Hydro-ecological and food web responses of Arctic lakes to climate-related landscape disturbance

加拿大北极地区的气候变异/变化预计将对淡水生态系统的水文生态产生深远影响（见气候小组2001年，2007年;北极气候影响评估2005年）。主要影响包括区域气候和水文变化，水生物种分布、丰度和生态的改变，地貌和相关水生生境的物理和化学环境的变化，以及作用于淡水生态系统及其内部的过程的改变。北极淡水系统对气候多变性/变化特别敏感，因为许多水文生态过程对相对较小的气候变化作出反应。这些变化反过来又直接和间接地影响景观和集水区一级的生态地球化学过程以及水生系统内相关的水文和生态反应。迄今为止，我们的研究已经确定了在北极高地湖泊的水质清澈度的生物模式，相反的是什么会预测从交替稳定状态理论（ASST）开发的温带湖泊。利用海岸线退化热岩溶塌陷作为气候变化引起的景观效应的模拟，拟议的研究的主要目标是确定外来（景观衍生）有机碳和营养素的外部补贴的作用和相对重要性的中上层和底栖生产力的关系和营养/食物网的反应在高地北极湖泊。景观/永久冻土地球化学和水文集水区的研究和“特定地点”的实验进行复制的中生态系统的组合将被用来测试ASST的一般预测。从拟议的研究结果将推进我们的理解ASST北极湖泊系统的一般适用性，并将进一步阐明可能的替代机制，可以操作和生产所观察到的模式的湖泊“状态”。此外，所获得的知识将直接适用于针对目前和未来的气候变异性和变化，制定养护、保护和管理北极湖泊系统的适应备选办法。

Climate variability/change in the Canadian arctic is expected to have far-reaching impacts on the hydro-ecology of freshwater ecosystems (see IPCC 2001,2007; Arctic Climate Impact Assessment 2005). Key effects include changes in regional climatology and hydrology, alterations in the distribution, abundance and ecology of aquatic species, changes in the physical and chemical environments of the landscape and related aquatic habitats, and alterations to the processes that act on and within freshwater ecosystems. Arctic freshwater systems are particularly sensitive to climate variability/change because numerous hydro-ecological processes respond to relatively small changes in climate. These changes in turn directly and indirectly affect landscape- and catchment-level biogeochemical processes and associated hydrological and ecological responses within aquatic systems. Our research to date has identified a biomodal pattern of water clarity in the Arctic upland lakes, opposite to what would be predicted from Alternate Stable State Theory (ASST) developed in temperate lakes. Using shoreline retrogressive thermokarst slumping as an analogue for climate change-induced landscape effects, the primary objective of the proposed research is to determine the role and relative importance of external subsidization of allochthonous (landscape derived) organic carbon and nutrients on pelagic and benthic productivity relationships and trophic/food-web responses in upland Arctic lakes. A combination of landscape/permafrost geochemical and hydrological catchment studies and "site-specific" experiments conducted in replicate mesocosms will be used to test the general predictions of ASST. Findings from the proposed research will advance our understanding of the general applicability of ASST to arctic lake systems and will further elucidate possible alternative mechanisms that could be operating and producing the observed pattern of lake "state". Furthermore, the knowledge obtained will be directly applicable to the development of adaptation options for the conservation, protection and management of arctic lake systems in response to present and future climate variability and change.