PARENT SESSION
Poster Session # 6: Urban Ecology.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Land use and stream biotic signatures: The effects of urbanization on periphyton, macroinvertebrates, and fish in watersheds of west Georgia.
Helms, Brian*,1, Feminella, John1, Chaney, Philip2, 1 Department of Biological Sciences, Auburn, Alabama, USA2 Department of Geology and Geography, Auburn, Alabama, USA
ABSTRACT- In 2002 we began a long-term study designed to examine the relationship between changes in land use associated with urbanization and stream communities. Twenty small watersheds (500-2500 ha) were selected along an urbanization gradient in the piedmont ecoregion north of Columbus, Georgia. Based on GIS data from 2002 Landsat 7 TM imagery, study streams drained watersheds that included largely urban, developing (suburban), agricultural (pasture), managed pine forest, and unmanaged mixed forest land uses. A representative 100-m reach including 3 separate run-pool segments was sampled seasonally for periphyton (attached algae and diatoms, quantified with artificial and natural substrates), benthic macroinvertebrates (Surber samplers), and fish (electrofishing and seining) in each watershed. Preliminary data indicated that abundance of tolerant fish species (e.g. , Lepomis cyanellus, Gambusia affinis, Semotilus atromaculatus, and Ameirus spp.) were higher in urban and or developing watersheds than in forested watersheds. In contrast, numbers of macroinvertebrate species in the aquatic insect orders Ephemeroptera, Plecoptera, and Trichoptera (EPT) and algal biomass (as chlorophyll a) were higher in mixed-forested watersheds than in urban watersheds. Taken together, these data suggest that particular biological signatures may be reliable indicators of human-induced disturbance at the landscape scale, which in turn may be useful in forecasting the magnitude of whole-system changes in stream structure and function associated with the conversion of forests to urban/suburban land in the Southeast.
Key words: indicators, streams, urbanization, land use