Effects of land use on water chemistry and macroinvertebrates in two streams of the Piracicaba river basin, south‐east Brazil

Abstract

Summary Several studies have shown that land use has a strong influence on river chemistry and its biotic components. Most of these studies focused on nitrogen in temperate American and European catchments. Much less is known about the relationship between stream conditions and land use in tropical areas of developing countries. Besides climate, there are three important differences between attributes of temperate and tropical catchments: non‐point sources are the dominant contributor of pollution in USA, whereas point source pollution is the most important in our study; use of fertilizer is much smaller in developing countries, and the type of agriculture and management practices are distinct. We test whether the chemical composition of streams and their macroinvertebrate communities can be related to land use. Accordingly, we compared the variability of chemical composition and macroinvertebrate communities in the streams of two catchments (Pisca and Cabras) belonging to the same ecoregion, but having different types of land use. The main land use in the Pisca catchment in 1993 was sugar cane (62%), followed by pasture (22%) and urban centres (10%). In contrast, the main land use in the Cabras catchment was pasture (60%), followed by annual crops (13%) and forest (10%); urban centres occupied only 2% of the catchment. In the Cabras catchment, most of the parameters correlated with a land use index (LUI) ( Fig. 2). However, only conductivity, major cations and major anions (with exception of sulfate) had a statistically significant correlation coefficient. More than 90% of the variance was explained for these parameters. DIC, NO3 and richness of invertebrates (RI) also strongly correlated with LUI (R2 = 0.75), although these correlation coefficients were not significant. Total suspended solids (TSS) had a significant correlation with LUI (R2 = 0.98), but, the correlation was inverse. In the Pisca catchment, conductivity, major cations (with exception of potassium), major anions, and DIC, DO, and DOC had a strong and statistically significant correlation with LUI. Correlation coefficients were also high for respiration rate, although the correlation was not statistically significant. 2 Relationships between variables and LUI (land use index) for the Cabras (closed circle) and Pisca (open circle) catchments. Both catchment were pooled together in this figure, however, statistical tests were performed separately for each catchment.

Can land use changes alter carbon, nitrogen and major ion transport in subtropical brazilian streams?

“…Therefore, evaluation of water chemistry and nutrient dynamics in streams under different land uses provides a better estimate of how anthropogenic factors affect the cycling of these elements and ecological processes. Climate, hydrology, soil properties, geomorphology, topography, soil covering and land use are the main factors altering stream water conditions (Ometto et al, 2000;McKee et al, 2001;Likens & Buso, 2006). Reports on carbon and nitrogen budgets in small watersheds, where channel conditions are less variable than in meso-scale watersheds, are widely found in the literature (McDowell & Asbury, 1994;Alexander et al, 2000;Biggs et al, 2004).…”

Primeiro registro de larvas de Chironomus inquinatus Correia, Trivinho-Strixino & Michailova (Diptera, Chironomidae) vivendo no casco do cágado Phrynops geoffroanus Schweigger (Testudines, Chelidae) na região Neotropical

“…O Ribeirão Piracicamirim é um tributário do rio Piracicaba e sua microbacia estende-se por uma área de 133 km 2 (Ometto et al 2000). O clima da região é subtropical, e as características meteorológicas definem uma estação chuvosa (outubro a março) e uma estação seca (abril a setembro) (Ometto et al 2000, Silveira et al 2000.…”

“…O clima da região é subtropical, e as características meteorológicas definem uma estação chuvosa (outubro a março) e uma estação seca (abril a setembro) (Ometto et al 2000, Silveira et al 2000. O ribeirão possui uma extensão de 24,6 km desde suas cabeceiras até a foz, no Rio Piracicaba, englobando três municípios: Piracicaba, Rio das Pedras e Saltinho (Ometto et al 2000). Atualmente, este curso d'água é considerado poluído (Ecoar 2007), mesmo após a construção de uma estação de tratamento de esgoto em 1997, em função de lançamentos de esgotos clandestinos e de insumos químicos das plantações de cana-de-açúcar (Ometto et al 2004).…”

Relações entre qualidade da água e uso do solo em Goiás: uma análise à escala da bacia hidrográfica

“…As relações entre uso do solo e as águas estão claramente demonstradas, sendo que a conversão de áreas florestadas, principalmente para o uso agrícola ou urbano, tem sido associada à diminuição da sua qualidade (FREITAS, 2000;TUCCI, 2000;OMETO et al, 2000;GERGEL et al, 2002;SANTOS, 2004;SNYDER et al, 2005). Em grandes extensões territoriais, o conhecimento de parâmetros que relacionem as condições da cobertura vegetal com a qualidade desejável das águas, conforme seu uso preponderante, pode embasar instrumentos de planejamento e padrões de uso do solo (RIPA et al, 2006).…”

“…Entre 2002 e 2004, seis variáveis foram monitoradas, mensal e regularmente, em 174 captações da empresa: turbidez, cor aparente, pH, cloretos, índices de coliforme total (ICT) e fecal (ICF). Elas são recomendadas para investigação de qualidade de águas de abastecimento superficiais (OMS, 1995;SPERLING, 1996;HERLIHY et al, 1998citado por OMETO et al, 2000 ), embora outras, como sabor e odor, temperatura, alcalinidade e acidez, ferro, manganês e nitrogênio, também o sejam (SPERLING, 1996).…”