Measurement of the Ecological Integrity of Cerrado Streams Using Biological Metrics and the Index of Habitat Integrity

Abstract

Generally, aquatic communities reflect the effects of anthropogenic changes such as deforestation or organic pollution. The Cerrado stands among the most threatened ecosystems by human activities in Brazil. In order to evaluate the ecological integrity of the streams in a preserved watershed in the Northern Cerrado biome corresponding to a mosaic of ecosystems in transition to the Amazonia biome in Brazil, biological metrics related to diversity, structure, and sensitivity of aquatic macroinvertebrates were calculated. Sampling included collections along stretches of 200 m of nine streams and measurements of abiotic variables (temperature, electrical conductivity, pH, total dissolved solids, dissolved oxygen, and discharge) and the Index of Habitat Integrity (HII). The values of the abiotic variables and the HII indicated that most of the streams have good ecological integrity, due to high oxygen levels and low concentrations of dissolved solids and electric conductivity. Two streams showed altered HII scores mainly related to small dams for recreational and domestic use, use of Cerrado natural pasture for cattle raising, and spot deforestation in bathing areas. However, this finding is not reflected in the biological metrics that were used. Considering all nine streams, only two showed satisfactory ecological quality (measured by Biological Monitoring Working Party (BMWP), total richness, and EPT (Ephemeroptera, Plecoptera, and Trichoptera) richness), only one of which had a low HII score. These results indicate that punctual measures of abiotic parameters do not reveal the long-term impacts of anthropic activities in these streams, including related fire management of pasture that annually alters the vegetation matrix and may act as a disturbance for the macroinvertebrate communities. Due to this, biomonitoring of low order streams in Cerrado ecosystems of the Northern Central Brazil by different biotic metrics and also physical attributes of the riparian zone such as HII is recommended for the monitoring and control of anthropic impacts on aquatic communities.

Effects of Environmental Variables and Habitat Integrity on the Structure of the Aquatic Insect Communities of Streams in the Cerrado-Caatinga Ecotone in Northeastern Brazil

“…In addition to these seasonal shifts in habitat characteristics, such as the stream structure and physicochemical gradients, the composition and density of the organisms found in a stream may be influenced by its drag, which is determined by the peaks in its discharge (Collier & Quinn 2003, Castro et al 2013. This confirms the fluctuations observed in the composition of aquatic organisms, including the EPT (Reis et al 2017, Montag et al 2019.…”

Benthic macroinvertebrates in a protected area within the Brazilian savannah: environmental factors negatively affect diversity

“…Higher BMWP' values indicate greater water quality (Junqueira and Campos, 1998). Furthermore, the use of both BMWP' biotic index and HII are recommended to better account for the complexity of stream ecosystems (Reis et al, 2017). Shannon's diversity (H') was calculated for each sample unity as this measure is sensitive to physical changes in the environment (Silveira et al, 2005).…”

Riffle algal and macroinvertebrate recovery from wet‐season flood disturbance in a tropical savannah river, Northern Australia

“…Blanchette and Pearson (2013) and Central and South America), excluding the Brazilian Cerrado (e.g. Macedo et al, 2014;Moreyra & Padovesi-Fonseca, 2015;Reis et al, 2017).…”