Figure 1.
Spatial extent and duration of preferred thermal habitat in contrasting years.
Days with available preferred temperature are shown for walleye, Chinook salmon, lean lake trout, and siscowet trout in 1979 and 2006 at all modeled lake points. Preferred temperatures for walleye, Chinook salmon, lean lake trout, and siscowet trout are 21(±2°C), 13(±2°C), 10 (±2°C), and 4 (±2°C), respectively.
Figure 2.
Spatially explicit trends in the duration of preferred thermal habitat.
Trends in the number of days (days•decade−1) when preferred temperatures are present between 1979–2006 for all modeled lake points. Trends were computed using ordinary least squares regression using α = 0.10 (see methods). White indicates no significant trend in growing days.
Figure 3.
Interannual variability in preferred thermal habitat.
Variability is shown as the standard deviation in days with available preferred habitat across all years from 1979 to 2006.
Figure 4.
Areal extent of preferred thermal habitat over time.
Areal extent is computed as the total surface area in each year that contains at least the historical (first three years) median number of days with preferred thermal habitat available for walleye, Chinook salmon, lean lake trout, and siscowet trout between 1979 and 2006. The threshold number of days for walleye, Chinook salmon, lean lake trout, and siscowet trout are 11, 106, 140, and 330 days respectively (see Methods). Solid lines depict three year running mean.
Figure 5.
Observed mid-lake summer water temperatures in Lake Superior.
Temperatures reported are the average observed mean summer surface water temperatures (1 June through 30 September) at the eastern, middle, and western Lake Superior NOAA buoys from 1981–2011.