Abstract：
Harmful algal blooms (HABs) producing toxic metabolites are increasingly threatening environmental and human health worldwide. Unfortunately, long-term process and mechanism triggering HABs remain largely unclear due to the scarcity of temporal monitoring. Retrospective analysis of sedimentary biomarkers using up-to-date chromatography and mass spectrometry techniques provide a potential means to reconstruct the past occurrence of HABs. By combining aliphatic hydrocarbons, photosynthetic pigments, and cyanotoxins, we quantified herein century-long changes in abundance, composition, and variability of phototrophs, particularly toxigenic algal blooms, in China\'s third largest freshwater Lake Taihu. Our multi-proxy limnological reconstruction revealed an abrupt ecological shift in the 1980s characterized by elevated primary production, Microcystis-dominated cyanobacterial blooms, and exponential microcystin production, in response to nutrient enrichment, climate change, and trophic cascades. The empirical results from ordination analysis and generalized additive models support climate warming and eutrophication synergy through nutrient recycling and their feedback through buoyant cyanobacterial proliferation, which sustain bloom-forming potential and further promote the occurrence of increasingly-toxic cyanotoxins (e.g., microcystin-LR) in Lake Taihu. Moreover, temporal variability of the lake ecosystem quantified using variance and rate of change metrics rose continuously after state change, indicating increased ecological vulnerability and declined resilience following blooms and warming. With the persistent legacy effects of lake eutrophication, nutrient reduction efforts mitigating toxic HABs probably be overwhelmed by climate change effects, emphasizing the need for more aggressive and integrated environmental strategies.
摘要：
产生有毒代谢物的有害藻华（HAB）正日益威胁着全球的环境和人类健康。不幸的是,由于缺乏时间监测,引发HABs的长期过程和机制仍不清楚.使用最新的色谱和质谱技术对沉积生物标志物进行回顾性分析提供了重建HAB过去发生的潜在手段。通过结合脂肪烃，光合色素,和氰毒素，我们在这里量化了长达一个世纪的丰度变化，composition,和光养生物的变异性，特别是产毒藻华，位于中国第三大淡水湖太湖。我们的多代理森林重建揭示了1980年代的突然生态转变，其特征是初级生产增加，微囊藻为主的蓝藻水华，和成倍的微囊藻毒素生产，为了应对营养丰富，气候变化,和营养级联。排序分析和广义加性模型的经验结果通过养分循环支持气候变暖和富营养化协同作用，并通过浮力蓝藻增殖支持它们的反馈，维持水华形成潜力，并进一步促进毒性越来越大的氰基毒素的发生(例如，微囊藻毒素-LR）在太湖。此外，使用方差和变化率指标量化的湖泊生态系统的时间变异性在状态变化后不断上升，表明开花和变暖后生态脆弱性增加，恢复力下降。由于湖泊富营养化的持续遗产效应，减少有毒HABs的营养减少努力可能会被气候变化的影响所淹没，强调需要更积极和综合的环境战略。
