Abstracts Category : Other

Scaling to the Organism: An Innovative Model of DynamicToxic Hotspots in Stream Systems

by Kristen M Harrigan

Water quality modeling of lotic systems typicallyrepresents the distribution and transport of pollutants at thescale of the water body and is used in research and management. Thedistribution of various pollutants at the scale of the water bodydoes not accurately represent the fine scale chemical exposureimpacting benthic organisms. In flowing systems, fluctuations inthe frequency, magnitude, and duration of exposure occurs due toturbulence, therefore causing spatial and temporal variations inchemical exposure at the scale of the organism. Thus, a gap inknowledge exists in applying spatial models of toxicant movement atappropriate scales to predict exposure impacts on stream organisms.In order to characterize the fine scale distribution of pollutantsin freshwater streams at the scale of a benthic organism, ninedifferent artificial stream habitats were created (riffle, pool,run, bend, woody debris) with either sand or gravel substrate.Dopamine was released as a chemical tracer into the flume to mimica groundwater source and measurements were recorded with amicroelectrode and Epsilon electrochemical recording system. Tensample points were taken throughout each habitat and recorded forfive minutes. Peak length, peak height, and intermittency data wereextracted and represented the frequency, magnitude, and duration ofchemical exposure. Geographic Information Systems (GIS) and anInverse Distance Weight (IDW) interpolation technique were used tospatially predict the chemical distribution throughout each of thehabitats based on the measurements of ten sampling areas. Modelswere scaled to represent chemical distribution within and acrosshabitats. Spatial and temporal variations of exposure wereexhibited within and across habitats, indicating that thefrequency, magnitude, and duration of exposure is influenced by theorganisms location within a habitat and the habitat it resides in.The run and pool with sand substrate habitats contained thegreatest frequency, magnitude, and duration of exposure, suggestinga more detrimental exposure compared to the other habitats.Conversely, no habitats measured in this study completely consistedof low frequency, magnitude, and duration of chemical exposure. Thespatial and temporal fluctuations of fine scale exposure need to beconsidered in both ecotoxicology and water quality modeling to moreaccurately represent and understand the exposure of pollutantsimpacting benthic organisms.Advisors/Committee Members: Moore, Paul (Advisor).