The Caraça Sanctuary as an ecological reference area for water quality in the Upper Rio Doce basin

Santuário do Caraça como uma área de referência para qualidade de água na bacia do Alto Rio Doce

Abstract

Aim  Our objective was to assess the extent to which reference sites within the Caraça Sanctuary protect surface water quality and physical habitat structure. We expected that outside the Sanctuary, human pressures—such as urbanization, untreated domestic sewage discharge, and riparian deforestation—would result in poorer water quality and altered physical habitat structure. We hypothesized that the Caraça Sanctuary maintains streams with high physical habitat integrity and water quality.

Methods  Data were collected from 28 stream sites, including assessments of 22 physical habitat attributes and 12 water quality parameters. In addition, land use and land cover in the upstream microbasins were analyzed, and a rapid assessment protocol was applied at each site to evaluate riparian vegetation and physical habitat diversity. Principal Component Analysis (PCA) was used to identify the key variables explaining variation among sites and to distinguish those located within and outside the Sanctuary. Two PCA biplots were generated: one for the habitat structure data and another for the water quality data.

Results  The first two PCA axes explained 50% of the variability in physical habitat structure and 48% in water quality, with the latter most affected at sites near urban and mining areas.

Conclusions  The results indicate that the Caraça Sanctuary provides a valuable reference area for the upper Rio Doce basin.

Keywords:
water quality; rapid assessment; physical habitat structure; Rio Doce