Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China.
Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China.
Water Res. 2022 Jan 1;208:117866. doi: 10.1016/j.watres.2021.117866. Epub 2021 Nov 13.
Human activities and climate change are two major stressors affecting lake ecosystems as well as phytoplankton communities worldwide. However, how the temporal dynamics of phytoplankton are directly or indirectly linked to anthropogenic activities and climatic oscillation remains unclear. We assessed the annual trends (1988-2018) in phytoplankton abundance (PA) in Lake Dongting, China and related it to five groups of variables characterizing human activities, global climate oscillation, water nutrients, hydrology, and meteorology. We found a significant increase in PA, urbanization (Upop), total nitrogen (TN), fertilizer application (FA), number of summer days (SU), and the warm speed duration index (WSDI) and a significant decrease in the water discharge of three inlets (TIWD) and the sediment discharge of three inlets (TISD) and four tributaries (FTSD) and the net sediment deposition (NSD). However, no significant annual trends were observed for the number of rainstorm days (R50mm), the simple precipitation intensity index (SDII) and yearly anomalies of El Niño-Southern oscillation events (ENSOi). Cross-correlation Function analyses demonstrated that the operation of the Three George Dam (TGD) strengthened the effects of hydrology, rainfall patterns and ENSOi on phytoplankton, but strongly weakened the association between water nutrients, human activities and phytoplankton abundance. Path analysis revealed that TP, TN, FA, R50 mm as well as WSDI had a direct positive effect on PA, while a direct negative effect was found for ENSO, NSD and TISD. Human activities (Upop and FA), warming (WSDI and SU), and rainfall patterns (SDII and R50 mm) exerted indirect controls on phytoplankton through changes in water nutrients and hydrology. Climate change (ENSOi) had a direct effect on PA, but also showed twelve indirect pathways via changes in hydrology and meteorology (both positive and negative effects were found). Overall, meteorology contributed most markedly to the variations of PA (29.3%), followed by hydrology (25.3%), human activities (24%), water nutrients (10.5%), and ENSOi (1.9%). Our results highlight a strongly causal connection between human activities as well as global climate change and phytoplankton and the benefits of considering multiple environmental drivers in determining the temporal dynamics of lake biotic communities.
人类活动和气候变化是影响全球湖泊生态系统和浮游植物群落的两个主要压力源。然而，浮游植物的时间动态如何直接或间接地与人为活动和气候振荡相关联仍不清楚。我们评估了中国洞庭湖浮游植物丰度（PA）的年度趋势（1988-2018 年），并将其与表征人类活动、全球气候振荡、水营养物、水文学和气象学的五组变量相关联。我们发现 PA、城市化（Upop）、总氮（TN）、肥料施用（FA）、夏季天数（SU）和温暖速度持续时间指数（WSDI）呈显著增加趋势，而三个入口的水流量（TIWD）、三个入口的泥沙流量（TISD）和四个支流（FTSD）以及净泥沙沉积（NSD）呈显著减少趋势。然而，暴雨天数（R50mm）、简单降水强度指数（SDII）和厄尔尼诺-南方涛动事件年际异常（ENSOi）的年际趋势并不显著。互相关函数分析表明，三峡大坝（TGD）的运行增强了水文学、降雨模式和厄尔尼诺-南方涛动对浮游植物的影响，但强烈削弱了水营养物、人类活动和浮游植物丰度之间的关联。路径分析表明，TP、TN、FA、R50mm 和 WSDI 对 PA 有直接的正向影响，而 ENSO、NSD 和 TISD 则有直接的负向影响。人类活动（Upop 和 FA）、变暖（WSDI 和 SU）和降雨模式（SDII 和 R50mm）通过改变水营养物和水文学对浮游植物施加间接控制。气候变化（ENSOi）对 PA 有直接影响，但也通过水文学和气象学的变化显示了 12 条间接途径（既有正效应，也有负效应）。总的来说，气象学对 PA 的变化贡献最大（29.3%），其次是水文学（25.3%）、人类活动（24%）、水营养物（10.5%）和 ENSO（1.9%）。我们的研究结果突出了人类活动和全球气候变化与浮游植物之间的强烈因果关系，以及在确定湖泊生物群落的时间动态时考虑多个环境驱动因素的好处。
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