HR: 16:15h
AN: NB14E-04 INVITED     [Abstracts]
TI: Using algal indicators to diagnose nutrient enrichment in the Northwestern Glaciated Plains
AU: * Zheng, L
EM: lei.zheng@tetratech.com
AF: Tetra Tech, Inc., 400 Red Brook Boulevard, Suite 200, Owings Mills, MD 21117 United States
AU: Suplee, M
EM: MSuplee@state.mt.us
AF: Montana Department of Environmental Quality, 1520 E. 6th Ave, P.O.Box 200901, Helena, MT 59620 United States
AU: Gerritsen, J
EM: Jeroen.Gerritsen@tetratech.com
AF: Tetra Tech, Inc., 400 Red Brook Boulevard, Suite 200, Owings Mills, MD 21117 United States
AU: Watson, V
EM: vicki.watson@umontana.edu
AF: Watershed Health Clinic(c/oEVST), Univ. of Montana, Missoula, MT 59812 United States
AB: The relationships among nutrients, benthic algal community, and aquatic plant biomass were examined in 21 different streams in Montana's Hi-line region, in the Northwestern Glaciated Plains ecoregion. We examined habitat, physical and chemical characteristics, aquatic macrophytes, and benthic algae in the stream segments. Based on multiple lines of evidence, nitrogen was the primary limiting nutrient in the Hi-line region. Correlation analysis indicated that annual total nitrogen concentration in the stream significantly increased with agricultural land use (r = 0.55). Diatom pollution indices and trophic indices also increased with rising nutrient concentrations and agricultural land use. Both structure and function of valued ecological attributes responded to the nitrogen gradient. Loss of sensitive taxa was observed with increased nutrient concentrations. Floating and benthic algal biomass was positively correlated with NO₂₊₃ concentrations in the water column. Benthic algal and aquatic macrophyte biomass also increase with diatom-inferred trophic status. The relationships indicate diatoms can be better indicators for algal community structure and primary productivity change than water chemistry in this system. Based on our results, both a reference approach and a stressor-response approach could be used to define nutrient criteria for this ecoregion.
DE: 4845 Nutrients and nutrient cycling
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly