Impacts of Urbanization on Stream Habitat and Fish Across Multiple Spatial Scales

Abstract

We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.

Long-term changes in fish assemblages of the Widawka and Grabia Rivers (Poland): pattern recognition with a Kohonen artificial neural network

“…The ecotones are responsible for the reduction of agricultural run off. They also serve for fish as foraging areas and provide shelter against predators (Zalewski et al 1995, Penczak 2001, Wang et al 2001. The availability of spawning and nursery grounds has been reduced because neighbouring areas are not flooded in spring (Bayley 1995, Kubečka & Vostradovský 1995, Ligon et al 1995, Jurajda et al 2001).…”

Quantifying the effect of catchment land use and water nutrient concentrations on freshwater river and stream biodiversity

“…Fitzpatrick et al (2001) found that increasing forest cover had a negative effect on fish taxon diversity and increasing nutrient concentrations had a positive effect. Wang et al (2001) also found that an increasing percentage of agricultural land use increased fish taxon diversity, while Harding (2003) and Mensing et al (1998) found that increasing non-natural catchment land use led to a reduction in taxon diversity. When studying the direction of the relationships with the IBI scores (lower part of Table 1) these contradictory results were not found.…”

Modifications of ecological trophic structures on chemical gradients in lotic ecosystems and their relations to stream ecosystem health

“…Thus, larger streams (high-order streams) located in downstream regions were largely impacted by the ecological health, compared to the references streams (An et al 2004). These circumstances are frequently reported in urban streams, which are directly impacted by discharge waters from WDPs or/and industrial complex (Wang et al 2001).…”