HR: 08:30h
AN: NB41C-01 [Abstracts]
TI: Temporal Variation in Nutrient Uptake in Three Headwater Streams in the Upper Peninsula of Michigan.
AU: * Hoellein, T J
EM: hoellein.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Tank, J L
EM: tank.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Rosi-Marshall, E J
EM: erosi@luc.edu
AF: Loyola University of Chicago, 6525 North Sheridan Rd, Chicago, IL 60626 United States
AB:
We conducted short-term nutrient additions of ammonium (NH4+), nitrate (NO3-), and phosphate
(PO4-3) to estimate whole-stream uptake in two reaches of three 2nd order streams in the Upper Peninsula of
Michigan approximately monthly from May 2003-April 2004 (N = 96). Extensive replication permitted a unique opportunity for
statistical analysis of seasonal variation in nutrient uptake within streams (between reaches) as well as variation among
replicate streams. We expected seasonal variation in light, organic matter standing stocks, and temperature would regulate
nutrient uptake via changes in autotrophic and heterotrophic biofilm activity. We initially predicted nutrient uptake
velocities (vf) for all three solutes would be highest in spring and fall because of increased light availability for
autotrophs (spring and fall) and microbial decomposition of leaves (fall). Among streams, NO3- and NH4+
uptake rates were significantly higher in spring and winter, lowest in fall, and rates in summer were variable, but
PO4-3 uptake was not significantly different among seasons. We found no significant differences in nutrient uptake between reaches within streams. In general, there were significant differences in nutrient uptake among seasons for
inorganic nitrogen forms, but not phosphorus, and nutrient demand was high in these streams despite low temperatures
(0.5-2°C) in winter.
DE: 0400 Biogeosciences
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly