Monday, June 4, 2007 - 4:00 PM
65

Impacts of changing land use on aquatic communities in streams of the Georgia Piedmont

Brian Helms1, Kyle Barrett1, Jon Schoonover2, and Jack Feminella1. (1) Biological Sciences, Auburn University, Auburn, AL 36849, (2) Forestry, Southern Illinois University, Carbondale, IL 62901

Beginning in 2002, we examined aquatic biotic responses to changing watershed land use/cover in the Lower Piedmont ecoregion north of Columbus, Georgia, USA.  We quantified benthic algae, macroinvertebrates, amphibians, fish, and habitat seasonally for multiple years in 18 small watersheds (500–­2500 ha) that vary in their degree of urbanization, residential development, pasture, and forest cover.  Benthic algal response (chlorophyll a and ash-free dry mass) was mixed among watersheds and showed considerable seasonal variation.  Macroinvertebrates, expressed as taxa richness, diversity (Shannon’s H’), %EPT, and %Scrapers, were negatively associated with increasing urbanization, stream water temperature and NH4+ and positively associated with increasing forest cover and dissolved oxygen (DO) levels.   Fish assemblages shifted from cyprinid-based in forested and pasture watersheds to centrarchid-based in urban and suburban watersheds; this shift was correlated with increasing spate frequency, stream temperature and decreasing DO.  Also, amphibian diversity and salamander survivorship was lower in urban and suburban as compared to undeveloped watersheds while overall food chain length was positively associated with stream habitat quality.  Our results suggest that changing land use exerts multiple direct and indirect stressors on aquatic biota and the influence of these vary considerably depending upon the biology of the organism or assemblage.

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