Environmental and aquatic macroinvertebrates metrics respond to the Eucalyptus afforestation gradient in subtropical lowland streams

Eucalyptus afforestation may affect stream ecosystems, but the magnitude of these effects on water quality and biota in subtropical lowland streams is little understood. We evaluated the potential effects of Eucalyptus afforestation on water quality and macroinvertebrate assemblage. Water quality parameters and macroinvertebrate assemblages were sampled in summer and winter in 30 streams covering an afforestation gradient (from 0.05 to 96% of the catchment area) and tested their relationship. We analyzed the taxa density distribution in afforestation and water parameters using the Thresholds Indicator Taxa Analyses (TITAN). Nutrient concentrations, conductivity, and total dissolved solids showed positive responses to the increase of afforestation, but the responses varied among seasons. Macroinvertebrate metrics showed negative (Ephemeroptera-Trichoptera-Plecoptera (EPT), sensitive families, scrapers), and positive (Chironominae, Oligochaeta) responses to the afforestation. Densities of sensitive taxa (mostly EPT) decrease with an increase in Eucalyptus afforestation, which is also related to water quality and possibly to habitat changes attributed to afforestation management. The use of water quality parameters in combination with macroinvertebrates assemblage contributes to managing these streams under catchment afforestation.