Catchment-fueled cyanobacteria blooms

全球变化率最高的是北部生态系统。气候变暖、水文强化和酸化恢复与北部湖泊陆源溶解有机物(DOM)输入的增加(即褐化)有关，这反过来又对藻类的生产力和多样性产生影响，藻类形成了向湖泊食物网转移能量的主要途径。蓝藻水华威胁着全世界的淡水资源。北方以前纯净的清水湖正在出人意料地经历蓝藻，这可能是未来更频繁、更强烈的蓝藻的早期预警。随着居住在北部湖泊沿岸的人们向政府报告的蓝藻数量显著增加，公众对蓝藻的关注程度也有所提高。普遍接受的概念模型是，蓝藻与磷(P)和/或氮(N)管理不善有关。然而，我们现在收到了北部农村和偏远湖泊的“新”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描述蓝藻的形成。我推测，气候导致的北方湖泊褐变为蓝藻的异常生长创造了光照和营养条件。虽然DOM对湖光和营养(如N、P和铁(Fe))条件的影响是已知的，但需要进一步的知识来了解藻类对褐变的特定适应。DOM的作用是作为营养载体从周围的集水区输送P、N和Fe，并作为营养海绵防止P和Fe的沉淀并将它们保持在水柱中。为了检验这一假设，我将(1)描述北纬地区的气候变化，侧重于那些导致湖泊褐化的变化以及与湖泊光照和营养条件相关的变化；(2)褐变与藻类生物量的变化以及蓝藻相对于其他藻类的丰富有关；以及(3)探索蓝藻优势度增加对湖泊食物网中必需脂肪酸(预计将减少)和氰化物(增加)转移的影响。从人类的角度来看，蓝藻并没有什么积极的东西。淡水资源和人类活动之间的密切联系将人类置于氰毒素暴露的道路上。直接影响包括人类通过饮用水或气雾剂接触氰基毒素，这可能导致神经和肝脏疾病。间接影响包括蓝藻引发一系列改变的生物结果，因为蓝藻可能减少基本脂肪酸组成，增加食用鱼中的毒素含量，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，这些知识将构成基本的“早期预警”系统的基础，这些系统可以预防和缓解北部湖泊中的蓝藻。

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.