An Uncommon Garden
Overflow on the Kuparuk River portends the onset of spring and its eminent “ice-out.”
The ability to either move or adapt will largely determine which species will persist under climate change change conditions. The Arctic provides the perfect setting in which to test predictions regarding local adaptation of populations to warmer climates because the Arctic is warming much faster than anywhere else on earth. Through my dissertation research, we discovered that the fish we study, the Arctic grayling, consists of many genetically distinct populations, but we now want to know if these populations have evolved local adaptations to their respective habitats. Populations that are locally adapted to warmer watersheds, such as the Oksrukuyik Creek, might fare better under future climate change scenarios. This season, we are gearing up to test our Arctic grayling populations for local adaptation by rearing individuals from three populations from eggs to fry in an experiment call a “common garden.” The common garden refers to raising individuals from different habitats under constant conditions in order to eliminate trait differences that might be due to environmental differences among habitats, such as food availability or temperature dependent growth rates, for example. By raising them under common conditions, we can be certain that any trait differences we find among populations are due to genetic differences that have evolve over time, a.k.a. local adaptation.
Our common garden experiment consists of three water baths set at three different temperatures, 8, 12 and 16 degrees C. We chose these three temperatures because they reflect summer averages of the rivers in which our fish populations live, the Kuparuk River = 8 degrees C and the Oksrukuyik Creek = 12 degrees C, and future climate change conditions, 16 degrees C. It sounds simple, but maintaining constant water temperature in the Arctic is trickier than you might think. Last year’s trials showed larger temperature swings than we liked and our temperature regulating system failed when outside temperatures dropped below freezing. This year, we have added in-line spa heaters to our water baths and increased insulation by wrapping pipes and adding insulated lids to compensate for low outside temperature. We also added a temperature controller that turns on either the water chiller or heater when the temperatures drift higher or lower than our ideal settings. Fingers crossed that these adjustments will do the trick to maintain temperatures for raising baby Arctic grayling in this rather uncommon garden.
Cameron MacKenzie and I head out from Fairbanks to Toolik Field Station on Alaska’s North Slope, Oreos and Gatorade provide sustenance for a long drive up the Haul Road.
My marigold makes it to the Yukon River!
Looks like winter, but feels like spring at Toolik Field Station. Although snow is still on the ground, sunny days will quickly turn frozen rivers to raging torrents. No time to waste in preparing for ice-out and Arctic grayling spawning migrations.
I found the missing piece! We spent hours driving around Fairbanks looking for parts for our common garden experimental tanks. This piece was particularly difficult to locate. Yet, I found a small catch of them here in the tool shed at Toolik.
Loaded with supplies still to be unpacked, our common garden facility (a.k.a. The Fish Spa) begins to take shape.
After multitudes of email exchanges and phone calls with Jeb Timm, Toolik’s science support manager, we decided upon this design to maintain temperatures in our experimental tanks: a 1.5 hp water chiller and an in-line spa heater both controlled externally by a thermistor regulated temperature controller. It’s a little leaky for now, but seems to do the trick.
The LIMS site (Lower I-Minus Spring), a newly discovered spring, provided open water all winter and formed this menthol blue ice field, known as an Aufeis.
Bear at the KUS pool! This rascal discovered our fish in this spring-fed area of the Kuparuk River, which provides overwintering habitat for Arctic grayling.
Now we know who’s been eating our fish! Although fish might survive the winter in the KUS pool, predators, like bears and gulls might cause increased mortality for fish because fish in these cold shallow springs become easy pickins. I opportunistically collected this fish’s otoliths (ear bones), which hold important age and life-history information, and a fin tissue sample, for genetic analysis. We left the rest of our bear’s lunch behind to be polished off by the bear and birds.
We spotted a moose at our KLAS (Kuparuk Lower Aufeis Spring) site. She was so large that we suspect she might have been pregnant with a calf or two.
Yet another bear! We spotted this bear near our old Kup7 antenna locations. What a great day for wildlife sightings!
Even though it’s still freezing at night and there’s always a chance the wind will shift to northerly, I pitched my tent by the lake. I never want to forget where I am and how lucky I am to research and explore this amazing land.