Integrating bacterial metabolism as a key modulator of the response of aquatic ecosystems to human disturbances

淡水生态系统是镶嵌在陆地景观中的生物地球化学热点，经历了农业和城市化等人类驱动的快速变化。这一作用的核心是异养细菌的代谢活动，它们除了为水生食物网提供营养和能量外，还负责内陆水域有机物（OM）的大部分降解和矿化。尽管在生态系统层面上认识到了这一作用，但人们对人为干扰如何以及在多大程度上通过改变输送到周围水域的OM的数量、化学性质和年龄来改变水生微生物群落的代谢和功能知之甚少。在微生物生态学和水生生物地球化学的界面上进行研究，我建议进一步了解微生物代谢与OM分子特性之间存在的联系，以更好地理解和预测内陆水体对人类活动的整体生态系统响应。我的研究计划的主要目标是：(i)确定从森林景观到农业和城市地区的土地覆盖梯度释放到水生界面的有机分子，（ii）评估人类活动对动员有机池的吸收所涉及的微生物策略，以及（iii）确定水生细菌群落沿着扰动梯度的代谢反应。依靠最先进的分析化学技术和独特的实验方法，我的研究计划将结合在quamezbec的Mauricie地区的时空实地调查，利用该地区存在的巨大的人为影响梯度，以及实验室分析，揭示代表性受影响系统中细菌资源利用策略。这一项目代表了迈向综合理解人类干扰如何不仅会破坏陆地-水界面元素的流动，还会破坏水生食物网和生态系统的功能的关键一步。这一认识反过来将使科学家和决策者能够预测水生生态系统和食物网对人类压力的反应，并指导受影响流域最紧迫的恢复工作。

Freshwater ecosystems are biogeochemical hotspots embedded in the*terrestrial landscape that undergoes rapid human-driven changes such as*agriculture and urbanization. Central to this role are the metabolic activities*of heterotrophic bacteria, which are responsible for most of the degradation*and mineralization of the organic matter (OM) transiting in inland waters in*addition to providing nutrients and energy to the aquatic food web. Despite the*recognition of this role at the ecosystem level, little is known about how and*to which extent anthropogenic disturbances may alter the metabolism and*functioning of aquatic microbial communities through changes in the amount,*chemical character, and age of the OM delivered to surrounding waters.*Conducting research at the interface of microbial ecology and aquatic*biogeochemistry, I propose to further our understanding of the links existing*between microbial metabolism and the molecular properties of OM across*perturbation gradients to better understand and predict the overall ecosystemic*response of inland waterbodies to human activities. The main objectives of my*research program are to: (i) identify the organic molecules released into the*aquatic interface along gradients in land-cover from forested landscapes to*agriculture and urban areas, (ii) assess the microbial strategies involved in*the uptake of the mobilized organic pool by human activities, and (iii)*determine the metabolic response of aquatic bacterial communities along*perturbation gradients. Relying on state-of-the-art technics in analytical*chemistry and unique experimental approaches, my research program will combine*temporal and spatial field-based surveys in the Mauricie region of Québec*taking advantage of the large gradient in anthropogenic influence present in this region, as well*as laboratory assays shedding light into the bacterial strategies of resource*utilization in representative impacted systems. This program represents a*crucial step towards an integrative understanding of how human disturbance may disrupt not only the flow of elements at the land-water interface, but also*the functioning of aquatic food webs and ecosystems. This understanding will in*turn allow scientists and policy makers to forecast the response of aquatic*ecosystems and food webs to human pressure and to direct the most pressing*restoration efforts in impacted watersheds.