Abstract
Overwintering habitat for Arctic freshwater fish is essential, such that understanding the distribution of winter habitat quality at the landscape-scale is warranted. Adequate dissolved oxygen (DO) is a major factor limiting habitat quality in the Arctic region where ice cover can persist for 8 months each year. Here we use a mixed-effect model developed from 20 lakes across northern Alaska to assess which morphology and landscape attributes can be used to predict regional overwintering habitat quality. Across all lakes, we found that the majority of the variations in late winter DO can be explained by lake depth and littoral area. In shallow lakes (<4 m), we found evidence that additional variables such as elevation, lake area, ice cover duration, and snow depth were associated with DO regimes. Low DO regimes were most typical of shallow lakes with large littoral areas and lakes that had high DO regimes often were lakes with limited littoral areas and deeper water. Our analysis identifies metrics that relate to late winter DO regimes in Arctic lakes that can aid managers in understanding which lakes will likely provide optimum DO for overwintering habitat. Conversely, lakes which predicted to have marginal winter DO levels may be vulnerable to disturbances that could lower DO below critical thresholds to support sensitive fish. In regions where lakes are also used by humans for industrial winter water supply, such as ice-road construction for oil and gas development, these findings will be vital for the management of resources and protection of Arctic fish.
Highlights
Lakes in the Arctic cover up to 40 % of the landscape (Grosse et al 2012) and provide important aquatic habitat including overwintering habitat for numerous Arctic fish (West et al 1992; Morris 2003; Morris et al 2006; Millar et al 2013)
dissolved oxygen (DO) measurements at three common types of Arctic lakes show that DO is greatest in the fall when lake ice begins to form, but decreases in unique ways at each lake over the winter (Fig. 5)
We found that lake depth (m) and littoral area (%) were the most important variables to predict DO for all lakes (Table 3)
Summary
Lakes in the Arctic cover up to 40 % of the landscape (Grosse et al 2012) and provide important aquatic habitat including overwintering habitat for numerous Arctic fish (West et al 1992; Morris 2003; Morris et al 2006; Millar et al 2013). In addition to rivers of sufficient depths, deeper lakes that do not freeze to the bed (i.e., floating-ice lakes) can provide important winter habitat for fish. These locations serve as water sources for oil and gas development within the region (Jones et al 2009, 2013). Limited roads and the sensitivity of permafrost peatland tundra to disturbance necessitate that the majority of travel for exploration and some developments be conducted in the winter using temporary ice roads. Understanding how landscape factors relate to DO in Arctic lakes will inform managers as to which lakes potentially serve as highquality overwintering habitat and the sensitivity to disturbance from winter water extraction
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