The synergistic effects of climate and anthropogenic drivers on toxic cyanobacterial blooms

项目摘要 蓝藻水华事件是由有害藻华（cHAB）的环境线索形成的 组成和生物活性。事实上，在伊利湖，两个明显不同的蓝藻属，微囊藻 和浮游发藻，产生微囊藻毒素，一种有效的肝毒素。而这两种蓝藻都在沃茨中大量繁殖 受农业径流输送的营养物质影响，微囊藻通常在近海沃茨大量繁殖， 浮游发藻在近岸海湾中占优势。先前的研究表明，气候变化引起的 温度升高促进微囊藻的生长，而浮游发藻在受温度升高影响的沃茨中持续存在。 长期的氮消耗。鉴于这两种生物的不同特性， 微囊藻毒素可能需要不同的管理策略来保护供水。我们的首要目标是 本项目旨在研究氮素有效性和温度在发展中的作用， 伊利湖和其他受水华影响的淡水中cHAB分类群的繁殖力和持久性。知情 通过元转录组学调查的基线数据，我们将设计微观世界和恒化器实验， 了解两个伊利湖cHAB属之间的竞争和导致水华毒性的因素。 具体而言，我们将在本项目中测试以下三个假设： 1)氮的有效性控制cHAB群落结构。混合微囊藻的微宇宙和 浮游发藻水华群落将暴露于不同的氮供应和温度制度， 确定每一种对一种开花形成剂相对于另一种开花形成剂的优势的贡献程度。 2)微囊藻毒素的产生依赖于温度和氮的形态。微囊藻的恒化器研究 在控制温度和更高温度下培养的浮游发藻将揭示不同的化学形式 氮（硝酸盐与尿素）促进生长和毒素的产生。 3)湖沼微生物组的活性促进了cHAB物种的增殖。 Bloom社区的元transsciptomic分析将提供对整个社区活动的评估。 微生物联合体的cHAB事件，以确定什么生物和途径有助于cHAB 发展、持续和衰退。 该项目的第二个目标是生成一个全面的伊利湖环境组学数据集， 由五大湖淡水沃茨中心内的综合研究项目共享和利用， 人体健康

Project Summary Cyanobacterial bloom events are shaped by environmental cues that contribute to harmful algal bloom (cHAB) composition and toxigenicity. Indeed, in Lake Erie, two distinctly different cyanobacterial genera, Microcystis and Planktothrix, produce microcystin, a potent hepatotoxin. Whereas both cyanobacteria bloom in waters affected by nutrients delivered by agricultural runoff, Microcystis typically blooms in offshore waters, and Planktothrix dominates nearshore embayments. Prior work has suggested a role of climate-change induced temperature increases in promoting growth of Microcystis, and that Planktothrix persists in waters affected by prolonged nitrogen depletion. Given the different characteristics of these two organisms, limiting exposure to microcystin may require different management strategies to protect the water supply. Our overarching aim in this project is to address the extent to which N availability and temperature play in the development, toxigenicity and persistence of cHAB taxa in Lake Erie and other bloom-affected freshwaters. Informed by baseline data from metatranscriptomic surveys, we will design microcosm and chemostat experiments aimed at understanding competition between the two Lake Erie cHAB genera and factors contributing to bloom toxicity. Specifically, we will test three hypotheses in this project listed below: 1) Nitrogen availability controls cHAB community structure. Microcosms of mixed Microcystis and Planktothrix bloom communities will be exposed to different regimes of N availability and temperature to determine the degree to which each contribute to the dominance of one bloom-former over another. 2) Microcystin production is dependent on temperature and N speciation. Chemostat studies of Microcystis and Planktothrix cultures at control and warmer temperature will reveal how different chemical forms of N (nitrate vs. urea) promote growth and toxin production. 3) The proliferation of cHAB species is promoted by the activity of the limnetic microbiome. Metatransciptomic analysis of bloom communities will provide an assessment of the activities of the entire microbial consortium in cHAB events in order to determine what organisms and pathways assist in cHAB development, persistence and decline. A second aim of this project is to generate a comprehensive Lake Erie environmental `omics data set that can be shared and utilized by the integrated research projects within the Great Lakes Center for Fresh Waters and Human Health.