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化/变化预计将对淡水生态系统的水生态系统产生深远影响(见气专委2001、2007；2005年北极气候影响评估)。主要影响包括区域气候学和水文学的变化，水生物种分布、丰度和生态的变化，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和淡水生态系统内的过程的变化。北极淡水系统对气候变化/变化特别敏感，因为许多水生态过程对气候的相对较小变化作出反应。这些变化反过来直接和间接地影响到景观和集水区一级的生物地球化学过程以及水生系统内相关的水文和生态反应。到目前为止，我们的研究已经确定了北极高地湖泊的水体透明度的生物模式，这与在温带湖泊中发展的交替稳定状态理论(ASST)所预测的相反。利用海岸线退行性热岩溶塌陷模拟气候变化引起的景观效应，拟议研究的主要目的是确定外来(景观衍生)有机碳和营养物质的外部补贴对北极高地湖泊中上层和底栖生产力关系以及营养/食物网响应的作用和相对重要性。将结合景观/永久冻土的地球化学和水文集水区研究以及在重复中尺度系统中进行的“特定地点”实验来检验ASST的一般预测。拟议的研究结果将促进我们对Asst对北极湖泊系统的普遍适用性的理解，并将进一步阐明可能的替代机制，这些机制可能正在运行并产生所观察到的湖泊“状态”模式。此外，所获得的知识将直接适用于为北极湖系统的养护、保护和管理制定适应方案，以应对当前和未来的气候多变和变化。

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.