HR: 13:45h
AN: NB13A-02    [Abstracts]
TI: Litter Processing in Arctic Headwater Streams Along a Glacial Chronosequence on the North Slope of Alaska
AU: * Rantala, H M
EM: ranta001@bama.ua.edu
AF: Aquatic Biology Program, Department of Biology University of Alabama, Tuscaloosa, AL 35487-0206 United States
AU: Huryn, A D
EM: huryn@bama.ua.edu
AF: Aquatic Biology Program, Department of Biology University of Alabama, Tuscaloosa, AL 35487-0206 United States
AU: Suberkropp, K
EM: suberkp@biology.us.ua.edu
AF: Aquatic Biology Program, Department of Biology University of Alabama, Tuscaloosa, AL 35487-0206 United States
AB: The north slope of the Brooks Range, Alaska, has a complex glacial history. At least four major glaciations have shaped the geomorphology of the region, resulting in a landscape composed of patches of different aged terrains. This may have consequences for spatial patterns of stream productivity, as glacially deposited sediments lose nutrients due to weathering; older terrains tend to be nutrient poor compared with younger terrains. We used a natural landscape-scale experiment to test the prediction that litter processing rates will decrease with surface age due to nutrient limitation. Salix litter was incubated in streams on four glacial terrains (ca. 25,000, 500,000 and >700,000 ybp glacial sediments and unglaciated bedrock). Processing rates and ergosterol concentrations (indicator of fungal biomass) were calculated for each stream. Processing rates ranged from 0.007 to 0.129 d^-1 and were highest on the bedrock, probably due to physical processes. Ergosterol concentrations were variable between dates at most sites, with concentrations typically increasing as incubation proceeded. Preliminary analysis indicated no difference in ergosterol concentrations between sites (ANOVA, p=0.08). These results suggest that litter processing among tundra streams on different aged terrains is not regulated by nutrient availability, as predicted, but by other factors such as physical processes.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly