Responses of benthic macroinvertebrates to environmental changes associated with urbanization in nine metropolitan areas

Abstract

Responses of benthic macroinvertebrates along gradients of urban intensity were investigated in nine metropolitan areas across the United States. Invertebrate assemblages in metropolitan areas where forests or shrublands were being converted to urban land were strongly related to urban intensity. In metropolitan areas where agriculture and grazing lands were being converted to urban land, invertebrate assemblages showed much weaker or nonsignificant relations with urban intensity because sites with low urban intensity were already degraded by agriculture. Ordination scores, the number of EPT taxa, and the mean pollution-tolerance value of organisms at a site were the best indicators of changes in assemblage condition. Diversity indices, functional groups, behavior, and dominance metrics were not good indicators of urbanization. Richness metrics were better indicators of urban effects than were abundance metrics, and qualitative samples collected from multiple habitats gave similar results to those of single habitat quantitative samples (riffles or woody snags) in all metropolitan areas. Changes in urban intensity were strongly correlated with a set of landscape variables that was consistent across all metropolitan areas. In contrast, the instream environmental variables that were strongly correlated with urbanization and invertebrate responses varied among metropolitan areas. The natural environmental setting determined the biological, chemical, and physical instream conditions upon which urbanization acts and dictated the differences in responses to urbanization among metropolitan areas. Threshold analysis showed little evidence for an initial period of resistance to urbanization. Instead, assemblages were degraded at very low levels of urbanization, and response rates were either similar across the gradient or higher at low levels of urbanization. Levels of impervious cover that have been suggested as protective of streams (5-10%) were associated with significant assemblage degradation and were not protective.

Impacts of urbanization on stream habitats and macroinvertebrate communities in the tributaries of Qiangtang River, China

“…However, research on impacts of human disturbance on aquatic organisms, and relations between water pollution and freshwater biodiversity in China is rather insufficient (Chen et al, 2009). Thereby, the impacts of urbanization and impervious area in watersheds on stream benthic macroinvertebrates have far received comparatively little study in China, while many such studies are found in North American (Wang et al, 1997Carter et al, 2009;Cuffney et al, 2010;King et al, 2011), Australian (Walsh et al, 2001;Davies et al, 2010), and South American (Ometo et al, 2000;Miserendina et al, 2008). Zhang et al (2010a) found that urban and rural land use had significant negative impact on water quality and macroinvertebrate diversity in East River in southern China.…”

“…The response patterns of macroinvertebrate assemblage metrics to intensity of urbanization has been described as linear (Moore & Palmer, 2005;Cuffney et al, 2010, King et al, 2011, wedge-shaped (Booth, 2005;Paul et al, 2009), or sharply linear-to-gradual (Walsh et al, 2005). The percent of impervious area (PIA) has been widely used as a measure of intensity of urbanization Walsh et al, 2005;Purcell et al, 2009).…”

Influences of catchment and corridor imperviousness on urban stream macroinvertebrate communities at multiple spatial scales

“…For example, Walters et al (2009) reported correlations between nutrient levels and baseflow water temperature for different macroinvertebrate community indicators. Cuffney et al (2010) reported conductivity was among the variables showing strong associations with urban intensity, and elsewhere it has been found to be a useful integrator of cumulative urban disturbances on water quality (Wang & Yin, 1997;Wenger et al, 2009). Associated water quality influences, along with reduced baseflow and increased sedimentation leading to the development of stagnant pools and accumulations of organic matter, can contribute to low dissolved oxygen levels in urban streams (Wenger et al, 2009).…”

“…Indeed, in revising the impervious cover model, Schueler et al (2009) proposed a curvilinear relationship that accounted for variability in ecological responses, particularly at the lower end of the imperviousness range. In support of this model, recent analyses across nine metropolitan areas in the USA revealed little evidence of an initial period of resistance by macroinvertebrate communities to urbanisation, leading to the conclusion that previously suggested thresholds of imperviousness area were not protective (Cuffney et al, 2010).…”

“…3 Coefficients of determination (R 2 ) from logarithmic regressions (see Fig. 2) at multiple spatial scales Cuffney et al, 2010). A range of water quality and habitat-related factors was also implicated as influencing macroinvertebrate metrics and community composition, with temperature and pH identified as the primary factors in a hierarchical analysis for taxa richness and UCI, and pH along with habitat quality score, stream width, macrophyte cover and dissolved oxygen concentration identified in biota-environment models.…”