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  • Land use and cover drives taxonomic and functional diversity of aquatic insects across tropical streams.

    Contieri, Beatriz Bosquê (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2024)
    Streams are ecosystems closely dependent to their adjacent ecotones, representing important water recharge sources for drainage networks and playing a central role in global nutrient cycling. The primary source of energy in streams comes from allochthonous material originating from riparian vegetation, which becomes available through processing performed by aquatic organisms. Modifications in the composition of the adjacent vegetation, which can be natural or due to land use and occupation, may alter the ecosystem functioning. Despite their critical role in preserving biodiversity, riparian ecosystems face continuous alteration or even removal. Anthropogenic activities, such as excessive use of pesticides and fertilizers in rural areas, and catchment imperviousness in urban areas, for example, negatively affect water quality, leading to contamination and disruptions in the food chain. Studies predominantly focus on densely forested riparian zones, composed mainly of trees, but natural riparian zones with herbaceous or shrubby vegetation have effects less explored when compared to woody vegetation. These include differences in channel stability and morphology, because woody vegetation is more suitable for stabilization of stream banks than herbaceous vegetation. These differences are particularly relevant for organisms like aquatic insects, that play a fundamental role in energy transfer to higher trophic levels and are widely used as bioindicators, given their sensitivity to environmental changes. Metrics such as richness and abundance are commonly used to estimate levels of biodiversity, but for a comprehensive understanding of the role of such species in ecosystem functioning, it is essential to also consider functional diversity. In this context, the following aspects were assessed: i) the effect of sub-basin riparian vegetation stratum (tree x shrub) on the composition and beta-diversity of aquatic insects in tropical streams and ii) the relationship between different levels of anthropogenic intensification and taxonomic and functional indices of aquatic insects, as well as their relationship with environmental variables. The study concluded that functional diversity was more sensitive than taxonomic diversity to changes related to land use and cover in riparian vegetation. Vegetation stratum (tree and shrub) significantly altered total functional diversity, while anthropogenic intensification significantly reduced all functional indices analysed and only one taxonomic index. The results obtained and analysed contributed to an analytical understanding of the functioning of tropical aquatic ecosystems. Furthermore, the study provides valuable parameters and insights for future predictions and mitigation strategies in environments affected by human activities.
  • Turnover e aninhamento de hifomicetos aquáticos em riachos subtropicais de diferentes usos da terra.

    Rasvailer, Vinícius da Silva (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2024)
    Streams, small rivers, are endowed with exclusive energetic dynamics: decomposition of allochthonous material, and formation of microhabitats and ecotones between aquatic communities and riparian vegetation. Regarding this input of organic matter, aquatic fungi make up most of the biomass of organic matter decomposers, they are biomineralizers of foliar nutrients and through decomposition link the matter to the entire trophic network. Aquatic fungi are a polyphyletic group adapted to this environment, and have different taxonomic levels grouped together. These microorganisms are the target of ecological studies due to their important, still their spatial distribution still lacks elucidation, as well as the influence of limnological on biotic parameters. The fungal communities, composition and beta diversity, were investigated in this study separated into two approaches: i) the beta diversity of aquatic fungi in streams under different land uses; ii) the nesting of fungal eDNA sequences in a protected area and an impacted area. The biotic data were obtained from leaf mixes, and represent the biodiversity of the aquatic FUNGA present in streams of the Atlantic Forest, being pioneering studies for the subtropical region. Furthermore, the results may contribute as a basis for future studies within the mycology of aquatic environments. Approach I, in a taxonomic approach, demonstrated fungal diversity in presence of ambiental heterogeneity. Approach II, through metabarcoding, demonstrates the sensitivity of the use of genomic databases in ecological analyses. The results presented here reinforce the need for management and conservation plans for riparian vegetation, which forms the aquatic microecosystem, used by fungi for their decomposition and other ecosystem functions.
  • Impactos das mudanças globais nos ecossistemas aquáticos: uma análise das respostas de microrganismos sob diferentes estressores ambientais.

    Matos, Matheus Henrique de Oliveira de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2024)
    Environmental changes occur at a global level and are enhanced by human activities, with significant impacts on natural ecosystems by affecting the temperature, nutrient load and input of organic debris in freshwater bodies or aquatic systems. In the first section, we investigated the impacts of increased temperature, nutrient input, predation by fish and a reduction in organic detritus on the community of testate amoebae, rotifers and periphytic cladocerans over 49 experimental days. The second section analyzed the effects of increased temperature, nutrient input and reduced organic detritus on the testate amoeba community during 160 experimental days. The experiments were carried out in mesocosms with three temperature conditions: control (referring to the ambient temperature), constant increase of +4°C and fluctuation between 2°C and 6°C above the control, with and without enrichment by nitrogen and phosphorus, and reduction of organic detritus, controlled by previous additions of this detritus. In relation to the results of the first section, the density of the groups analyzed was significantly impacted by the increase in temperature, while the other stressors explored in this work did not represent a significant influence on the abundance of the communities. As for community composition, the presence of nutrients had a more predominant impact on community structure, although specific species distribution patterns were not identified. For the second section, it was evident that warming resulted in a reduction in species diversity (demonstrated by the Shannon index), with a tendency for species richness to decrease in the face of this stressor. On the other hand, nutrient enrichment was responsible for an increase in richness, with time being a relevant factor in this context. As for changes in community density, nutrients and time emerged as the main factors influencing these changes. Analysis of species diversity using the Shannon index revealed greater diversity in the temperature control treatments, with time exerting a significant influence on community structure throughout the experiment. For species composition, the βtotal diversity analysis highlighted the importance of temperature, presence of detritus and time. The βrepl and βrich components were notably affected by temperature and time, indicating changes in species identity.
  • Phylogenetic systematics of Mesonauta Günther 1862 (Cichliformes: Cichlidae: Cichlinae).

    Oliveira, Rianne Caroline de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2024)
    Cichlids have evolved into models for studying the evolutionary history of Neotropical fish. Many authors attempted to recover the group's phylogeny using morphological and molecular data, presenting satisfying solutions across a wide range of genera. However, intrageneric relationships remain obscure in a number of genus, potentially complicating species delimitation. Mesonauta presents six distinct species that are highly valued by aquarists. Currently, there is no proposed phylogenetic relationship between its species; however, it has a wide geographic distribution and phenotypic variations, with the possibility of new species not yet described. Species of the genus were delimited using molecular and morphometric data from preserved and deposited species in ichthyological collections. From the six previously described species, COI delimitate different species, since two of them (Mesonauta egregius and M. guyanae) were not corroborated by delimitation analysis and two are putative new species, showing six different species: M. mirificus, M. festivus, Mesonauta sp. “Pantanal”, M. acora, Mesonauta sp. “Amapá” and M. insignis. The results showed a new basis for studies within the genus and further research is needed to understand the wide distribution of M. mirificus. Mesonauta's monophyly was tested and the relationships between species by constructing concatenated cladograms based on molecular characters (COI, 16S) using three phylogenetic methods, from which two main clades were recovered a new species of Mesonauta was described from the Amapá Grande river basin, based on morphological and molecular characteristics, in a region affected by the presence of mercury. This is the first step in investigating the molecular phylogeny of Mesonauta, which showed intrageneric relationships based on molecular data, enabled the description of a new species of the genus and provided information for future research on the evolutionary history of the group.
  • Patterns of parasitic infections in fish from a floodplain: use of functional traits and phylogeny from fish and parasites.

    Lehun, Atsler Luana (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2024)
    Functional traits are the measurable properties of organisms that influence their performance through their effects on individual growth, survival, and reproduction. Therefore, the choice of functional characteristics is essential for drawing solid ecological conclusions and predicting ecosystem properties and interactions between organisms. The structure of the parasite community can vary over time and space, resulting from variations in host characteristics, phylogenetic relationships, and environmental characteristics. These can be examined at different levels of diversity: alpha (local diversity) and beta (variation in community composition between locations), including multiple facets such as taxonomic (TD), functional (FD), and phylogenetic (PD). We evaluated which host characteristics may be determinant in the composition of fish parasites from the upper Paraná River floodplain; and compared different facets of endoparasite biodiversity at the sampling unit level (α diversity or parasite diversity at the level of an individual host) and between sampling units (parasite diversity within (β1) or between (β2) host individuals of a species). The host's diet was the factor that had the greatest influence on the composition and similarity of endoparasites in floodplain fish. The α diversity of endoparasite species differed mainly in terms of TD and PPD. Regarding β diversity, the parasite communities presented patterns grouped at different levels (β1 and β2, respectively). To explain patterns in endoparasite diversity, functional traits, and fish phylogeny act as drivers of parasite community structure, with diet being one of the main factors. And the assembly patterns in the endoparasite infracommunities of different floodplain host species reflect the characteristics of their component and composite communities.
  • Efeitos de ações antrópicas sobre as interações bióticas entre os peixes de uma planície de inundação Neotropical: alterações nos padrões de coocorrência de espécies.

    Andreotti, Gustavo Faccin (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2024)
    The freshwater ichthyofauna is largely threatened by the anthropogenic impacts in these ecosystems. The climatic changes caused by human actions and dams’ constructions concerningly affects the freshwater fishes, including its biotic interactions network. Thus, this work aimed at evaluating the Upper Paraná River floodplain’s (UPRF) ichthyofauna under the impacts caused by climate changes, years of extreme drought an extreme flood, and under the impacts caused by the construction of an upstream dam, the Sérgio Motta Hydroelectric Power Plant, Brazil. The sampled years were classified in extreme drought, neutral and extreme flood, according to the predominant characteristics of its hydrological regime, and in pré-damming years, before the upstream hydroelectric power plant construction and reservoir’s flooding, and post-damming years. The abiotic and hydrometric variables were concurrently sampled with the abundance of fish species, allowing to exclude the environmental variables’ effects over the species’ cooccurrence, using multivariate generalized linear models with latent variables. The force of the interspecific biotic interactions was obtained through cooccurrence values for each pair of species, visualized through negative, neutral, and positive values. Regarding the results involving the hydrological regime influence, it was observed differences between drought, neutral and flood years, with stronger cooccurrence values between the UPRF’s ichthyofauna in drought years (for positive and negative values). Regarding the results involving the construction of the UPRF’s upstream dam, it was observed differences comparing the pré-damming and post-damming years cooccurrence patters, with predominantly positive values in post-damming years, and predominantly neutral cooccurrences in pré-damming years. These work results indicate the increment of the cooccurrence values between a floodplain’s fish species due to extreme droughts and upstream dams’ constructions, once the cooccurrence values were more intense under these conditions. Stands out the importance of biotic interactions for the elaboration of management plans and freshwater species conservation in response to anthropogenic actions.
  • Landscape of the Tocantins-Araguaia Basin: challenges, dynamics, and future prospect for conservation.

    Schmitz, Marcelo Henrique (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2024)
    Tropical deforestation and unsustainable policies are current challenges in the Tocantins-Araguaia River basin (TOAR), located in the heart of the Cerrado biome. In the first article, the dynamics of land use were analyzed over a period of 35 years (1985-2020). The results showed relevant anthropogenic changes driven by agricultural activities, resulting in major vegetation losses, especially in natural forests, savannas and pastures. During this period, there was an exponential growth in pastures and agriculture to the detriment of natural categories. Part of TOAR's stable areas corresponded to legally protected areas. Considering the challenges highlighted in the first article, in the second, future scenarios of land use and cover (2015-2045) were analyzed under three area demand scenarios: "Business-as-usual" (BAUS), "Conservation-based" (CONS) and "Production-based" (PROD). Analysis of future projections indicated the persistence of deforestation and fragmentation patterns, especially in the PROD scenario. The notable predicted loss in Natural Forest and Savanna, even in the conservation scenario, highlights the urgent need for proactive conservation efforts, stricter regulations, and enhanced environmental considerations in development plans. Considering the context explored and discussed in the articles presented, this study not only highlights the complexities of the past dynamics of land use in TOAR, but also points to the urgency of coordinated actions to ensure a sustainable future. The persistence of deforestation even in conservation-oriented scenarios raises questions about the effectiveness of current protection measures, emphasizing the need to re-evaluate and strengthen conservation strategies. The TOAR is at an ecological crossroads, requiring concrete and targeted efforts on the part of decision makers, researchers and the population to ensure its sustainable management and the preservation of its unique ecosystems, biodiversity and cultural heritage amidst increasing anthropogenic pressures.
  • Foraging in the Anthropocene: exploring the dynamics of reservoir and plastic pollution in freshwater organisms.

    Yofukuji, Kátia Yasuko (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2024)
    Freshwater ecosystems face serious threats in our increasingly human-dominated world, particularly from pressures such as impoundment and plastic pollution due to mismanagement of plastic waste. Both anthropic disturbances have been linked to global declines in freshwater area and biodiversity. Evaluating how these disturbances affect organisms is of extremely importance for conservation purposes and the implementation of effective public policies and management strategies.The effects of river impoundment and plastic pollution through the lens of fish trophic ecology were assessed. A global synthesis was conducted to unravel the current knowledge on plastic occurrence regarding freshwater fish and invertebrates. The trophic ecology of fish from the Itaipu reservoir was assessed, revealing shifts in diet and trophic structure along longitudinal gradients induced by damming. The transition from predominantly allochthonous to autochthonous resources significantly influenced the spatial distribution of trophic guilds across the reservoir. We highlighted changes in dominant guilds with the reservoir's aging, particularly the rise and fall of planktivores and aquatic insectivores. Microplastic occurrence in a Neotropical fish community was evaluated. Low incidence of plastic ingestion was evident, with fibers and fragments of plastics identified as polyamide, polystyrene, and polyethylene. Fish from the lacustrine zone, insectivores, and benthopelagic species showed a significant correlation with plastic ingestion. A systematic review synthesizing literature on plastic occurrence in freshwater fish and invertebrates was conducted globally. It was highlighted that reporting on plastic occurrence has primarily focused on fish, with recent efforts acknowledging the threat to invertebrates. Biological and ecological factors were explored to influence plastic prevalence, revealing limited predictive power for increased plastic occurrence in both groups, emphasizing the vulnerability of both taxa to plastic pollution. We emphasize the critical need to understand and address the impacts of impoundment and plastic pollution on freshwater ecosystems to ultimately safeguard freshwater biodiversity.
  • Diversidade beta taxonômica e funcional de Rotifera em quatro grandes planícies de inundação neotropicais, Brasil.

    Delgado, Tayná de Almeida (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2023)
    The taxonomic and functional beta diversity of rotifers in floodplains can help understand responses to environmental changes as well as ecosystem dynamics. The taxonomic and functional beta diversity of rotifers was analyzed in four neotropical floodplains (Amazonas, Araguaia, Pantanal, Paraná River), in order to verify whether there are differences in the composition and structure of the rotifer community in the different plains and within each plain between the different periods. Differences in taxonomic and functional beta diversity were tested using multivariate statistics. 128 species of rotifers were identified, 84 in the Paraná River, Amazonas (78), Araguaia (77) and Pantanal (75). Functionally equal species were grouped together. The plains of the Paraná and Amazon rivers were those that showed a significant difference in taxonomic and functional beta diversity during the rainy season. During the dry period, the plains that showed differences were Araguaia and Amazonas and the Paraná and Araguaia rivers. Functional beta diversity did not show a significant difference during the dry period. Changes in taxonomic beta diversity can result in long-term loss of ecosystem function, potentially altering its functioning. Therefore, the study of taxonomic beta diversity must be followed by functional beta diversity to better understand the dynamics and functioning of the ecosystem, as well as its preservation.
  • Análise espaço-temporal do ictioplâncton em uma sub-bacia do alto rio Paraguai: conhecendo sua contribuição para o Pantanal brasileiro.

    Souza, Mateus Babichi Veiga de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2023)
    The spatial and temporal distribution of ichthyoplankton, taxonomic composition, and its relation to environmental factors were analyzed in the upper Taquari River sub-basin, upper Paraguay River, aiming at the conservation of Pantanal ichthyofauna. Egg and larval collections were conducted at eleven sampling points between October and March of 2017/2018 and 2018/2019. Significant differences were observed between collection points, months, and years, with higher ichthyoplankton densities in the Coxim and Taquari rivers, particularly between November and January. Twenty-eight genera and/or species of fish were identified, including ten long-distance migratory species. Eggs density showed a negative correlation with water temperature and rainfall. For larvae, water transparency and rainfall were both significant, negatively influencing larval abundance. However, different species tend to occur in environments with distinct abiotic qualities. Yolk-sac, pre-flexion, and flexion larval development stages were distributed throughout the sub-basin, especially near the Pantanal. Considering the data and analyses presented in this study, the importance of connectivity between these environments, specifically between the plateau and Pantanal, is evident, highlighting the significance of the entire sub-basin for fish reproductive processes. Thus, studies highlighting ecological processes affecting ichthyoplankton distribution provide valuable information for ecosystem conservation and contribute to fisheries stock management.
  • Threatened, rare, and functionally rare species of fish in the Upper Paraná River floodplain: ecological perspectives and conservation.

    Nunes, Lucas Machado (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2023)
    Understanding how the loss of a species is related to its functional role in a community or ecosystem is essential. To explain why some species are more prone to be endangered than others is a major goal of conservation biology. Beyond the loss of a species, the loss of ecological processes that sustain ecosystem functioning can be the most critical influence. To evaluate the threatened, taxonomical, and functional rare species, we used fish data from 2000 to 2019, collected from nine sampling points on the Upper Paraná River floodplain (the large rivers on the floodplain, Ivinheima, Baía and Paraná, and six lakes eventually connected to the rivers: Ventura and Patos lake (Ivinheima River), Guaraná and Fechada Lakes (Baía River), Ressaco do Pau Velho and Garças Lake (Paraná River). Fish were collected using gillnets with different size mesh, and the number of individuals caught as an estimation of abundance. We obtained geographic range, habitat specificity, and population size for the taxonomical rarity index. To estimate the functional rarity, we used eleven functional traits in the composition of a functional distance matrix, together with and relative abundance matrix to obtain Functional Uniqueness and Functional Restrictedness. The outcome was a 58 species list. 76% of the species shared taxonomical and functional rarity, four were endangered, and 17 species are considered exotic to the Upper Paraná River.
  • Sobre a invasão de parasitas de peixes em ambientes de água doce: desenovelando eventos de spillback e spillover.

    Moraes, Luddy Searom Carias de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2023)
    Free-living invasive species are frequently considered in ecological studies, while parasitic invaders are neglected. Given the current concerns regarding emerging diseases, parasites circulating in wildlife communities have demonstrated their significant impact on the environment and public health. In this context, this study aims to conduct a systematic review in order to identify the focal areas of parasite invasions in freshwater fish worldwide and the characteristics of hosts and parasites associated with these invasion events. Searches were conducted in Web of Science and Scopus, yielding 16,121 studies, of which 233 published between 1974 and 2021 were eligible according to pre-established criteria, with 834 invasion records. There was no trend regarding increase or decrease in studies on this subject when controlled for academic production growth. The main groups of recorded parasites were Platyhelminthes, Nematoda, and Arthropoda, mostly endoparasites, generalists, and with heteroxenous life cycles. Spillover events were found to be more prevalent compared to spillback across all continents. The North American and European regions exhibited greater abundance of invasion records, which can be attributed to higher sampling efforts in these areas. Regarding the introduction routes of parasites in the analyzed studies, pisciculture, followed by aquarism and ballast water, were identified as the main pathways. However, a considerable number of studies did not report the invasion route or lacked knowledge regarding it. The processes related to spillover and spillback are complex, and the higher frequency of spillover events seems to be due to the perception that invasive parasites infecting native species are more severe than native parasites infecting invasive species. Most of spillover events are associated to parasites indigenous to Asia, where is the global focus of fishing trade. These findings highlight the importance of considering parasitic invaders in ecological studies, and the potential association of commercial routes to the invasion events registered herein.
  • Fatores responsáveis pela variação dos componentes da diversidade beta na assembleia de peixes em riachos de cabeceira.

    Pessoa, Leonardo Antunes (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    Fish assemblage composition varies across time and space, and beta diversity has been a valuable tool for quantifying this variation and understanding associated mechanisms. Understanding which factors determine the action of these mechanisms is fundamental for headwater stream management and conservation projects. Therefore, was evaluated which component of total beta diversity (species replacement or difference in richness) is most representative for the fish assemblage between streams, identified the scale of effect of land use on this assemblage, and evaluated the relative influence of land use, local environment and distance between collection points on beta diversity components. The study was carried out in 12 headwater streams close to and located in the municipality of Maringá, Paraná, Brazil. The percentage of land use classes was measured at 11 spatial scales, five buffers from the sampled section and six from the water network upstream of the sampled section. The data was analyzed using Redundancy Analysis based on distance and variance partition. The results showed that species replacement was the most important component for total beta diversity, with land use in buffers 100 and 500 meters from the sampled section considered the scale of effect for the variation of the components. Land use and local environmental variables were more representative for total beta diversity and richness differences and the distance between collection points for species replacement. It was concluded that land use and local environmental variables select fish species, reducing richness in urban areas, while the dispersal limit acts on species replacement. Therefore, it is suggested that management and conservation projects should be focused on land use, conserving or restoring riparian forest, which would improve the local quality of streams, mainly urban streams, which are the most altered.
  • Influência de fatores bióticos e abióticos para a diversidade e abundância de invertebrados aquáticos ao longo de uma planície inundável Neotropical.

    Amo, Vanessa Ernandes de (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    Weather events such as El Niño and La Niña alter the water level amplitude in floodplain systems. Some groups of benthic invertebrates, such as Chironomidae, respond to these oscillations, which makes this community an important tool in climate change studies. In addition, changes caused by climate change in aquatic environments may favor the introduction of invasive species, such as Limnoperna fortunei. This species, which is a filter feeder, feeds mainly on organisms such as phytoplankton, which can lead to a reduction in its abundance. To this end, we analyzed how weather events affect the Chironomidae community and how L. fortunei larvae densities can affect the densities of phytoplankton and protozooplankton communities in the upper Paraná River floodplain. We observed that weather events did not have a negative effect on Chironomidae community attributes and that L. fortunei larval densities were positively correlated with high phytoplankton and protozooplankton densities, due to high food supply. Another extremely importante highlight not recorded in the literature consulted, refers to the fact that hydroelectric act as envitonmental filters in the densities of L. fortunei, as the turbines damage the larvae, which affects their survival In view of this, we conclude that studies that address climate effects on species diversity and the impacts that invasive species cause on local communities are of great importance to assess current and future changes in ecosystems and thus develop management plans.
  • Relações entre a assembleia de peixes e a biomassa, riqueza de espécies e diversidade funcional de macrófitas aquáticas.

    Costa, Isadora Cristina Bianchi (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    The aquatic macrophytes are considered an essential component of freshwater ecosystems, influencing the structure of fish assemblage that use macrophyte stands in search of food resources and refuge. These plants affect the fish trophic interaction, reducing the competition and predation pressure between the organisms. The goal of this study was to evaluate the relationship between biomass, richness and functional diversity of aquatic macrophytes and theabundance, richness and fish size that use plants as habitat. Fish and macrophytes were sampled in the drought period, in 30 macrophytes stands along a 13.7 km long stretch in the Baía river, located in the Upper Paraná River floodplain. The fish were captured using plexiglass, and the macrophytes were sampled using a square. The relationship between the abundance and richness of fish and the biomass, functional diversity and richness of macrophytes was tested using a generalized linear model (GLM). The relationship between the size of individuals and the biomass of plants was tested using a linear mixed model (LMM). Were captured 25 fish species, totaling 4648 individuals, and 18 macrophytes species. Our results indicate that abundance and richness of fish responded negatively to plant biomass and showed a positive trend in relation to macrophyte richness. However, significant values were verified only in the relationship between abundance of fish and plant biomass, which indicated that this variable may respond better to these changes compared to fish richness. The relationship between macrophyte functional diversity and abundance of fish, showed a significant non-linear response,confirmed bysignificance value, obtained throughathird-orderpolynomial model,being higher in intermediate values of functional diversity, which is associated with greater structuring provided by plants alongofthe gradient.The total length of fish decreased as plant biomass increased, which indicates that the small interstitial spaces in habitats with high macrophyte biomass can restrict the body size of fish, affecting their movement. These results suggest that biomass and functional diversity of macrophytes can influence fish assemblage, as abundance decreases in more complex stands and increases in stands with intermediate functional diversity. The body size of fish also decreases in places with higher plant biomass. Theresults show that macrophytes can structure an environment, modifying the compositionof fish assemblages, and even being able to select characteristics of these animals according to structural complexity.The plantbiomassinfluencesthe abundance and the body size of fishes, reducingthe significant roleofmacrophytes intheformation andselection of aquatic habitats.Thus, this study emphasizes the importance ofpreservationofaquatic macrophytes,protectingthe biodiversity of freshwater ecosystems.
  • Estrutura populacional de Jacaratia spinosa (Aubl.) A. DC. (CARICACEAE) no Parque Estadual de Vila Rica do Espírito Santo (Fênix, PR, Brasil).

    Assad Filho, Nabi (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2001)
    The present study refers to the survey of the population structure of Jacaratia spinosa, in the riparian forest of the Ivaí River, located in the State Park of Vila Rica do Espírito Santo, Municipality of Fênix, PR. Sampling was carried out from May to June 2001, in an area of 1ha, divided into 25 plots of 20m x 20m. Forty-five individuals were sampled, 20 young and 25 juveniles/adults, distributed mainly in the range from 40 to 100 m from the river bank. Cluster analysis indicated the existence of four groups, related to the density of juveniles and juveniles/adults, per plot and the Spearman correlation test showed that the groups of juveniles are independent of the distance with the juveniles/adults. Higher percentages of number of individuals were verified in the lower classes of diameter and height.
  • The trophic dynamic of fish from the Upper Paraná River Floodplain through stable isotopes : 20-year scenario of serial impoundments, biological invasions, and protected areas.

    Santos, Driele Delanira dos (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    The Paraná River basin is affected by a series of impoundments that alter the natural river flow, with significant impacts on the water's chemical and physical characteristics with serious consequences for the aquatic biota. The Upper Paraná River Floodplain (UPRF) suffered biological invasions directly influenced by two damming events and, due to its importance for the conservation of biodiversity, it also received mitigation measures with the installation of protected areas in its surroundings. Considering the potential consequences of impacts caused by extensive flow regulation and biological invasions, but also mitigation measures, this study aimed to investigate long-term changes in the trophic dynamics of UPRF fish through the analysis of stable isotopes. Analyzes were carried out in three periods (the early 2000s, 2010s, and 2020s) regarding food chain energy sources, trophic niche, and trophic position of fish from different guilds in the floodplain associated with the Paraná River and the floodplain associated with the Ivinhema River that make up the UPRF, in the years following the installation of a dam directly upstream of the floodplain and the creation of protected areas around the plain. The results show that in the plain associated with the Paraná River, an invasive fish is inserting carbon from an invasive macrophyte into the green food chain, and a native detritivore fish is probably moving to lagoons to utilize the abundant detritus from native emersed macrophytes. In the floodplain associated with Ivinhema, despite the more restrictive protection area in its surroundings, the riparian vegetation did not become an important carbon source, only the emersed macrophytes increased their contribution to the fish. Still, fish from both systems showed an increase in the trophic niche in the second studied period, potentially due to the occurrence of El Niño, which caused the largest and longest flood in the analyzed period. Thus, our study reveals that invasive species can replace native food sources, alter local food chains, and amplify the negative consequences of impoundments. Furthermore, we reveal that the trophic dynamics of fish species from different guilds continue to suffer from anthropic impacts, despite the protected areas surrounding the floodplain. Therefore, measures that mimic the natural flow and water fluctuations would make the positive effects of protected areas tangible for the functioning of aquatic communities.
  • Efeitos do alagamento e suspensão hídrica na morfologia e fisiologia em plantas jovens de Peltophorum dubium (Spreng) Taubert (Fabaceae).

    Lourenço, Luiz Fernando Gonçalves (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    Riparian zones are subject to water variations, flooding and drought, altering the characteristics of the environment, which can cause stress in plants that, in response, can alter their morphological and physiological characteristics. With this, we aimed to analyze how: (i) water variations (waterlogging and water suspension) can affect morphological characteristics and their growth? (ii) can they generate changes in chlorophyll and total soluble carbohydrates content? (iii) can physiological characteristics promote plant recovery when returning to field capacity? Peltophorum dubium (Sprengel) Taubert plants were maintained at field capacity (control), waterlogging and water suspension for 15 days, followed by submission to the recovery treatment for 25 days, for morphological, physiological and survival evaluation. Morphological characteristics, growth parameters and chlorophyll and total soluble carbohydrate contents were analyzed; at the end of the experiments, the number of surviving individuals was counted. Waterlogging caused yellowing of leaves and appearance of hypertrophied lenticels and water suspension caused leaf wilting followed by abscission. The stress induced by water suppression negatively affected the fresh and dry biomass of the leaves, stem and root, the number of leaves and the diameter of the stem, in relation to waterlogging the height of the aerial part, fresh biomass of the root, and the diameter of the stem showed significant differences, when compared to the control. Regarding the chlorophyll contents analyzed, only the chlorophyll a/b ratio showed significant differences between the water suspension treatment and the control and waterlogging treatments. The analyses of soluble carbohydrate contents in leaves and roots indicated that the water suspension differed significantly from the control and waterlogging treatments. After the end of the recovery treatment, all post-waterlogging plants survived, while post-water suspension plants showed no signs of recovery. Although waterlogging negatively affected the plants in their leaves and growth parameters, the results indicate that the investigated species has greater tolerance to this type of stress when compared to that subjected to water suspension.
  • Primeiro registro de miniaturização em Parodontidae (Actinopteri: Characiformes), com a descrição de quatro novas espécies nas bacias do alto rio Paraná e rio São Francisco.

    Cardoso, Marcelo Henrique Fressatti (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, 2023)
    The fish de the genus Apareiodon belonging to the family Parodontidae comprises 14 valid species. They are rheophilic species, usually living in places with running water e rocky bottom. The three genera can be differentiated by the absence e presence de anatomical characters. Miniature fishes are those that have reduced standard length in the adult stage, compared to non-miniature species, relative to non-miniature species, and are often accompanied by pedomorphism. Miniaturization can be separated into two groups: those with identical shape to non-miniature species but reduced size, e those with reduced size with juvenile characteristics. In this paper, the first four miniature species de the genus are described. The new species are: Apareiodon sp. n. 1 known from a marginal pond of the Rio Verde, upper Paraná river basin; Apareiodon sp. n. 2 known from the Rio Mourão, upper Paraná river basin; Apareiodon sp. n. 3 known from Lagoa 45 and Lagoa do Parente from the Rio Turvo, upper Paraná river basin e Apareiodon sp. n. 4 known from a marginal pond of the Rio Boa Vista, São Francisco river basin. The species differ from their congeners by their reduced size, a black spot on the caudal peduncle, more rays on the pectoral fin e fewer cusps on the teeth. The lack of research and data on miniaturization in this genus regarding taxonomic, ecological e natural history aspects is highlighted,and this work is the first record containing data and information on the group. The miniaturization, taxonomic aspects e geographical distribution de the new species are discussed.
  • Influência da “ceva” na fauna endoparasitária de Brycon falcatus (Characidae: Bryconinae) do rio Teles Pires, sul da Amazônia.

    Boller, Larissa Liber de Almeida (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2023)
    Studies on endoparasitic fauna provide valuable biological information, such as migration habits, population breakdown and host feeding habits. Several species of endoparasites are transmitted via trophic web and have complex life cycles with two or more hosts, which characterizes the trophic interactions between organisms. In this sense, the objective of this work was to evaluate the impact of attractant feeds (soybeans, corn) on the diet and on the endoparasitic fauna of Brycon falcatus, collected in the Amazon basin. The specimens were collected using a line hook, fishing rod and gill nets. Then the fish were euthanized and the stomach and intestines of each specimen were analyzed fresh. Two species of nematodes were identified, Procamallanus (Spirocamallanus) inopinatus and Philonema sp.. The diet of B. falcatus was composed of aquatic and terrestrial insects and attractant feeds, which are composed of soybeans and corn, being considered as an item of anthropic origin, which characterized it as an omnivore with a tendency to herbivory. The aquatic insects found in the diet of B. falcatus may possibly act as intermediate hosts for P. (S.) inopinatus and Philonema sp.. Among the endoparasites, it was observed that P. (S.) inopinatus presented greater abundance, intensity and prevalence parasitic compared to Philonema sp.. It was found that non-parasitized individuals had a higher condition factor than parasitized individuals. There was a significant difference in the condition factor between individuals who had the presence or absence of attractant feeds in the digestive tract. Consequently, B. falcatus was influenced by anthropic items on Kn, as specimens that did not consume this food item had a higher Kn compared to fish that ate attractant feeds. Based on the results obtained, it is possible to verify that the diet of B. falcatus had a greater representation of natural food items, such as stems and barks, Coleoptera and Ephemeroptera. However, there was an impact of attractant feeds ingestion on the relative condition factor of the specimens, requiring greater inspection to avoid this anthropic action that can negatively affect the environmental and the local fauna.

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