Acta Limnologica Brasiliensia

(631 Artigos indexados)

Coordinating in situ lake sampling with satellite acquisition days provides a mechanism for addressing data scarcity: a case study from Lake Yojoa, Honduras - (2025)

Jemma Fadum, Bethel Steele, Matthew Ross, Mia Groff, Ed Hall

Volume: 37 - Issue: 0

Resumo. Abstract: Aim In this study, we present the results of a project which used Landsat Collection 2 Surface Reflectance data and European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) data to develop a machine learning model to estimate Secchi depth in Lake Yojoa, Honduras. Methods Satellite remote sensing data obtained within a 7-day window of an in situ measurement were matched with in situ Secchi depth measurements and were partitioned into train-test-validate data sets for model development. Results The machine learning model had good (R2= 0.57) agreement and reasonable uncertainty (MAE = 0.58 m) between remotely estimated and in situ observed Secchi depth. Application of the machine learning model increased the monitoring record of Lake Yojoa from 6 years of measured data to a 23-year record. Conclusions This model demonstrates the utility of coordinating in situ sampling schedules of short-term research projects with satellite imagery acquisition schedules in order to increase the temporal coverage of remote sensing derived estimates of water quality in understudied lakes.

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Diversity and distribution of testate amoebae in freshwater ecoregions of Rio de Janeiro State, Brazil - (2025)

Larissa Souza Monteiro, Karen Helena Costa Santos, Manoela dos Santos Moreira, Ana Caroline Quirino da Silva, Viviane Bernardes dos Santos Miranda, Christina Wyss Castelo Branco

Volume: 37 - Issue: 0

Resumo. Abstract: Aim: Testate amoebae are a group that remains understudied. The present study conducted a survey on the testaceans’ records in several biotopes in ecoregions of the State of Rio de Janeiro, exploring differences in the occurrence of taxa. Methods A literature survey was carried out in the Scopus, Web of Science, Google Scholar and Scielo databases using the keywords in English and Portuguese "Testate Amoebae", "Thecamoebian", "Zooplankton" and accompanied by "Rio de Janeiro". Further, samples (collected by plankton mesh nets from 50 to 68 µm; bucket and bottle) from 12 locations were analyzed. The identification of taxa was conducted using an optical microscope with digital camera and Toup-View software for morphological measurements and with specific bibliography. All the records were georeferenced across the freshwater ecoregions of Rio de Janeiro. Statistical analyses were performed using R 4.3.3 Software (R Core Team 2024) through the Vegan package, a species accumulation curve (specaccum function), non-metric multidimensional scaling (nMDS) analysis based on ‘Jaccard’ dissimilarity and the PERMANOVA test performed. Results The bibliographic survey resulted in 35 publications from 1910 to 2023. The sum of records from the literature and from the samples analyzed comprised 37 localities and 250 taxa, including new records for the State of Rio de Janeiro. Centropyxis aculeata was the most frequent species (63.7%), and Difflugia, Centropyxis and Arcella were the most diverse genera. The species accumulation curve indicated that testaceans’ richness is underestimated, evidencing insufficient sampling. There was no significant difference between testaceans’ assemblages from different biotopes. Conclusions The records in Rio de Janeiro are underestimated due to insufficient sampling in some ecoregions. Future studies are needed to produce a taxonomic inventory more faithful real diversity.

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Effects of urban pollution on zooplankton diversity along the Almada River (Bahia, Brazil) - (2025)

Jovenilson Ferreira dos Santos, Jaielle Rodrigues Nascimento, Nadson Ressyé Simões

Volume: 37 - Issue: 0

Resumo. Abstract: Aim This study aimed to analyze the influence of small cities on the diversity of the zooplankton community along the Almada River, Bahia. Methods The samples were collected at points upstream (Clean Waters - CW) and downstream (Active Decomposition - DA) of the urban area of three cities: Almadina, Coaraci and Itajuípe, between the years 2020 and 2023. Results Among the physical and chemical variables, only dissolved oxygen and water temperature varied significantly between CW and DA. 90 taxa were identified, of which: 60 from Rotifera, 17 from Cladocera and 13 from Copepoda. It was possible to verify the presence of dominant taxa, characteristic of eutrophic environments, in points downstream of urban areas, namely: Lecane bulla bulla, Bdelloidea, Testudinella patina and Platyias quadricornis. The community attributes with significant variation between CW and DA were: abundance, evenness and the Shannon diversity index. The Jaccard dissimilarity between the CW and DA zones was high, indicating a low rate of species sharing between the CW and DA zones. In the BIOENV analysis, the variables of dissolved oxygen and electrical conductivity associated with variation in community structure were chosen. Conclusions pollution from urbanized regions in the Almada River reduces the evenness and diversity index of shannon, and increases the abundance of the zooplankton community.

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Environmental heterogeneity in wetlands increases alpha and beta diversity of cladocerans (Crustacea, Branchiopoda) at local and regional scale - (2025)

Francisco Diogo Rocha Sousa, Lourdes Maria Abdu Elmoor-Loureiro, Luciana Mendonça-Galvão, Nadson Ressyé Simões

Volume: 37 - Issue: 0

Resumo. Abstract: Aim The goal of this study was to investigate the effect of habitat heterogeneity on diversity on a local and regional scale. We tested two hypotheses: (i) the habitat diversity, given by quantity of microhabitat by macrophytes richness, increases the alpha diversity of organisms that live in those environments; (ii) the habitat heterogeneity, given by compositional difference of microhabitat, increases the beta diversity of organisms that live in those environments. Methods Samples contained cladocerans and macrophytes were collected in six wetlands from the Brazil Central during dry and rainy seasons, in Brazilian National Park (BNP) and Formosa Instruction Field (FIF). Results In local scale (wetlands) the number of macrophyte morphospecies shows the positive effect on alpha diversity of cladoceran; the compositional difference of the microhabitat positively affected the beta diversity in three wetlands studied. In regional scale, the number of macrophyte morphospecies showed the positive effect on alpha diversity; the beta diversity was higher in the BNP than in the FIF. Conclusions Our findings suggest that the species richness and dissimilarity of aquatic macrophytes increased to alpha and beta diversity of cladocerans on the local and regional scales. Thus, cladocerans richness was correlated with the number of microhabitats and the variability between microhabitats in wetlands.

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Environmental impacts shape the density-size relationship of benthic macroinvertebrates in Amazonian streams (Serra dos Carajás, Pará, Brazil) - (2025)

Maria Eduarda Cabral Liberal, Camila Pinto Leão, Jaqueline Silva de Oliveira, Francisco Valente-Neto, Bruno Spacek Godoy

Volume: 37 - Issue: 0

Resumo. Abstract: Aim Streams are small lotic ecosystems essential for aquatic biodiversity and nutrient cycling. However, they are highly susceptible to anthropogenic pressures, such as the replacement of native vegetation by plantations, which can affect aquatic communities—especially benthic macroinvertebrates, due to their sensitivity to environmental changes. While most studies rely on taxonomic metrics, there is growing evidence that changes in riparian vegetation can alter size-density relationships. We hypothesized that impacted streams would exhibit shifts in macroinvertebrate size-density patterns reflecting environmental degradation. Methods We sampled 15 Amazonian streams in the Serra dos Carajás region, southeastern Pará State, Brazil, an area influenced by agriculture, livestock, and mining. Sampling occurred during the dry season across two campaigns. Macroinvertebrates were collected using a kick-net, and physical-chemical variables were measured with a multiparameter probe and turbidimeter. Environmental variables were analyzed using principal component analysis, and size-density relationships were evaluated with a second-order polynomial model. Results Agricultural impact altered size-density relationships. Impacted sites showed reduced macroinvertebrate density across all size classes and a concentration of individuals in intermediate sizes. These changes suggest a simplification of trophic networks and decreased energy transfer efficiency. Conclusions Anthropogenic impacts significantly alter aquatic communities in Amazonian streams. The study demonstrates that agricultural activity reduces macroinvertebrate density in all size classes, signaling a widespread collapse of trophic networks. These findings highlight the vulnerability of Amazonian streams to human disturbances and underscore the importance of monitoring size-density relationships as indicators of ecosystem integrity.

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Evaluating the growth potential of harmful cyanobacteria in aquatic environments under climate change scenarios - (2025)

Ariane Guimarães, Pablo Silva, Daniel Paiva Silva

Volume: 37 - Issue: 0

Resumo. Abstract: Aim Neotropical freshwater environments face severe threats from climate change, posing significant risks to global water security. Extreme hydrological events, such as torrential rains and prolonged droughts, are expected to become more frequent and intense. These conditions increase the residence time of nutrients, especially phosphorus and nitrogen, favoring the proliferation of harmful cyanobacteria (cyanoHABs). Furthermore, cyanobacteria are competitive in environments with few nutrients and high CO2 concentrations. This feature exacerbates ecological and public health challenges, as these cyanobacteria can cause harmful algal blooms that contaminate water supplies and disrupt aquatic ecosystems. We aimed to evaluate the growth of cyanobacteria in specific regions concerning the prevalence of three representative species of cyanoHABs. Methods We used ecological niche modeling tools (ENMs) based on occurrence records from available databases to predict the distribution of the three most frequently representative species of cyanoHABs. We employed three different modeling methods: generalized linear models (GLM), Gaussian models (GAU), and maximum entropy (MXS). Results The potential distributions for the current scenario were consistent with known distributions for the modeled cyanoHABs in the ENMs results. Still, we identified new areas of research for future scenarios. Conclusions The variations we observed indicate that the impacts of climate change vary regionally, affecting the future fitness of cyanobacteria. In the short term, they may maintain stable fitness, but a significant reduction is expected in the long term due to high temperatures. This result highlights the urgent need for mitigating actions to protect aquatic ecosystems.

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Experimental approach on the contribution of wind and animal vectors in the dispersal and colonization of testate amoebae (Protista, Amoebozoa) in freshwater ecosystems - (2025)

Matheus Henrique de Oliveira de Matos, Felipe Rafael de Oliveira, Fernando Miranda Lansac-Tôha, Melissa Progênio, Bianca Ramos de Meira, Loiani Oliveira Santana, Crislaine Cochak, Luiz Felipe Machado Velho

Volume: 37 - Issue: 0

Resumo. Abstract: Aim We aimed to understand how testaceous amoebae spread in new sites, assessing their dispersal potential by wind and animals in freshwater ecosystems. Methods We conducted a field experiment over 33 days between July and August 2018. The study included four different approaches: (i) a control group exposed exclusively to wind, (ii) the addition of propagules dispersed by Odonata (aquatic insects), (iii) the addition of propagules dispersed by amphibians, and (iv) the combined addition of propagules of both animals. Results We detected a total of 13 species of testate amoebae. Regarding species richness, we observed a steady increase throughout the experimental period. In terms of abundance, a similar trend was observed, with differences in the treatment of all vectors combinated, when comparing the treatments with only wind, and the combination of wind and vectors alone, indicating a possible progressive colonization of these organisms in the new aquatic environment. Regarding the composition of testate amoebae, we did not detect significant differences between treatments within each period or between different treatments throughout the experiment. Conclusions Our results demonstrate the importance of animal vectors in the transport of testate amoebae cysts.

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First record of Melanorivulus decoratus (Costa, 1989) (Cyprinodontiformes: Rivulidae) in the lower-middle São Francisco River, Brazil - (2025)

Augusto Luís Bentinho Silva, Giancarlo Arraes Galvão, Silvia Maria Millan Gutierre, Luanny Rainy de Almeida Silva, Luiz Cezar Machado Pereira, Patricia Avello Nicola

Volume: 37 - Issue: 0

Resumo. Abstract The non-annual rivulid Melanorivulus decoratus is an endemic fish from the São Francisco River basin that was previously recorded only in small tributaries along river’s middle stretch in northwestern Bahia. The present record marks the first appearance of M. decoratus in the lower-middle São Francisco, approximately 450 km northeast of the closest previously documented site, providing an updated map of the species’ distribution. Currently classified as Least Concern (LC), this new occurrence record expands knowledge of the species’ range and conservation status.

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Fish community composition differs in rural and urban Neotropical streams - (2025)

Eduarda Samantha Ribeiro, Tatiane Mantovano, Dyego Leonardo Ferraz Caetano, Luana Gabriela Marques da Silva, Leandro da Silva, Thiago Rodrigues Barbosa, Fernando Emmanuel Gonçalves Vieira

Volume: 37 - Issue: 0

Resumo. Abstract: Aquatic ecosystems have a great diversity of habitats, including streams that are of extreme ecological and economic importance but have undergone impacts, such as the input of domestic and industrial waste and deforestation of riparian forest. However, few studies have been carried out on the diversity, specifically beta diversity, of fish assemblages in urban and rural streams. Aim In this context, the objective of this work was to verify if there are differences in fish assemblage structure between urban and rural streams, with focus on beta diversity. Methods We selected 12 streams, 6 urban and 6 rural, located in the municipalities of Ourinhos (SP) and Jacarezinho (PR) in the Paranapanema river basin. Fishes were collected using a sieve. Concomitantly water quality variables were also measured, such as temperature, pH, conductivity and total dissolved solids. To assess whether fish beta diversity differed between streams, a dispersion homogeneity test (Permutational Analysis of Multivariate Dispersions) was calculated. Results Significant differences were observed in conductivity and total dissolved solids, both with higher values for urban streams. In urban streams, 12 species of fish were identified, five of which were exclusive, while in rural streams, 18 species were recorded, ten of which were exclusive. Furthermore, both composition and beta diversity were significantly different between rural and urban streams, with the highest values recorded in rural streams. Conclusions This study provides evidence of how urbanization impacts the composition and beta diversity of fish in streams and highlights the importance of sustainable management such as effluent control, restoration of riparian vegetation, and the determination of protection areas.

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Ichthyofauna of the Brazilian semiarid region reservoirs: a scientometric analysis of publications from the last 50 years - (2025)

Ana Luisa Eufrasio Pinto, Juan Alves Pereira, Bianca de Freitas Terra

Volume: 37 - Issue: 0

Resumo. Abstract: Aim The construction of reservoirs in the Brazilian semiarid region is a predominant practice aimed mainly at water supply. Introducing fish in these ecosystems has generated environmental and social consequences. We analyzed articles on the ichthyofauna found in reservoirs from this region over the past 50 years. Methods This qualitative-quantitative scientometric analysis considered the scientific impact of the articles, the origin of the species studied, the main topics covered, and women´s participation in the authorship. The articles were collected from the leading research databases: Google Scholar, SciELO (Scientific Electronic Library Online), and Web of Science. Results We found 60 scientific papers on the subject. Most had low impact and visibility, and the state that contributed the most was Rio Grande do Norte (RN). The three most studied reservoirs made up almost half of the articles found (28). Research has only advanced considerably in the last decade, and the most discussed topics are related to the cultivation of commercial fish species, emphasizing pisciculture, reproductive biology, and fish nutrition. Conclusions Despite the significant number of women participating, their visibility in the scientific community remains limited, which affects the community as a whole. Besides, it is crucial to continue promoting research on fish taxonomy, phylogenetics, and functional ecology in the reservoirs of the Brazilian semiarid region.

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Importance of abiotic factors and hydroperiod for the zooplankton community from ponds with different hydrological dynamics - (2025)

José Gabriel Melo da Cruz, Fernanda Zucoloto Domingues, Luisa Rodrigues dos Santos, Rayanne Barros Setubal, Elder de Oliveira Sodré, Reinaldo Luiz Bozelli

Volume: 37 - Issue: 0

Resumo. Abstract: Aim The increasing impact on natural environments has led to changes in ecosystem characteristics. When not properly understood and managed, these changes can negatively affect the dynamics of aquatic environments, particularly small ones such as temporary ponds. Hydroperiod can influence the structure of aquatic ecosystems and the factors determining species occurrence in these water bodies. Within this context, studies assessing the influence of hydroperiod become highly relevant. This study evaluates how zooplankton species are distributed across five ponds with different hydroperiods in the Restinga de Jurubatiba National Park and the importance of water retention time for the taxonomic and functional diversity of this community. Methods We indirectly assessed water retention time through daily temperature measurements over three years and analyzed the main limnological parameters. The zooplankton community was sampled from the five studied ponds, and its diversity was evaluated using species richness (S), Shannon-Wiener diversity index (H’), functional richness (FRic), functional divergence (FDiv), and functional dispersion (FDis). Results We observed that even though the ponds are part of the same natural mosaic, they exhibit distinct characteristics. Abiotic factors such as water salinity and a more unstable hydroperiod negatively impacted zooplankton taxonomic and functional diversity, as shown by the integrated analysis of both diversity components. The highest taxonomic diversity values were found in ponds with intermediate water retention conditions (seasonal droughts). Conclusions Our results indicate that seasonal environments favor the co-occurrence of species from both perennial and ephemeral ponds, showing higher Shannon-Wiener diversity index (H’), functional richness (FRic), and functional divergence (FDiv) values when analyzed through an integrated approach. Furthermore, we observed that even under the same regional species pool, differences in desiccation frequency were sufficient to determine variations in the zooplankton community.

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Microcrustaceans structure determined by the type and trophic state of lakes - (2025)

Bharguan Pizzol Nogueira, Camila Moreira-Silva, Thaís Coimbra Marigo, Gilmar Perbiche-Neves

Volume: 37 - Issue: 0

Resumo. Abstract: Aim In this study, we investigated the response of microcrustaceans composition, diversity and abundance (Cladocera and Copepoda) to the lake’s origin (natural and man-made) and trophic state (mesotrophic and eutrophic, with natural eutrophication and artificial eutrophication). We tested the following hypotheses: (I) the increase in the abundance of certain microcrustacean species may indicate a rise in the trophic level; (II) the richness and abundance vary amongst lakes and are higher in the lake with natural eutrophication; and (III) the microcrustaceans abundance is associate with high primary productivity, being higher in the eutrophic environment with artificial eutrophication. Methods The study was conducted in a segment of the Paranapanema River basin, in southeastern Brazil, focusing on five lakes spanning an eight-kilometer stretch, to understand the different organisms' responses to distinct conditions of aquatic environments. Sampling was carried out bimonthly over the course of a year. Results A principal component analysis (PCA) separated three types of lakes: eutrophic (natural and man-made) to mesotrophic. Additionally, 25 taxa were found. SIMPER analysis filtered six species with more than 70% dissimilarity contribution. Five species exhibited differences amongst the lakes, one species correlated with natural variables as depth. The redundancy analysis associated the Bosminopsis deitersi abundance with man-made eutrophic lakes and with the variables electrical conductivity, phosphorus, nitrogen, chlorophyll-a, and hardness. High abundances of B. deitersi indicated artificial eutrophication especially in man-made lakes, while natural lakes with natural eutrophication were not favorable environments for the increase of B. deitersi abundance. Conclusions This study highlights the neotropical oxbow lakes, emphasizing the significance of physicochemical characterization, detailed temporal sampling, and lake classification by origin and trophic level.

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Morphological variation between two fish populations – phenotypic radiation in a rare case of geographical isolation - (2025)

Fernanda Biscaino Saluceste, Fábio Teruo Mise, Bruna Angelina Mayer, Franciele Fernanda Kerniske, Roberto Ferreira Artoni, Jean Ricardo Simões Vitule, Letícia Cucolo Karling, Igor de Paiva Affonso

Volume: 37 - Issue: 0

Resumo. Abstract Aim We examined the morphology of two populations of the Neotropical Characidae Psalidodon aff. fasciatus from two distinct environments with different selective pressures. One is the single fish population from an isolated lake, hence is deprived of interaction with any other fish species for countless generations. The other shares life-history with several fish. Methods We obtained 10 linear body measurements from 294 specimens from both populations, calculated and compared the ecomorphological indices for each population. Results We found significant distinct morphometry between populations, primarily attributed to the high level of isolation observed in individuals from the isolated population. This population exhibited greater morphological variation, likely due to reduced selection pressure and limited ecological interactions (e.g., absence of other fish species). Conversely, the non-isolated population displayed less morphological variation, possibly as a result of more intense intra- or interspecific interactions, such as competition and predation. Conclusions Considering that allopatry and major factors such as “isolation time” and “ecological interactions” are crucial drivers of evolution, this study highlights a rare case of natural isolation and provides insights for evolutionary investigations on isolated populations, allopatric speciation, and the role of ecological interactions in phenotypic intrapopulation variation.

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Predictive capacity of phytoplankton functional groups in a tropical wetland (Pantanal, Brazil) - (2025)

Renata Felicio-Santos, Simoni Maria Loverde-Oliveira, Wilkinson Lopes Lázaro, Patricia Fernanda dos Santos de Loureiro Nunes, Carolina Joana da Silva

Volume: 37 - Issue: 0

Resumo. Abstract: Aim Considering the prediction capacity of the phytoplankton community, this study analyzed the environmental factors that influenced the Reynolds Functional Groups (RFG) in hydrological period (dry, rising, flood and ebb) and the type of environment (river and lake), in the Pantanal wetland (Brazil). We expect environmental variability to reflect in the predictive ability of phytoplankton to describe habitat types and flood-pulse periods, where the seasonality (high and low water) are the main drivers of phytoplankton distribution, biomass and functional groups. Methods We collected environmental variables and phytoplankton quarterly in 2018 from 18 points in the flood, rising, dry and ebb. Results recorded 425 taxa distributed into 13 taxonomic groups and 20 RFGs, of which nine groups (D, F, J, G, K, MP, N, S1, and P), represented by green algae, cyanobacteria, and diatoms, had the highest predictive value, characterizing lentic environments as rich in nutrients and light, and the Paraguay River as having a lower availability of these resources for phytoplankton. The variation in biomass was related to the phases of the flood pulse, being higher in low waters in floodplain lakes and smaller in high waters in the river. Conclusions Thus, the predictability of the phytoplankton community structure was directly associated with the environment types in the Pantanal wetland and with the homogenization or isolation of the systems promoted by the flood pulse that acted as drivers of phytoplankton distribution, biomass and functional groups.

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Review of biomonitoring metals in rivers using bullfrog tadpoles: an applicability study of exposed animals to Sorocaba River - (2025)

Victor Holanda Arjonas, Isabela Ferreira Fernandes, Mayara de Almeida Ribeiro Carvalho, Luciana Camargo de Oliveira, Heidi Samantha Moraes Utsunomiya, Gabriel Hiroshi Fujiwara, Cleoni dos Santos Carvalho

Volume: 37 - Issue: 0

Resumo. Abstract: Aim This study reviewed recent literature on the use of the bullfrog species (Aquarana catesbeiana, Shaw, 1802) as an environmental bioindicator of pollution. Additionally, the total concentration of metals in the skin of bullfrog tadpoles exposed to the Sorocaba River was evaluated to explore the potential of this tissue as a biomonitoring tool and assess the bioavailability of metals in the river to aquatic organisms. Methods A bibliographic review was conducted using the Scopus and PubMed platforms with the search terms “Lithobates catesbeianus biomarkers,” “Aquarana catesbeiana biomarkers,” and “Rana catesbeiana biomarkers.” Tadpoles were exposed for 96 hours to water from two points along the Sorocaba River: Point Ibiúna (PI), representing the river's source, and Point Itupararanga Reservoir (PIR), a key water supply location for the Sorocaba-SP region. Deionized, contaminant-free water served as the control. Metal concentrations (Ba, Cu, Mn, Sr, and Zn) in skin samples (n=30) were analyzed after sample digestion using HNO3 and HCl, with determination via Microwave Plasma Atomic Emission Spectrometer (MP-AES). Results A review of the last 10 years of bibliographic production revealed 35 articles, where metals were the second most studied contaminant using this species (approximately 34% of articles), following agricultural pesticides (43%). Metal concentrations of Ba and Zn in the PI group varied compared to the control group. For the PIR group, Mn concentrations varied significantly relative to both the control and PI groups. No significant variation in Cu and Sr concentrations was observed across the groups. Conclusions Existing literature supports the use of various bullfrog tissues as bioindicators of environmental pollution. In this study, Ba concentrations increased by 12% and Mn by 54% in the PIR group compared to the PI group. No differences were observed for Cu, Sr, and Zn across groups. Metals such as As, Cd, Co, Mo, Ni, and Pb were below the quantification limit in all groups. The increased Mn concentration in PIR-exposed tadpoles suggests metal accumulation, pointing to a potential decline in water quality downstream from the river's source.

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Seasonal variation of the zooplankton communities’ diversity in ponds of the Atlantic Forest - (2025)

Maria Eduarda Turcato de Souza, Natan Guilherme Dos Santos, Laura Jardim Chiarelli, Maria Stela Maioli Castilho Noll

Volume: 37 - Issue: 0

Resumo. Abstract: Aim This study analyzed the structure and seasonal variation of the zooplankton community in five ponds in a preserved Atlantic Forest environment in Brazil, the Betary Reserve. Methods Sampling took place in March and September 2022, January and July 2023, covering the summer (rainy) and winter (dry) seasons. Vertical trawls were carried out with a 45μm plankton net and, at the same points, physical-chemical parameters of the water were measured with a multi-parameter probe. Results Fifty-nine taxa were recorded, distributed between Copepoda (1), Cladocera (5) and Rotifera (53). Among them, the families Lecanidae, Brachionidae and Trichocercidae were the most representative in number of species. Mesocyclops longisetus longisetus, Ceriodaphnia cornuta and Brachionus quadridentatus were present in all samples. The highest richness was observed in January/23. There was a difference in the composition of the assemblage between the seasons. Conductivity and temperature were structuring factors for some populations. Conclusions The study pointed to a high diversity of the zooplankton in ponds within the Atlantic Forest, demonstrating the importance of preserved sites for the conservation of the biodiversity of this threatening biome. Further studies are needed to understand the distribution pattern of zooplankton species, the seasonal variation and their relationship with the physical-chemical parameters of the water.

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Spatial and temporal factors determining the structure of ciliate protist communities in neotropical streams - (2025)

Carolina Leite Guimarães Durán, Felipe Rafael de Oliveira, Matheus Henrique de Oliveira de Matos, Leonardo Antunes Pessoa, Melissa Progênio, Loiani Oliveira Santana, Aline Aparecida Aguiar Ferreira, Luiz Felipe Machado Velho

Volume: 37 - Issue: 0

Resumo. Abstract: Aim In this study, we focused on patterns of ciliate protist community composition in urban and rural streams. Methods We analyzed 12 urban and rural streams during two different periods of the year (rainy and dry seasons) across three different stream mesohabitats (riffles, runs, and pools). We predicted that the species composition of ciliates would differ between types of environments (rural and urban), between basins (Pirapó and Ivaí), between mesohabitats (riffles, runs, and pools), and between seasonal periods. We also expected that ciliate species composition would be similar between streams within the same basin. Results Contrary to our expectations, our results showed that the richness and abundance of ciliates were higher in urban streams than in rural streams. In the analysis of beta diversity, we observed that this measure was higher in rural environments, but only during one period (dry season). Among the mesohabitats, no significant alterations in ciliate species composition were noted, contrary to our predictions. Conclusions The results obtained in this study demonstrated the effect of multiple spatial (basin, type of environment) and temporal (rainy and dry seasons) factors on the structure of ciliate protists in the water column of neotropical streams. No differences in ciliate attributes were found among the mesohabitats analyzed in this study.

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Tailwater fish of a Brazilian dam: abundance estimation and protection from turbine-induced mortality - (2025)

Ana Carolina Lacerda Rêgo, Kátia Gomes Facure, Alexandre Lima Godinho

Volume: 37 - Issue: 0

Resumo. Abstract: Aim To determine for Pimelodus maculatus, the fish most affected by the operation and maintenance (O&M) of the Amador Aguiar II Hydropower Dam, Araguari River, Brazil, (i) the most suitable fishing gear for its sampling, (ii) the seasonal variation in catches, (iii) the abiotic variables that most influence catches and (iv) the best period of the year to schedule O&M risky to the species. Methods We collected fish by hook-and-line, cast net, and gillnet in the first 300 m downstream of the dam every two months for three consecutive years. We analyzed the catches of P. maculatus and its temporal variation as a function of fishing gear type, year's season, dissolved oxygen, water temperature, water transparency, rainfall, turbine discharge, spillway discharge, and tailwater discharge. Results We captured 5,117 individuals of 32+ species. Pimelodus maculatus (52.6% of the total) was the most sampled species for all fishing gear types. Gillnet captured 70.2% of all P. maculatus, followed by hook-and-line (22.6%) and cast net (7.3%). The bycatch of gillnet (55.4%) was much higher than that of cast net (10.9%) and hook-and-line (7.6%). Temporal variation in the catch of P. maculatus by the three types of fishing gear showed synchrony. Between the two best fishing gear types for sampling P. maculatus, gillnet caught more individuals but caused more bycatch and fish death than hook-and-line. Season of the year and water temperature were the abiotic variables that most influenced temporal variation in the number of P. maculatus sampled. We sampled more individuals during the wet season when the water temperature was higher. Conclusions For any O&M activity that poses a risk of fish death, particularly turbine dewatering, we recommend scheduling it for the dry season when the catch of P. maculatus near the dam is lower. Additionally, we advise sampling fish in the tailwater before the O&M using gillnet or hook-and-line, with the latter preferred due to its lower bycatch and fish mortality.

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Extemporaneous environmental legislation: an analysis of the conflicts underlying Law 3824/1960 on coarse wood removal in Brazilian artificial reservoirs - (2025)

Lívia Helena Tonella, Oscar Barroso Vitorino Junior, Dilermando Pereira Lima Junior, Luiz Carlos Gomes, Fernando Mayer Pelicice, Angelo Antonio Agostinho

Volume: 32 - Issue: 0

Resumo. Abstract This article discusses the purpose and effects of Law 3824/1960, which makes mandatory the removal of vegetation and consequent cleaning of land sites subject to flooding by the construction of artificial reservoirs. The importance of this reflection is to avoid having a law that is considered effective, though if questioned, may prove contrary to the objectives for which it was created. Thus, this article aims to awaken decision makers to the possibility that this law is considered inapplicable to the current reality, according to the social, scientific, legal and environmental advances achieved in recent years. As a specific objective, based on the findings obtained, we aim to stimulate authorities to act in favor of the elaboration of a law that will meet these advances.

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Seasonal variation on diet of juvenile Elops saurus Linnaeus, 1766 (Ladyfish) in the Parnaiba River Delta - (2025)

Tatiane Araujo Santos, Thamires Souza Gonçalves, Patricia Silva do Nascimento, Cézar Augusto Freire Fernandes, Francisca Edna de Andrade Cunha

Volume: 32 - Issue: 0

Resumo. Abstract: Aim Identify seasonal variations in the diet of juvenile living in the estuary of the Parnaíba River Delta. Methods Food items were identified through analysis of stomach contents, and later submitted to analysis by regular methods for Frequency of Occurrence (FO), Frequency Numerical (FN), Gravimetric Frequency (FW) and Relative Importance Index (IRI). Results Juvenile diet of Elops saurus that inhabit the lagoons in the Parnaíba delta was composed in order decreasing of importance by Osteichthyes (Teleostei), Insecta and Crustacea in addition to Polychaeta and Nematoda. It was also observed a high frequency of occurrence of fragments of plastics in the diet. In the rainy season, 17 items were recorded in the diet, whereas in the dry season only 7 items were present. Relative Importance Index showed high presence of the Teleostei fish (69.93%) on diet of E. saurus during the rainy season, whereas during the dry period the insects of the families Corixidae (43.25%) and Dysticidae (39.16%). Conclusions With the study it was possible to identify that juvenile are piscivorous in the rainy season when there is a higher availability of prey in the environment and insectivores in the dry season when it reduces the supply of food, indicating feeding flexibility to environmental alterations.

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Biomass and abiotic variables change in phytotelmic environment in the tank-bromeliad Nidularium longiflorum Ule in tropical forest - (2025)

Karina Margaret Silva das Neves, Armando Reis Tavares, llka Schincariol Vercellino, Carla Ferragut

Volume: 31 - Issue: 0

Resumo. Abstract Aim Phytotelm plays an important role in plant growth and ecosystem functioning, but this natural aquatic microcosm is poorly known. We evaluated the seasonal (dry and rainy seasons) and spatial variations (forest trail and stream sites) of the phytotelm in Nidularium longiflorum, bromeliad that occurs in the Atlantic Forest. Methods Abiotic and biotic variables were measured in tank-bromeliad phytotelms. The biomass was analyzed by ash-free dry mass and chlorophyll-a concentration. Results Abiotic variables measured in the phytotelmic environment of bromeliads varied between sampling sites and seasons. Temperature, electrical conductivity and total nitrogen values were significantly different between seasons and sites. Chlorophyll-a and ash-free dry mass (organic matter) in phytotelm were significantly different between sampling sites. Eleven genera of algae in the phytotelm were identified. PCA axis 1 ordination evidenced the seasonal variation of environmental conditions. Conclusions Our findings suggest that environmental and micro-environmental conditions do not favor the development of algal community in the phytotelm. Biomass and abiotic variables in phytotelm of Nidularium longiflorum change seasonally, however biomass accumulation was strongly influenced by site characteristics.

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Habitat, limnological signatures and spatial modeling: a zoning proposal for the Curuá-Una hydroelectric reservoir, Pará, Brazil - (2025)

Juciley de Almeida Santos, Keid Nolan Silva Sousa, Paulo Roberto Brasil Santos, Joelson Leal de Lima, Rivolo de Jesus Bacelar

Volume: 31 - Issue: 0

Resumo. Abstract Aim The objective of this work is to characterize, spatially model and to perform the zoning of the aquatic environment in the Curuá-Una HPP reservoir, in the state of Pará, in the Brazilian Amazon. Methods The data were collected from 77 sampling points distributed over 20 transects in the Curuá-Una reservoir, in November 2016. The data were obtained through descriptive templates of the landscape, and assessment of limnological, bathymetry and georeferencing variables. To describe and model spatial patterns for the limnological Proxies, geostatistical analysis was used with semivariogram fitting, and interpolation using Ordinary Kriging to generate the maps. To determine the degree of association of the landscape Proxies, Correspondence Analysis (CA) was chosen, and to relate the landscape Proxies with the limnological Proxies, Canonical Correspondence Analysis (CCA) was carried out. Results The results of the analysis of the limnological Proxies showed that the variables presented normal distribution according to the Shapiro-Wilk test (5%) except for transparency and temperature. Most of the variables obtained well-defined, level and good geostatistical analysis. There was a prevalence of gaussian and spherical adjustment models. Different zones in the distribution of the limnological variables in the longitudinal axis of the reservoir were observed. The CA showed a short local gradient in the variables, which effectively characterizes the interface of landscape and human. In Figure 5, the first two axes of the CCA showed 61.17% of the data variability. The limnological signatures showed 42.3% of variability, with high correlation between the landscape Proxies and the environmental Proxies in both axes. Conclusions This type of approach should be useful in managing Brazilian river basins, especially in the Amazon, a focus for the construction of numerous hydroelectric dams, as it can indicate the limnological and environmental state and provide a clearer view of these environments.

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Spatial and temporal trends in freshwater fish research: the case of three neotropical river basins from Goiás State, Central Brazil - (2025)

Rodrigo Assis Carvalho, Francisco Leonardo Tejerina-Garro

Volume: 31 - Issue: 0

Resumo. Abstract Aim In this paper, we conducted a scientometric analysis on published studies related to freshwater fish species at Goiás State to evaluate: i) their spatial and temporal trends; ii) areas of knowledge; iii) scientific journals where these papers were published and their comprehensiveness; iv) the role of institutions and financial support on fish research. Methods Using Google Scholar and Lattes platform, we searched for scientific papers related to freshwater fish, and we extracted the following information of each paper: title, author and co-authors’ name, number of authors, year, authors and co-authors’ affiliation, journal, field/area of the research, and financial support. Results We found 322 scientific papers related to Goiás State with a slightly growth in the number of publications over time. Most of these papers are related to Ecology, Systematic/Taxonomy and Fish Biology, and the participation of local institutions in these studies was mainly concentrated in Paraná River basin. Although most of funding were granted by agencies or institutions located outside Goiás State, the results showed that fish papers achieved a broad audience with publications in national and international journals with impact factor. Conclusions Our study revealed that: 1) freshwater fish research at Goiás State has a slow increase trend; 2) there are gaps in Education, Conservation and Fisheries knowledge areas; 3) local institutions’ contribution is spatially concentrated; 4) studies achieved a broad audience with many scientific papers published in journals with impact factor; 5) financial support was granted in most part by agencies or institutions located outside Goiás State. These findings suggest that despite achievements in freshwater fish research in this region, local investments in infrastructure, materials and human resources are still necessary to improve the production of studies.

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The role of sediments in the carbon and pollutant cycles in aquatic ecosystems - (2025)

Simone Jaqueline Cardoso, Gabrielle Rabelo Quadra, Nathália da Silva Resende, Fábio Roland

Volume: 31 - Issue: 0

Resumo. Abstract Aim Anthropogenic modifications in the landscape are accelerating biogeochemical cycles and causing unbalances in terrestrial and aquatic ecosystems with still unknow impacts on biotic and abiotic processes. Therefore, there has been increasing scientific interest in the links between human activities and ecosystems functions. Methods Here we review the role of aquatic sediments in the carbon and pollutant cycle. Results We briefly explore the historical context, origin, and composition of the sediments, as well as the factors that influence the processes of carbon and contaminants cycling and the role of sediments in the greenhouse gases emissions in aquatic ecosystems. Conclusions Aquatic sediments can help to understand the terrestrial and aquatic ecosystem changes, once they are good sentinels, reflecting key biogeochemical processes over time.

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Adult emergence of Phyllocycla Calvert, 1948 (Odonata: Gomphidae) in artificial environments - (2024)

Carolina Gomes Viana, Lucas Pereira-Moura, Daniel Silas Veras

Volume: 36 - Issue: 0

Resumo. Abstract Aim This study aimed to analyze aspects of adult emergence of Phyllocycla Calvert, 1948 (Odonata: Gomphidae) in artificial environments. Samplings were conducted in Sanharó stream, Caxias municipality, Maranhão State, Brazil. Methods Specimens were examined under a stereomicroscope and identified to the lowest possible taxonomic level. Polystyrene boxes were used as rearing sites, and the following methods were analyzed: a) sand; b) strips of filter paper simulating substrate; c) without substrate. For emergence, the rearing sites had their lids removed and were placed inside larger jars with mesh windows, less water, with most of the substrate exposed above the water level. To verify the difference between treatments, the Log-rank test and Kaplan-Meier survival curves were used. Results The curves indicated that emergences occurred more frequently in the initial days of rearing. There was an absence of statistical difference between groups. Despite that, all treatments showed success in emergence, with larvae without substrate emerging more quickly. Conclusions By exploring the use of different substrates in Odonata rearing, this research provides guidelines for optimizing laboratory conditions, helping to overcome experimental challenges and supporting new studies and inventories.

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