Detection of biotic responses to urbanization using fish assemblages from small streams of western Georgia, USA

Abstract

We examined relationships between stream fish assemblages and land use alteration associated with urbanization in 15 lower Piedmont watersheds along an urbanization gradient north of Columbus, western Georgia. Based on land cover data from 2002 Landsat 7 TM imagery aerial photos, streams drained watersheds that were largely urban, developing (suburban), agricultural (pasture), managed pine forest, and unmanaged mixedforest. We quantified fish seasonally from 3 run-pool segments in each stream, and used a variety of metrics as response variables in analyses of relationships between fish assemblage structure and land use and natural basin variation. In general, Georgia-Index of Biotic Integrity (GA-IBI) values, Bray-Curtis faunal similarity of streams to mean conditions within reference streams, proportions of fish as lithophilic spawners, and fish lacking eroded fins, lesions, tumors decreased with increasing urbanization. Multiple regression indicated that assemblages were explained by a combination of land use and natural basin variables (basin size, average discharge, nearest distance to a larger downstream tributary [colonization source]), with land use variables being important predictors of summer assemblages and natural basin variables being more important in winter and spring assemblages. Non-metric multidimensional scaling (NMDS) ordinations revealed strong separation between assemblages in urban watersheds and forested watersheds, whereas assemblages in agricultural and developing watersheds were intermediate between those in urban and forested watersheds. Our data suggest that fish are reliable indicators of anthropogenic disturbance at the landscape scale, at least seasonally, and may be used to forecast the magnitude of landscape-level changes in stream structure and function associated with the conversion of forests to urban/suburban land in the Southeast.

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

“…For example, in watersheds of the lower piedmont in Georgia, fish species richness and diversity did not correlate significantly with percent urban land cover (Helms, Feminella, & Pan, 2005). However, with increasing percent urban land cover, herbivorous species became relatively more abundant and lithophilic spawners became relatively less abundant.…”

Fluctuating Asymmetry in Two Common Freshwater Fishes as a Biological Indicator of Urbanization and Environmental Stress within the Middle Chattahoochee Watershed

“…We use GIS to spatially characterize urbanization and a land-use gradient (e.g., [33][34][35]) across eight creeks to investigate if increased urbanization would predict an increased degree of FA within resident fishes (Lepomis) of the Bull and Upatoi Creeks watershed. We predicted that fishes in Lindsey Creek, the most urban located within the urban center of Columbus, would have the highest FA and that the degree of FA would decrease predictably to the most rural, Baker Creek.…”

“…While some researchers have shown FA to be a poor indicator (e.g., [58]), community and assemblage indices may still predict urbanization (e.g., [28,29,34,39,47]). When considering potential bioindicators of environmental stress, specifically urbanization stress, community indices such as species diversity, richness, and total abundance seem to act as reliable bioindicators (e.g., [39]).…”

“…Eight creeks (Lindsey, Cooper, Flatrock, Bull, Dozier, Randall, Kendall and Baker) within the Bull and Upatoi Creeks Watershed (within the Middle Chattahoochee basin, Muskogee County, Georgia) create a sampling design typical of urbanization studies located in western-central Georgia where the level of urbanization and land use change spatially along a gradient (e.g., [33][34][35]). Creeks are located north of Fort Benning and east of Columbus (Figure 1), flow southward and are considered Piedmont streams based upon stream characteristics and location [36].…”

Integrity of fluvial fish communities is subject to environmental gradients in mountain streams, Sierra de Aroa, north Caribbean coast, Venezuela

“…We used oneway ANOVA tests to detect differences in means for habitat and fish variables between river groups. The Pearson coefficient was used to correlate the habitat variables and fish community descriptors (Helms & Feminella, 2005). The abundance variable was not transformed for the IBI procedures.…”