diatom assemblages followed by hydrological fluctuation. Our results illustrated that ecological restoration and catchment management of Chenghai Lake not only need to focus on the control of nutrient enrichment and pollutant input, but also should consider hydrological regulation and water level fluctuation.

[Identification of the long-term patterns of catchment development and diatom community changes in Xihu Lake, Dali, Yunnan, China]. / å¤§ç†è¥¿æ¹–æµåŸŸå¼€å‘åŽ†å²ä¸Žç¡ è—»ç¾¤è½å˜åŒ–çš„æ¨¡å¼è¯†åˆ«.

Limnological studies have long focused on the nine largest plateau lakes and ecological assessment of lake eutrophication in Yunnan. However, comprehensive surveys of small and me-dium-sized lakes and their response to multiple stressors are largely absent. Here, we combined multi-proxy sediment analyses and documentary data, aiming to identify the long-term pattern of diatom community changes under the influence of climate change and anthropogenic disturbances, and to quantify their driving strengths. The results showed that Xihu Lake was in a pre-impact state with little ecological variability before the 1950s. Thereafter, expansion of land use increased the nutrient input and altered the lake hydrology, resulting in a significant shift of dominant diatoms from Cocconeis placentula to Fragilaria spp. From 1997, accelerating nutrient enrichment and hydrological changes led to the replacement of benthic diatoms by planktonic ones, resulting in a consistent loss of macrophytes and a decrease of ecological stability. Therefore, the types and strength of catchment development should be fully evaluated for effective protection of small and medium-sized alpine lakes in the context of global warming.