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

淡水生态系统是嵌入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，除了为水生食物网提供营养和能量外，异养细菌还负责内陆水域有机物（OM）的大部分降解和矿化。尽管在生态系统水平上认识到这一作用，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开展研究，进一步了解微生物代谢与OM跨扰动梯度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沿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quamezi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利用资源的策略。这个项目代表了迈向综合理解人类干扰如何不仅破坏陆地-水界面元素流动，而且破坏水生食物网和生态系统功能的关键一步。这种理解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 theterrestrial landscape that undergoes rapid human-driven changes such asagriculture and urbanization. Central to this role are the metabolic activitiesof heterotrophic bacteria, which are responsible for most of the degradationand mineralization of the organic matter (OM) transiting in inland waters inaddition to providing nutrients and energy to the aquatic food web. Despite therecognition of this role at the ecosystem level, little is known about how andto which extent anthropogenic disturbances may alter the metabolism andfunctioning 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 aquaticbiogeochemistry, I propose to further our understanding of the links existingbetween microbial metabolism and the molecular properties of OM acrossperturbation gradients to better understand and predict the overall ecosystemicresponse of inland waterbodies to human activities. The main objectives of myresearch program are to: (i) identify the organic molecules released into theaquatic interface along gradients in land-cover from forested landscapes toagriculture and urban areas, (ii) assess the microbial strategies involved inthe uptake of the mobilized organic pool by human activities, and (iii)determine the metabolic response of aquatic bacterial communities alongperturbation gradients. Relying on state-of-the-art technics in analyticalchemistry and unique experimental approaches, my research program will combinetemporal and spatial field-based surveys in the Mauricie region of Québectaking advantage of the large gradient in anthropogenic influence present in this region, as wellas laboratory assays shedding light into the bacterial strategies of resourceutilization in representative impacted systems. This program represents acrucial step towards an integrative understanding of how human disturbance may disrupt not only the flow of elements at the land-water interface, but alsothe functioning of aquatic food webs and ecosystems. This understanding will inturn allow scientists and policy makers to forecast the response of aquaticecosystems and food webs to human pressure and to direct the most pressingrestoration efforts in impacted watersheds.