Pristine aquatic systems in a Long Term Ecological Research (LTER) site of the Brazilian Cerrado

Abstract

The maintenance of limnological monitoring programs in the Cerrado Domain is crucial as a provision of useful information about temporal variations in land use and their respective water quality responses, considering its importance as water source for different Brazilian hydrographic basins. The purpose of this research was to describe limnological variables of low-order lotic systems located in the Cerrado Long Term Ecological Research (LTER) site (Environmental Protection Area (APA) Gama and Cabeça de Veado, Federal District of Brazil). Altogether, nine different streams were considered in this study. Samplings were conducted between 2010 and 2012, concentrated in the dry and rainy seasons. The sampling sites were generally characterized by low nutrient concentrations (e.g., medians, TP = 14.8 μg L(-1), TN = 20.0 μg L(-1), NO3 = 13.8 μg L(-1)) and slightly acidic waters (median, pH = 5.3), with quite low electrical conductivity values (median = 6.4 μS cm(-1)). However, water quality degradation as a response to diffuse pollution was reported in some sampling points (e.g., Onça and Gama streams), expressed by relatively higher N and P concentrations, which were probably highlighted by the good water quality of the data set as whole. Although there was a trend to higher values of nitrogen forms during the dry season, significant statistical differences between the seasonal periods were reported only for the variables temperature and dissolved silica, which were higher in the dry and rainy season, respectively. The streams located in the preserved areas inside the ecological stations of APA Gama and Cabeça de Veado can still be considered good examples of reference lotic systems in the Cerrado Domain; notwithstanding, this study reported incipient signs of water quality degradation which cannot be overlooked in future limnological monitoring.

The Brazilian Cerrado: assessment of water and soil degradation in catchments under intensive agricultural use

“…Extremely weathered, undisturbed watersheds are characterized by very low in-stream ionic concentrations z z z Figure 6. For pristine Cerrado streams, Fonseca et al (2013) and Fonseca and de Mendonça-Galvão (2014) found very low nutrient baselines for first to third streams compared with other natural areas in Brazil or temperate regions. The published value is averaged over the depth.…”

“…Thus, Markewitz et al (2006) showed for second-order streams that most measured ionic components (Ca 2+ , Mg 2+ , K + , Na 2+ , Cl À , SO 4 2À and alkalinity), excluding NH 4 + -N and NO 3 À N, show a seasonal variation: high values in the dry season were at least three times larger in the wet season. For pristine Cerrado streams, Fonseca et al (2013) and Fonseca and de Mendonça-Galvão (2014) found very low nutrient baselines for first to third streams compared with other natural areas in Brazil or temperate regions. The authors concluded that the response to anthropogenic impacts was slower in these regions than in the Amazon.…”

An evaluation of freshwater monitoring programs in ILTER nodes and mountain national parks: identifying key variables to monitor global change effects

“…(1) they respond to changes in the aquatic environment and in the adjacent terrestrial ecosystems(Álvarez-Cabria et al 2016;Lei et al 2020);(2) they are easily and inexpensively measurable; (3) they are useful to develop data bases representing pristine conditions(Fonseca and Mendonça-Galvão 2014), and (4) are useful…”

Effects of land use and sampling distance on water quality in tropical headwater springs (Pimenta creek, São Paulo State, Brazil)

“…Although more data are available from local and regional studies by local water managers or environmental protection agencies, they are not published in scientific journals and thus the impacts of land use on aquatic systems, that is, pollution from nutrients and pesticides, their in-stream processes, and their effects on aquatic habitats, are not well understood (Hunke et al, 2015a). Biome-specific water quality thresholds lack in Brazil (Hunke et al, 2015b), except for baselines for physical-chemical water parameters ranging from natural to very impacted conditions in the Cerrado area reported by Fonseca et al (2014).…”