The expansion of agriculture is particularly worrying in tropical regions of the world, where native forests are being replaced by crops at alarming rates, with severe consequences for biodiversity and ecosystems. However, there is little information about the potential effects of agriculture on the functioning of tropical streams, which is essential if we are to assess the condition and ecological integrity of these ecosystems. We conducted a litter decomposition experiment in streams within a tropical catchment, which were subjected to different degrees of agricultural influence: low (protected area, PA), medium (buffer area, BA) and high (agricultural area, AA). We quantified decomposition rates of litter enclosed within coarse-mesh and fine-mesh bags, which allowed the distinction of microbial and detritivore-mediated decomposition pathways. We used litter of three riparian species representing a gradient in litter quality (Alnus acuminata > Ficus insipida > Quercus bumelioides), and examined detritivore assemblages through the contents of litterbags and benthic samples. We found that the increasing agricultural influence promoted microbial decomposition, probably due to nutrient-mediated stimulation; and inhibited detritivore-mediated and total decomposition because of reduced detritivore numbers, most likely caused by pesticides and sedimentation. Effects were evident for Alnus and Ficus, but not for Quercus, which was barely decomposed across the gradient. Our study provides key evidence about the impact of agriculture on tropical stream ecosystem functioning, which is associated to changes in stream assemblages and may have far-reaching repercussions for global biochemical cycles.

Mesoamerican nephropathy (MeN) is a non-traditional chronic kidney disease in some areas of Mesoamerica. The health risk from nephrotoxic metals, such as arsenic (As), lead (Pb), mercury (Hg), vanadium (V), cadmium (Cd), rubidium (Rb), chromium (Cr), and nickel (Ni), was assessed in drinking water and soils. These metals, even at low concentrations, have the capacity to induce epigenetic damage and a nephrotoxic effect. The quantification of metals in soils was made through X-ray fluorescence spectrometry (XRF) and inductively coupled plasma optical emission spectrophotometry (ICP-OES), while the quantification of metals in water was carried out through inductively coupled plasma mass spectrometry (ICPMS) and atomic absorption (AA) spectrometry. The levels of As, Hg, Cd, and V in water were within the permissible limits, whereas Pb was found to be double and triple the value recommended by the World Health Organization. The non-carcinogenic risk from As in soil was evaluated using the Hazard Index (HI), and the route of ingestion was found to be the most important route. The results indicate that consuming water or ingesting soil particles with Pb and As poses a health risk to humans. Therefore, these findings identify the presence of toxicants in an exposure scenario and justify further research into these metals in people and the analysis of exposure routes.

This study evaluated spatial and seasonal patterns of physicochemical water quality in the Chiriquí Viejo River basin (western Panama), a tropical watershed characterized by strong seasonal variability. A total of 90 water samples were collected at ten stations during the rainy season (May to October 2024) and dry season (January to March 2025). Dissolved oxygen (DO), turbidity, potential of hydrogen (pH), apparent color, total dissolved solids (TDS), and electrical conductivity (EC) were analyzed following ISO/IEC 17025:2017 accredited methods, and precipitation patterns were characterized using spatial interpolation of meteorological data. Spatio-temporal variability was assessed using linear mixed-effects models, with season and basin position as fixed effects and sampling site as a random factor. Results showed a spatial and seasonal structuring of water quality, with the upper basin exhibiting high and stable DO concentrations and low turbidity and apparent color. In contrast, the middle and lower basin showed rainy-season increases in turbidity and apparent color, supported by a significant season × basin interaction, indicating that precipitation driven impacts are heterogeneous along the basin. EC and TDS displayed spatial gradients, while DO remained relatively stable across seasons and basin levels. These findings highlight turbidity and apparent color as sensitive indicators of precipitation-driven impacts.