Characterizing how fish communities and physical habitat structure are affected by urbanization in an East Tennessee watershed [Electronic resource]

Urbanization alters watershed hydrology, which leads to degradation of physical and biological components of urban streams. A part of this scenario is thought to be a product of increased storm water runoff due to excessive impervious surface. Impervious surface runoff increases the peak discharge in urban streams, causing a flushing or rapid flooding effect to occur. This flushing effect can overwhelm the natural pattern and profile of a stream channel, causing degradation of habitat and the fish population. This study investigates urbanization effects on habitat structure and fish communities in a rapidly urbanizing watershed in East Tennessee. Field measures of habitat complexity and fish indices of biotic integrity (IBI) were gathered for twenty-four stream reaches in the Beaver Creek watershed, Knox County, Tennessee. Habitat inventory produced 291 Channel Geomorphic Units (CGU) with up to 20 measurements taken in each unit. Average width and depth measurements were performed on 10 different types of pools. IBI sampling produced 7185 fish, yielding 21 species of 7 families in the 24 sites. A combination of Pearson correlations, multiple and simple linear regression, and Analysis of Variance (ANOVA) means separation techniques were used to see if changes in measured habitat and fish metrics occurred in relation to increased urbanization. Potential urbanization effects on physical habitat structure and fish communities were first considered at the (p< .10) significance, using the Pearson correlation technique. Multiple and linear regressions were used to explain the strongest relationships found for fish and habitat, to increase in urbanization (p< 0.05). ANOVA means separation was used to examine and validate relationships found using the six sub-watersheds as treatments, and the four reaches within each sub-watershed as replicates. Mosaics of urban land use varied from 1 to 54% in the watershed catchments. The statistical techniques described earlier were employed to gather relationships found between fish and habitat sites relative to an urbanization gradient. Measures of physical habitat structure were weakly correlated with percent urbanization. As percent urbanization increased, IBI scores decreased (p = 0.0004), and the number of darters decreased (p = 0.0041). Sub-watersheds significantly differed for IBI scores (p = 0.0015), and for curve number values (p = 0.0048). Results suggest that within the range of urbanization used for this study (1 to 54% total urban and 1 to 18% commercial/ industrial) channel geomorphic units such as scour pools and riffles are not significantly altered. However, fish community assemblages did show a shift towards impairment as quantified by the IBI. This indicates that a stressor other than physical habitat degradation causes a negative effect on fish in the Beaver Creek watershed.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006.

Title from title page screen (viewed on Sept. 28, 2006).