Response of Epilithic Diatom Communities to Downstream Nutrient Increases in Castelhano Stream, Venâncio Aires City, RS, Brazil

Abstract

The Castelhano Stream Hydrographic Basin, located in the city of Venâncio Aires, RS, Brazil, shows an area of 675.3 km 2 , highlighting the Castelhano Stream as their main water course. The stream is the main responsiblity for the local water supply; however, there are no published studies in the literature regarding their water quality. In this context, the present research aimed to assess the water quality of Castelhano Stream in terms of organic pollution and eutrophication, applying the Biological Water Quality Index (BWQI), which uses epilithic diatoms communities as bioindicators. Biological samples were collected at three sampling stations along the stream in the months of September, November and December 2012. The results showed 81 identified species, distributed in 30 genera. The water pollution levels detected ranged from "strong" (66.7%) and "very strong" (33.3%), with differences in species composition between sampling stations. The sampling station S1 in the upper reaches was characterized by the presence of indicative species of acidophilus and lentic environments with large amounts of organic matter. The sampling stations S2 and S3, in the intermediate and lower reaches, respectively, showed a substitution of species in the community, with the presence of highly tolerant taxa to organic pollution and eutrophication. The high pollution levels detected along the basin are related to the nutrients and high organic load originating from livestock, domestic and industrial waste, as well as excess fertilizers and agricultural inputs used in farming. The results demonstrate the necessity to implement mitigation measures to contain the processes of organic pollution and eutrophication detected due to the dangers offered to public health and the environment.

Evaluation of water resource preservation areas in the Hydrographical Basin of Andreas Stream, RS, Brazil, using environmental monitoring programs

“…Thus, according to these variables, it is concluded that organic contamination and eutrophication of the water are the main environmental problems that characterized these water bodies. These results corroborate the environmental monitoring work in the regional water systems performed by UNISC, which has demonstrated that these water systems already have advanced stages of eutrophication (Bes et al, 2012;Böhm et al, 2013;Düpont et al, 2007;Hermany et al, 2006;Lobo et al, 2004aLobo et al, , 2004bLobo et al, , 2004cLobo et al, , 2004dLobo et al, , 2010Lobo et al, , 2014Oliveira et al, 2001;Salomoni et al, 2006;2011;Schuch et al, 2012;Wetzel et al, 2002). According to Tundisi (2006), this condition characterizes in a general way all the waterways throughout the southern region of Brazil, according to the results obtained by the project "Brazil Waters.…”

Avaliação da qualidade da água na Bacia Hidrográfica do Arroio Preto, Santa Cruz do Sul, RS, Brasil

“…Estes resultados vêm corroborar trabalhos de monitoramento ambiental em sistemas hídricos regionais realizados pela UNISC, os quais têm demonstrado que estes já apresentam estados bastante avançados de eutrofização (BES et. al., 2012;BÖHM et. al., 2013;HEINRICH et al, 2014;LOBO et.…”

Diatomeas como bioindicadores: Aspectos ecológicos de la respuesta de las algas a la eutrofización en América Latina

“…El uso de diatomeas para la evaluación de la calidad del agua ha recibido poca atención, y la mayoría de las investigaciones se han concentrado en el uso de índices bióticos, especialmente en la región sur (p. ej., Lobo et al, 2002Lobo et al, , 2004aLobo et al, ,b, 2010Lobo et al, , 2014Lobo et al, , 2015Lobo et al, , 2016aLobo et al, ,b, 2017Hermany et al, 2006;Salomoni et al, 2006Salomoni et al, , 2011Düpont et al, 2007;Bes, et al, 2012;Schuch, et al, 2012Schuch, et al, , 2015Böhm, et al, 2013;Heinrich, et al, 2014). En Lobo (2013) y Lobo et al (2014) se presenta una revisión detallada de los estudios relacionados con el uso de diatomeas epilíticas como organismos indicadores en los sistemas lóticos del sur de Brasil.…”