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

Abstract

The impacts of watershed urbanization on streams have been studied worldwide, but are rare in China. We examined relationships among watershed land uses and stream physicochemical and biological attributes, impacts of urbanization on overall stream conditions, and the response pattern of macroinvertebrate assemblage metrics to the percent of impervious area (PIA) of watersheds in the middle section of the Qiantang River, Zhejiang Province, China. Environmental variables and benthic macroinvertebrates of 60 stream sites with varied levels of watershed urban land use were sampled in April, 2010. Spearman correlation analysis showed watershed urbanization levels significantly correlated with increased stream depth, width, and values of conductivity, total nitrogen, ammonia, phosphate, calcium, magnesium, and chemical oxygen demand for the study streams. There was significant difference in total taxa richness, Empheroptera, Plecoptera, and Trichoptera (EPT) taxa richness, and Diptera taxa richness, percentages of individual abundances of EPT, Chironomidae, shredders, filterers, and scrapers, and Shannon-Wiener diversity index between reference streams and urban impacted streams. In contrast, percentages of individual abundances for collectors, oligochaeta, and tolerant taxa, and biotic index were significantly higher in urban impacted than reference streams. All the above metrics were significantly correlated with PIA. The response patterns of total taxa richness, EPT taxa richness, and Shannon-Wiener diversity index followed a drastic decrease at thresholds of 3.6, 3.7, and 5.5% of PIA, respectively. Our findings indicate that stream benthic macroinvertebrate metrics are effective indicators of impacts of watershed urban development, and the PIA-imperviousness thresholds we identified could potentially be used for setting benchmarks for watershed development planning and for prioritizing high valued stream systems for protection and rehabilitation.

Influences of dispersal and local environmental factors on stream macroinvertebrate communities in Qinjiang River, Guangxi, China

“…Although a direct comparison between our RDA results and results obtained through canonical correlation analysis (CCA) is not plausible since the variation is not defined in the same way, existing results from the literature, based on CCA among environmental variables from different spatial scales, still partly support our findings (Death & Joy 2004, Johnson et al 2007, Wang et al 2012. For example, Sandin & Johnson (2004), using a variance partitioning approach (pCCA), showed that local physical (water velocity) and local chemical (e.g.…”

“…At each site, water temperature (T), pH, conductivity, mean wetted width (WW), current velocity (V), dissolved oxygen (DO) concentrations, and the dominant substrate were measured using the methods described by earlier studies (Wu et al 2010, Wang et al 2012. Before collecting macroinvertebrate samples, water samples were collected, preserved, and analyzed according to the standard methods for the analysis of water and wastewater (EPBC 2002).…”

Systematic processes of land use/land cover change to identify relevant driving forces: Implications on water quality

“…Chu et al (2013), for instance, found that the frequency of average-and highflow events increased with urbanization and decreased with vegetation cover. Wang et al (2012) found that stream benthic macroinvertebrate metrics are significantly correlated with the percent of impervious area.…”

Quantitative Estimation of the Velocity of Urbanization in China Using Nighttime Luminosity Data

“…A few but notable observations commonly show geographically explicit consequences of accelerating urban growth in China's cities: for instance, spatially shrinking and fragmentizing lake wetlands within Wuhan [33], gradually disappearing mangrove swamps with the expansion of urban areas to the shoreline in Shenzhen [34], changes in nest features of Magpies along the urban-rural gradient in Hangzhou [35], human settlement density-related fluctuations in baseline hormone levels in Beijing [36], decreased macroinvertebrate richness in stream habitats in relation to urban development level in the Qiantang River [37], and altered surface albedo owing to rapid urbanization [38]. All these observed changes and shifts seem to geographically coincide well with the dispersal of urban activities.…”