HR: 08:45h
AN: NB21D-02    [Abstracts]
TI: Effects of Landscape Age and Nutrients on N-fixation and Primary Production in Arctic Lakes
AU: * Gettel, G M
EM: gmg7@cornell.edu
AF: Cornell University, Department of Ecology and Evolutionary Biology Corson Hall, Ithaca, NY 14850 United States
AU: Giblin, A
EM: agiblin@mbl.edu
AF: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Howarth, R W
AF: Cornell University, Department of Ecology and Evolutionary Biology Corson Hall, Ithaca, NY 14850 United States
AB: Primary production in most oligotrophic lakes in the Arctic is limited by nitrogen. Because water clarity is high and littoral zones are large, benthic production and N-fixation are important to whole-lake processes. Our objectives were to determine nutrient and landscape controls of benthic primary production and N-fixation in high-latitude arctic lakes at the arctic LTER site, Toolik Field Station, northern Alaska. A survey of benthic primary production (summers 1998 - 2002) and benthic N-fixation (summers 2000 and 2002) showed higher rates on younger substrates than on older substrates. Benthic fixation rates ranged from 0.1 to 1 mg N/m2/day respectively. Benthic primary production rates ranged from 70 - 300 mg C/m2/day respectively. Nutrient additions to intact mud cores from young surface lakes indicated that benthic primary production and N-fixation were not strongly phosphorus limited. This suggests that weathered material such as phosphorus from young landscapes may alleviate P limitation of N-fixation, causing overall lake production to increase and/or a change in nutrient limitation status. Variation across the landscape was much greater than variation caused by nutrients or other controls such as grazers, indicating that landscape-level controls may be more important than in-lake processes in determining lake productivity.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly