Abstract
Aim: This study aimed to assess the spatial and seasonal variation of the water quality and physical habitat characteristics along the upper-middle stretch of the Paraitinga River, a tributary of Tietê River, considering the potential influence of different riparian conditions along the stretch studied.MethodsSixteen sites with different riparian vegetation, including native forest, secondary forest, pasture, and eucalyptus were sampled during the dry and rainy seasons of 2004/2005, before the damming of the Paraitinga Reservoir. Several physicochemical and habitat parameters were determined and data analyzed in relation to spatial distribution and potential influence of riparian conditions.ResultsWater quality parameters were in general within the limits established by CONAMA for Class 2 waters, except for turbidity and total phosphorus. There were seasonal and spatial differences in the limnological parameters along the stretch studied and apparently they were related to point specific influences associated with land use and canopy cover. Habitat characteristics were markedly different between the upper and middle river stretches, especially in relation to depth, width, substrate and canopy cover.ConclusionsAlthough a direct influence on the observed variables could not be attributed solely to the riparian vegetation, vegetation cover seemed to affect particular stream characteristics. Open pasture and eucalyptus sites were subject to point specific effects that caused phosphorus inputs and higher turbidity and temperature, and showed different morphological features, suggesting that land use at the sub-watershed scale was an important factor affecting stream conditions.
Highlights
River chemical properties are influenced by many landscape factors that operate on a variety of spatial and temporal scales (Allan, 2004), with geomorphological and hydrological processes acting as the main ecosystem drivers, while chemical and biological factors act as secondary response variables
The present study focused on the sub-basin of the Paraitinga River, one of the main tributaries on the right bank of the Tietê River, which has been subjected to removal of riparian vegetation in the last decades, showing a mosaic of native forest, secondary forest, pasture and reforestation
Within the Upper Tietê River Basin, the sub-basin of the Tietê Cabeceiras where the Paraitinga River is located is considered the area with best water quality, in contrast to the poor water quality of surface water of the other courses (FUSP, 2002)
Summary
River chemical properties are influenced by many landscape factors that operate on a variety of spatial and temporal scales (Allan, 2004), with geomorphological and hydrological processes acting as the main ecosystem drivers, while chemical and biological factors act as secondary response variables. Since the creation of the River Continuum Concept (Vannote et al, 1980) and the Nutrient Spiraling Concept (Newbold et al, 1982), riparian areas have been considered as important compartments of stream ecosystems. Rivers and their riparian areas can be viewed as open ecosystems interconnected longitudinally, laterally and vertically by hydrological and morphological processes that occur within a temporal hierarchy (Ward, 1998). Riparian buffers can reduce the amount of sediment, nutrients, and other contaminants that enter surface waters, and these effects vary from one riparian area to another (Klapproth & Johnson, 2000)
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