Interactions between terrestrial and aquatic systems influence the structure of river habitats and, consequently, affect their benthic macroinvertebrate composition. The aim of this study was to evaluate the effects of spatial and environmental variables (local physical and chemical variables of water and regional landscape characteristics) on the benthic macroinvertebrate community of the Pandeiros River Basin. Biotic and abiotic variables were evaluated at 20 sampling sites distributed across the primary sub-basins of the Pandeiros River Basin. We found that the macroinvertebrates were primarily affected by environmental variables. The most important environmental variables were pebble proportion and water conductivity at the local scale (7.2% of explained variation) and elevation and nonforest areas at the regional scale (6.9% of explained variation). The spatial variables were representative only in shared explained variation with the environmental matrices (local-spatial = 0.2% and regional-spatial = 2%; all matrices combined = 4.4%). Sampling sites with higher non-forest areas, lower elevations, and steeper slopes presented low pebble fractions and higher electrical conductivities. Habitat diversity was lower when the percentage of pebbles decreased, resulting in decreased taxonomic richness and diversity in macroinvertebrate communities. High electrical conductivities and non-forest areas also had negative effects on macroinvertebrate density due to the loss of habitat diversity. We conclude that higher proportions of pebbles in the substrate and higher altitudes were likely the primary variables for positive effects on the taxonomic richness and density of macroinvertebrate communities

In the face of global climate change, there has been an increase in wildfires around the world, highlighting the need for improved firefighting techniques, such as the use of fire retardants (FRs). These products can enter aquatic systems directly or through runoff, posing potential risks to aquatic biota. In this study, the acute toxicity (24-h/48-h EC50) of three distinct FRs (N-Borate, N-Phosphate+, and N-Phosphate−) was assessed on the immobility of freshwater microcrustaceans Ceriodaphnia dubia and Daphnia magna. The toxicity of the FRs varied up to two orders of magnitude, all of which presented risks to cladocerans even at dilutions much below those recommended by their manufacturers. Among the tested FRs, N-Phosphate− emerged as the most harmful to both species. Specifically, for C. dubia, the 24 h EC50 was 0.005% and the 48 h EC50 was 0.0019%, while for D. magna, 24 h EC50 was 0.003% and the 48 h EC50 was 0.0023%. With the increasing use of FRs for wildfire control, our study highlights the toxicity of newly formulated FRs to daphniid species and emphasizes the need for further evidence-based evaluations of their effects on freshwater ecosystems, which is crucial for choosing FRs that pose the lowest hazard to zooplankton communities.

A expansão de áreas de pastagens e cultivos agrícolas foi responsável pela maior parte do desmatamento no norte do estado de Minas Gerais. No presente estudo, avaliou-se a dinâmica do uso e cobertura da terra ocorrida nas últimas décadas (1986 a 2015) na Reserva de Desenvolvimento Sustentável Nascentes das Geraizeiras (RDS-NG) e em uma zona de 10 km do seu entorno no estado de Minas Gerais. Avaliaram-se também os efeitos do desmatamento sobre a fragmentação da vegetação natural usando dados de sensoriamento remoto e análise da paisagem. Os resultados deste estudo indicam que o desmatamento afetou mais da metade da vegetação natural até 2015, agravando a integridade dos fragmentos de vegetação nativa na área de estudo. A RDS-NG contribuiu para mitigar a fragmentação da vegetação natural ocorrida no entorno daquela Reserva com a regeneração natural de algumas áreas degradadas. Observou-se que a maior ameaça ambiental à reserva é a ocorrência do fogo, que varia anualmente em extensão e danos socioambientais. O uso sustentado das terras na RDS-NG pode ser melhorado com a ampliação das práticas de atividades econômicas sustentáveis, como o aproveitamento de produtos florestais não madeireiros, a implantação de consórcios agroflorestais e outras atividades econômicas de forma moderada. Essas práticas contribuirão para garantir a manutenção dos recursos naturais, a produção econômica e a geração de renda e trabalho à comunidade local, com inclusão de todos os segmentos sociais da população da Reserva e seu entorno.

With the escalating frequency and intensity of global wildfires driven by climate change, fire retardants (FRs) have become essential tools in wildfire management. Despite their widespread use, the environmental safety of newer FR formulations—particularly in relation to aquatic ecosystems and developmental toxicity—remains insufficiently understood. In particular, their effects on fish embryos, which represent a sensitive and ecologically important life stage, are poorly characterized. This study investigated the acute toxicity of three commercially available FRs—N-Borate, N-Phosphate+, and N-Phosphate-—on early life stages of zebrafish (Danio rerio), based on an OECD 236 Fish Embryo Toxicity (FET) test. Notably, N-Phosphate- FR exhibited significant toxicity with a 96 h LC50 of 60 mg/L (0.0055%), while N-Borate (>432 mg/L, >0.032%) and N-Phosphate+ (>1181 mg/L, >0.08%) showed substantially lower toxicity. Sublethal effects, including reduced yolk sac absorption and yolk sac darkening, were observed across all FRs, highlighting potential developmental disruptions. The elevated toxicity of N-Phosphate- FR likely stems from its surfactant content. These findings reveal variations in the acute toxicity of different FR formulations, emphasizing the need for ecotoxicological assessments to guide the selection of safer FRs for wildfire management and to protect aquatic biodiversity. The results highlight the importance of incorporating developmental endpoints in FR risk assessments and provide foundational data for regulatory decisions regarding FR application near aquatic habitats. Further research is necessary to elucidate the mechanisms underlying observed effects and to evaluate cross-species toxicity at environmentally relevant concentrations.

Understanding how pollinators navigate human-modified landscapes is essential for conservation planning, yet movement ecology remains poorly resolved for most stingless bees. We experimentally assessed the homing ability of Melipona quadrifasciata by releasing 1,200 RFID-tagged workers across four seasonal periods. A total of 165 individuals returned (13.75%), including two bees that successfully returned from 7.5 km—the longest homing distance recorded for this species. Return probability declined steadily with distance (~ 41% lower odds per km), with model comparison showing that this pattern does not reflect a discrete homing threshold. Landscape structure significantly influenced navigational success: higher maximum NDVI along least-cost corridors increased return probability, while greater NDWI range along corridors—indicating moisture variability—also favored successful returns. Survival analyses yielded consistent patterns for return time, and including remote-sensing metrics substantially improved model performance relative to distance-only formulations. A multi-criteria prioritization revealed a temporally dynamic but spatially constrained network of return routes, including a subset of persistent core corridors that remained functional across all seasons, in contrast with transient seasonal corridors sensitive to environmental fluctuations. Collectively, our findings show that M. quadrifasciata possesses greater navigational capacity than previously assumed and that stable structural features of the landscape repeatedly provide favorable conditions for orientation and successful homing. By integrating RFID tracking, remote sensing, and resistance-based modeling, this study provides an empirical framework for identifying pollinator movement corridors and guiding connectivity-oriented conservation strategies in fragmented tropical landscapes.