Limnology and Biogeochemistry of Arctic Delta Lakes

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Lakes associated with large river floodplains are among the most hydrologically complex, biologically productive, and biodiverse freshwater habitats in the world. They also face a wide range of threats and remain poorly understood because such systems represent vast areas of aquatic habitat world-wide, and global change is modifying the complex water level regimes that created these systems. The circumpolar Arctic coast is rich in such habitat, and is a region where climate is changing rapidly. The Mackenzie Delta is the second largest river floodplain in this region, and is one of the world's prominent aquatic ecosystems and a key ecosystem of the Canadian north because it functions as a biological hotspot relative to the surrounding arctic landscape. This delta is also on the leading edge of Arctic coastal changes because it is located in an area of subsidence that has enhanced relative sea level rise. It thus represents an exceptional model ecosystem to advance our fundamental understanding of aquatic habitat on large river floodplains. My long-term goal is to develop a general ecosystem paradigm for lakes on large river floodplains, not before possible, by teasing apart the varied mechanisms that create the combination of productivity, complexity, and diversity characteristic of these systems. This will advance our basic understanding of ecosystem complexity, and facilitate modeling of whether such systems respond resiliently or in surprising ways to multiple stresses of global change.       Over the next 5 years, I will focus on advancing our understanding of how changing coastal Arctic water levels will affect: (1) the ability of methane cycling microbial communities to either release carbon in these waters to the atmosphere as greenhouse gases or convert the carbon to forms consumed by fish and other organisms; and (2) the ability of Arctic delta habitat to function as a biogeochemical hotspot that affects delivery of riverine nutrients to the ocean. Our work represents an exceptional opportunity for training highly qualified people in Arctic fieldwork and in fundamental research of broad interest in aquatic and Arctic sciences.