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地球化学热点，经历了快速的人类驱动的变化，如农业和城市化。异养细菌的代谢活动是这一作用的核心，它负责内陆沃茨中有机物（OM）的降解和矿化，并为水生食物网提供营养和能量。尽管在生态系统水平上已经认识到这一作用，但对于人为干扰如何以及在多大程度上通过改变向周围沃茨输送的有机质的数量、化学性质和年龄来改变水生微生物群落的代谢和功能，人们知之甚少。我建议进一步了解微生物代谢和OM分子特性之间的联系，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中沿沿着释放到水生界面的有机分子，（ii）评估人类活动对动员的有机库的吸收所涉及的微生物策略，以及（iii）确定沿扰动梯度的水生细菌群落的代谢反应。依靠分析化学和独特的实验方法中最先进的技术，我的研究计划将结合魁北克省Mauricie地区的时间和空间实地调查，利用该地区存在的人为影响的大梯度，以及实验室测定揭示代表性受影响系统中资源利用的细菌策略。该计划代表了对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综合理解的关键一步。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 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.