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

预计加拿大北极地区的气候变率/变化将对淡水生态系统的水文生态产生深远的影响（见IPCC 2001、2007；北极气候影响评估2005）。主要影响包括区域气候和水文的变化，水生物种的分布、丰度和生态的变化，景观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在淡水生态系统内的过程的变化。北极淡水系统对气候变率/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流域水平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中水清晰度的生物模式，这与温带湖泊中发展的交替稳定状态理论（Alternate Stable State Theory，简称“候补稳态理论”）的预测相反。利用海岸线退退性热岩溶塌陷作为气候变化引起的景观效应的模拟，本研究的主要目的是确定外来（景观衍生的）有机碳和营养物质的补贴对北极高地湖泊中上层和底栖生物生产力关系和营养/食物网响应的作用和相对重要性。景观/永久冻土地球化学和水文集水区研究的结合以及在复制的中尺度环境中进行的“特定地点”实验将用于测试ASST的一般预测。拟议研究的结果将促进我们对北极湖泊系统的一般适用性的理解，并将进一步阐明可能运行和产生观察到的湖泊“状态”模式的可能替代机制。此外，所获得的知识将直接适用于制定北极湖泊系统养护、保护和管理的适应方案，以应对当前和未来的气候变率和变化。

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.