Collaborative Research: Shifting seasonality of Arctic river hydrology alters key biotic linkages among aquatic systems

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?本研究旨在厘清北极河流水文季节性变化如何重塑流域内湖泊与溪流组分内部及彼此间的关键生物联系，并可能改变北极系统的整体功能。北极茴鱼（Arctic grayling，*Thymallus arcticus*）是典型的环北极物种，可作为理解季节性变化对北极生态系统功能影响的模式系统——因其种群存续依赖于由大型苔原河流、小型溪流与湖泊构成的连通且多样的景观格局。任何破坏其洄游行为的环境条件变化，都将影响水生生态系统的系统级功能。茴鱼既是湖鳟、鸟类与人类等其他生物类群的食物来源，同时也是溪流生态系统中的顶级下行调控者，这意味着其种群数量变化将产生连锁效应，波及整个河湖连通系统。当前影响苔原湖泊与溪流的环境变化，其波及范围与演进速度凸显了理解这些景观如何彼此关联、并作为一个系统运行的紧迫性。本研究将围绕4个核心问题展开：1）气候变化如何影响茴鱼洄游的季节性、速率与距离？2）溪流昆虫种群的生活周期季节性、生活史特征与种群属性是否会随气候变化发生改变？3）河流水文季节性变化与昆虫生产力如何相互作用，进而影响溪流生产力向茴鱼的可利用性与传递效率？4）气候驱动的洄游联系中断，对冬季避难所的结构与功能将产生何种影响？