Tuesday, June 5, 2007
502

The influence of contrasting lithologies on physical, chemical, and biological characteristics of oligotrophic streams in the Noatak Arctic Preserve, Alaska

Michael B. Flinn1, William B. Bowden1, Bruce J. Peterson2, Andrew Balser3, Julia R. Larouche1, Angela R. Allen2, and Diane Sanzone4. (1) Rubenstein School of Natural Resources, University of Vermont, Burlington, VT 05405, (2) Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543, (3) Institute of Arctic Biology, University of Alaska - Fairbanks, 158 Irving I Building, Fairbanks, AK 99775, (4) National Park Service, 4175 Geist Rd., Fairbanks, AK 99709

In 2006, we examined freshwater resources of the Noatak River Watershed in northwest Alaska. This was the second of a multiyear investigation with the National Park Service Inventory and Monitoring Program. The Feniak Lake area of the Noatak Arctic Preserve has contrasting lithologies including ultramafic, non-carbonate, and complex sedimentary formations. Important physical, chemical, and biological characteristics differed significantly among these lithologies, consistent with a priori hypotheses. There were no statistical differences in chlorophyll a concentrations between lithologies. However, significantly higher (P<0.05) amounts of metals (Fe, Ni, Si (3x)), dissolved organic carbon (4x), and benthic organic matter (5/3x) were found in streams in non-carbonate watersheds compared to ultramafic watersheds. Analysis of macroinvertebrate communities revealed similar trends with significantly (P<0.01) higher abundance (2x), biomass (5x), taxa richness (4/3x), Shannon’s diversity (2x) and ratios of collector-filterer (3/2) and scraper (4x) functional feeding groups in streams of non-carbonate versus ultramafic origin. Streams with complex sedimentary watersheds were variable, but were mostly intermediate with respect to other lithologies in measured attributes. These data (and similar data from 2005) suggest that lithology is an important variable that can be used to direct future surveys of freshwater resources in the Noatak River basin.

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