The effect of landscape age and nutrients on benthic N-fixation and primary production in arctic lakes
Abstract
Primary production in most oligotrophic lakes in the Arctic is N-limited. 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 -- 2000) and benthic N-fixation (summer 2000) showed higher rates on younger substrates than on older substrates. Benthic fixation rates ranged from 0.1 to 1 mg N/m^2/day respectively. Benthic primary production rates ranged from 70 - 200 mg C/m^2/day respectively. Nutrient additions to intact mud cores on young and old surface lakes indicated that benthic primary production and N-fixation were limited by phosphorus. This suggests that weathered material such as phosphorus from young landscapes may stimulate 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.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....8114G