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Nunataks and Noah's Ark

Posted: Friday, March 11, 2011

The 2007 Live Earth Concert was a worldwide rock and roll extravaganza that played out on all seven continents. The promoters ought to consider themselves darn lucky to have found a group of scientists in Antarctica who also happened to play indie rock. Their band's name, "Nunatak," introduced global audiences to a unique geologic feature found only in glaciated areas of the world including the Kenai Peninsula.

Kenai National Wildlife Refuge Photo
Kenai National Wildlife Refuge Photo
A nunatak in the Harding Icefield.

Nunatak is derived from the Greenlandic Inuit word "nunataq," which means an exposed, often rocky ridge or mountain not covered by ice or snow within an ice field or glacier. Not surprisingly, the almost 700 square-mile Harding Icefield, which is the largest one wholly within the U.S., has a lot of them. Biologists at the Kenai National Wildlife Refuge have identified about 1,900 possible nunataks within the Harding Icefield from satellite imagery, ranging from 0.3 to almost 5,000 acres!

In a more technical sense, not all exposed peaks are nunataks. In the world of glaciology, nunataks are mountain peaks that were not glaciated during the Wisconsin Ice Age. As such, nunataks may represent repositories for relict and endemic biota that managed to survive even as these mountain peaks became islands in a sea of ice.

When the last glaciation (known locally as the Naptowne) ended on the Kenai Peninsula about 11,000 years ago, nunataks and other unglaciated areas such as the Caribou Hills served as Noah's Arks, natural reserves from which plants and animals were able to repopulate this newly deglaciated landscape.

To explore this idea that nunataks may harbor unusual biota, ecologists from the National Park Service and Alaska Natural Heritage Program surveyed vegetation on seven nunataks in the Harding Icefield and Wosnesenski-Grewingk Glacier complex in 2005. They found 75 vascular plant taxa, including 16 species that were new records for Kenai Fjords National Park and three species considered globally rare: Alaska rock jasmine (Douglasia alaskana), arctic pennycress (Thlaspi arcticum), and dunhead sedge (Carex phaeocephala).

In 2007, refuge biologists Ed Berg, Matt Bowser and I visited three nunataks in the Harding Icefield to survey vegetation, arthropods, and soil. These sites resembled alpine tundra found elsewhere in the Kenai Mountains, perhaps a bit starker but carpeted in lusher areas by crowberry, moss campion, arctic willow, and bog blueberry, with solitary spikes of mountain harebell, yellow-dot saxifrage and cinquefoil.

Our complete species inventory included 46 vascular plants and 34 lichens. Although some plants we found such as Alaska rock jasmine, horned dandelion (Taraxacum officinale ssp. ceratophorum) and northern dandelion (T. phymatocarpum) have been rarely collected on the refuge, none were new records for the refuge.

We had more success identifying unusual specimens in the 36 arthropod taxa that were collected. Most were varieties of springtails, but three other arthropod species were particularly noteworthy. A spider (Tiso aestivus) and aphid (Thecabius populimonilis) were two new records for Alaska, representing range extensions for these two otherwise widespread species. Interestingly, the aphid forms galls on cottonwoods, but it also feeds on the roots of willows. In this case, we collected the root-feeding form in a soil sample. They were likely feeding on Salix rotundifolia, an extremely diminutive alpine willow.

We also collected one terrestrial mite (Erythraeus tonsus) which eventually made the front cover of the June 2010 issue of the International Journal of Acarology. I know that's a lot of excitement to handle in one newspaper article, but you'll be even more impressed to note that it was regarded as a "monstrosity," a genetic anomaly which resulted in an 10-legged (rather than 8) mite. OK, this is even more nerdy than guys in Antarctica who name their band Nunatak.

But in this landscape of blinding sun, endless ice, and rushing water (at least in July), nunataks really do offer safe harbor for wildlife which seem very much out of place here. A solitary black bear on one nunatak watched us the whole time, perhaps the only humans seen during its lifetime. Snow buntings and gray-crowned rosy finches nest here.

A dropped caribou antler was found on another nunatak, a tangible sign that some caribou cows calve here, far away from most predators. And bumble bees, of all things, buzz among the few flowers.

Nunataks are clearly special places. But nunataks are threatened by our rapidly warming climate. For most habitats, fragmentation and loss of connectivity are the primary concerns. The opposite is true for nunataks. Nunataks will lose whatever uniqueness they may possess when they become contiguous with the surrounding landmass as ice recedes.

The Harding Icefield has shrunk, on average, 21 meters in elevation and 5 percent in surface area in the past 50 years. Over this same period, the Park Service's analysis of satellite imagery shows that nunataks have increased in area by an average of 30 percent. On Petrof Glacier in the southern Kenai Mountains, the Park Service found that the flora appeared to be transitioning from "snowbed" species to a community of more temperate coastal plants such as bluejoint reedgrass, Merten's sedge and Nootka lupine. On one nunatak we visited in the northern Harding Icefield, we found a single stunted white spruce, perhaps the beginning of a forest.

These are early signs that nunataks may not always be part of the Kenai landscape. We'll need to study their ecology over the coming years to fully understand and appreciate the genetic and taxonomic diversity they support.

John Morton is the Supervisory Fish & Wildlife Biologist at the Kenai National Wildlife Refuge. For more detailed information about the refuge, you can check the refuge website at http://kenai.fws.gov or on Facebook at http://www.facebook.com/kenainationalwildliferefuge.



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