| Summary: | This research will determine how the shifting seasonality of arctic river hydrology alters key biotic linkages within and among lake and stream components of watersheds and may alter the function of the arctic system. Arctic grayling (Thymallus arcticus) is a quintessential, circumpolar arctic species that provides a model system for understanding the impacts of changing seasonality on arctic ecosystem function because an interconnected and varied landscape (large tundra rivers, small streams and lakes) is required to maintain their population viability. Changes to environmental conditions that disrupt their migration will affect the system-level function of aquatic ecosystems. Grayling serve as food for other biota, including lake trout, birds and humans, and as top-down controls in stream ecosystems suggesting that changes to their populations will have effects that reverberate throughout the coupled river-lake system. The scale and pace of the changes now impacting tundra lakes and streams imparts an urgency to understand how they are linked and how they function as a system. This work will address 4 questions: 1) How are seasonality, rate and distance of grayling migration affected by climate change? 2) Are the seasonality of life-cycles, life-history and attributes of stream insect populations changing in response to climate change? 3) How does changing seasonality of river discharge interact with insect production to affect availability and transfer of stream production to grayling? 4) What is the effect of climate driven disruption of the migratory link on the structure and function of winter refugia?
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