Limnology and Biogeochemistry of Arctic Delta Lakes

与大型河流漫滩相关的湖泊是世界上水文最复杂、生物生产力最高和生物多样性最丰富的淡水栖息地之一。它们还面临着广泛的威胁，但人们对它们仍然知之甚少，因为这些系统代表了世界范围内广阔的水生栖息地，而全球变化正在改变创造这些系统的复杂水位状况。环极北极沿岸富含此类栖息地，并且是气候变化迅速的地区。麦肯齐三角洲是该地区第二大河流漫滩，是世界上著名的水生生态系统之一，也是加拿大北部的关键生态系统，因为它相对于周围的北极景观而言是一个生物热点。该三角洲也处于北极海岸变化的前沿，因为它位于一个下沉区域，导致海平面相对上升。因此，它代表了一个特殊的生态系统模型，可以增进我们对大型河流洪泛区水生栖息地的基本了解。我的长期目标是通过梳理创造这些系统的生产力、复杂性和多样性特征组合的各种机制，为大型河流泛滥平原上的湖泊开发一个通用的生态系统范式，这在之前是不可能的。这将增进我们对生态系统复杂性的基本理解，并有助于对此类系统是否能够弹性地或以令人惊讶的方式应对全球变化的多重压力进行建模。       在接下来的五年里，我将重点推进我们对北极沿海水位变化将如何影响的理解：（1）甲烷循环微生物群落将这些水域中的碳作为温室气体释放到大气中或将碳转化为鱼类和其他生物体消耗的形式的能力； (2) 北极三角洲栖息地作为影响河流营养物质向海洋输送的生物地球化学热点的能力。我们的工作为培训北极实地考察以及对水生和北极科学广泛感兴趣的基础研究的高素质人才提供了绝佳的机会。

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.