Nédia de Castilhos Ghisi

Microplastic (MP) contamination in freshwater ecosystems remains insufficiently investigated, particularly in tropical and subtropical regions, despite their ecological relevance and increasing exposure to plastic pollution. This study investigated microparticles ingestion by two fish species with different feeding habits (Astyanax sp. and Rhamdia quelen) in four streams in the Iguaçu River basin (PR), under different land uses: urban, rural, forested, and protected (conservation unit). The gastrointestinal tracts of 402 individuals were analyzed by oxidative digestion with hydrogen peroxide (30%) and sorting under a stereomicroscope with polarized light. A total of 241 anthropogenic particles were identified, with a predominance of fibers (93.8%). Characterization by Raman spectroscopy and FTIR-ATR identified the polymers polyethylene terephthalate (PET), polyethylene (PE), and polyamide (PA). The analysis considered both occurrence (presence or absence of microparticles per individual) and ingestion (number of particles) in relation to land use and seasonality (dry and rainy). For Astyanax sp., occurrence was higher in the dry season, while ingestion was higher in individuals during the rainy season. R. quelen showed higher intake in the dry season, with no significant variations in occurrence between seasons. The lowest occurrence and ingestion of microparticles were observed in fish collected from the protected area, highlighting the role of conserved areas in reducing exposure to microparticles. The results demonstrate that land use, species, and seasonality differently influence the exposure and ingestion of microparticles by fish.

Biological treatment of dairy wastewater depends on complex microbial communities that vary widely across reactors, influent sources and operating conditions. Whether stable treatment performance arises from conserved taxa or from redundancy in functional potential remains unclear. In this study, we conducted a meta‐analysis and reprocessing of 239 samples from nine independent studies spanning six countries and multiple reactor configurations. Taxonomic profiles showed extreme heterogeneity, with no ASV detected in at least 50% of samples and most genera exhibiting strong study‐specific patterns. In contrast, the predicted functional repertoire was highly conserved. PICRUSt2 analysis identified 196 MetaCyc pathways present in at least 90% of samples, and these pathways accounted for approximately 90% of total predicted functional abundance. Generalised linear latent variable models showed that temperature and pH created consistent but modest ecological gradients, while study‐ and reactor‐level factors dominated community structure. Despite substantial taxonomic turnover, functional signatures associated with fermentation, biosynthesis, nitrogen cycling, and degradation of complex substrates remained stable across systems. Treatment‐stage transitions also followed predictable metabolic trajectories. These results show that dairy wastewater treatment systems are taxonomically flexible but functionally robust, and that extensive redundancy supports consistent metabolic capacity across diverse operational and environmental contexts.

Cadmium (Cd) is a toxic and bioaccumulative metal widely distributed in aquatic environments due to anthropogenic activities, posing significant risks to ecosystems and human health. This study presents Part 1 of a complementary two-part scientometric review on Cd toxicity in aquatic organisms, in which the global literature was organized into two major biological groups: (i) Aquatic vertebrates and invertebrates (Part 1) and (ii) photosynthetic aquatic organisms. A comprehensive literature search was conducted in the Web of Science database (1945–2024), retrieving 6,531 records, of which 3,837 were retained after refinement. The dataset was initially analyzed as a whole to identify global publication trends, research hotspots, and influential countries and institutions. Subsequently, a detailed scientometric analysis was performed focusing on aquatic vertebrates and invertebrates. The results revealed a substantial increase in scientific production over recent decades, with China leading in publication output and institutional influence. The most recurrent research themes were related to heavy metals, toxicity, and oxidative stress. Fish were the most studied vertebrate group, particularly Danio rerio, whereas among invertebrates, mollusks and crustaceans were the most frequently investigated groups, with Daphnia magna being the most commonly used model species. Bioaccumulation was the most frequently evaluated biological endpoint, while laboratory-based experiments predominated among study designs. Overall, the findings demonstrate a growing scientific concern regarding Cd contamination and its biological effects. Current research is strongly focused on mechanisms of toxicity, particularly oxidative stress and bioaccumulation, whereas future studies should prioritize integrated approaches and the development of effective remediation strategies to mitigate the environmental impacts of this metal.

Micro- and nanoplastics (MNPs) are emerging contaminants widely distributed across environmental compartments and associated with potential ecological and human health risks. Given the rapid expansion of review literature on this topic, we conducted an umbrella review integrating scientometric mapping and thematic synthesis to evaluate research trends, methodological patterns, convergent evidence, and knowledge gaps in MNPs research. Review articles indexed in the Web of Science Core Collection up to June 2025 were analyzed using combined manual refinement, automated text-mining workflows, and CiteSpace network analyses. A total of 7,349 review articles were included. The results revealed strong thematic concentration around aquatic ecosystems, fish-based models, contamination studies, and adverse biological effects, particularly involving polyethylene (PE), polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). There was a broad consensus on the widespread environmental occurrence of MNPs and their potential to induce oxidative stress, inflammation, cytotoxicity, and bioaccumulation. However, substantial methodological heterogeneity and structural biases were identified, including the predominance of narrative reviews, limited taxonomic diversity, and inconsistent analytical and experimental approaches. Several domains remained comparatively underexplored, especially environmental transport, degradation pathways, microorganism interactions, combined exposure scenarios, and environmentally realistic conditions. In addition, terrestrial organisms, atmospheric systems, and less frequently studied polymer types remain insufficiently represented in the current review literature. Overall, this umbrella review demonstrates that, despite the rapid consolidation of MNPs research, important limitations persist regarding evidence integration, methodological standardization, and ecological representativeness. These findings highlight the need for more integrative, standardized, and ecologically relevant approaches capable of improving ecological risk assessment and advancing the understanding of MNPs dynamics and impacts across environmental systems.

Cadmium (Cd) is a highly toxic and bioaccumulative heavy metal widely detected in aquatic environments due to anthropogenic activities. This study presents a scientometric analysis of Cd toxicity in photosynthetic aquatic organisms, as part of a complementary two-part review based on a single comprehensive dataset of aquatic organisms. Publications indexed in the Web of Science from 1945 to 2024 were analyzed using bibliometric tools and manual data extraction. A total of 7,198 records were identified, of which 4,052 were retained, including 704 studies focused on photosynthetic aquatic organisms. The results indicate continuous growth in research output, with a predominance of laboratory-based studies. Algae and angiosperms were the most frequently studied groups, with species such as Chlamydomonas reinhardtii and Lemna minor being widely used as model organisms. The most frequently evaluated biological and ecotoxicological parameters were related to bioaccumulation and growth, particularly algal proliferation. Overall, this study highlights key research trends and gaps, emphasizing the need for future studies to adopt environmentally relevant exposure conditions and develop efficient remediation strategies to mitigate Cd’s impacts on aquatic ecosystems.

Agricultural and urban waste contains various contaminating substances that reach rivers and bodies of water daily. Anthropogenic activities threaten the integrity of aquatic ecosystems and the resident species. Hypostomus ancistroides is a neotropical fish that is part of the South American fauna. Due to their benthic habit and trophic niche, these organisms can be directly exposed to mutagenic pollutants. Therefore, this study aimed to investigate the toxicity of urbanized and rural river waters (Toledo River and Santa Quitéria River, Toledo, Paraná, Brazil) by evaluating the genotoxic and biochemical effects in H. ancistroides. Fish were collected at two urbanized points on the Toledo River (P1, urban; P2, urban and rural-influenced) and at one point on the Santa Quitéria River (P3), located in the rural area of Toledo. The frequency of micronuclei, erythrocyte nuclear abnormalities (ENAs), and biochemical biomarkers (superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and lipid peroxidation) were analyzed across two seasons (summer and winter). Micronuclei and ENAs were observed in H. ancistroides specimens both in urban and rural areas, with the highest occurrence in P2 during the winter. Concerning biochemical biomarkers, H. ancistroides showed a significant increase in SOD during summer in P2 but no significant difference in CAT. Lipid peroxidation during winter in P2 and P3 was higher than in P1 during summer. Higher GST activity was observed in the specimens in P1 and P2 during winter. Both rivers suffer from the impact and contamination caused by human activities, especially during winter. However, the greatest genotoxicity was observed in P2, indicating a high risk of contamination to the aquatic organisms inhabiting the local area.

1. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is widely used in modern agriculture (Islam et al., 2018). This compound was developed to simulate auxins, which are plant hormones that indu...