Mission: Acta Limnologica Brasiliensia is a journal by the "Associação Brasileira de Limnologia" (Brazilian Association of Limnology - ABLimno) which publishes original articles, short notes, review articles and opinion articles aiming to contribute to the scientific development of Limnology. The Journal covers a broad spectrum, including any theme of the ecology of continental waters from ecosystems such as rivers, lakes, floodplain, swamps, reservoirs and estuarine zones.
Brazilian Association of Limnology - ABLimno
The authors: (a) agree to the exclusive publication of the article in this journal; (b) agree to automatically transfer copyrights and permissions to the journal publisher; (c) take the intellectual and legal responsibility for the results and the considerations presented.
Evaluating the growth potential of harmful cyanobacteria in aquatic environments under climate change scenarios
Neotropical freshwater environments face severe threats from climate change, which pose 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. Objectives: Our objective was to evaluate the vulnerability of specific regions to 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: In the ENMs results, the distributions for the current scenario were consistent with known distributions. 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.
Copyright (c) 2025 http://creativecommons.org/licenses/by-nc/4.0
Coordinated in situ lake sampling concurrent with satellite acquisition days provides a mechanism for addressing data scarcity: A case study from Lake Yojoa, Honduras
Abstract: Remote sensing is a powerful tool for expanding the temporal and spatial coverage of data collection in inland aquatic systems. 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 at Lake Yojoa, Honduras. Methods: Satellite remote sensing data obtained within a five-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= 0.62) agreement and reasonable uncertainty (MAE = 0.61 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.
Experimental approach on the contribution of wind and animal vectors in the dispersal and colonization of testate amoebae (Protista, Amoebozoa) in freshwater ecosystems
Aim: This study aimed to understand how testaceous amoebae spread in a new ecosystem, assessing their dispersal potential in freshwater. Methods: In this context, we conducted a field study over 33 days between July and August 2018. The study included four different approaches: (i) a control group exposed exclusively to wind, (ii) addition of propagules dispersed by Odonata (aquatic insects), (iii) addition of propagules dispersed of amphibians, and (iv) the combined addition of propagules of both animals. The objective was to evaluate the influence of these vectors on the dispersal of testate amoebae. Results: We detected a total of 13 species of testate amoebae. In terms of species richness, we observed a steady increase throughout the experimental period. In terms of abundance, a similar trend was observed, with significant values in the last sampling period and greater differences in the treatment of all vectors, 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: These results demonstrate the importance of animal vectors in the transport of testate amoebae cysts and contribute to the dispersal and structuring of these organisms.
Review of biomonitoring metals in rivers using bullfrog tadpoles: An applicability study of exposed animals to Sorocaba River
Aim: In this study, the recent bibliography on the use of the bullfrog species (Aquarana catesbeiana, Shaw, 1802) as an environmental bioindicator of pollution was verified, and the total concentration of metals in the skin of bullfrog tadpoles exposed to the waters of the Sorocaba River was evaluated in order to analyze the potential use of the tissue as a tool for environmental biomonitoring and to verify the disponibility of metals in the Sorocaba River to animals. Methods: The recent bibliography was evaluated through the Scopus and Pubmed platforms using the terms ¨Lithobates catesbeianus biomarkers¨ and ¨Rana catesbeiana biomarkers¨. Tadpoles were exposed for 96 hours to the waters of 2 points of the Sorocaba River, with the point Ibiúna (PI) representing the source of the river Sorocaba and the point Ituparanga Reservoir (PIR) representing an important point of water supply to region of the city of Sorocaba-SP and using contaminant-free deionized water as a control. The evaluation of the concentration of metals Ba, Cu, Mn, Sr and Zn in skin samples (n=30) was carried out after digestion of the samples in a closed system using HNO3 and HCl and determination in Microwave Plasma Atomic Emission Spectrometer (MP-AES). Results: The review of bibliographical production over the last 10 years resulted in 35 articles on the topic, where metals were the second most studied contaminant using this species (around 34% of articles), behind only agricultural pesticides (around 43% of articles ). The concentration of Ba and Zn metals in the group PI varied in relation to the control group, and the concentration of Mn in the PIR group varied in relation to the control group and in relation to the group exposed to the waters from group PI. For the metals Cu and Sr there was no significant variation between the groups. Conclusions: The existing literature demonstrates the ability to use various tissues from bullfrog tadpoles as environmental bioindicators. An increase in Ba (12%) and Mn (54%) was identified in the PIR group in relation to the PI group in the tadpoles' skin. For the metals Cu, Sr and Zn there was no difference between the groups. As, Cd, Co, Mo, Ni and Pb had results below the limit of quantification in the groups studied. The increased concentration of Mn in the skin of bullfrog tadpoles exposed to the waters of the PIR in relation to the group PI may indicate the accumulation of this metal, pointing to a worsening of water quality in relation to the initial point of the river's course.
Obituary: Claudio Gilberto Froehlich (1927-2023): A mentor for multiple generations of researchers on biodiversity
Prof. Claudio Gilberto Froehlich, an inspiring zoologist and limnologist of the University of São Paulo (USP, Brazil), died on November 27, 2023. He began his career in 1950 and since then has continuously contributed to a better understanding of Neotropical biodiversity. Here, we present his academic life and his contributions to science and training of new researchers.
Aquatic macrophytes in Amazon: review, knowledge and gaps
Objetivo: A região amazônica apresenta peculiaridades em sua hidrologia e vegetação, essenciais para o equilíbrio climático. Por esta razão, a Amazônia necessita de uma melhor amostragem de sua biodiversidade, aumentando assim o conhecimento dos organismos presentes nesta área. Neste estudo gostaríamos de avaliar os avanços nas pesquisas de teorias ecológicas e verificar as etapas da pesquisa da biodiversidade de macrófitas na Amazônia. Métodos: Foram utilizadas bases de dados disponíveis na Web of Science e Scopus. As palavras-chave utilizadas para a busca foram: amazônia, macrófitas e planta aquática. O período de pesquisa designado foi entre 1970 e 2022. Os dados processados ​​foram agrupados em tipos específicos de acordo com o objeto de estudo. Resultados: Nossos resultados mostraram que a maioria dos estudos abordou a influência das macrófitas aquáticas nos organismos aquáticos, bem como sua influência nas características abióticas dos ambientes aquáticos da floresta amazônica. Os estudos focaram principalmente na relação entre macrófitas e outros organismos e variáveis ​​ambientais. Conclusões: Nesta revisão, identificamos lacunas e perspectivas para estudos que avancem nas ciências aquáticas na Amazônia, especialmente no que se refere a estudos ecológicos e invasão biológica. Aumentar a cooperação internacional e a produção científica são cruciais para preencher lacunas fundamentais de conhecimento para a preservação dos ecossistemas.
Spatial and Temporal Factors Determining the Structure of Ciliate Protist Communities in Neotropical Streams
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.
Effects of urban pollution on zooplankton diversity along the Almada River (Bahia, Brazil)
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 municipalities along the Almada River: Almadina, Coaraci and Itajuípe, in the years 2020 to 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 areas was high, indicating a low rate of species sharing between the CW and DA areas. 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.
Thematic Section: “Simpósio de Zooplâncton Neotropical"
Microcrustaceans structure determined by the type and trophic state of lakes
Aim: In this study, we investigated the response of microcrustaceans 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). Methods: We tested the following hypotheses: (I) the richness and abundance vary amongst lakes and are higher in the lake with natural eutrophication; (II) the microcrustaceans abundance is associate with high primary productivity, being higher in the eutrophic environment with artificial eutrophication; and (III) the increase in some species’ abundance can indicate increase of the trophic level. 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 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 sheds light on neotropical meander lakes, emphasizing the significance of physicochemical characterization, detailed temporal sampling, and lake classification by origin and trophic level.
Importance of abiotic factors and hydroperiod for the zooplankton community from ponds with different hydrological dynamics
The increase in impacts on natural environments has led to changes in the characteristics of ecosystems. Such changes, when not understood and controlled, can negatively impact the dynamics of aquatic environments, especially the small ones such as temporary ponds. Hydroperiod can change the structure of aquatic ecosystems and the factors that determine the species occurrence in these water bodies. Within this context, studies that assess the influence of the hydroperiod become extremely relevant. In this study we evaluated how zooplankton species are distributed along five ponds with different hydroperiods located in the Restinga de Jurubatiba National Park and the importance of the water retention time for the taxonomic and functional diversity of this community. Methods: We evaluated the water retention time indirectly by daily temperature measurements over three years and the main limnological parameters. The zooplankton community was sampled from the five studied ponds. Its diversity was evaluated through richness (S), Shannon diversity index (H’), functional richness (FRic), functional divergence (FDiv) and functional dispersion (FDis). Major results: We observed that the ponds, even being inserted within the same natural mosaic, can present different characteristics. Abiotic factors such as water salinity and more unstable hydroperiod negatively impacted zooplanktonic diversity. The highest values of taxonomic diversity were found in ponds with intermediary conditions of water retention (seasonal droughts). Conclusion: According to our results, seasonal environments favor the co-occurrence of species from both perennial and ephemeral ponds and presented higher diversity. Furthermore, we observed that even under the same regional species pool, differences in desiccation frequency were sufficient to determine differences in the zooplankton community.
Epistylid ciliates as epibionts on calanoid copepods in an Amazonian floodplain lake (Batata Lake)
This is the first record of peritrichous epibiont ciliates Epistylis sp. colonizing calanoid copepods in Amazonian ecosystems (Lake Batata, Pará, Brazil). The main objective was to investigate changes in the prevalence and infestation intensity of the epibiotic relationship in relation to the impact of bauxite tailings (natural and impacted areas) during two distinct periods of the hydrological pulse (rising and high-water). The hydrological pulse of this system can be characterized with four distinct phases: rising, high-water, falling, and low-water. After degradation by bauxite tailings for ten years (1979-1989), and despite an ongoing long-term ecological restoration process, it is still possible to recognize two distinct regions in the lake: the area impacted by the tailings and the natural area. We sampled zooplankton (calanoids and epibiont ciliates) and limnological variables during the high-water period (March 2015) and rising-water period (June 2019) at twelve sampling points in Lake Batata, six in the impacted area and six in the non-impacted area. We recorded epibiont ciliates in the calanoid copepodite and adult stages, as well as the main location sites on the thorax and abdomen. Our study recorded a significant difference in the prevalence and mean infestation intensity between the natural and bauxite tailings-impacted areas, and in the prevalence of infestation between the rising -water (2015) and high-water (2019) collections. The prevalence of infestation was higher in the impacted area and during the rising-water period. Although the host/epibiont/environment interaction is complex and requires analysis with a larger number of temporal samples, this study records a clear effect of flooding in this Amazonian system on the spatial and temporal dynamics of epibiont ciliates associated with calanoid copepods.
Hatching of Cladocera (Crustacea: Branchiopoda) rest eggs from permanently hydrated and temporarily dehydrated sediments of an Amazon lake
Abstract: Aim: i) to characterize the composition of the Cladocera species hatched from the rest eggs of permanently hydrated and temporarily dehydrated sediments; and ii) to test whether periodic dehydration affects the hatching of the rest eggs. Methods: Cladocera rest eggs were collected from the sediment of Tupé lake, Amazonas, Brazil. Sampling was performed in the dry season, when the sediment is found in two conditions: Permanently Hydrated Sediment (PHS) and Temporarily Dehydrated Sediment (TDS). With this was carried out an experiment of hatching, with temperature of 24 °C (± 2 °C) and photoperiod of 12h light: 12h dark, for 20 days. Results: Of the two types of sediments, eight Cladocera taxa were counted. In PHS five taxa (one exclusive) were identified and in TDS seven taxa (three exclusive) occurred. When compared the proportion of hatching of Cladocera eggs between sediment types there was a higher proportion in TDS (0.36 ± 0.48 %) than in PHS (0.32 ± 0.49 %), but no statistically significant difference between them (GLM: χ21= 0.012; P > 0.05; Pseudo-R2M= 0.0006). Conclusions: This study was a pioneer with Cladocera rest eggs in the Western Amazon. In this was found eight taxa from the hatching of rest eggs found in PHS and TDS. The hypothesis that periodic dehydration of Cladocera rest eggs reduces egg hatching has been refuted. Still, the inverse of what was predicted occurred, since TDS had the highest proportion of hatching.
Environmental heterogeneity in wetlands increases alpha and beta diversity of cladocerans (Crustacea, Branchiopoda) at local and regional scale
Aim: The goal of this study was to investigate the effect of the different levels of habitat heterogeneity on diversity on a local and regional scale. We tested two hypotheses: (i) the habitat diversity, given by quantity of microhabitat, 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 specimens of microphytes 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 is correlated the number of microhabitats and the variability between microhabitats in wetlands.
Seasonal variation of the diversity of zooplankton communities in ponds of the Atlantic Forest
This study analyzed the structure and seasonal variation of the zooplankton community in five ponds in a preserved Atlantic forest environment, the Betary Reserva (24º35'16"S; 48º37'44"W). Sampling took place in March and September 2022and January and July 2023, covering the summer and winter seasons. Vertical trawls were carried out with a 45μm plankton net and, at the same points, physical and chemical parameters of the water were measured with a multi-parameter probe. 59 taxa were recorded, distributed inCopepoda (1), Cladocera (5) and Rotifera (53). Among them, the families Lecanidae, Brachionidae and Trichocercidae were the most representative in terms of number of species. Some of them were present in all samples (Mesocyclops longisetus, Ceriodaphnia cornuta, Brachionus quadridentatus, many species of the genus Lecane and others), but there were also less abundant and rare species that were exclusive to one season. The highest richness was observed in January/23, while the other summer month showed the lowest value. There was a difference in the composition of the assemblage (F= 2.00; p= 0.045), which showed variation in the occurrence and relative abundance of species between seasons. Conductivity and temperature were structuring factors for some populations in the periods studied. The results show the richness found in the pools and demonstrate the importance of protected areas in maintaining the biodiversity of this biome, which is under threat. Further studies are needed to understand the distribution pattern of zooplankton species, the seasonal variation of their communities and their relationship with the physico-chemical parameters of the water.
Beta diversity of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) across stream microhabitats
Aim: The aim of this study was to evaluate how the combination of environmental characteristics affects the beta diversity of the EPT (Ephemeroptera, Plecoptera and Trichoptera) community at the habitat level and how the ecological uniqueness of the habitat is reflected in the local contribution to beta diversity (LCBD). Methods: The samples were collected in 12 streams, all sampled microbasins belong to the Hydrographic Basin of Paraná 3. Four types of substrates were sampled in a 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 in RLP (rapid leaf packs) and BLP (backwater leaf packs). Results: Thus, we found the highest beta diversity value in the CSD (sand and clay) category and the greatest contribution of the turnover component. We recorded a significant effect on the change in composition among the microhabitats evaluated and the association of genera with each category. However, beta diversity did not significantly differ among microhabitats. The LCBD was greater at more degradation points, regardless of the type of microhabitat sampled, and exhibited a significantly negative relationship with richness in the BLP (backwater leaf pack) microhabitat. Conclusions: The partitioning of beta diversity into its components, combined with the LCBD approach, helped in the understanding of ecological patterns at local scales, proving to be an effective tool in the assessment of biodiversity and making decisions related to the definition of priority areas for conservation.
Predictive capacity of phytoplankton functional groups in a tropical wetland (Pantanal, Brazil)
Aim: Considering the prediction capacity of the phytoplankton community, this study analyzed the environmental factors that influenced the distribution patterns of species and 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, biovolume 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 biovolume 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, biovolumes and functional groups.
Patricia Fernanda dos Santos de Loureiro Nunes
Experimental studies on freshwater zooplankton in Brazil: A scientometric analysis from 1978 to 2023
This study aims to contribute to elucidating the importance of experimental research on freshwater zooplankton communities in Brazil through a scientometric analysis. The Web of Science, Scielo, and Scopus databases were used to compile 249 scientific papers published between 1978 and 2023. Data extracted from the papers included the year of publication, geographical location, experiment characteristics (type, scale, duration), species or taxa studied, and research topics. Quantitative and qualitative syntheses were performed to provide a systematic understanding of experimental studies on freshwater zooplankton. The analysis revealed a significant increase in the number of experimental papers over time, with a higher concentration of studies in the southeastern region of Brazil. Laboratory experiments were more commonly conducted than field experiments, mainly microcosms. Predation, chemical pollutants, and eutrophication emerged as frequently addressed research topics. On the other hand, certain topics, such as metapopulation dynamics and microplastics, were relatively underrepresented in the literature. Despite the crucial role of experimental research on freshwater zooplankton in advancing ecological understanding in Brazil, there is an unequal distribution of these studies across the country, indicating the need for investments and more researchers prepared to work with experiments in certain regions. Addressing gaps identified in this review, such as metapopulation dynamics and the role of microplastics in zooplankton ecology, will be essential for generating scientific knowledge to inform effective management strategies to preserve freshwater zooplankton biodiversity amidst ongoing environmental changes.
Copyright (c) 2024 http://creativecommons.org/licenses/by-nc/4.0
Substrate influence on Perlidae (Plecoptera) nymph shape in Parque Nacional da Serra dos Órgãos, Teresópolis, Rio de Janeiro, Brazil.
Aim: Ecological studies on Plecoptera in Brazil are still in their initial stages, as is morphometric knowledge on Plecoptera nymphs. In this study, we determined whether Perlidae found in leaf litter were morphometrically distinct from those found in stony substrates. Methods: Specimens were collected in Parque Nacional da Serra dos Órgãos, Teresópolis, Rio de Janeiro, Brazil. Each insect was assigned to a morphotype and was subsequently measured. Data was logarithmically transformed and subjected to a size-free discriminant analysis. Analysis of variance tests were made to assess the relationship between shape, genus and substrate choice. Major results: We collected 562 insects belonging to two genera of Perlidae, Kempnyia Klapálek, 1914 and Anacroneuria Klapálek, 1909. Perlidae occurred primarily in leaf litter. We found significant morphometric differences among genera and substrates. Insects occurring in leaf litter were shown to have wider heads and longer fore femurs than those found in stones, likely indicating a bigger need for anchoring to the substrate and resisting stronger water currents. Conclusions: This study shows the complex relationship between body shape and substrate choice in neotropical Perlidae. Considering that different substrates bear varying ecological pressures on aquatic insects, morphometrics are a capable tool for assessing ecological relationships between these insects and their environment.
Willian Fernandes de Azevedo Cunha de Moura
Use of submerged trunks by stream fishes in the Lower Negro River, Amazon
Fish make use of different microhabitats, such as submerged trunks, branches, foliage, crevices and between stones, with different purposes, whether in search of shelter, refuge, food and even as a substrate for reproduction. The present study aimed to increase the knowledge about fish species that make use of the micro-habitat of trunks on the banks of streams in the conservation unit (CU) known as the Tupé Sustainable Development Reserve, Lower Negro River region, Amazonas. The data analyzed come from two days of collections, carried out in the falling water periods of 2020 in the Central stream. Six species, Pseudanos trimaculatus, Tatia strigata, Trachelyopterichthys taeniatus, Trachelyopterichthys sp. "negro", Ancistrus dolichopterus and A. hoplogenys were captured inside the submerged trunks. The order Siluriformes was the most abundant and represented (83.33%) of the sample. The most abundant species were T. strigata (N=46), followed by A. dolichopterus (N=35). Although most species are of the order Siluriformes, it is worth mentioning the encounter of a species of Characiforme, P. trimaculatus (N=1). In addition, an individual of A. hoplogenys was found in association with eggs deposited and fixed within a trunk, performing the behavior of care and protection. The finding of these species inside trunks may be associated with their foraging site, refuge and parental care in order to increase the chances of survival of the offspring. Therefore, the conservation of these microhabitats is important for the maintenance of aquatic organisms.
Cladocerans (Crustacea, Branchiopoda) from Mount Roraima, Venezuela, with new species record for this country and the Neotropical region
Introduction and Objectives: 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. Its true biodiversity is underestimated, especially for microcrustaceans of the Superorder Cladocera. Mount Roraima is considered a conservation unit, and understanding its fauna is an important tool for species preservation. This study presents a preliminary inventory of the cladocerans of this mountain. Methodology: 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 were evaluated. Main 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. Discussion: Samplings in peculiar and remote environments have the potential to reveal new species and records. Further samplings are suggested on Mount Roraima to reduce potential sampling biases. Keywords: altitude, biogeography, Chydoridae, sampling effort, Tepui.
Sandbar breaching promotes long lasting changes on limnological dynamics along the water column of a tropical coastal lagoon
Aim: In this study, we investigated the impact of an episodic marine intrusion on the water column characteristics of Jurubatiba lagoon, a tropical coastal ecosystem, for 12 months following a sandbar breaching event to elucidate the duration of its effects. Methods: Monthly, we sampled the physical, chemical and biological characteristics along the water column for one year after a sandbar breaching event and seawater inflow. We assessed the temporal (monthly) and spatial (along depth profiles) associations among these variables and the temporal correlation among vertical heterogeneities in these variables and environmental drivers of stratification. Results: Marine intrusion resulted in salt wedges formation in the short-term, leading to stratification in dissolved oxygen, pH, salinity, and chlorophyll-a concentration along the water column for at least four months. However, rainfall and temperature also emerged as crucial factors associated to vertical heterogeneity in limnological variables, influencing water density, pH, and turbidity throughout the study period. Wind speed had marginal effects on thermal stratification, probably due to the lagoon’s orientation in the landscape. Conclusions: Our data unveiled that, despite their shallowness and wind exposure, coastal lagoons can exhibit considerable vertical heterogeneities in limnological variables due to various climatic and hydrodynamic aspects. Notably, the effects of marine intrusions on salinity and ectogenic column stratifications can persist for several months, affecting water quality and, probably, biotic communities and ecosystem functioning. Once human activities and climate change may intensify marine intrusions on coastal lagoons, understanding these dynamics and their drivers is fundamental to anticipating their effects and conserving such vulnerable ecosystems.
Ichthyofauna of the Brazilian semiarid region reservoirs
The construction of reservoirs in the Northeast is a prevalent practice intended mainly for water supply, and with the introduction of fish as a widely practiced activity, it generates environmental and social consequences. Aim: This study analyzed articles on the ichthyofauna found in reservoirs in the Northeast over the last 50 years. Methods: It considered the scientific impact of these publications, the origin of the species studied, the main topics covered, and the participation of women in the authorship of these works. Results: A few publications on ichthyofauna were found, most of them of low impact and low visibility. This scenario highlights a concern about research promotion policies and reveals a gap in this area of knowledge. Conclusions: There are still regional asymmetries in publications, a reflection of the disparity in the distribution of incentives and funding actions. Investment in research in this area reflects directly on how research is carried out and viewed in Northeast Brazil. In addition, female participation has been significant in numbers but not visibility. It also reverberates in the scientific community as a whole.
Phytoplankton functional groups associated with the trophic state of tropical reservoirs
Abstract: Aim: The present study investigated functional groups representing reservoirs of different trophic states, identifying indicators of eutrophication. Methods: Water samples were collected to evaluate physical and chemical characteristics and the phytoplankton composition in five reservoirs during dry and rainy periods. Results: Low concentration of dissolved nutrients (nitrite, orthophosphate, and total dissolved phosphorus) and total phosphorus described the oligotrophic and mesotrophic reservoirs, and the opposite the eutrophic and hypertrophic reservoirs. Twenty-four functional groups were identified, eight of which were considered reservoir descriptors due to high biomass. Functional groups were influenced by the trophic state, and secondarily by seasonality. Typical functional groups represented the hypertrophic, eutrophic, and mesotrophic reservoirs. However, an oligotrophic reservoir was represented by a functional group commonly associated with environmental eutrophic. Conclusions: The functional groups were representative of the trophic state of systems and detected signs of early eutrophication.
Community attributes reflecting the zooplankton secondary production in a neotropical floodplain
Aim We investigated the relationship between ecological attributes of the zooplankton community and its secondary production. Methods Samples were taken from lakes in the floodplain of the Upper Paraná River (Brazil), in low and high-water periods, and in a manipulative experiment realized in mesocosms. Results The highest amount of production was related to the dominance of few species. Secondary production of larger and long-lived organisms, such as copepods, had been most associated with the biomass, whereas smaller ones, such as rotifers, with the abundance. Conclusions These attributes of the zooplankton community (biomass and abundance) can be used as proxies to estimate the zooplankton secondary production in the floodplain, supporting the studies on monitoring and conservation of these ecosystems.
Diel dynamics and environmental influences on phytoplankton communities in an Andean lagoon: implications for management and conservation
Lacustrine environments are unique locations to study temporal fluctuations derived from natural and artificial sources within a hydrographic basin. The objective was to analyze the diel cycle of physicochemical parameters in a shallow lacustrine environment and its influence on the phytoplankton community, as well as to identify the phytoplankton assemblage in the water column during rainy and dry seasons. The epilimnion and hypolimnion zones of an open water area were assessed over 24 hours, starting at 10:00 on day one and finishing at 10:00 on day two, obtaining a total of 36 samples (9 samples in a 3-hour interval in duplicate for both rainy and dry seasons). Sampling employed a Van Dorn sampling bottle. Six of the seven parameters monitored registered higher values during the rainy season; only transparency was higher during the dry season. Fifteen genera distributed in nine classes were identified, with richness and dominance being higher in the rainy season. Richness and dominance were more relevant in the hypolimnion than in the epilimnion zone in both seasons. The diel cycle assessment provided a clearer vision of physicochemical and biological fluctuations along the periods analyzed, mainly in the rainy season.
Morphological variation between two fish populations – phenotypic radiation in a rare case of geographical isolation
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.
Adult emergence of Phyllocycla Calvert, 1948 (Odonata: Gomphidae) in artificial environments
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: The research identified species not previously recorded in the region, highlighting the complexity of dispersal and geographical distribution of these insects. This study underscores the importance of considering adaptive variability to comprehend comprehensive ecological and geographical patterns within the Odonata order, providing a valuable basis for future investigations.
Predatory behavior of Frontonia leucas (Ehrenberg, 1833) (Alveolata, Ciliophora, Hymenostomatida) in different bodies of water in the Brazilian semi-arid region
Resumo: Objetivo: Análise do comportamento predatório do microeucarioto ciliado Frontonia leucas (Ehrenberg, 1833) em cinco corpos aquáticos do sudoeste da Bahia, região semiárida brasileira. Métodos: Foram coletadas amostras de água em cinco corpos d'água do Sudoeste da Bahia, Brasil, sendo três lóticos e dois lênticos. Os indivíduos foram analisados ​​in vivo por meio de específico óptico com câmera acoplada, totalizando 20 horas de observação. Durante a coleta das amostras foram registradas as seguintes variáveis ​​físico-químicas: sólidos totais dissolvidos, transparência da água, pH, condutividade elétrica e temperatura da água. Resultados: Foi observada a ingestão de 18 tipos de alimentos por F. leucas, distribuídos nos seguintes grupos: i) Amoebozoa: (7 táxons ), ii) Bacillariophyta (2 táxons ), iii) Ciliophora (1 táxons ), iv) Zygnematophyceae ( 5 táxons ) ev) Rotifera: (3 táxons ), e incluem 13 táxons registrados aqui pela primeira vez, cinco espécies de amebas testadas dos gêneros Cylindrifflugia, Difflugia e Netzelia , um gênero de Vorticella ciliada, quatro gêneros de microalgas, três desmídeos ( Micrasterias , Pleurotaenium e Cosmarium ) e uma Zygnematophyceae filamentosa ( Spirogyra ) e três táxons de micrometazoários Rotifera ( Lecane e Bdelloidea). O tamanho dos alimentos varia de 50 a 1100 µm de comprimento, sendo muitos maiores que o próprio ciliado. Conclusões: Os resultados indicam que F. leucas é um predador onívoro, contribuindo significativamente para o controle populacional em ecossistemas aquáticos. Palavras-chave: ciliados; itens alimentares; predador; presa.
Streams pollution in a luxury tourism municipality located in the Serra da Mantiqueira (Southeast Brazil)
Aim: Our aim was to analyze the limnological characteristics and evaluate the pollution levels of streams located in a luxury tourism municipality in the Serra da Mantiqueira (southeast Brazil). Methods: We analyzed the limnological characteristics of six sampling sites located in three streams of the Sapucaí-Guaçú River Basin along the urban area of the municipality of Campos do Jordão and one sampling site in the Rio da Prata stream (Point 7), as a reference location not impacted by urban pollution (São Paulo, Brazil). We measured some physical and chemical variables of the water and analyzed the concentration of nutrients (forms of N and P) in the streams close to the basin's sources (Sites 1, 2 and 3), within and downstream of the urban area (sites 4 and 5), downstream of the municipality's Wastewater Treatment Plant (WWTP) (Site 6) and the reference location (Site 7). We tested for significant differences in the limnological variables among the sampling sites using the ANOVA. To order the sampling sites according to the variation in their limnological characteristics we applied a PCA. Results: Our results showed that sites 1, 2 and 3, although close to the sources, presented limnological changes in relation to the reference location (Site 7) due to urban occupations in their surroundings. The sampling sites 4 and 6 are the most polluted due to urbanization and the discharge of effluents from the WWTP, respectively. The stretch between these two locations (Site 5) proved to be less polluted due to the autodepuration process. Conclusions: We concluded that the streams in the Sapucaí-Guaçú River Basin are polluted, although at different levels. The urban area of Campos do Jordão causes pollution of the streams in its surroundings due to surface runoff and the discharge of untreated sewage due to the lack of access to sewage services for a large part of the population. The absence of tertiary treatment at the WWTP leads to pollution of the stream after the release of its effluent.
Phytoplankton in lake water quality assessment: a review of scientific literature based on bibliometric and network techniques
Aim: This study aims to analysis of scientific literature based on bibliometric and network techniques on phytoplankton community in assessing lake water quality. Methods: PRISMA criteria were adopted to produce reliable results. Scopus and Web of Science were consulted to retrieve the documents to be studied. The number of publications, citations and co-citations, and bibliographic coupling were techniques used to identify relevant journals, countries, authors, and articles. The conceptual evolution was analyzed by keywords co-occurrence and thematic mapping. Results: Based on 219 documents selected from the annual period 1986-2022, the main results indicated 101 journals, 1007 authors, 11437 references, and 534 keyword authors, among others. The annual growth index was 12.2%, reflecting the upward trend at the time. Maria Moustaka-Gouni denoted as the top influential author, China leaded in publications and collaborations with The United States. Hydrobiologia was the top journal. Top influential articles content theme related to phytoplankton community as an indicator of water quality in lakes and functional groups in the phytoplankton community. According to the conceptual structure analysis results, lake, phytoplankton, eutrophication, phosphorus, water quality, and cyanobacteria were the most relevant themes. Furthermore, the trending topics were mainly toxicity, dynamic, functional groups, and restoration. Conclusion: This comprehensive analysis allowed us to interpret the development of research related to the subject of the study.