SS3.16 Lentic-Lotic Linkages in Freshwaters: Comparisons from Different Ecosystems
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
RoachWJ, Arizona State University, Tempe, AZ, USA, john.roach@asu.edu
Grimm, N, B, Arizona State University, Tempe, AZ, USA, nbgrimm@asu.edu
 
NUTRIENT CYCLING ALONG AN URBAN DESERT LAKE CHAIN: THE EFFECTS OF ANTHROPOGENIC MODIFICATIONS OF INDIAN BEND WASH
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Indian Bend Wash is an urban desert stream characterized by a string of shallow artificial lakes whose water levels are maintained by anthropogenic diversions as well as periodic flooding. Modifications of the hydrology and morphology of the wash affect both nitrogen and phosphorus cycling. Analysis of samples collected on seven dates from approximately 17 sites along a 4-km section of the wash suggest that nutrient concentrations are highly variability both in space (coefficients of variations as high as 226% for nitrate and 90% for SRP) and in time (average concentrations ranged from .055 mg/L to 5.46 mg/L for nitrate and from .004 mg/L to .093 mg/L for SRP). Although some of this variation appears to be a function of the different water sources, lake-specific factors also appear important. We quantified diel fluctuations in water chemistry in three of the lakes during July 2001. Diel changes in dissolved oxygen and nitrate concentrations were most striking in the shallowest lake where DO increased by approximately 20 mg/L as nitrate declined by 1 mg/L, but were more modest in the deeper lakes.