Assessment of the environmental quality of two urbanized lotic systems using multiple indicators

Abstract

Urbanization impacts ecosystems through loss and fragmentation of habitat, loss of diversity, increase in runoff, and contaminant discharges, and the invasion of exotic species. Potrero de los Funes Village (San Luis, Argentina) is experiencing not only a population increase during summer months due to tourism but also an accelerated growth of its permanent population. In order to evaluate the potential effects of urbanization, the environmental quality of Potrero de los Funes River and Las Chacras Stream was assessed, using physical-chemical and biological indicators. Macroinvertebrates, through the application of the Biotic Index for San Luis Sierras (BISLS), anuran amphibian richness and relative abundance, and riparian vegetation were used as bioindicators. While the Simplified Index of Water Quality (SIWQ) was used to characterize the physical-chemical quality of water at each site. SIWQ and BISLS scores were significantly different between sites (F 7,28 = 9.88, p < .001 and F 7,28 = 24.18, p < .001, respectively). SIWQ was significantly correlated with BISLS (Spearman correlation coefficient = 0.8, p < .001). Four anuran species were registered along Potrero River, with no significant differences in the intensity of vocalizations between sites. No species were detected in Las Chacras Stream.Average total plant species richness, exotic plants richness, and vegetation cover were higher at the most impaired system, Las Chacras Stream. The principal component analysis showed that the first two principal components (PCs) explained 76.3% of the total variance. PC1, with strong loadings of SIWQ, BISLS, and amphibian richness, was principally driven by chemical water quality and biological conditions. PC2 was mainly determined by plant richness. The chemical and biological water quality of Potrero and Las Chacras is somewhat impaired, being the upper Las Chacras Stream the most compromised area. This study provides information that will certainly be used to manage future impacts of urbanization on aquatic resources.

The systematic logic of the urban built environment

“…8,9 Urbanization is one of the most common reasons for the change of the natural ecosystem at present. 10 On the other hand, a large number of man-made natural landscapes also have the function of natural systems, such as the urban stormwater system, which is also an intersection of the natural system and the artificial system.…”

“…Lack of systematic perspective and neglect of some components will produce 'shortboard effect', which will inevitably become the bottleneck for the development of a healthy system and would lead to a metabolic disorder of the urban system. 10 The damages imposed on an ecosystem caused by the rapid urbanization are a typical case. 15 Setting up different city management departments to conduct professional management of the city is a requirement for different professional divisions of labor, but reductionism oversimplification makes us lose the overall grasp of the complex giant system, the increasing professional system stratification is impeding the information, material and energy flow.…”

“…Lack of systematic perspective and neglect of some components will produce ‘shortboard effect’, which will inevitably become the bottleneck for the development of a healthy system and would lead to a metabolic disorder of the urban system. 10 The damages imposed on an ecosystem caused by the rapid urbanization are a typical case. 15…”

Environmental factors affecting the success of exotic plant invasion in a wildland-urban ecotone in temperate South America

“…The province of San Luis, Argentina is characterized by a low industrial development in contrast with accelerated urban growth (Calderon et al 2017). Specifically, the total population of Potrero de los Funes Village has increased from 410 to 1698 which is equivalent to a 300% population increase in the last 25 years (Instituto Nacional de Estadística y Censos 2010), and this has been accompanied by the constant expansion of infrastructure.…”