Stream macroinvertebrate response to catchment urbanisation (Georgia, U.S.A.)

Abstract

SUMMARY 1. The effects of catchment urbanisation on water quality were examined for 30 streams (stratified into 15, 50 and 100 km2 ± 25% catchments) in the Etowah River basin, Georgia, U.S.A. We examined relationships between land cover (implying cover and use) in these catchments (e.g. urban, forest and agriculture) and macroinvertebrate assemblage attributes using several previously published indices to summarise macroinvertebrate response. Based on a priori predictions as to mechanisms of biotic impairment under changing land cover, additional measurements were made to assess geomorphology, hydrology and chemistry in each stream. 2. We found strong relationships between catchment land cover and stream biota. Taxon richness and other biotic indices that reflected good water quality were negatively related to urban land cover and positively related to forest land cover. Urban land cover alone explained 29–38% of the variation in some macroinvertebrate indices. Reduced water quality was detectable at c. >15% urban land cover. 3. Urban land cover correlated with a number of geomorphic variables such as stream bed sediment size (–) and total suspended solids (+) as well as a number of water chemistry variables including nitrogen and phosphorus concentrations (+), specific conductance (+) and turbidity (+). Biotic indices were better predicted by these reach scale variables than single, catchment scale land cover variables. Multiple regression models explained 69% of variation in total taxon richness and 78% of the variation in the Invertebrate Community Index (ICI) using phi variability, specific conductance and depth, and riffle phi, specific conductance and phi variability, respectively. 4. Indirect ordination analysis was used to describe assemblage and functional group changes among sites and corroborate which environmental variables were most important in driving differences in macroinvertebrate assemblages. The first axis in a non‐metric multidimensional scaling ordination was highly related to environmental variables (slope, specific conductance, phi variability; adj. R2=0.83) that were also important in our multiple regression models. 5. Catchment urbanisation resulted in less diverse and more tolerant stream macroinvertebrate assemblages via increased sediment transport, reduced stream bed sediment size and increased solutes. The biotic indices that were most sensitive to environmental variation were taxon richness, EPT richness and the ICI. Our results were largely consistent over the range in basin size we tested.

Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States

“…Researchers have recommended several variables as the most responsive for monitoring urban systems, for example (1) taxon richness, EPT richness, and the ICI in GA [156]; (2) Margelef's richness, predator richness, and omnivore richness in Texan streams [105]; and 3) the stream condition index (SCI) in FL, USA [157]. While urbanization is known to decrease the abundance and diversity of organisms living in streams, it is not clear which forcing factors, such as changes in discharge, sediment, and pollutant concentrations, are most important for causing decreased diversity [101].…”

Overview and application of the National Aquatic Ecological Monitoring Program (NAEMP) in Korea

“…The macroinvertebrate and fish classes showed a closer relationship with BOD (r= 0.50, 0.43, respectively) than with habitat quality (r= 0.41, 0.32, respectively), confirming the findings of previous studies. Nonetheless, numerous studies have reported that watershed land use influences the physical and chemical characteristics of streams, including water and habitat quality (Omernik et al, 1981;Osborne and Wiley, 1988;Richards et al, 1993;Allan, 1995;Richards et al, 1996;Allan et al, 1997), and the ecological communities in streams (Roth et al, 1996;Allan et al, 1997;Kennen, 1999;Wang et al, 2001;Roy et al, 2003;Moerke and Lamberti, 2006). Companion studies under NAEMP at site and regional scales have indicated significant relationships between human land uses, including urban and agricultural land uses, and all biological criteria for streams in Korea; human uses have been found to negatively affect biological criteria, while natural areas have shown positive effects on biological communities in streams (Wallace et al, 1997;Moore and Palmer, 2005).…”

Evaluating Morphological Asymmetry in Three Species of the Genus <i>Hydrocynus</i> from the White Nile in Sudan

“…Therefore, environmental condition takes part for the overall condition of the species and may enhance its fitness to resist alterations. According to Allan (2004), Richards et al (1996) and Roy et al (2003), human activities along the Nile can have some impacts on water quality, habitat, and aquatic biota and can play a significant role in defining Nile condition and thus create developmental stressors resulting in FA. In addition, pesticides and fertilizers are main factors to contamination of water and aquatic natural resources (Manjare et al, 2010).…”