Amanda Selinger

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.

The Atlantic Forest is one of the top five biodiversity hotspots on the planet and is considered a global priority for conservation, largely due to extensive human‐driven deforestation. Temporary pools in the Atlantic Forest harbour unique and vulnerable fish assemblages, yet remain poorly studied, particularly within protected areas. In this study, we assessed fish diversity, composition and environmental drivers in 34 temporary pools sampled across dry and wet hydrological periods in the Serra do Mar State Park, southeastern Brazil. A total of 574 individuals representing eight species were recorded, indicating low regional richness, with estimates not exceeding 10 species. Fish abundance, richness, effective number of species, Margalef's K and species composition did not differ between periods. Habitat availability and isolation influenced fish abundance only during the dry period, reflecting contrasting ecological strategies of dominant species. In the wet period, the assemblage structure showed no association with environmental predictors, suggesting a stronger influence of stochastic processes driven by unpredictable flood dynamics. Shrimp abundance had no detectable effect on fish assemblage metrics. Our results indicate that temporary pools are shaped by a combination of historical environmental filtering acting on the regional species pool and contemporary stochastic processes. These findings highlight the ecological dynamics of temporary aquatic habitats, often overlooked in conservation planning, and also reinforce the role of protected Atlantic Forest areas as microclimatic refugia in a rapidly changing world.

We provide the first quantitative description of intersexual behavioral interactions in the critically endangered annual killifish Leptopanchax itanhaensis, aiming to characterize its behavioral repertoire, sex-specific expression of behaviors, and variation associated with couple size. Behavioral observations were conducted on seven couples sampled from a roadside ditch in the coastal Atlantic Forest of southeastern Brazil. Behavioral frequencies were recorded during standardized observation periods, converted to relative proportions, and analyzed using generalized linear mixed models to test for sex differences in total behavioral activity and behavioral diversity while accounting for couple identity. Behavioral composition varied markedly among couples and across size classes. Resting in the bottom was the most frequent behavior in both sexes, while courtship-related behaviors were more prevalent in larger couples. Total behavioral activity and behavioral diversity did not differ significantly between sexes. However, males more frequently exhibited courtship and harassing behaviors, whereas females more frequently exhibited being courted and escape behaviors. These findings provide the first behavioral baseline for this critically endangered species and highlight the importance of behavioral studies for understanding habitat use and reproductive interactions in annual killifishes.

Aim In the present study, we investigated the existence of intraspecific variation in the morphology and diet of the catfish Imparfinis schubarti as body length increases, evaluating whether morphological changes are associated with changes in food, as well determining the degree of individual specialization in the species' diet. Methods Sixty-one individuals were collected by electrofishing in August 2017, in Areia stream, located in northwestern Paraná, Brazil. The individuals were subjected to geometric morphometric, and stomach content analyses. To investigate trophic specialization, indices that evaluate the overlap of the diet between individuals, the average degree of individual specialization, the pairwise similarity of the diet, and the grouping of individuals based on the sharing of food resources were applied. Results No significant morphological or dietary changes were observed as body length increased. The population exhibited a high degree of individual specialization, characterized by the coexistence of generalist individuals and those with highly specialized diets, with no significant influence of body size on specialization. Conclusions The results suggest that, in I. schubarti, morphological and trophic aspects may remain relatively constant as body length increases. Furthermore, the coexistence of generalist and specialized individuals, without association with apparent morphological variations, suggests that individual specialization may be modulated by non-morphological factors, such as behavioral or physiological differences, reflecting distinct adaptive strategies within the population.

This study demonstrates the potential of Raman spectroscopy as an effective and accurate tool for identifying and classifying postconsumer plastics, achieving 100% accuracy for plastics classified from types 1 to 6 according to the recycling triangles. The ability to differentiate plastic types, including the detection of dyes commonly used in packaging and labels, can significantly enhance sorting efficiency in recycling facilities. By improving plastic separation, this method can contribute to more sustainable recycling practices, reducing contamination in recycled materials and supporting the development of a circular economy.

Temporary aquatic habitats are essential for maintaining regional fish diversity, especially in tropical ecosystems. However, artificial ephemeral environments such as roadside ditches remain largely overlooked in ecological research, despite their potential to support native, threatened and even invasive species. In this study, we first assess the fish community composition in roadside ditches of the Atlantic Forest, southeastern Brazil. These habitats exhibited extreme environmental conditions, including hypoxic waters, elevated temperature fluctuations and very acidic waters. Throughout the year, we recorded 17 fish species, including endangered and exotic taxa, across 36 ditches sampled in the Preto River microbasin. Species richness was higher during the Wet Period, likely due to increased hydrological connectivity with nearby streams. Although species richness was higher during the Wet Period, species composition did not differ between periods. Redundancy analysis revealed low explanation of environmental variables on community structure, while a significant positive correlation between spatial distance and community dissimilarity suggested dispersal limitation as a major structuring force. These findings highlight both the ecological relevance of artificial temporary habitats in fragmented landscapes and the requirement to integrate such environments into regional species inventories, especially as natural wetlands continue to decline.

Temporary aquatic habitats are essential for maintaining regional fish diversity, especially in tropical ecosystems. However, artificial ephemeral environments such as roadside ditches remain largely overlooked in ecological research, despite their potential to support native, threatened and even invasive species. In this study, we first assess the fish community composition in roadside ditches of the Atlantic Forest, southeastern Brazil. These habitats exhibited extreme environmental conditions, including hypoxic waters, elevated temperature fluctuations and very acidic waters. Throughout the year, we recorded 17 fish species, including endangered and exotic taxa, across 36 ditches sampled in the Preto River microbasin. Species richness was higher during the Wet Period, likely due to increased hydrological connectivity with nearby streams. Although species richness was higher during the Wet Period, species composition did not differ between periods. Redundancy analysis revealed low explanation of environmental variables on community structure, while a significant positive correlation between spatial distance and community dissimilarity suggested dispersal limitation as a major structuring force. These findings highlight both the ecological relevance of artificial temporary habitats in fragmented landscapes and the requirement to integrate such environments into regional species inventories, especially as natural wetlands continue to decline.

Freshwater temporary pools are ephemeral habitats with high structural and physicochemical variability. Many dry out during the dry season and host seasonal killifishes, among the most threatened freshwater fishes. These ecosystems support diverse fish communities and are highly vulnerable to climate change. This systematic review aimed to uncover global research trends and gaps concerning fish inhabiting freshwater temporary pools and to test the hypothesis that public policies influence scientific production. Covering the period from 1981 to 2024, it analyses 115 peer-reviewed articles. Geographically, research was concentrated in South America and Africa, particularly in Brazil. Reproduction and taxonomy were the most common study areas, with the focus primarily on Rivulidae and Nothobranchiidae. Notably, 62 species of Rivulidae and 12 of Nothobranchiidae were studied, while other 100 species from other families received limited attention. Knowledge gaps persist in areas such as ecotoxicology, physiology, trophic ecology, behavior and parasitology. Our findings suggest that public policies did not directly influence publication trends about fish in freshwater temporary pools and emphasize the need to integrate scientific knowledge with conservation planning. A broader focus on other fish clades and ecological aspects will be critical for protecting the biodiversity of these vulnerable ecosystems.

Aim Here we investigated the diet of Mimagoniates lateralis (Nichols, 1913) in a blackwater restinga stream of the Atlantic Forest, aiming to identify the main food sources consumed and to verify if ontogenetic variations occur. Methods Specimens were sampled in January 2024 in the Panema stream, Itanhaém – SP. The diet of 124 individuals was determined through stomach content analysis, and the Feeding Preference Degree (FPD) was used to measure the importance of the consumed items. Results The diet comprised 21 items, among which detritus, plant fragments, and adult Hymenoptera were predominant. Only detritus was classified as a secondary item in terms of feeding preference, while all other items were considered occasional. Larger fish were more likely to consume adult Coleoptera and Hymenoptera, while smaller individuals were more likely to consume items such as Trombidiformes and detritus. Conclusions The results suggest an ontogenetic dietary shift, favoring specific prey and reducing dependence on other food items. The high presence of allochthonous items in the diet of M. lateralis highlights the crucial role of riparian vegetation as an essential source of food resources. The preservation of riparian forests supports the balance of these ecosystems and is vital for the survival of M. lateralis, a species vulnerable to extinction, reinforcing the urgency of effective measures of conservation.