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Assessing the Ecological Condition of Streams in a Southeastern Brazilian Basin using a Probabilistic Monitoring Design
Citation:
Jimenez-Valencia, J., Phil Kaufmann, A. Sattamini, R. Mugnai, AND D. Baptista. Assessing the Ecological Condition of Streams in a Southeastern Brazilian Basin using a Probabilistic Monitoring Design. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, 186(8):4685-4695, (2014).
Impact/Purpose:
The manuscript entitled, “Assessing the Ecological Condition of Streams in a Southeastern Brazilian Basin using a Probabilistic Monitoring Design” by Juliana Jiménez-Valencia; Philip R. Kaufmann, Ana Sattamini, Riccardo Mugnai and Darcilio F. Baptista, is intended for submission as an article in Environmental Monitoring and Assessment. Although probability-based surveys demonstrably improve the quality of regional estimates and recent survey-assessments indicate that neglecting this approach can be serious, they are not commonly used by regional aquatic resource researchers and managers in South America and other continents. The authors applied the generalized random tessellation stratified (GRTS) sampling design the used by the U.S. EPA in the EMAP and NARS sample surveys. Their application of random sampling to stream networks in Southeastern Brazil is a pioneering step that demonstrate that these statistical sampling methods can be used routinely in Brazilian rain forests and other South American regions with similar challenges. Their article will be particularly useful to scientists, agencies, and managers engaged in regional sampling and assessment because they describe field sampling and implementation issues encountered in the Brazilian survey and discuss design options to remedy them. The results of the survey itself will aid the growing effort to quantify ecological condition globally.
Description:
Prompt assessment and management actions are required if we are to reduce the current rapid loss of habitat and biodiversity worldwide. Statistically valid quantification of the biota and habitat condition in water bodies are prerequisites for rigorous assessment of aquatic biodiversity and habitat. We assessed the ecological condition of streams in a southeastern Brazilian basin, quantifying the percentage of stream length according to benthic macroinvertebrate assemblage condition class and the association of aquatic-riparian physical habitat condition, watershed condition and water quality with biological integrity. We describe field sampling and implementation issues encountered in our survey and discuss design options to remedy them. Survey sample sites were selected using a spatially-balanced, stratified random design, which enabled us to put confidence bounds on the stream population estimates derived from the survey. The benthic condition index indicated that 62% of stream length in the basin was in poor ecological condition, and 13% of stream length was in fair condition. We found the risk of not finding good biological condition in streams to be 2.5 to 4 times higher for locations with degraded riparian vegetation and degraded forest in upstream catchments than for streams rated as good for the same stressors. We demonstrated that the GRTS statistical sampling method can be used routinely in Brazilian rain forests and other South American regions with similar conditions. This survey establishes an initial baseline for monitoring the condition and trends of streams in the region.
