Temperature
For the two main study systems, Lake Skrukkebukta and Lake Vaggatem,
daily water temperature measurements were available from an automated
datalogger at the Skogfoss hydropower plant situated 25 km upstream from
Lake Skrukkebukta and 23 km downstream from Lake Vaggatem. We calculated
annual mean water temperature, mean summer temperature (Jun-Jul-Aug) and
mean autumn temperature (Sep-Oct-Nov) from the logger data. Mean annual
water temperature has increased significantly by 0.3°C per decade
(p<0.01, F=9.3611,25,
adj-R2= 0.243, Appendix Table S4), mean autumn
temperature (September-November) has also increased significantly by 0.4
°C per decade (p<0.01, F=11.261,26,
adj-R2= 0.275, Appendix Table S5), and mean summer
water temperature increased (June-August) by 0.4 °C per decade (Fig. 1)
(p=0.037, F=4.871,25, adj-R2= 0.13,
Appendix Table S6).