Water quality decreased by urbanisation and Pinus based silviculture in Southern Brazil

Abstract

Changes in land use and land cover (LULC) can largely decrease water quality across spatial scales. Watercourse degradation is caused mainly by urbanisation, however other activities such as agriculture can also negatively affect the water quality. Regional characteristics may produce specific responses to different changes in the river basin, but there is few information from some regions and landscapes (e.g. Pinus silviculture). Here we compared two river basins in southern Brazil: Antas River subbasin (urban) and Faxinalzinho Stream Basin (agricultural). LULC was evaluated in the basin and at three sample points—at 450 m proximity buffers. We collected aquatic macroinvertebrates (AMI) and identified them at the family and genus levels to calculate biotic indices. LULC and AMI data were associated with the NMDS and redundancy analyses. We observed high percentage of vegetation in both basins, with predominance of urban + rural areas in the Antas River and mostly rural area in Faxinalzinho Stream. Biotic indices showed good water quality in the rural watercourse, NMDS and RDA associated resistant taxa with urbanisation, showing the sufficiency of family-level identification for water quality assessment. Despite presenting good conditions, the Pinus associated stream requires proper management to maintain its quality, and the urban river urgently requires recovery endeavours.