Timing since deforestation for pastures implementation in the western Amazon: Impacts on stream water biogeochemistry.

Water quality degradation is a global concern and land use changes is one of the main causes of water pollution globally. In the Brazilian Amazon, large-scale deforestation is mostly associated to pasturelands, with strong implications for soils and stream waters biogeochemistry and resulting in environmental degradation. Studies addressing soil biogeochemistry in Amazonian pastures of different ages documented a consistent pattern of elements peaking on the first years after deforestation, followed by a continuous decrease until reach depletion in older, degraded pastures.

Cost-effective alternatives to facilitate biomonitoring and bioassessment of neotropical streams.

A reliable response of bioindicators to environmental variation is a cornerstone for effective bioassessment and biomonitoring. Fish and aquatic macroinvertebrates are widely used as bioindicators of different human impacts in freshwater ecosystems, but the cost-effectiveness of their usage can be improved through the use of surrogates. We investigated congruence patterns between using different taxonomic and numeric resolutions for aquatic macroinvertebrates and fish to assess community-environment relationships.

Population size, income and poor sanitation interact to explain widespread streamwater contamination by antidepressants in the Metropolitan Region of São Paulo.

The expansion of urban settlements over native environments may expose biodiversity to a host of emerging contaminants, with unintended ecological effects. This study evaluated patterns of contamination of streamwater by antidepressants in the Upper Tietê River Basin, a watershed of high social, economic and environmental relevance for comprising both the largest urban settlement in South America (the Metropolitan Region of São Paulo) and remnants of a globally important biodiversity hotspot (the Atlantic Rainforest). We sampled 53 third-order streams draining catchments regularly distributed across a gradient in urban cover.

Factors affecting the transferability of bioindicators based on stream fish assemblages.

The development of multimetric indices (MMIs) to measure the biotic condition of aquatic habitats is based on metrics derived from biological assemblages. Considering fish assemblages, the inconsistencies in metrics responses outside of the places where they were developed limit MMI transferability and applicability to other locations, requiring local calibration. The factors behind the low transferability of these MMIs are still poorly understood.

A multiple hypothesis approach to explain species richness patterns in neotropical stream-dweller fish communities.

Several hypotheses are used to explain species richness patterns. Some of them (e.g.

Effects of agriculture and topography on tropical amphibian species and communities.

Habitat loss is the greatest threat to the persistence of forest-dependent amphibians, but it is not the only factor influencing species occurrences. The composition of the surrounding matrix, structure of stream networks, and topography are also important landscape characteristics influencing amphibian distributions. Tropical forests have high diversity and endemism of amphibians, but little is known about the specific responses of many of these species to landscape features.

Threshold responses of Amazonian stream fishes to timing and extent of deforestation.

Deforestation is a primary driver of biodiversity change through habitat loss and fragmentation. Stream biodiversity may not respond to deforestation in a simple linear relationship. Rather, threshold responses to extent and timing of deforestation may occur.

More of the same: high functional redundancy in stream fish assemblages from tropical agroecosystems.

In this study, we investigated the influence of environmental variables (predictor variables) on the species richness, species diversity, functional diversity, and functional redundancy (response variables) of stream fish assemblages in an agroecosystem that harbor a gradient of degradation. We hypothesized that, despite presenting high richness or diversity in some occasions, fish communities will be more functionally redundant with stream degradation. Species richness, species diversity, and functional redundancy were predicted by the percentage of grass on the banks, which is a characteristic that indicates degraded conditions, whereas the percentage of coarse substrate in the stream bottom was an important predictor of all response variables and indicates more preserved conditions.