Inadequate riparian zone use directly decreases water quality of a low-order urban stream in southern Brazil

Abstract

Considering the current importance watercourses quality conservation, it is important to establish relationships between parameters that enable evaluation of the origins of changes in water quality, allowing actions to mitigate them. However, it is important to improve the association of different variables and to take sufficient samples. This study associates usual techniques and parameters to analyse the water quality of an urban river from Paraná State, Brazil. For this, we used biological indicators (aquatic macroinvertebrates), physical-chemical (temperature, turbidity, true colour, pH, DO and BOD5,20) indicators and microbiological (faecal and total coliforms) indicators. These indicators were related to land use and occupation classes obtained from high resolution QuickBird 2 images. For this association, the surroundings (450 meters buffer) of three distinct points of the river were considered: I. Near the spring; II. In the downtown city; and III. In a residential neighbourhood. Different values of physical, chemical and microbiological variables were detected along the river, showing evident relationships between them and with the use and occupation of the urban and peri-urban space in the characterization of surface waters. The association design was able to detect the landscape effect on water quality in a coherent way and that these connections were mainly related to suppression of the riparian forest present in the surroundings, further demonstrating the importance of this vegetation for the maintenance of watercourse quality.

Componentes da paisagem associados à silvicultura na Mata Atlântica que influenciam a comunidade de macroinvertebrados aquáticos: um estudo de caso no sul do Brasil

“…Zequi et al, 2019). The lowest values found here are similar to the highest value found near headwater in an urban watercourse from the same municipality (Crisigiovanni et al, 2020). The %Chironomidae was very lower than found in agriculture-associated sites (Zequi et al, 2019), but similar to that found in protected sites (e.g.…”

“…In this way, the relationship between land use and occupation and the water quality values found by the evaluation of macroinvertebrates showed reasonable values for biotic indices and RAPHD, mainly compared to the quality of rivers in the region, both in urban and rural areas (e.g. Crisigiovanni et al, 2020).…”

“…The taxa with the highest values of total abundance were Aeglidae at points 2 and 3, followed by Leptoplhebiidae (Ephemeroptera), corroborating data from Santestevan (2004) and Raio et al (2011), who observed this family as one of the most abundant in Paraná State watercourses. The construction of such knowledge is fundamental since the lack of consistent knowledge regarding aquatic invertebrates of watercourses in Paraná state (mainly low-order rivers in small municipalities, see Crisigiovanni et al, 2020) is an impediment to further applied researches, such as preventing data use in an important and large-scale analysis like the one performed by Dala-Corte et al (2020). Chironomidae were not abundant, presenting relative abundance between 0.7 to 2.2%, indicating good water quality.…”

“…It is possible to evidence the contrast between the width of riparian vegetation of the margins, where the first point presents a small portion of riparian forest concerning P2 and P3, besides being directly associated with sloping Pinus plantation. This data is important to show that water quality can be reestablished downstream by the forest/riparian forest recomposition, although some water quality parameters do not present a prompt return to natural conditions (Collier et al, 2019;Crisigiovanni et al, 2020).…”