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

项目摘要 蓝藻水华事件是由导致有害藻华(CHAB)的环境线索决定的 成分和致毒性。事实上，在伊利湖，两个截然不同的蓝藻属--微囊藻 和Planktothrix产生微囊藻毒素，这是一种强有力的肝脏毒素。而这两种蓝藻都在水域中繁殖 受农业径流输送的营养物质的影响，微囊藻通常在近海水域繁殖， Planktothrix主宰着近岸海湾。先前的研究表明，气候变化引起的 温度升高促进微囊藻生长，浮游藻类在受影响的水域中持续存在 长时间的氮气耗竭。鉴于这两种生物的不同特点，限制接触 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 该项目旨在解决N的有效性和温度在开发中发挥作用的程度， 伊利湖和其他受水华影响的淡水中CHAB类群的毒性和持久性。知情者 根据元翻译调查的基线数据，我们将设计缩微和恒化实验，目的是 了解两个伊利湖藻属之间的竞争和造成水华毒性的因素。 具体地说，我们将测试该项目中列出的三个假设： 1)氮素有效性控制CHAB群落结构。微囊藻和混合微囊藻的微观世界 浮游植物水华群落将暴露在不同的N有效性和温度制度下 确定它们在多大程度上促成了一种开花方式对另一种开花方式的支配地位。 2)微囊藻毒素的产生依赖于温度和N的形态。微囊藻的化学恒化器研究 而在控制和较高温度下的Planktothrix培养将揭示不同化学形式的 N(硝酸盐和尿素)促进生长和毒素产生。 3)赤潮微生物群落的活动促进了CHAB菌种的增殖。 对水华群落的偏横切分析将提供对整个 CHAB事件中的微生物联盟，以确定哪些生物和途径在CHAB中起辅助作用 发展、坚持、衰落。 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，该数据集可以 由五大湖淡水中心内的综合研究项目共享和利用 人类健康。

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.