Catchment-fueled cyanobacteria blooms

全球变化的最高速率发生在北方生态系统。气候变暖、水文加剧和酸化恢复与陆地溶解有机物（DOM）向北方湖泊（即，布朗宁），这反过来又对藻类的生产力和多样性产生影响，而藻类是能量转移到湖泊食物网的主要途径。蓝藻水华（cyanobloom）威胁着全球的淡水资源。北部以前原始的清水湖泊意外地经历了蓝藻水华，这也许是未来更频繁、更强烈的蓝藻水华的早期预警。随着居住在北方湖泊沿岸的人们向政府报告蓝藻的数量显著增加，公众对蓝藻的关注程度有所提高。普遍接受的概念模型是，蓝藻与磷（P）和/或氮（N）管理不善。然而，我们现在在北方农村和偏远的湖泊收到了“新”的报告，这些湖泊没有已知的蓝藻历史。我们需要一个新的概念模型来解释蓝团的形成。我假设气候引起的北方湖泊的布朗宁为特殊的蓝藻生长创造了光照和营养条件。而DOM对湖泊光照和营养盐的影响（例如，N、P和铁（Fe））条件下，需要进一步的知识来理解藻类物种特异性对布朗宁的适应。DOM作为营养载体从周围集水区运输P、N和Fe，并作为营养海绵阻止P和Fe沉淀并将它们保持在水柱中。为了验证这一假设，我将（1）描述北方纬度的气候变化，重点是那些导致湖泊布朗宁的变化以及与之相关的湖泊光照和营养条件的改变;（2）将布朗宁与藻类生物量的变化和蓝藻相对于其他藻类的富集联系起来;和（3）探索蓝藻优势的增加对湖泊食物网中必需脂肪酸（预计减少）和蓝藻毒素（增加）转移的影响。从人类的角度来看，没有什么积极的关于cyanobloom。淡水资源和人类活动之间的密切联系使人类处于蓝藻毒素暴露途径中，直接影响包括人类通过饮用水或气溶胶暴露于蓝藻毒素，可导致神经和肝脏疾病。间接影响包括蓝细菌引发一连串的生物结果改变，因为蓝细菌可能减少必需脂肪酸的组成，增加食用鱼的毒素含量，或导致湖泊缺氧和鱼类或鱼类繁殖地的丧失。我的研究计划将创造知识，将形成必要的“预警”系统，可以导致预防和减轻北方湖泊蓝藻的基础。

The highest rates of global change are occurring in northern ecosystems. Climate warming, hydrological intensification, and acidification recovery are linked to increased inputs of terrestrial dissolved organic matter (DOM) into northern lakes (i.e., browning) which in turn have consequences to the productivity and diversity of algae that form a major pathway of energy transfer to food webs in lakes. Cyanobacterial blooms (cyanoblooms) threaten freshwater resources worldwide. Formerly pristine clear water lakes in the north are unexpectantly experiencing cyanoblooms, perhaps an early warning of more frequent, intense cyanoblooms in the future. Heightened public concern for cyanoblooms has been observed with a significant increase in the number of cyanobloom reports to governments by people living on the shores of northern lakes. The commonly accepted conceptual model is that cyanoblooms are associated with phosphorus (P) and/or nitrogen (N) mismanagement. However, we are now receiving “new” reports in northern rural and remote lakes with no known history of cyanoblooms. A new conceptual model of what forms cyanoblooms is needed. I hypothesize that the climate-induced browning of northern lakes creates light and nutrient conditions for exceptional cyanobacterial growth. While the effects of DOM on lake light and nutrient (e.g., N, P, and iron (Fe)) conditions is known, further knowledge is needed to understand algae species-specific adaptations to browning. DOM functions as a nutrient vector transporting P, N, and Fe from the surrounding catchment, and as a nutrient sponge preventing the precipitation of P and Fe and keeping them in the water column. To test this hypothesis, I will (1) Characterize climate changes at northern latitudes, focusing on those changes that lead to lake browning and the associated alterations to lake light and nutrient conditions; (2) Link browning to changes in algal biomass and the enrichment of cyanobacteria over other algae; and (3) Explore consequences of an increase in cyanobacteria dominance on the transfer of essential fatty acids (predicted to decrease) and cyanotoxins (to increase) in lake food webs. From a human perspective, there is nothing positive about cyanoblooms. The close association between freshwater resources and human activities place humans in the cyanotoxin exposure path. Direct effects include human exposure to cyanotoxins through drinking water or aerosols that can cause neurological and hepatological disorders. Indirect effects include cyanobacteria initiating a cascade of altered biological outcomes, as cyanobacteria may reduce the essential fatty acid composition and increase the toxin content in dietary fish or lead to lake hypoxia and the loss of fish or fish breeding grounds. My research program will create knowledge that will form the basis of essential “early warning” systems that can lead to the prevention and mitigation of cyanoblooms in northern lakes.