Collaborative LTREB Proposal: Will increases in dissolved organic matter accelerate a shift in trophic status through anoxia-driven positive feedbacks in an oligotrophic lake?

LTREB 协作提案：溶解有机物的增加是否会通过寡营养湖泊中缺氧驱动的正反馈加速营养状态的转变？

• 批准号: 1754271
• 负责人: Cathy Collins
• 金额: $ 1.5万
• 依托单位: Bard College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1754271&HistoricalAwards=false
• 关键词: Collaborative; LTREB; Proposal; Will; increases

Lakes provide many services to society, such as clean drinking water and productive fisheries. Many lakes, however, are now experiencing increased input of carbon and nutrients, warming temperatures, and declining ice cover, which may reduce water quality or cause blooms of potentially harmful algae. Specifically, many lakes across the United States are experiencing increased browning due to high loading of organic matter leached from land plants. Browning reduces water clarity and interferes with drinking water management practices. In addition, it can cause other changes that may lead to rapid long-term declines in water quality. This research will test the hypothesis that browning may reduce oxygen concentrations in lakes. Low oxygen can cause nutrient release from lake sediments that may increase algae blooms, leading to lake eutrophication. Understanding the effects of browning will increase knowledge of lake ecosystems, and improve forecasts of how lakes will change as their surrounding environments change. This research will also train graduate and undergraduate students, and will lead to better public understanding of threats to lake water quality.Ecological tipping points are of vital interest as anthropogenic activities rapidly transform natural ecosystems. Changes in dissolved organic matter (DOM) represent one important potential driver of tipping points in aquatic ecosystems. This project will investigate whether increases in terrestrial DOM loading can push clear-water oligotrophic lakes beyond a critical tipping point by stimulating hypolimnetic anoxia and sediment DOM and phosphorus release, which may initiate a positive feedback loop of decreasing water clarity, stronger thermal stratification, and enhanced hypolimnetic anoxia. This feedback loop accelerates ecological change and ultimately may shift lake trophic status toward greener, mesotrophic to eutrophic as well as browner, dystrophic conditions. This project will extend a long-term data set of water quality variables sampled since the late 1980s in two lakes in or near the Lacawac Sanctuary and Biological Field Station, located in northeastern Pennsylvania. Complementing these long-term observations, experiments and modeling will be carried out to understand feedbacks associated with browning and enhancing understanding of broader patterns of change in inland water bodies. The project will support a regional lake monitoring network in Pennsylvania and closely interface with GLEON, the Global Lake Ecological Observatory Network.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

湖泊为社会提供许多服务，例如清洁的饮用水和高效的渔业。然而，许多湖泊现在正在经历碳和营养物质输入的增加、气温变暖和冰盖减少，这可能会降低水质或导致潜在有害藻类的大量繁殖。具体来说，由于陆地植物浸出的有机物含量过高，美国许多湖泊的褐变程度正在加剧。褐变会降低水的透明度并干扰饮用水管理实践。此外，它还可能引起其他变化，可能导致水质快速长期下降。这项研究将检验褐变可能降低湖泊中氧气浓度的假设。低氧会导致湖泊沉积物释放营养物质，从而增加藻类繁殖，导致湖泊富营养化。了解褐变的影响将增加对湖泊生态系统的了解，并改进对湖泊随周围环境变化而变化的预测。 这项研究还将培训研究生和本科生，并使公众更好地了解湖泊水质所面临的威胁。随着人类活动迅速改变自然生态系统，生态临界点至关重要。溶解有机物（DOM）的变化是水生生态系统临界点的重要潜在驱动因素之一。该项目将研究陆地 DOM 负荷的增加是否可以通过刺激低浅度缺氧和沉积物 DOM 和磷释放来推动清水寡营养湖泊超过临界临界点，这可能会启动水体透明度降低、热分层增强和磷释放的正反馈循环。增强的低浅层缺氧。这种反馈循环加速了生态变化，并最终可能将湖泊的营养状况从绿色、中营养状态转变为富营养状态以及棕色、营养不良状态。该项目将扩展自 20 世纪 80 年代末以来在位于宾夕法尼亚州东北部的拉卡瓦克保护区和生物田站或其附近的两个湖泊采样的水质变量的长期数据集。为了补充这些长期观察、实验和建模，我们将进行实验和建模，以了解与褐变相关的反馈，并加强对内陆水体更广泛的变化模式的理解。该项目将支持宾夕法尼亚州的区域湖泊监测网络，并与全球湖泊生态观测站网络 GLEON 密切配合。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。