I-Minus Outlet Stream
Visiting our sites while the Arctic still clings to winter provides important insights for our research, particularly factors that might impart resilience to tundra stream communities as Arctic conditions become more variable with climate change. Last summer, two of our streams showed extensive river drying due to severe summer drought, but miraculously the I-Minus outlet stream continued to flow. As we traveled the I-Minus today by snow machine, possible reasons for the streams resilience to drying revealed themselves in the form of overflow ice, aufeis, and a fish-supporting spring. Overflow ice and aufeis both result from water flowing during winter and freezing when it hits the -40 degree air temperature. If spring water is warm enough, just above freezing, small stretches of unfrozen river might persist throughout the winter and provide overwintering refuge in an otherwise uninhabitable stream. Today, impressive amounts of overflow ice filled stream channels to the brim, and in some cases over the brim and onto our antenna stations! Most excitingly, the expansive I-Minus lower aufeis appeared largely to be sourced from a single spring located in the main stem of our study river and our guest, Dana Truffer-Moudra, found a young Arctic grayling alive and well after a long cold winter. Best of all, where there’s one Arctic grayling overwintering, there’re probably many more.
Waking up to icy fog means less snow melt today than yesterday, translating to more time on the ground with the snow machines. : )
CH2M Hill Polar Services coordinator, Dana Truffer-Moudra, joins us for a day on the snow.
Putting Dana to work on the IM1 antenna.
IM1 antenna installed and ready to track tagged fish as soon as winter releases its icy hold on the outlet stream.
Overflow ice encases the willows surrounding our IM2 antenna, which we incidentally place just out of reach. This antenna, however, remains untuned as its nearby tuner box lies embedded within layers of overflow ice.
Eureka! Open water when all else remains solid! Just in case we found a spring like this, I brought along water sampling gear and pulled a few water samples to analyze later for elemental and isotopic ratios back in Woods Hole, MA
A juvenile Arctic grayling finds refuge from freezing in this relatively warm spring water.
Cam MacKenzie leads us across the frozen tundra from one study site to the next along the I-Minus outlet stream.
Another piece of sampling gear succumbs to the overflow ice. Cam points to the location of our game camera, once situated on the river bank, now buried in 2 meters of aufeis.
We conclude our day with the IM3 antenna imprisoned in overflow ice. Nothing to be done here but wait for the thaw.