The role of algal-bacterial interactions in aquatic ecosystem function

微生物是水生生态系统中生物地球化学循环和碳(能量)流动的基本驱动力。在生态系统功能方面，自由漂浮的光合藻(浮游植物)和异养细菌(浮游细菌)分别作为初级生产者和分解者发挥着不同的作用。尽管藻类和细菌群落在水生生态系统中经常被研究为自治的官能团，但它们可以以各种相互作用的方式相互作用，这些方式是拮抗的和/或协同的。为了更好地了解淡水生态系统中的能量流动和营养循环，我的研究计划将重点放在藻类和细菌在水生生态系统功能和污染物归宿中的重要作用。具体地说，我的研究小组将确定藻类和细菌之间的协同和拮抗相互作用如何调节湖泊系统中的碳、营养和污染物动态。来自安大略省中南部交错带的一系列小湖泊将是我们研究计划的重点。这片土地是五大湖盆地从帕里湾到金斯敦的一条横断面上，石灰岩和花岗岩为主的基岩之间的狭窄生态过渡带。由于地形不同，这片土地的地质镶嵌提供了一系列理想的环境梯度(即PH值、溶解有机碳和营养物质)。因此，我们将能够直接评估代表一系列环境特征的湖泊中的藻类细菌群落，所有这些都在相对较小的地理和气候区域内。这项研究计划将首次(1)描述湖泊中代谢不同的微生物群落的结构/功能，以及(2)展示藻类和细菌的相互作用如何影响淡水系统中的碳、营养和污染物动态。

Microbes are the essential drivers of biogeochemical cycling and carbon (energy)-flow in aquatic ecosystems. Within the context of ecosystem function, free-floating photosynthetic algae (phytoplankton) and heterotrophic bacteria (bacterioplankton) have distinct roles as primary producers and decomposers, respectively. Though often studied as autonomous functional-groups in aquatic ecosystems, algal and bacterial communities can interact in a variety of ways that are antagonistic and/or synergistic. To improve our understanding of energy flow and nutrient cycles across freshwater ecosystems, my research program will focus on the important roles of algae and bacteria as key players in aquatic ecosystem function and contaminant fate. Specifically, my research group will determine how the synergistic and antagonistic interactions between algae and bacteria mediate carbon, nutrient, and contaminant dynamics in lake systems. A series of small lakes from the "Land Between" ecotone in south-central Ontario will be the focus of our research program. The Land Between is a narrow ecological transition zone between limestone and granite-dominated bedrock along a transect from Parry Sound to Kingston in the Great Lakes Basin. The geological mosaic of the Land Between offers an ideal array of environmental gradients (i.e. pH, dissolved organic carbon, and nutrients) due to the variable physiography. As such, we will be able to directly assess the algal-bacterial communities in lakes representing a range of environmental characteristics, all within a relatively small geographic and climatic region. This research program will be the first of its kind to (1) Characterize the community structure/function of metabolically-distinct microbial groups in lakes, and (2) Show how algal-bacterial interactions influence carbon, nutrient, and contaminant dynamics in freshwater systems.