Acta Limnologica Brasiliensia

(681 Artigos indexados)

Nutritional value changes in response to temperature, microalgae mono and mixed cultures - (2026)

Frederico Pacheco Militão, Valéria de Oliveira Fernandes, Kathiani Victor Bastos, Aline Paternostro Martins, Pio Colepicolo, Levi Pompermayer Machado

Volume: 31 - Issue: 0

Resumo. Abstract Aim The response of mixed cultures and monocultures of Pseudopediastrum boryanum (Turpin) E. Hegewald and Scenedesmus obliquus (Turpin) Kützing was assessed in the laboratory at three different temperatures: 20, 30 and 40 °C. The change in biomass and biochemical composition of these cultures was evaluated. Methods Microalgae were placed in a batch culture over 21-days in ASM1 medium. Cell density was directly counted every two days using a Fuchs-Rosenthal hemocytometer. Chlorophyll ‘a’ and total carotenoids were extracted twice. Protein, carbohydrate, total lipid and fatty acid contents were determined at the end of the experiment. Results Cultures grown in 40 °C exhibited no growth. However, there was increased cell density (13.6 x 106 cell.mL-1) and biomass (55 g.L-1) in the S. obliquus monoculture at 30 °C. High protein concentrations (672.6 mg.g-1) were observed in monocultures P. boryanum and S. obliquus at 20 °C treatments. There were high carbohydrate concentrations (6.17 mg.g-1) in P. boryanum unialgal at 30 °C. There was no significant difference in total lipid content between S. obliquus (95.5 mg.g-1), P. boryanum (96.3 mg.g-1) and the mixed culture at 20 °C (105.3 mg.g-1). FAMEs varied significantly regarding the number of unsaturated components, which predominantly consisted of fatty acids with two or more unsaturated bonds. Conclusions The biomass of the treatments analyzed was rich in proteins and essential fatty acids (such as linolenic acid), yet low in carbohydrate content, suggesting its potential use as a food supplement. Our results indicate that mixed culture of P. boryanum and S. obliquus was inefficient in cultivating biomass or biochemical compounds as compared to the unialgal cultivations. However, algae grown together showed better stability in their biochemical composition in response to changes in temperature, an important factor for microalgae production in open ponds and in food safety measures. These results suggest the consortia among different species of microalgae should be tested to determine better methodologies for the production of biomass and metabolites with greater stability towards environmental factors.

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Post-fire consequences for leaf breakdown in a tropical stream - (2026)

Renan de Souza Rezende, Cristiano Queiroz de Albuquerque, Andrezza Sayuri Victoriano Hirota, Paulo Fernandes Roges Souza Silva, Ricardo Keichi Umetsu, Helena Soares Ramos Cabette, Paulino Bambi, Natália Guedes, Cássia Alves Lima-Rezende, José Francisco Gonçalves-Júnior

Volume: 31 - Issue: 0

Resumo. Abstract Aim Wildfire is a natural pulsed disturbance in landscapes of the Savannah Biome. This study evaluates short-term post-fire effects on leaf litter breakdown, the invertebrate community and fungal biomass of litter from three different vegetal species in a tropical stream. Methods Senescent leaves of Inga laurina, Protium spruceanum and Rircheria grandis (2 ± 0.1 g dry mass) were individually placed in litter bags (30 × 30 cm: 10 mm coarse mesh and 0.5 mm fine mesh) and submerged in the study stream before and after fire. Replicate bags (n = 4; individually for each species, sampling time, fire event and mesh size) were then retrieved after 20 and 40 days and washed to separate the invertebrates before fire event and again immediately after fire. Disks were cut from leaves to determine ash-free dry mass, while the remaining material was oven-dried to determine dry mass. Results The pre-fire mean decomposition coefficient (k = -0.012 day-1) was intermediate compared to that reported for other savannah streams, but post-fire it was lower (k = -0.007 day-1), due to decreased allochthonous litter input and increased autochthones production. Intermediate k values for all qualities of litter post-fire may indicate that fire is equalizing litter quality in the stream ecosystem. The abundance of scrapers was found to be more important than fungal biomass or shredder abundance, probably due to their functioning in leaf fragmentation while consuming periphyton growing on leaf litter. Conclusions Theses results indicate that fire can modify the relationships within decomposer communities in tropical stream ecosystems.

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Spatial and temporal trends in freshwater fish research: the case of three neotropical river basins from Goiás State, Central Brazil - (2026)

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 Ecology and Conservation of Wild Rice, Zizania palustris L., in North America - (2026)

David Dean Biesboer

Volume: 31 - Issue: 0

Resumo. Abstract Wild rice is an enigmatic plant species in the upper northern Midwestern U.S. Wild rice (Zizania palustris L.) is widespread in the region. However, it is both a wild species and a semi-domesticated crop. It is enigmatic because it is grown and harvested by machine in large paddies by commercial farmers but wild populations are considered to be important spiritually to native Americans in the United States. Native Americans and the public harvest wild rice by hand and sell and trade it on a local basis. This has caused a political controversy between people who consider wild rice to be a crop belonging only to native Indian bands and those who consider that it belongs to citizens of the U.S. Conservation of populations of wild rice has become politically difficult because of these contrasting views. This paper discusses this controversy and addresses the difficulty of conserving this economically widespread plant that is under ecological pressure in modern times.

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The role of sediments in the carbon and pollutant cycles in aquatic ecosystems - (2026)

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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The structuring role of macrophytes on plankton community composition and bacterial metabolism in a large subtropical shallow lake - (2026)

Ng Haig They, David da Motta Marques

Volume: 31 - Issue: 0

Resumo. Abstract Aim We aimed at investigating changes in major groups of plankton (bacterioplankton, phytoplankton and zooplankton) and bacterioplankton metabolism along a transect covering a littoral, macrophyte dominated zone to a pelagic, phytoplankton dominated zone in the large subtropical shallow lake Mangueira, Rio Grande do Sul State, Brazil. Methods The 3.2 km littoral-pelagic transect (7 points) was sampled in October 2007 in the southern section of the lake. Major taxonomic groups of phytoplankton and zooplankton were counted and identified by optic microscopy. The bacterioplankton was identified by FISH (Fluorescent in situ Hybridization), and bacterial abundance, biovolume and biomass were quantified by epifluorescence microscopy. Primary and bacterial productions were measured by incorporation of radioactive bicarbonate and leucine, respectively. Bacterial respiration was measured by experiments of oxygen consumption, and an extensive data set of limnological variables were measured through standard methods. Results Sharp changes in chemical/physical variables, as well as in bacterial density, biovolume, biomass and bacterial growth efficiency occurred on average at 30% of macrophyte coverage, with most of them increasing towards pelagic zones. The composition of major groups of zooplankton, phytoplankton, bacterial morphotypes and phylotypes indicated that different planktonic assemblies live apart in these two zones. Conclusions Our results demonstrate that macrophytes are a structuring driver of the plankton community and bacterial metabolism in this large subtropical shallow lake.

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Tunnel vision in current chemicals management cannot deal with the unknown risk of synthetic chemicals in aquatic systems - (2026)

Anna Sobek, Emma Undeman

Volume: 31 - Issue: 0

Resumo. Abstract Chemicals management is focused around the hazard, exposure and risk assessment of single chemicals. This is a slow process which cannot keep pace with chemical innovation and development of use. Environmental monitoring focuses on few, and well-known, chemicals. As a consequence, the majority of all chemicals emitted to the aquatic environment remain unstudied, and so does their risk. We conclude that to understand how chemical pollution affects aquatic ecosystems, requires reformation of current chemicals management, moving away from the single chemical approach. It requires increased transparency regarding chemical content in materials, products and articles, and importantly, a management system that covers different aspects of the many unknowns related to chemical pollution of aquatic systems. This implies for instance, environmental monitoring that screens for a wide range of chemicals and effects, and that is able to detect more unexpected effects of chemical pollution than what is possible today.

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Wastewater infrastructure and the ecology and management of freshwater systems - (2026)

Krista Arminty Capps

Volume: 31 - Issue: 0

Resumo. Abstract Globally, freshwater resources are influenced by inputs of energy, nutrients, and pollutants from human wastewater. Local resource managers and policy-makers are tasked to address ecological and human-health concerns associated with aging and obsolete water infrastructure using limited financial resources. Nevertheless, there is limited information available describing how waste streams vary in their pollutant load or their subsequent effects on ecosystem structure and function in streams and rivers. Consequently, as wastewater systems degrade, local resource managers and policy makers are forced to develop watershed management strategies to deal with increasing effluent discharge without an understanding of how their decisions will influence local ecological processes or the structural and functional integrity of downstream habitats. Here, I discuss some of the ecological implications of obsolete or absent wastewater treatment, and describe how mismatches between the governance of wastewater management and watershed ecology may exacerbate environmental problems.

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A decade of invasion: distribution patterns and temperature influence on Kellicottia bostoniensis (Rousselet, 1908), in the Upper Uruguay River Basin - (2025)

Michelle das Neves Lopes, Lorena Pinheiro-Silva, Lucas Garbo Miguel, Claudia Costa Bonecker, Grasiela Fagundes Cardoso, Alex Pires de Oliveira Nuñer, Nei Kavaguichi Leite, Maurício Mello Petrucio

Volume: 37 - Issue: 0

Resumo. Abstract: Aim This study reports the spread dynamics of the non-native species Kellicottia bostoniensis across all reservoirs in the Upper Uruguay River Basin, a decade after its initial recorded occurrence. Additionally, it assesses the role of temperature in shaping its distribution within this subtropical system. Methods Spatial and temporal variations in K. bostoniensis density and environmental parameters were analyzed over a 12-month period. Generalized Linear Models (GLMs) were applied to evaluate the relationship between environmental parameters and species density, providing insights into the key drivers of its distribution. Results The connectivity among reservoirs within the cascade system of the Upper Uruguay River has facilitated the continued spread of the non-native species K. bostoniensis. The detection of this species in all reservoirs a decade after its first recorded occurrence suggests its successful establishment and widespread distribution within the system. The observed high densities were likely influenced by the consistently low temperatures characteristic of subtropical regions, particularly those associated with the Serra Geral Mountains, with a more pronounced effect during colder months. Conclusions The widespread distribution of K. bostoniensis across the Upper Uruguay River Basin underscores its potential for further expansion into similar environments, driven by a combination of environmental and anthropogenic influences. The species’ ability to disperse and establish in diverse habitats highlights the critical need for continuous monitoring and management strategies to mitigate its spread and prevent additional ecological invasions.

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A record of pughead deformity in Satanoperca jurupari (Heckel, 1840) (Teleostei: Cichlidae) in the Lower Rio Tocantins Basin - (2025)

Lais Lobato Jacob, Felipe Arian de Andrade Araújo, Renan Leão Reis, Júlia Gabrielle Carvalho Nascimento, Alberto Akama

Volume: 37 - Issue: 0

Resumo. Abstract: The pughead condition is a cranial deformity characterized by a shortened upper jaw relative to the lower jaw. In this study, we report the occurrence of this deformity in a single specimen of the Demon Eartheater, Satanoperca jurupari, collected in the Lower Rio Tocantins Basin. The most affected anatomical regions include the upper jaw, suspensorium, and anterior portion of the neurocranium. Although pollution from agrochemicals used in palm monoculture near the collection site is a plausible contributing factor, no direct evidence currently confirms this as the cause. This report represents the first documented case of the pughead condition in Satanoperca and the first record of this deformity in a species from rivers of the Brazilian Shield.

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A systematic review of the water quality in the Doce River Basin: following the Fundão dam collapse - (2025)

Bianca Loureiro do Valle, Lorena Torres Oporto, Diego Guimarães Pujoni, José Fernandes Bezerra-Neto

Volume: 37 - Issue: 0

Resumo. Abstract: Aim The Doce River Basin has a high ecological and socioeconomic relevance. This basin faces considerable challenges, especially after the Fundão dam collapse in 2015, which contaminated the river system with iron ore tailings, impacting the river's biota and the communities that depend on it. This study aimed to identify thematic patterns, knowledge gaps, and temporal trends in scientific production based on a systematic review and scientometric analysis of water quality studies. Methods This study searched for articles focusing on the basin using the Web of Science and Scopus databases, following the PRISMA criteria for systematic reviews. Articles published up to December 2024 were included, using terms related to water quality and the Doce River Basin and its main tributaries. In addition, temporal trend analysis and thematic categorization of the studies were conducted. Results A total of 88 studies were identified, 76 of which were published after the disaster, with an emphasis on metal and metalloid concentrations, followed by physicochemical indicators such as pH and conductivity. In contrast, nutrients, emerging contaminants, and bioindicators were significantly less addressed. There are critical gaps in the assessment of chronic impacts such as changes in land use and effluent discharge, which could potentially hinder the assessment of the effects of dam failure. In addition, most tributaries remain poorly studied. Conclusions Scientific production increased substantially after the disaster but remained concentrated on specific themes and regions. Expanding the geographic and thematic scope, as well as integrating biological indicators and chronic contaminants, is essential to support conservation policies and the integrated management of water resources in the basin.

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Aquatic macrophytes in Amazon: review, knowledge and gaps - (2025)

Antônio Augusto de Souza Costa, Nayara Louback Franco, Raimundo Luiz Morais de Sousa, Ana Luísa Biondi Fares, Flávia Alessandra Silva Nonato, Rayssa Silva Carmo, Marcelle Fernanda Oliveira Barbosa, Thaisa Sala Michelan

Volume: 37 - Issue: 0

Resumo. Abstract: Aim The Amazon region presents peculiarities in its hydrology and vegetation, which are essential for climate balance. For this reason, the Amazon requires better sampling of its biodiversity, thus increasing knowledge of the organisms present in this area. In this study, through a systematic review, we evaluated to assess the advances in ecological theories research and we verified the stages of macrophyte biodiversity research in the Amazon. Methods We used databases available on Web of Science and Scopus. The keywords used for the search were: amazon, macrophytes, and aquatic plant. The designated research period was between 1970 and 2022. The processed data were grouped into specific types according to the object of study. Results Our results showed that the majority of studies addressed the influence of aquatic macrophytes on aquatic organisms (e.g., fish, insects, plankton, and manatees), as well as their influence on the abiotic characteristics of aquatic environments in the Amazon forest. Studies mostly focused on the relationship between macrophytes and other organisms or environmental variables. Conclusions We identified research gaps in ecological and biological invasion studies with macrophytes in the Amazon and highlight the importance of international cooperation and scientific production for ecosystem conservation.

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Asymmetric dispersal in freshwater species distribution models varies depending on the spatial pattern of fish species - (2025)

Micael Rosa Parreira, João Carlos Nabout

Volume: 37 - Issue: 0

Resumo. Abstract: Aim We estimated the relative contribution of environmental and dispersal predictors in distribution models of freshwater species with different distribution ranges (29 fish species). Specifically, we tested whether model performances vary depending on the fish species' range and distribution across sub-basins and whether the relationship with those predictors is stronger depending on the type of variables (environmental or asymmetrical dispersal) used for modeling. Methods The study area used for modeling was the Tocantins-Araguaia River basin, encompassing the entire hydrographic network. We applied six niche modeling methods to project the geographic distributions of 29 fish species within the Tocantins-Araguaia River basin, using environmental and asymmetrical dispersal predictors. Results Generally, the models built using dispersal predictors generated more accurate predictions than those using environmental variables. However, although we found no significant difference in the accuracy among models built using different variables, their accuracy metrics were correlated with the species range and distribution across sub-basins. Also, more restricted species (i.e., lower range and distribution limited to one sub-basin) showed a greater difference in model accuracy between models built using dispersal and environmental predictors, with more accurate models being generated for restricted species when modelled using dispersal-related predictors only. Conclusions the use of asymmetric dispersal predictors in SDM, besides generating accurate models, avoids/reduces model overpredictions to geographically close and climatically suitable areas, especially for restricted species, by predicting the species’ distribution based on their dispersal routes through the actual directional gradient of the basin’s hydrographic network.

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Beta diversity of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) across stream microhabitats - (2025)

Jhenifer Simões dos Santos, Rogério Campos de Oliveira, Tácio Duarte, Cleto Kaveski Peres

Volume: 37 - Issue: 0

Resumo. Abstract: Aim We evaluated how the combination of environmental characteristics affects the beta diversity of the EPT (Ephemeroptera, Plecoptera and Trichoptera) community across stream microhabitats. Methods The samples were collected in 12 streams around the Itaipu Reservoir (Paraná, Brazil). We sampled four types of substrates in triplicate with the aid of a Surber sampler. The samples were classified into CSD (sand and clay) and STO (gravel, pebbles, and boulders). The composite substrate of leaf packs (leaves and twigs) was divided into RLP (rapid leaf packs) and BLP (backwater leaf packs). Results We recorded a significant change in EPT composition among the microhabitats evaluated and different genera associated with each substrate category. However, beta diversity did not significantly differ among microhabitats. Thus, we found the highest beta diversity value in the CSD (sand and clay) category and the greatest contribution of the turnover component. Conclusions The partitioning of beta diversity into its components helped understand ecological patterns at local scales, highlighting the importance of microhabitat diversity in stream systems for maintaining the structure and composition of aquatic fauna.

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Cladocerans (Crustacea, Branchiopoda) from Mount Roraima, Venezuela, with new records for this country and the Neotropical region - (2025)

Vinícius Vilela Carvalho, Francisco Diogo Rocha Sousa, Lourdes Maria Abdu Elmoor-Loureiro, Gilmar Perbiche-Neves

Volume: 37 - Issue: 0

Resumo. Abstract Aim Venezuela, located in the north of South America, has ecosystems with great potential for diversity. Among these ecosystems, Mount Roraima located at the border of Venezuela, Brazil, and Guyana, stands out. Mount Roraima is considered a conservation unit, and understanding its fauna is an important tool for species preservation. Its true biodiversity is underestimated, especially for microcrustaceans of the Superorder Cladocera. This study presents a preliminary inventory of the cladocerans of this mountain. Methods Samples were collected from two ponds located in the upper part of Mount Roraima using a conical plankton net. The specimens were then analyzed, photographed, and identified. The richness and relative abundance in each sample were calculated. Results Three species were recorded for the first time in Venezuela. There is a possibility that the Orinoco Basin endemic species Streblocerus superserricaudatus occurs in Brazil and Guyana, since the ponds are very close to the border of both countries. There is a co-occurrence of three Flavalona species in the territory of Roraima, a fact so far only known for Brazil. Adding the new records to the previously known lists, the cladoceran richness for Venezuela is now 105. Conclusions Samplings in peculiar and remote environments have the potential to reveal new species and records. Further samplings are suggested on Mount Roraima to mitigate potential sampling biases.

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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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Development and field application of a low-cost device for sampling greenhouse gas fluxes at the air-water interface in limnological studies - (2025)

Lúcia Helena Gomes Coelho, Tatiane do Nascimento Lopes, Tatiane Araujo de Jesus, Roseli Frederigi Benassi

Volume: 37 - Issue: 0

Resumo. Abstract Aim The objective of the present study was to develop and field-apply a simple device for sampling greenhouse gas flows (CO2 and CH4) at the air-water interface. Methods The device consisted of a cylindrical chamber made of high-density polyethylene with a valve to collect gases. The chamber sealing materials (silicone rubber and epoxy resin) and the system configuration (area/volume ratio A/V, and influence of ventilation) were evaluated. The device was applied in five field campaigns (n = 45). The samples were stored in gasometric containers until analysis by gas chromatography with flame ionization detection. Results The epoxy resin sealed the chambers better, while the non-vented device with a higher A/V ratio showed better mixing with fewer uncertainties in gas diffusion through boundary layer disturbance. The flow rates of the target gases varied greatly, from below the limit of quantification for CH4 (< 0.062 mg m-2 min-1) to 0.214 mg m-2 min-1, and from 0.3 to 42.3 mg m-2 min-1 for CO2. Conclusions These chambers minimize disturbances to the water body and the natural gas exchange processes obtaining more representative data on the natural emissions. Our floating chamber device proved robustness and versatility for determining gas flows at the air-water interface. However, its use must be evaluated in preliminary field work to define the sampling interval time, uncertainties and main analytical challenges to be overcome.

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Distribution of functional feeding groups of aquatic and semi-aquatic insects on macrophytes in an artificial lentic system in southern Brazil - (2025)

Thaiz Ramos, Silvia Rafaela Alves Pereira, Leandro Juen

Volume: 37 - Issue: 0

Resumo. Abstract: Aim To understand the distribution of functional feeding groups (FFGs) of aquatic and semiaquatic insects associated with macrophytes in a lentic system, we tested whether the abundance of FFGs varied across sampling periods and analyzed the variation of environmental variables related to FFG composition. Methods We evaluated the distribution of FFGs in four samplings conducted in March, May, July, and September of 2022, during different seasons of the year. The sampling locations were three sites in the Ponte Lake, located in the Porto Alegre Botanical Garden, southern Brazil. Relative abundances (%) were calculated for each family and for each FFG per sampling period. In this study, each seasonal sampling was considered a sample, and the three lake points were treated as subsamples. Data analysis was performed using Principal Component Analysis (PCA), Permutational Multivariate Analysis of Variance, and the Chi-square test (χ2). Results The two-axis PCA explained 90.47% of the variation. The variables that most contributed to the formation of the first axis were temperature, pH, and dissolved oxygen, with a positive relationship, while turbidity contributed most to the second axis, with a negative relationship. The χ2 test confirmed differences in FFG abundances among the sampling periods. We collected 4.872 specimens, representing 24 families distributed across five orders. Collector-gatherers were the most abundant in the study (N = 3.126), with higher abundance in autumn (N = 899), followed by predators (N = 1.385), more abundant in summer (N = 582), and collector-filterers (N = 359), also more abundant in summer (N = 158). Conclusions These findings contribute to a better understanding of how environmental factors drive the diversity of functional feeding groups in lentic systems and highlight the ecological role of macrophytes as complex mesohabitats that are essential for the structuring of aquatic insect communities.

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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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Empirical evaluations between beta-diversity, environmental heterogeneity, and spatial extent among multiple taxonomic groups - (2025)

Carlos Henrique Lopes Liborio

Volume: 37 - Issue: 0

Resumo. Abstract Aim Beta diversity is expected to increase due to environmental heterogeneity and spatial extent. However, it remains unknown whether the response of beta diversity to these variables is consistent among different taxonomic groups. I investigated whether the beta diversity of lacustrine phytoplankton, zooplankton, and macroinvertebrate communities within nine ecoregions in the United States of America correlates with environmental heterogeneity and spatial extent. Methods I used simple linear regression analyses to examine how the beta diversity of different communities was related to environmental heterogeneity and spatial extent. Results Phytoplankton and macroinvertebrate community's beta diversity was positively related to environmental heterogeneity, while zooplankton and macroinvertebrates' beta diversity was significantly related to the spatial extent (within ecoregions). Conclusions My results align with theoretical expectations that beta diversity increases due to environmental heterogeneity and spatial extent. These results contribute to a better understanding of processes structuring the composition of different aquatic communities in the United States.

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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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