Researching the role of dissolved organic matter as a nutrient resource in freshwater ecosystems

淡水正在以比任何其他行星领域更快的速度丧失生物多样性。推动这一趋势的压力因素很多，其中气候变化和食品生产和消费带来的养分输送增加无处不在。到目前为止，由于在快速变化的环境中进行实验的物理挑战，以及对生物可用养分形式的狭隘理解，关于营养丰富对淡水生物群的影响的研究一直受到限制。它侧重于物种对无机营养物质形态的特定反应，通常是在体外或在湖泊中，很少是在环境条件下的流水，通常是对微生物或浮游生物的反应，而忽略了其他生物群体的反应、群落一级对富集的反应以及淡水中一系列可生物利用的有机化合物的综合影响。为了更新当前河流生态系统的营养循环理论，需要进行变革性研究，从解释生态系统的一部分如何对有限范围的压力源做出反应的研究，转变为解释整个生态系统如何对广泛的压力源做出反应的基本的整体理论。我将领导一个多学科团队来应对这一挑战，在野外和气候变化的条件下，在分子尺度分析、稳定同位素探测和环境基因组学方面应用创新技术。然后，我们将使用新的数据驱动的建模来了解分类和功能变化之间的关系，以响应溶解有机物(DOM)和无机养分暴露，揭示环境x基因在生物响应营养和气候应激源中的相互作用。这将推动当前的理论，改变我们对全部营养组合对淡水生态系统影响的理解，揭示DOM的具体作用，因为DOM池的组成、生态系统的物种组成、溪流化学计量和环境特征不同，DOM的作用也不同。

Freshwaters are losing biodiversity at a higher rate than any other planetary domain. A wide range of stressors are driving this trend, of which climate change and increasing nutrient delivery from food production and consumption are ubiquitous. Research to date on nutrient enrichment impacts on freshwater biota has been limited by the physical challenge of experimentation in a rapidly changing environment, and a narrow perception of bioavailable nutrient forms. It has focused on species-specific responses to inorganic nutrient forms, often in vitro or in lakes, rarely for flowing waters under ambient conditions, and usually for microbial or planktonic organisms, ignoring the responses of other biotic groups, community level responses to enrichment, and the combined impacts of the range of bioavailable organic compounds in freshwaters. Transformational research is needed to update current nutrient cycling theory for stream ecosystems, shifting from research explaining how part of the ecosystem responds to a limited range of stressors, to fundamental, holistic theory explaining how whole ecosystems respond to a broad palette of stressors. I will lead a multidisciplinary team to tackle this challenge, applying innovative techniques in molecular scale analysis, stable isotope probing and environmental genomics, under field and climatically-altered conditions. We will then use new data-driven modelling to understand relationships between taxonomic and functional shifts in response to dissolved organic matter (DOM) and inorganic nutrient exposure, revealing environment x gene interactions in biotic responses to nutrient and climate stressors. This will advance current theory and transform our understanding of the impacts of the full nutrient portfolio on freshwater ecosystems, revealing the specific role of DOM as this varies according to the composition of the DOM pool, species composition of the ecosystem, stream stoichoimetry and environmental character.