Effects of land use on water quality and aquatic biota of three North Carolina Piedmont streams

Abstract

Three streams in the Piedmont ecoregion of North Carolina were studied to evaluate the effect of land use (forested, agricultural, urban) on water q uality and aq uatic biota . In comparison with the forested stream, there were few changes in water q uality at the agricultural and urban streams . Suspended-sediment yield was greatest for the urban catchment and least at the forested catchment. Suspended-sediment concentrations during storm events followed this same pattern, but at low-moderate flows suspended-sediment concentrations were greatest at the agricultural site . Most nutrient concentrations were highest at the agricultural site, and the amount of `available' dissolved nitrogen was elevated at both the urban and agricultural sites . High concentrations of metals (totals) in the water column were sometimes observed at all sites, but maximum average concentrations were recorded at the urban site (especially Cr, Cu, and Pb) . Maximum sediment metal concentrations, however, were not found at the urban site, but were usually recorded at the forested site . Only minor differences were noted between fish communities of the forested and agricultural sites, although both abundance and average size of some species increased at the agricultural site . The fish community at the urban site was characterized by low species richness, low biomass, and the absence of intolerant species .Invertebrate taxa richness, a biotic index, and the number of uniq ue invertebrate species (found at only one site) indicated moderate stress (Fair water q uality) at the agricultural site and severe stress (Poor water q uality) at the urban site . At the agricultural site, declines in taxa richness within intolerant groups were partially offset by increases within tolerant groups . The agricultural stream had the highest abundance values, indicating enrichment . The urban site, however, was characterized by low species richness for most groups and very low abundance values . Analysis of seasonal patterns suggested detritus was the most important food source for invertebrates in the forested stream, while periphyton was of greater importance in the agricultural stream . Dominant macroinvertebrate groups shifted from Ephemeroptera at the forested site, to Chironomidae at the agricultural site, and Oligochaeta at the urban site . There was little between-site overlap in dominant species (8-17%), indicating that land use strongly influenced the invertebrate community . Chemical and physical parameters measured at the three sites did not seem sufficient to account for all of the observed differences in the invertebrate communities, suggesting some unmeasured toxicity . Biological measurements, especially macroinvertebrates community structure, consistently indicated strong between-site differences in water and habitat q uality .

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

“…This contrasts with other studies in which urbanization appears to negatively affect fish abundance, richness, and/or diversity in the southeastern United States (Lenat & Crawford, 1994;Long & Schorr, 2005;Weaver & Garman, 1994). Given our small sample sizes, it is possible that we failed to detect real effects of urban land cover on fish.…”

Effects of Hurricane Katrina on Freshwater Fish Assemblages in a Small Coastal Tributary of Lake Pontchartrain, Louisiana

“…While the poststorm removal of debris helped restore water flow and decrease the build-up of decaying organic material, the impacts of mechanical clearing of bank vegetation were obvious and appear to be longlasting (VV, personal observation). In other streams, deforestation of riparian zones has caused bank destabilization and increased sedimentation while altering light and thermal regimes, all of which can impact fish assemblages (Schlosser 1991;Lenat and Crawford 1994;Jones et al 1999).…”

Comunidade de Odonata (Insecta) em áreas naturais de Cerrado e monocultura no nordeste do Estado de São Paulo, Brasil: relação entre o uso do solo e a riqueza faunística

“…Observações semelhantes foram feitas por LENAT & CRAWFORD (1994) em córregos dos EUA. Estes autores não encontraram diferenças entre parâmetros físicos e químicos em cursos d'água influenciados por diferentes usos do solo para explicar as diferenças encontradas por eles na estrutura das comunidades de macroinvertebrados.…”

“…Várias pesquisas têm demonstrado que a conversão de florestas em pastagens ou áreas residenciais pode influenciar os habitats e as comunidades aquáticas de várias maneiras (GURTZ & WALLACE 1984, LENAT & CRAWFORD 1994, OMETO et al 2000, SPONSELLER et al 2001. Por isso, conhecer a relação da biota aquática com o uso do solo do entorno é de grande importância e oferece suporte na elaboração de estratégias regionais de manejo (ALLAN & JOHNSON 1997).…”