Acta Limnologica Brasiliensia

(631 Artigos indexados)

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

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

Volume: 37 - Issue: 0

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

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

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

Volume: 32 - Issue: 0

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

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

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

Volume: 32 - Issue: 0

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

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

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

Volume: 31 - Issue: 0

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

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

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

Volume: 31 - Issue: 0

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

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

Rodrigo Assis Carvalho, Francisco Leonardo Tejerina-Garro

Volume: 31 - Issue: 0

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

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

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

Volume: 31 - Issue: 0

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

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

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

Volume: 36 - Issue: 0

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

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Are functional freshwater Nematode traits a good tool for view an early succession on hard artificial substrate in a reservoir of Brazilian semiarid? - (2024)

Fábio Lucas de Oliveira Barros, Sebastião Tilbert, Taciana Kramer Pinto, Maria Cristina da Silva, Francisco José Victor de Castro, Miodeli Nogueira Júnior

Volume: 36 - Issue: 0

Resumo. Abstract Aim The Brazilian tropical semiarid is a biome with small freshwater ecosystems, often intermittent, acting as a mosaic in constant transformation between dry and rainy seasons. Meiobenthic communities play crucial roles in these environments, and understanding their colonization and succession processes is essential to comprehend how these organisms’ structure in a defaunated habitat. In addition to the traditional taxonomic approach, functional traits provide valuable insights into the dynamics of these processes. In this study, we tested the following hypotheses: i) although meiofauna consists of microscopic organisms with limited active dispersion, they quickly colonize new substrates, increasing in abundance, richness, and diversity; ii) functional traits of freshwater Nematoda are a good tool for view an early succession on hard artificial substrate in a lentic reservoir. Methods We placed 27 ceramic plates in a reservoir in the Brazilian semiarid and randomly sampled three replicates each week over nine weeks. Weekly differences in community abundance, richness, and diversity were tested with one-way ANOVA and pairwise PERMANOVA. Results Nematoda predominated in the first week, with Rotifera taking over from the second week of the experiment. No differences were observed in the Nematode taxonomic structure over the weeks. There was an increase in the functional complexity of the Nematoda community over time, as indicated by the maturity index and trophic structure. Colonizers/persistents emerged quickly in the first week. Deposit feeders dominated, but an increase in trophic diversity was observed with the growing presence of chewers over the weeks. Conclusions This study highlights that the functional traits of Nematoda represent a robust tool for assessing ecological succession in freshwater lentic environments in the tropical semiarid.

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Assessing the occurrence of alien species on Brazilian freshwater ecosystems: insights from a comprehensive survey - (2024)

Anderson Oliveira Latini, Daniela Chaves Resende, Daniel Paiva Silva, Dilermando Pereira Lima-Junior

Volume: 36 - Issue: 0

Resumo. Abstract: Aim Assessing the damage caused to natural environments and native biodiversity by alien species is challenging. We tested whether the number of detections of alien species is affected by total alien or total invader alien species richness, considering the importance of predicting which species are more probable future invaders. Methods We summarized a research information survey conducted on alien amphibians, annelids, aquatic macrophytes, cnidarians, crustaceans, fish, microorganisms, mollusks, nemathelminths, platyhelminths, and reptiles, and for Brazilian watersheds. We used linear regressions between detections and total alien species richness and between detections and invader species richness. Results We obtained 1,896 alien detections of 183 aquatic species in Brazil. Fish and mollusk species were the commonest invaders due to their detections being more frequent than expected by chance, considering all the alien species occurring in Brazilian freshwater ecosystems. We also found positive and robust linear relationships between alien species detections and alien species richness. Conclusions Our results illustrate how Brazilian freshwater systems are fragile to alien invasions and highlight the need for effective action to address this question. Scientific uncertainty in Brazil regarding the status of some alien species and their potential harm is high, highlighting the need for a cautionary overview of invaders. Despite this scenario, new policies create opportunities for aquatic parks with exotic organisms to spread further in Brazil, which, in actual Brazilian conditions, is likely to increase the pressure on natural ecosystems and native species. This reinforces the already expressed need by the scientific community for greater attention to the issue.

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Assessing the taxonomic sufficiency of macroinvertebrate communities and their potential to distinguish the impacts of land use on lowland streams in Uruguay - (2024)

Bárbara Suárez, Margenny Barrios, Franco Teixeira de Mello

Volume: 36 - Issue: 0

Resumo. Abstract: Aim Macroinvertebrates are extensively employed as bioindicators for evaluating how stream ecosystems respond to alterations in physical and chemical habitats caused by human activity. Although family-taxonomic level is usually used to identify macroinvertebrates in biomonitoring programs, coarser taxonomic resolution may provide similar information. We aim to evaluate taxonomic sufficiency by comparing macroinvertebrate communities at the order and family levels to differentiate the effects of different land uses. Methods We conducted colonization experiments using artificial substrates in streams representing three land use types: urban (U, n=3), intensive agriculture - dairy production (AD, n=4), and extensive cattle ranching (CR, n=4). Results We obtained similar results using both taxonomic levels, which effectively distinguished the impacts of different land uses. In the sites examined, the majority of indicator groups exhibited only one family per order, with the exception of Ephemeroptera (Leptophlebiidae, Baetidae, and Caenidae). Notably, Baetidae and Caenidae were more prevalent in streams associated with extensive cattle ranching (CR). Conclusions Although this study provides a clear precedent, further investigation of these systems and other land uses (e.g., afforestation) is needed to validate this pattern. Coarser taxonomic assessment holds potential as a cost-effective method for stream monitoring and assessment in Uruguay.

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Bacterial community dominance in a sewage-driven eutrophic coastal lagoon by next generation sequencing: initial findings - (2024)

Analy Machado de Oliveira Leite, Mauricio Mussi Molisani, Renan Monte de Oliveira, Paula Veronesi Marinho Pontes, Rodrigo Nunes da Fonseca, Jackson de Souza Menezes, Lupis Ribeiro Gomes Neto, Francisco Assis Esteves

Volume: 36 - Issue: 0

Resumo. Abstract: This study investigates the presence of bacterial dominance in one of the most studied sewage-driven eutrophic coastal lagoons, the Imboassica Lagoon in Macaé (RJ), Brazil, utilizing high-throughput sequencing of 16S rDNA. Water samples were collected from three sites within the lagoon. Total microbial DNA was extracted, and the V3-V4 region of the 16S rRNA gene was amplified and sequenced on the Illumina MiSeq platform. A total of 744,879 partial 16S rRNA sequences were clustered, revealing the absence of a single bacterial dominance in the sewage-driven eutrophic coastal lagoon. The prominent phyla detected in the lagoon were Cyanobacteria (27.8%), Proteobacteria (23.7%), and Actinobacteria (14.6%). Proteobacteria emerged as the most abundant phylum in the sewage-impacted lagoon site, whereas Cyanobacteria dominated the other two sampling sites. Among families, Synechococcaceae predominated with genus Synechococcus exhibited the highest prevalence. Families of potentially toxic Cyanobacteria represented less than 1% of the total families. The sewage-impacted lagoon section displayed greater bacterial diversity and richness. The dominance of bacterial communities associated with raw sewage, such as members of the Enterobacteriaceae family, was not confirmed, constituting only 0.75% of the families in the most affected site. This study presents the initial analysis of the bacterial community in the Imboassica Lagoon and suggests that dominance in the lagoon responds to the eutrophication and sewage discharge.

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Beta diversity of macroinvertebrate assemblages associated with aquatic macrophytes in shallow lakes within a tropical floodplain-dammed river - (2024)

Marcos Callisto, Ricardo Solar, Daiana dos Reis Pelegrine, Marden Seabra Linares

Volume: 36 - Issue: 0

Resumo. Abstract: Aims We assessed the beta diversity of macroinvertebrates associated with aquatic macrophytes in a dam-regulated river floodplain. We tested two hypotheses: (1) macroinvertebrates associated with aquatic macrophytes have higher beta diversity (higher turnover and nestedness components) in the downstream areas closer to the São Francisco River compared to upstream sites; (2) closer lakes share a higher similarity of aquatic macroinvertebrates, disregarding their position relative to the dam. Methods We sampled four lakes, including two upstream (L1- natural and L2- regulated by a Small Hydropower Dam - SHD) and two downstream (L3, L4, unregulated) by the SHD. Results We corroborated our first hypothesis because we found a higher turnover of macroinvertebrates associated with aquatic macrophytes close to the São Francisco River (L4 downstream), where higher non-native mollusk species richness occurs, while we found higher nestedness upstream and downstream of the SHD (L1, L2, L3). We corroborated our second hypothesis, as closer lakes are more similar than distant lakes. Finally, these differences were consistent between lakes for emergent, floating leaf, and submerged aquatic macrophytes. Conclusions Aquatic macrophytes are essential habitats for macroinvertebrates in the Pandeiros River basin, with higher beta diversity in the lake closer to the São Francisco River.

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Community attributes reflecting the zooplankton secondary production: using field and experimental approaches - (2024)

Juliana Deo Dias, Nadson Ressye Simões, María Rosa Miracle, Thais Xavier de Melo, Claudia Costa Bonecker

Volume: 36 - Issue: 0

Resumo. Abstract 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.

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Comparative analysis of ex situ zooplankton hatching methods - (2024)

Daniel Nino Flores-Mendez, María Florencia Gutierrez

Volume: 36 - Issue: 0

Resumo. Abstract: Aims This study aims to analyze the efficiency of two novel methods for ex situ zooplankton hatching experiments, compared with a traditional one. Both proposed methods were specifically designed to minimize sediment resuspension during the sampling of hatched individuals when no previous egg isolation is performed. Methods Sediment samples were collected from shallow lakes, homogenized, and incubated for 18 days under stable laboratory conditions. The traditional method (1M) involved simple water filtration from incubated sediments. The so called “inverted funnel filtering” method (2M) includes an inverted funnel located above the sediment to trap zooplankton that passes through the funnel aperture, and the “levels filtering” method (3M) involves perforated plates above the sediment. The efficiency of each method was evaluated by analyzing the cumulative abundance and number of taxa in hatched total zooplankton, rotifers, and microcrustaceans, as well as the overall composition. Results The new proposed methods significantly favored higher abundances than 1M for total zooplankton and rotifers. Even more, 3M outperformed 2M in the case of microcrustacean hatching abundances. Conclusions Our findings suggest that despite all analyzed methods being suitable for studying zooplankton hatchings, the newly proposed methods incorporating internal structures to minimize sediment resuspension displayed increased capture efficiency.

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Composition, life-history, and population dynamics of the Chironomidae from a tropical high-altitude stream (Saltana River, Ecuador) - (2024)

Narcís Prat i Fornells, Andrea C. Encalada, Christian Villamarín, Blanca Ríos-Touma

Volume: 36 - Issue: 0

Resumo. Abstract: Aim To study the composition and population dynamics of Chironomidae (Diptera) from a high-altitude tropical stream in Ecuador. Methods Samples were taken at Saltana River between April 2009 and November 2010. Physico-chemical parameters, such as flow, dissolved oxygen, conductivity, pH, and temperature, were measured in each sampling campaign. Larvae and pupae sampling was conducted with a Hess sampler in different substrates. During each sampling campaign, adults were sampled using amphibious emergence traps for 24 hours. All materials collected were separated and classified in the laboratory. The biomass was calculated using the individual weight of the larvae of different instars multiplied by the density of each instar at each sample. Results A total of 18 larval taxa were found in 14 different genera in the benthic samples. The subfamily Orthocladiinae showed the highest richness (12 genera), followed by Podonominae, Diamesinae, and Chironominae, with two genera each. The most frequent taxa were Cricotopus sp.3, C. (Oliveiriella) rieradevallae, and Genus 1 sp.a. Total densities fluctuate very much from one month to another following the changes of the most abundant species, and only one species showed a relationship with the substrates. Biomass values are lower from June to August of both years, which matches the high flow season. Conclusions The Saltana River’s cold temperature (6-7 °C) and the flow variability determine the low richness, density and biomass throughout the year. It is unclear if individuals showed very short or long-life cycles due to constant temperature throughout the year. However, there is a clear asynchrony in life cycles due to the presence of emerging adults throughout the year.

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Concentrations of metals in water, sediments and aquatic macrophytes in a river located in a region with a hot semi-arid climate - (2024)

Camila Tâmires Alves Oliveira, Antonio Fernando Monteiro Camargo, Eulene Francisco da Silva, Gustavo Gonzaga Henry-Silva

Volume: 36 - Issue: 0

Resumo. Abstract Aim i) is there a difference in the level of contamination in the different parts of the basin in the water, sediment and aquatic macrophytes compartments? and ii) do the three compartments respond similarly to metal contamination? Methods Samples of water, sediment and aquatic macrophytes (Salvinia auriculata Aubl., Pistia stratiotes L., Ludwigia helminthorrhiza (Mart.) H. Hara and Eichhornia crassipes (Mart.) Solms) were collected at 10 sampling sites in different stretches of a tropical hydrographic basin. We determined the metal concentrations of Fe, Pb, Ni, Zn, Mn, Cr, Cu and Cd, and to the results we applied Principal Component Analysis (PCA), separately for each compartment, to order the sampling sites. Results Fe and Mn had higher concentrations than other metals in plants and sediment. With the exception of Mn, the order of metals was similar between water and sediment. However, the PCAs ordered the sampling sites differently. Our results demonstrated that the ordering of sampling sites by metal concentrations differs among water, sediment and macrophytes. Conclusions We conclude that to evaluate the contamination of aquatic environments by metals and the effects of contamination on the food chain, it is not enough to evaluate them only in water or sediment, but also in an aquatic community.

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Diel dynamics and environmental influences on phytoplankton communities in an Andean lagoon: implications for management and conservation - (2024)

Ivan Edward Biamont-Rojas, Herminio René Alfaro-Tapia

Volume: 36 - Issue: 0

Resumo. Abstract: Aim Lacustrine environments are unique locations to study temporal fluctuations derived from natural and artificial sources within a hydrographic basin. The objective of this study was to analyze the diel cycle of physicochemical parameters and their influence on the phytoplankton community structure in open waters, as well as, to evaluate the total phosphorus and nitrogen contents in the vicinity of fish tanks in the lagoon, and to identify the phytoplankton assemblage in the water column in a diel cycle in an open water area during the rainy and dry seasons. Methods 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 at 3-hour intervals, in two lake zones, in two seasons). Sampling employed a Van Dorn sampling bottle, and the Morphologically Based Functional Groups (MBFG), Shannon-Weaver and Simpson Indices were employed to describe the identified genera. Results 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 diversity being higher in the rainy season. Conclusions The MBFG and sinking properties of group and genera has influenced the vertical migration of phytoplankton. The daily cycle method effectively captured the fluctuations in physicochemical and phytoplankton parameters over a 24-hour period in both seasons in Chacas Lagoon.

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Distribution of invasive bivalves in Paraguay: filling the gaps in the heart of South America - (2024)

Igor Christo Miyahira, Rebeca Carballo, Héctor Samuel Vera-Alcaraz, Cristhian Clavijo

Volume: 36 - Issue: 0

Resumo. Abstract La Plata Basin is the second largest hydrographic system in South America but the most impacted by invasive species of molluscs in the continent. Paraguay is a land-surrounded South American country with scarce information about malacological fauna. To fill some of these gaps, a large field expedition was conducted to analyze the distribution of invasive freshwater bivalves in Paraguay. The field survey encompassed 41 sampling stations in seven Departments of Paraguay. The mussels were searched using bare hands and feet. All stations were georeferenced and some environmental parameters were measured. Results indicated the presence of three invasive species of freshwater bivalves in Paraguay: Corbicula fluminea, C. largillierti, and Limnoperna fortunei. The Asiatic clam Corbicula fluminea was the most widespread invasive species, covering main rivers and small tributaries in the four freshwater ecoregions of Paraguay. The two remaining invasive species were more restricted. Corbicula largillierti were found at the lower section of the Paraná River, and Limnoperna fortunei inhabits the main river canals of the Paraguay River and the lower section of the Paraná River. The invasive species were found in three protected areas of Paraguay and can represent a threat to the mostly unknown fauna of native mussels. The invasive bivalves are widespread in Paraguay. Mitigation measurements must be taken to avoid the spread of these species and more drawbacks over native fauna.

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Ecophysiological investigation of the cyanobacteria Anabaenopsis elenkinii and Limnospira platensis: predominant species in saline/alkaline lakes of the Pantanal Wetland - (2024)

Kleber Renan de Souza Santos, Guilherme Scotta Hentschke, Arnaldo Yoso Sakamoto, Luciana Retz de Carvalho, Célia Leite Sant’Anna

Volume: 36 - Issue: 0

Resumo. Abstract: Aim In this study, we investigated the distribution of Anabaenopsis elenkinii and Limnospira platensis in the saline-alkaline lakes of Nhecolândia (Pantanal wetland) and evaluated the impact of pH, temperature, and nitrogen on their growth and development to understand their ecological responses, showing insights into their ecophysiology in both cultured and natural environments. Methods Both species were collected in the subsurface, using a plastic bottle (200 mL) and the parameters temperature, conductivity, and pH were measured in situ. From these samples, the strains A. elenkinii CCIBt1059 and L. platensis CCIBt3335 were isolated and underwent six different cultivation treatments, in triplicate, during 30 days, with daily cell count, photoperiod of 12-12 hours of light-dark, and light intensity between 80-100 µmol photons m-2.s-1, using BG-11 modified medium, as follows: nitrate concentration experiments were performed with a 750 mg.L-1 NaNO3 (50%) and a nitrogen-free condition (0%) (T1 vs T2); temperature experiments were performed with 30 °C and 35 °C (T3 vs T4); pH experiments with 10.5 and 7.0 (T5 vs T6). The adopted control conditions were BG-11m medium (3% NaNO3, 45 mg.L-1), pH adjusted to 9.5, and temperature set at 25 °C. Results We have found that the treatment with the highest nitrogen availability (T1), pH of 9.5, and a temperature of 25 °C, provides the most favorable conditions for the growth of both studied species. In nature, A. elenkinii occurred predominantly between pH 9.04 to 10.4 (average 9.8) and L. platensis at pH 9.22 to 10.23 (mean 9.9), highlighting the alkaliphilic nature of these species. Furthermore, we observed that temperature influences the frequency of heterocyte formation in A. elenkinii. At elevated temperatures (30 and 35 °C), the frequency of heterocytes was higher compared to 25 °C during the exponential growth phase, indicating that increased heterocyte formation is a strategy in response to temperature stress. Conclusions This research provides valuable insights into the ecological aspects and optimization of the cultivation of the two species studied, which hold ecological significance to saline lakes. Further studies are recommended to explore their potential biotechnological applications.

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Environmental monitoring of sediment quality and trace metal status in a tropical perennial river in South India: an exploration using multivariate analysis - (2024)

Dani Benchamin, Sreejai Raghavan, Arya Madhu Sajidevi

Volume: 36 - Issue: 0

Resumo. Abstract: Aim The Kallada River is exposed to several kinds of pollution from domestic, civic, recreational, and agricultural activities and human settlements. The objectives of the study were to assess sediment quality, especially the trace metal concentration and to compare with the previous reports on the sources of pollutants in the Kallada River. Methods A total of 12 sediment variables including the following metals: iron (Fe), manganese (Mn), chromium (Cr), and zinc (Zn) were analyzed. Atomic Absorption Spectrophotometer (AAS) was used to detect trace metal concentration in the sediment samples. Statistical tools such as Pearson’s correlation, Principal component analysis (PCA), and Cluster analysis (CA) were employed to analyze the data and source of pollutants. Results This investigation indicated that Fe was the most accumulated element in the sediments, and the midstream (K6 and K10) and downstream sites (K11 to K15) showed a much higher concentration level than the upstream sites. The concentrations of trace metals in sediment samples followed the order Fe> Mn> Cu>Zn. Conclusions The present study concluded that major sources of pollutants were sewage and civic effluents and agricultural discharges. These may cause a severe threat to the Kallada River and health risk to the local populations, which rely on the river, primarily for drinking purposes. Hence, appropriate conservation policies to reduce pollution are therefore essential.

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Environmental variables as predictors of fish community composition in semiarid aquatic systems - (2024)

Elvio Sergio Figueredo Medeiros, Marcio Joaquim da Silva, Telton Pedro Anselmo Ramos, Robson Tamar Costa Ramos

Volume: 36 - Issue: 0

Resumo. Abstract Aim To understand the distribution of fish species and their use of habitat, a range of environmental variables were evaluated as predictors of fish assemblage composition and richness in tropical semiarid aquatic systems. Methods We surveyed the species composition of fish assemblages in semiarid aquatic systems and established their degree of association with the structure of the aquatic habitat. Sites consisted of stream reaches with surface water flow, isolated temporary pools, and man-made reservoirs. Fish sampling was conducted on four occasions during the wet (April and June 2006) and dry seasons (September and December 2006). The correlation between richness and abundance with the habitat structure was evaluated using stepwise multiple regression. Patterns of variation in fish assemblage composition across sites were evaluated using Nonmetric Multidimensional Scaling, and the Indicator Species Analysis was used to determine which species were significant indicators of sites. To establish multivariate correlations and test the hypothesis of local fish composition being associated with the environmental variables we used a Canonical Correspondence Analysis. Results Morphometric variables, stream reach width, stream length and elevation explained 75.6% of the variation in fish richness. Macrophyte cover and overhanging vegetation added to the predictive power of the model equation, where the final model explained 86.9% of the variation in fish richness. Canonical Correspondence Analysis showed a significant relationship between fish composition data and site morphology (altitude, bank slope and littoral depth). Among the water quality, habitat composition and substrate variables, temperature, sand, and gravel showed higher correlation with the CCA axes. Conclusions These results indicated that fish communities assume different structures and compositions across different habitat types following the environmental heterogeneity in dryland aquatic systems.

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Epistylid ciliates as epibionts on calanoid copepods in an Amazonian floodplain lake (Batata Lake) - (2024)

Wésley Altino Flores, Pedro Mendes de Souza, Iollanda Ivanov Pereira Josué, Roberto Júnio Pedroso Dias, Reinaldo Luiz Bozelli

Volume: 36 - Issue: 0

Resumo. Abstract Aim The main objective was to investigate changes in the prevalence and infestation intensity of the epibiotic relationship (ciliates/calanoids) in relation to the impact of bauxite tailings (natural and impacted areas) during two distinct periods of the hydrological pulse (rising and high-water). Methods 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. Results This is the first record of peritrichous epibiont ciliates Epistylis sp. colonizing calanoid copepods in Amazonian ecosystems (Lake Batata, Pará, Brazil). 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. Conclusions 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.

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Experimental studies on freshwater zooplankton in Brazil: a scientometric analysis from 1978 to 2023 - (2024)

Jorge Laço Portinho, Larissa Ferreira Brandão, Marco Antonio Azevedo Machado, Clarice Casa Nova, Maiby Glorize da Silva Bandeira, Juliana Deo Dias, Amanda Costa Ferreira, Reinaldo Luiz Bozelli

Volume: 36 - Issue: 0

Resumo. Abstract Aim This study aims to contribute to elucidating the importance of experimental research on freshwater zooplankton communities in Brazil through a scientometric analysis. Methods Web of Science, SciELO, and Scopus databases were used to compile 249 scientific papers published between 1978 and 2023. The extracted data 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. Results 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 conducted with greater frequency 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 investment and more researchers prepared and interested in studying with experiments in certain regions. Addressing the gaps identified in this review, such as metapopulation dynamics and dispersion, along with emerging threats like invasions, microplastics, pathogens, cumulative stressors, emerging contaminants, and nanomaterials, will be essential for generating scientific knowledge to inform effective management strategies to preserve freshwater zooplankton biodiversity amidst ongoing environmental changes. Conclusions This review underscores the importance of expanding experimental research across diverse regions and underexplored topics to enhance our ecological understanding and better manage freshwater zooplankton biodiversity in Brazil.

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Factors stimulating the hatching of resting eggs and their contribution to the composition of cladoceran assemblages in tropical temporary lagoons - (2024)

Wesley Luiz Guimarães, Eliana Aparecida Panarelli, Natan Guilherme dos Santos, Maria Stela Maioli Castilho-Noll

Volume: 36 - Issue: 0

Resumo. Abstract: Aim We aimed to verify the contribution of cladocerans’ resting eggs to the active communities of temporary lagoons and, through an experiment, identify which conditions induce high hatching rates. Methods Cladocera assemblages were sampled in four temporary lagoons in the Turvo River floodplain (20° 22’S and 49° 16’W), in the northwest region of São Paulo State, Brazil. Sediment samples were taken during the dry season from a depth of 5 cm, using a 4.5 cm diameter corer. Plankton samples were taken from the water column before and after the dry season. For the hatching test, two treatments were performed 1. Natural condition – without light and temperature control; 2. Controlled condition – with controlled photoperiod and temperature. Temperature, pH, conductivity, dissolved oxygen and hatching of resting eggs were monitored for two weeks. The influence of the parameters on hatching in both treatments was evaluated using Hierarchical Partition Analysis. Results Hatching of resting eggs was higher in the Controlled condition than in the Natural one. Thirty percent of species observed in the active community after flooding hatched in the laboratory test. Conductivity, pH, and dissolved oxygen were positively correlated to the hatching of some species, e.g., Ephemeroporus hybridus, Leydigiops ornata, Notoalona sculpta and Ilyocryptus spinifer. The first species to hatch were those living associated with macrophytes and at low depths. Conclusions Our results show that stable temperature and photoperiod with similar light and dark hours stimulate greater hatching of Cladocera resting eggs. Variables such as pH, conductivity and dissolved oxygen were also correlated with the hatching of some species. We observed that the first contributions to activating the community after drought came from hatching of species usually associated with macrophytes and low depth conditions.

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