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

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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.