Acta Limnologica Brasiliensia

(681 Artigos indexados)

Evaluation of the status of ecological quality of tropical estuaries using meiofauna as biological indicators on the Northeast coast of Brazil (7°S) - (2026)

Sebastião Tilbert, Miodeli Nogueira Júnior

Volume: 38 - Issue: 0

Resumo. Abstract: Aim The status of ecological quality (EcoQ) has been used as a tool of ecological evaluation of water bodies based on benthic communities. It has been extensively used in temperate estuaries, but its usage for tropical environments has not been tested yet. To evaluate if EcoQ can be used as a reliable anthropic disturbance indicator in tropical estuaries, we sampled meiofaunal assemblages on two Brazilian tropical estuaries with extensive mangrove areas submitted to different levels of anthropic impact. Methods This study was conducted in the Mamanguape River estuary, a Protected Landscape (IUCN, category V), and Paraíba River estuary, adjacent to an urban center with 1,380,923 citizens, both at tropical Northeastern Brazilian coast (~7°S). Sampling campaigns were performed on 17 and 24, April 2016, in the Mamanguape and Paraíba estuaries, respectively. During the low tide eight sites on each estuary were sampled on triplicates, totaling 48 samples. Samples were taken using a corer with 11 cm2 introduced 10 cm deep in the sediment. Additionally, sediment samples were taken at each site to analyze the amount of organic matter and granulometric characteristics. Results Sites were grouped as sandy and sandy mud regions. As expected, the Global Human Influence Index was considerably higher in the more impacted estuary, in both granulometric regions. However, the EcoQ values were roughly similar comparing both estuaries and were significantly different (ANOVA, p<0.05) comparing the granulometric profiles. Conclusions These results suggest that meiofaunal-based EcoQ was more sensitive to the granulometric gradient than to the anthropogenic impact. This is likely to be associated with environmental particularities of tropical estuaries and consequent biological adaptations of meiofaunal assemblages, which may result in distortions in the EcoQ as currently used. Thus, it is important to calibrate the index to tropical estuaries with fine sediments and, therefore, a more robust baseline data is necessary, including a higher spatial and temporal coverage, and lower taxonomic resolution.

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Ichthyofauna of streams in Maringá municipality, Paraná, Brazil: an updated checklist, threats, and conservation perspectives - (2026)

Rianne Caroline de Oliveira, Renan Borges dos Reis, Augusto Frota, Cláudio Henrique Zawadzki, Carla Simone Pavanelli, Weferson Júnio da Graça

Volume: 38 - Issue: 0

Resumo. Abstract Aim The following list aims to provide the most recent taxonomic surveying of fish species inhabiting the Ivaí and the Pirapó/Parapanema river basins from the Maringá municipality, using material from the Coleção Ictiológica do Nupélia (NUP) and the available literature. Methods We compiled all the available records of fish species housed in the NUP from the SpeciesLink database, and compared them with those in a previously published study. Results The total number of species identified was 81, distributed across 24 families and six orders. The richest order is Characiformes, comprising 34 species. The data analysed reveal that 11 species are recorded as non-native, highlighting the alarming case of introduced species, especially by aquarium keeping. Regarding the threat categories analysed by the IUCN, only one species, Bryconamericus coeruleus, is considered Near Threatened. Further, a noteworthy feature is the presence of seven putative new species, which underlines the necessity for further studies to be conducted to facilitate a more complete understanding and description of the ichthyofauna of the region. The results of this study show that the fish species composition in the streams of the Maringá municipality is diverse and taxonomically complex. Conclusions Further investigation is needed to address the aforementioned issues regarding conservation and possible species description. Furthermore, more surveys are needed in the Ivaí River basin to expand the species registry, especially in urban streams. We hope that the list of freshwater fish species from Maringá municipality will be a useful source of information for people who make decisions and for people who want to create plans to manage and protect the fish in the region.

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Impact of unpaved roads on the fluvial ecosystems in the XXI century: a review - (2026)

Jeferson Eslei Mazur, Valdemir Antoneli, Edivaldo Lopes Thomaz

Volume: 38 - Issue: 0

Resumo. Abstract Aim Considering the strategic role of water resources for ecosystem sustainability and the increasing anthropogenic pressure, particularly from roads, this study aimed to analyze the impacts of unpaved roads on fluvial ecosystems, with emphasis on erosion processes and related mechanisms. Methods A systematic literature review was conducted using the Methodi Ordinatio, with searches in the Scopus and Web of Science databases. After applying the selection criteria, 29 articles published between 2001 and the present were analyzed. Initially, a scientometric analysis was carried out, followed by a knowledge synthesis and suggestions for future research directions. Results The findings indicate a growing interest in the topic, with a geographic concentration of studies in countries such as the USA, China, and Australia, predominantly focused on forest roads in mountainous regions and streams. Most investigations addressed hydro-sedimentological dynamics and the effectiveness of best management practices (BMPs), while fewer studies examined direct impacts on water quality and aquatic biota. The studies showed that unpaved roads reduce infiltration, increase surface runoff, and intensify the production and delivery of fine sediments, with strong hydrological connectivity, especially at stream crossings and roadside ditches. BMPs such as road decommissioning, gravel surfacing, revegetation, and the establishment of riparian zones were effective in mitigating these impacts, particularly when well-implemented and adapted to local conditions. Conclusions Although the reviewed studies provide evidence of the impacts of roads on fluvial systems, gaps remain in the literature. It is necessary to expand the geographical scope of investigations, deepen the evaluation of direct impacts on water quality and biodiversity, especially at a longitudinal scale, and test the effectiveness of BMPs under different environmental conditions to support the conservation of fluvial ecosystems in rural areas.

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Potential impacts of sea-level rise on fish communities in coastal lakes and lagoons of the Tramandaí River Hydrographic System, southern Brazil - (2026)

Taís de Fátima Ramos Guimarães, Fernando Gertum Becker, Ana Cristina Petry, Sandra Maria Hartz

Volume: 38 - Issue: 0

Resumo. Abstract Climate changes are predicted to strongly affect aquatic communities and consequences in coastal lakes and lagoons might be worsened by the tendency of salinization due to sea-level rise. Aim This study aims to evaluate potential fish community changes caused by a potential increase in salinity in a system formed by 41 interconnected lakes/lagoons. Methods We modeled the occurrence and abundance of 12 fish species under two scenarios of salinity change via marine water intrusion through the estuary of the Tramandaí river, in south Brazil, based on their contribution to β diversity. This was determined by the difference between the average number of recorded individuals and the salinity condition using ANOVA and Tukey's test, followed by generalized linear models with the estuarine connection projected for two future climate scenarios. In addition, we evaluated the effects of increased salinity on endemic species and the consequences of this environmental change on their endangered status. Results According to our results, salinity increases will lead to reductions in the distribution of freshwater fish species, which would become restricted to fewer lakes/lagoons (a 10 to 60% reduction in habitat area within the study region). These reductions in geographic distributions are even more concerning for the endemic species. Conclusions Our results demonstrate the need to assess vulnerability to climate change and that these criteria should be more clearly incorporated into species assessment protocols, such as those of the IUCN.

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Taxonomic structure and spatial distribution of aquatic invertebrates from temporary wetlands after a severe drought event in southern Brazil - (2026)

Bárbara Oleinski, Cleber Palma-Silva, Edélti Faria Albertoni

Volume: 38 - Issue: 0

Resumo. Abstract Aim The aim of this study was to evaluate the composition and spatial distribution of aquatic invertebrates in temporary wetlands following a severe drought event in southern Brazil. Methods Aquatic invertebrates and limnological variables were collected from 14 temporary wetlands located on the campus of the Federal University of Rio Grande, Rio Grande do Sul State, Brazil, after a severe drought period in the summer de 2024. Results The temporary wetlands were characterized by small size (70.8 – 336.0 m2), shallow depth (9.0 – 36.0 cm), and water temperature between 20.5 and 29.4 ºC. A total of 3230 invertebrates were identified, encompassing 55 different taxa. The most frequent groups were Diptera (761 individuals), Collembola (526 individuals), and Gastropoda (498 individuals). Additionally, 11 unique taxa were found in temporary wetlands analyzed, with the majority belonging to Arachnida. Based on taxa abundance, two main clusters were observed, the first being composed of temporary wetlands (TW) from 1 to 9, and the second cluster with areas 10 to 14. Conclusions Climate change projections suggest a rising frequency and potential for severe drought events. Temporary wetlands, which harbor significant diversity of aquatic invertebrates, are particularly vulnerable due to their characteristics and dependence on hydroperiods. Severe drought events may impact species composition and distribution, highlighting the need for monitoring and protection of these habitats.

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Understanding anthropogenic pressures on freshwater ecosystems: recent trends and emerging issues (2019-2023) - (2026)

Layla Mayer Fonseca, Gabrielle Passos Pereira Rosário, André Megali Amado

Volume: 38 - Issue: 0

Resumo. Abstract Aim To identify and analyze the most frequently investigated anthropogenic pressures and emerging research themes in freshwater ecosystem studies recently published (between 2019 and 2023). Methods A bibliometric literature review was conducted using the Web of Science and Scopus databases. Articles were selected based on predefined search strings related to freshwater systems and human impacts. A total of 5,549 peer-reviewed articles in English were analyzed using the Bibliometrix package in R®, focusing on abstracts and author keywords to detect trends in stressors, contaminants, ecosystem types, and research collaboration networks. Results Rivers were the most frequently studied ecosystems (4,848 records; 90%), followed by lakes (621; 11%) and wetlands (337; 6%). Agriculture (35%), urbanization (28%), and mining (11%) were the top referenced drivers. Mentions of emerging pollutants grew sharply, with microplastics rising from 19 in 2019 to 198 in 2023, surpassing nutrients and pharmaceuticals. China (3,089), the United States (1,207), Canada (353), and Brazil (309) led in research output, with increasing international collaborations and adoption of advanced tools such as machine learning and remote sensing. Conclusions The literature reveals a growing interest in understanding complex human pressures on freshwater ecosystems. Strengthening international cooperation and integrating policy-oriented research emerge as frequently highlighted strategies in the literature to address these challenges.

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Using social media to describe catches of recreational fishing in an amazonian hotspot - (2026)

Beatriz Leite-Silva, Cleomara Ramos Almeida, Jonison Vieira Pinheiro, Cleverson Zapelini, Vinicius José Giglio

Volume: 38 - Issue: 0

Resumo. Abstract Aim We used social media posts to describe recreational fishing catches in Cachoeira Porteira, Trombetas River basin, Amazon. Methods We analyzed images and videos publicly shared on Instagram between 2019 and 2024, identifying captured fish species, number of individuals, conservation status, and estimated body size. Results We recorded 245 individuals belonging to 10 families and 18 species, with trophic groups carnivorous (55%) and piscivorous (34%) dominating the catch composition. The most frequently recorded species were Cichla thyrorus (37.2%) and Hoplias aimara (15.8%). Only 6% of individuals were caught below the first gonadal maturation size (L50), composed of three species of large migratory catfishes (Brachyplatystoma filamentosum, Zungaro zungaro, and Phractocephalus hemioliopterus). However, P. hemioliopterus showed a high proportion of catches below its first gonadal maturation size L50 (42%). Conclusions Recreational fishing in Cachoeira Porteira targets mainly large predatory fishes, generally at or above maturation size, but with a considerable proportion of immature large catfishes. Social media provides insights into catch composition and size structure, offering an alternative approach to investigate data-poor Amazonian fisheries.

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Effects of freezing on the carbon and nitrogen stable isotopic compositions of fish tissues - (2026)

Luciana Mulero Beloto, Thiago Simon Marques, Barbara Protocevich, Ronnie Von Mateus Ferreira, Plinio Barbosa de Camargo

Volume: 37 - Issue: 0

Resumo. Abstract Stable isotope analysis is a vital tool for elucidating nutrient flow within food chains. Studies utilizing this methodology must consider potential variables that could influence the δ13C and δ15N values of the species being examined. One such variable is the preservation of samples in a frozen state during field studies, particularly when immediate sample processing is not possible. Aim The objective of this study is to investigate the long-term effects of freeze-thaw at intervals of 1, 2, 7, 15, 30, 90 and 180 days on the δ13C, δ15N, and C:N ratios in biological samples from three fish species. Methods Tissues from three estuarine fish species (Cathorops spixii, Genidens barbus and Chloroscombrus chrysurus) were frozen and aliquots were subjected to thawing for sample collection aimed at isotopic determination. Results The discrepancies observed in this study were related to the δ13C and C:N ratios in the skin samples of C. spixii and G. barbus, as well as the muscle samples of C. chrysurus. These variations seem to be more closely linked to the potential volatility of the 12C isotope within the samples, resulting in δ13C enrichment and an increase in C:N values. Conclusions This suggests that these changes are not solely attributable to the freeze-thaw process, but may also be influenced by other factors like the lipid oxidation. Our findings suggest that this process significantly influences the δ13C and C:N ratios of skin and muscle tissues. Furthermore, we advocate for prompt processing of samples to minimize the impacts of freeze-thaw events.

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Extemporaneous environmental legislation: an analysis of the conflicts underlying Law 3824/1960 on coarse wood removal in Brazilian artificial reservoirs - (2026)

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 - (2026)

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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Advances and limitations of using satellites to monitor cyanobacterial harmful algal blooms - (2026)

Igor Ogashawara

Volume: 31 - Issue: 0

Resumo. Abstract The use of satellites for monitoring forests is common and well-known practice. However, the operational remote monitoring of water quality from space is still under development. In the United States of America (USA), the use of this type of data is just now being applied to operationally monitor cyanobacterial harmful algal blooms (CHABs). This powerful tool can be used to generate temporal and spatial assessments of CHABs, however the validation of the retrieved information is still a challenge - especially in tropical and equatorial countries. This commentary discusses the advantages and challenges of current initiatives that use Earth Observation data for managing CHABs such as “Lake Erie’s HAB Bulletin” and “Project CYAN” - both in the USA. Additionally, it was also discussed the application of remote sensing techniques to monitor CHABs in Brazilian inland waters.

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Advancing impact evaluation in applied limnology - (2026)

Luiz Guilherme dos Santos Ribas, André Andrian Padial, Luis Mauricio Bini

Volume: 31 - Issue: 0

Resumo. Abstract Accurate impact evaluations of different interventions are paramount in environmental sciences. In this context, the main challenge is to identify causal relationships to understand how different interventions affect the systems of interest. For this task, the counterfactual thinking can be used to estimate the impacts of interventions on the real scale of the problem using observational data. By definition, counterfactuals are states contrary to facts. In the context of interventions, they are the states of the units of analysis in the absence of intervention. This approach allows one to estimate the impact more accurately by comparing the differences between factual and counterfactual states. In this essay, we present some basic elements of the counterfactual thinking and discuss how it, based on experiences in other areas (e.g., medicine and economics), may be useful for the research of complex problems in aquatic ecology.

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Allelopathic effects of the aquatic macrophyte Ceratophyllum demersum L. on phytoplankton species: contrasting effects between cyanobacteria and chlorophytes - (2026)

Cihelio Alves Amorim, Rafael Henrique de Moura-Falcão, Celina Rebeca Valença, Vitor Ricardo de Souza, Ariadne do Nascimento Moura

Volume: 31 - Issue: 0

Resumo. Abstract Aim To assess the allelopathic effects of the submerged macrophyte Ceratophyllum demersum on four strains of phytoplankton species: two cyanobacteria (Microcystis aeruginosa - microcystin producing and M. panniformis - non-microcystin producing), and two chlorophytes (Ankistrodesmus falcatus and Raphidocelis subcapitata). Methods A coexistence experiment between C. demersum and the four strains was carried out for six days, with eight treatments and three replicates. The strains were cultivated in ASM1 culture medium, under controlled laboratory conditions. Two treatments were assigned for each strain, one with 6 g.L-1 of the macrophyte, and the control without the plant. Biomasses and growth rates of the strains were evaluated every two days, which were compared through the T-test and two-way ANOVA, respectively. Results The results varied among the strains, with toxic M. aeruginosa being intensely inhibited by C. demersum, with a decrease of 99.5% in its biomass (p<0.001), while non-toxic M. panniformis was less affected by the allelochemicals, with a reduction of 86.2% (p<0.001). Ankistrodesmus falcatus delayed its growth when in coexistence with the macrophyte, decreasing its biomass in 50.4% (p<0.01), while R. subcapitata was not altered (p>0.05). In coexistence with C. demersum, M. aeruginosa exhibited the lowest growth rates (-0.65 d-1), followed by M. panniformis (-0.15 d-1), A. falcatus (0.19 d-1), and R. subcapitata (0.34 d-1), with significant differences between all strains (p<0.001). Microcystis aeruginosa presented higher inhibition rates than M. panniformis (p<0.001), as well as, A. falcatus was more inhibited than R. subcapitata (p<0.05). Conclusions The presence of microcystins could influence the allelopathic responses of C. demersum, that may release more allelochemicals in coexistence with toxic strains of M. aeruginosa. Accordingly, C. demersum can be used in biomanipulation strategies to control toxic and non-toxic cyanobacterial blooms, without damaging other phytoplankton species, like chlorophytes.

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Big things come in small packages: why limnologists should care about small ponds - (2026)

Melissa L. Mullins, Robert D. Doyle

Volume: 31 - Issue: 0

Resumo. Abstract There is a substantial, and increasing, body of evidence that small ponds are critically important in diverse landscapes around the world by providing habitat, processing carbon, and mediating hydrological and nutrient fluxes to other larger surface waters (rivers, lakes, coastal). They are also among the most abundant surface water bodies in many areas. In an urbanizing planet, ecosystem services provided by ponds may become even more important. However, they have been historically neglected by limnologists and including them in global analyses can still be problematic. We propose that more limnologists should include small ponds in research programs; and we argue that these are also ideal systems for teaching the next generation of limnologists as well as for engaging the public.

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Biomass and abiotic variables change in phytotelmic environment in the tank-bromeliad Nidularium longiflorum Ule in tropical forest - (2026)

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 - (2026)

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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Longitudinal dimensions of land-use impacts in riverine ecosystems - (2026)

Rafael Feijó-Lima, Eugenia Zandonà, Bruna Suelen da Silva, Flavia Tromboni, Timothy Peter Moulton, Steven Arnold Thomas

Volume: 31 - Issue: 0

Resumo. Abstract: Aim Rivers are linked longitudinally via the flow of water and the spatial dimensions of the changes in local riparian vegetation are still poorly understood. Recent modifications to the Native Vegetation Protection Law allow reduction of lateral buffer strips and amnesty for riparian vegetation removal, which might increase the fragmentation of native riparian vegetation, especially for Atlantic Rainforest streams. Methods We present two case studies conducted in a stream draining a fragmented landscape in the Atlantic Rainforest. The stream flows through two abrupt transitions (forest-pasture-forest) and we investigated how far the upstream effects of a given riparian condition could be detected in the downstream reach for a suite of variables. Results We show that the effects of land cover propagate downstream for both algal and macroinvertebrate communities. For some variables of interest, these effects might extend up to a km downstream from the transition. Conclusions There is a need to understand how the distribution of riparian forest remnants contribute to maintaining watershed-scale resilience to impacts.

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Mollusks associated with the Avicennia schaueriana (Magnoliophyta: Acanthaceae) roots of a hypersaline estuary in northeastern Brazil - (2026)

Ana Priscila Amancio Muniz, Rafaela Cristina de Souza Duarte, Ellori Laíse Silva Mota, Jessica de Oliveira Lima, Thelma Lúcia Pereira Dias

Volume: 31 - Issue: 0

Resumo. Abstract Aim Avicennia schaeuriana is one of the six species that composes the mangrove forests of Brazil and form mangrove fringes along waterways. The mangrove-roots of the A. schaeuriana act as one of the microhabitats used by the invertebrate biodiversity of the estuarine ecosystem. The present note aimed to inventory the malacofauna associated with roots of Avicennia schaueriana of the hypersaline and inverse estuary, highlighting variations in abundance and diversity along a salinity gradient and different seasonal periods. Methods Three sampling stations were delineated along the course of the estuary. At each station 3 transects of 10 meters were placed, and for each of them 3 sample points were selected, and at each point 3 samples of roots of A. schaueriana were obtained. A total of 108 samples were stored in plastic bags containing 4% formaldehyde and subsequently passed through a screening process, with identification of the associated specimens with the lowest possible taxonomic level. Results A total of 171 specimens was recorded, belonging to 10 species, 7 families, and 9 genera of the Bivalvia and Gastropoda classes. The abundance of the specimens differed between the seasonal periods analyzed. Conclusions The highest species richness and abundance of organisms in the rainy period allows inferences about the importance of the estuarine water cycle in regulating the biodiversity of these environments. Thus, the importance of the maintenance and protection of the mangrove forests composed of A. schaueriana, as well as the need for more in-depth studies becomes evident.

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Monitoring simplification in plankton communities using different ecological approaches - (2026)

Carla Albuquerque de Souza, Karine Borges Machado, João Carlos Nabout, Daphne Heloisa de Freitas Muniz, Eduardo Cyrino Oliveira-Filho, Cleber Nunes Kraus, Rômulo José da Costa Ribeiro, Ludgero Cardoso Galli Vieira

Volume: 31 - Issue: 0

Resumo. Abstract Aim This study aimed to answer: (i) can phytoplankton communities be used as surrogate of zooplankton communities?; (ii) can we use ecological approaches like functional groups (FG) or morphofunctional classification (MBFG) as surrogate for phytoplankton species?; (iii) can we use substitute groups (cladocera, copepod, rotifer or testate amoebae) as surrogate for zooplankton species?; (iv) are the environmental variables’ ordination standards concordant with the ordering patterns of phytoplankton and zooplankton species?; and (v) for both communities, is the spatial pattern of ordination maintained using density data or presence/absence of individuals or lower taxonomic resolutions? Methods The study was conducted in 25 water bodies that supply central-pivot irrigation in the Federal District - Brazil (Rio Preto Basin), in October 2012. We evaluated some physical and chemical variables as well as phytoplankton and zooplankton samples. To evaluate correlation among biological groups, numerical and higher taxonomic resolutions, we performed some Mantel and Procrustes analyses. Results Evaluating the use of substitute groups, comparisons between phytoplankton and zooplankton, FG and MBFG classifications and almost all the comparisons between zooplankton groups suggested concordant patterns. However, the values of r were low, all below 0.70. Biological analyses with phytoplankton and zooplankton can be performed using presence/absence of individuals without significant loss of information, except for MBFG classification and copepods. Data may also be used at genus or family level for copepods and testate amoebae and only data at genus level for cladocerans and rotifers. Different results were found concerning taxonomic resolution for phytoplankton considering that, while being significant, the r value was less than 0.70. Conclusions For environmental monitoring purposes, it is important to sample both phytoplankton and zooplankton communities because one is not surrogate of the other one, in the same way as phytoplankton density and their functional and morphofunctional approaches. On the other hand, to simplify the environmental monitoring, it is possible to adopt presence/absence species data instead of abundance data for both zooplankton and phytoplankton communities, except for copepods and morphofunctional approach. It is also possible to adopt genera level for zooplankton community and family level for copepods and testate amoebae.

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

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

Volume: 31 - Issue: 0

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

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

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

Volume: 31 - Issue: 0

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

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

Rodrigo Assis Carvalho, Francisco Leonardo Tejerina-Garro

Volume: 31 - Issue: 0

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

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

David Dean Biesboer

Volume: 31 - Issue: 0

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

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

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

Volume: 31 - Issue: 0

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

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

Ng Haig They, David da Motta Marques

Volume: 31 - Issue: 0

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

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