RSS 1.0Universidade Estadual de Maringá, Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, Dissertações e Teses
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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.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.
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Efeitos do alagamento e suspensão hídrica na morfologia e fisiologia em plantas jovens de Peltophorum dubium (Spreng) Taubert (Fabaceae).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.
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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.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.
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Influência da “ceva” na fauna endoparasitária de Brycon falcatus (Characidae: Bryconinae) do rio Teles Pires, sul da Amazônia.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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Efeito do aquecimento e do uso do solo sobre a comunidade de protistas ciliados planctônicos.Anthropogenic actions have contributed significantly to the increase in temperature and the addition of nutrients to aquatic bodies. Among the organisms that make up the aquatic microbiota, ciliated protozoa are able to respond quickly to environmental changes imposed on these systems. Thus, the objective of this work was to experimentally investigate the effects of warming and nutrient enrichment on the patterns of richness, density and species composition of the ciliate community, using mesocosms as a model system. Effects on all attributes studied were produced only by nutrient enrichment, while changes in temperature and detritus concentration did not produce significant changes in the community. It is suggested that the bottom up effect is probably the control mechanism that is prevailing in the structuring of the community of ciliate protists in this study, as the high nutrient load is probably providing greater availability of niches, through food resources, which favor the increase the abundance and richness of protists.
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Redescrição de Bryconamericus iheringii (Boulenger, 1887) (Characiformes: Characidae).Bryconamericus iheringii (Boulenger, 1887) was described from the laguna dos Patos basin, where it is widely distributed. Together with other species that occur exclusively in the south of Neotropical region, B. iheringii forms a clade characterized by the subterminal mouth, always at level of ventral margin of the orbit; 5–6 rows of scales above lateral line; teeth of the outer row of premaxilla aligned; and dentary with teeth gradually decreasing in an anteroposterior direction. The lack of taxonomic studies regarding B. iheringii makes it difficult to identify it in relation to other congeners, as well as to determine its area of occurrence. The objective of this work was to restrict Bryconamericus iheringii to populations that are phenotypically closer to the lectotype of the species. For this, 225 specimens from the laguna dos Patos and rio Uruguai basins were analyzed. Of these, 131 specimens were identified as B. iheringii and supported the redescription proposed here. Furthermore, we present a new diagnostic proposal for B. ikaa and B. ytu. Bryconamericus iheringii is diagnosed from B. ikaa by color and B. ytu by the number of gill-rakers. Bryconamericus pliodus and B. boops are maintained as junior synonyms of B. iheringii. Finally, we suggest carrying out analyzes in populations distributed in other basins (upper and lower Paraná basins) to determine whether or not these populations belong to B.
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Efeito do uso da terra na qualidade da água de riachos neotropicais em múltiplas escalas espaciais.Increased human activities are threatening watershed landscapes and water quality monitoring and multiscale analysis have become essential tools for water resource management. In order to evaluate the influence of land use on water quality at different spatial scales. Twelve low-order streams were selected in which limnological samplings (physical, chemical and biological) were carried out during the dry season. The water quality index was used, based on the quality standards of Canada and Brazil. The percentage of land use was measured at local scale and water network. The environmental variables were summarized through Principal Component Analysis (PCA) and subsequently used in the construction of Linear Models (lm) for each axis resulting from the PCA, using the percentage of land use classes and land slope. The presence of contamination by Lead, Chromium, Copper, Nitrogen and Escherichia coli was verified. It was found that the Canadian Water Quality Guidelines for the Protection of Aquatic Life (CWQG-PAL) were more effective in protecting aquatic ecosystems than the National Council for the Environment Resolution No. 357/2005 (CONAMA 357/2005), due to its constant, more rigorous and sensitive monitoring. Agricultural activities and those inherent to urban areas were the main responsible for the degradation of water quality. The negative impact of agriculture was observed both on a local scale and on the water network, while urban areas had a negative effect only on the water network scale. It was also found that forests on a local scale are associated with improved water quality. It emphasizes the importance of the multiscale approach in the management of watersheds and in public policies, which should consider not only forest preservation on a local scale, but also human activities throughout the watershed. It is recommended the need for a reformulation of CONAMA Resolution No. 357/2005 with a methodology applied to conservationism and holistic, as well as the importance of public policies and changes in the law of the Brazilian Forest Code on areas of permanent preservation.
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Ostracoda (Crustacea) biodiversity: a taxonomic and functional approach.The impacts of human actions, as deforeations, pollution and introduction of species have been causing negative effects on the environment. The extinction of species, and change of distribution range, are some of them, especially in the aquatic environment were it is observed a hogh richness compared to its extension. Thus, the knowledge about biodiversity is of extreme importance conservation of ecosystems. Ostracods are one example of a group constantly affected but ill studied. It was performed a revision of Cyprettinae s.l. from circumtropical regions, using morphological taxonomy. The first step in the revision of Cyprettinae s.l. was redescribe the type species of Cypretta Vavra, 1895 from the original type material, discuss the morphology and diagnosis of the genus. After that it was described two new species from Pseudocypretta Klie, 1932 genus from South Africa and Brazil; and described a new genus and four new species from Brazil. With the redescription of the type species of the Cyprettathe diagnosis characters for the species and genus were delimited. Analyzing the features of the new species of Pseudocypretta this genus was moved from the Cyprettinae subfamily to the Cypridopsinae subfamily, and expanded the distribution of this genus to the Afrotropical and Neotropical regions. The new genus and new species were recorded from the four main floodplain of Brazil and were designated to the Cyprettinae subfamily. Both Cypretta, Pseudoypretta and new genus are characterized by presence of septas in its valves, however they vary in level of development (complete or incomplete) and disposition along the margins of the valves. Using a database of ostracods distribution and ecological niche modelling (ENMs) the effects of climate change were evaluated to the functional diversity of ostracods in the South Cone of South America, in the moderate-optimistic and pessimistic scenarios of 2050 and 2080. It is projected that the ostracod functional diversity will suffer a gradual reduction in 2050 and 2080on bothscenarios of carbon emission, but especially in the pessimistic scenario of 2080. The results highlight the importance of evaluate the functional diversity for ostracod conservation, since several areas marked to have low taxonomic richness supported intermediate and high levels of functional diversity.
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Diversidade beta espacial e temporal de peixes em um rio tropical fragmentado.The overexploitation of natural resources by human beings in recent centuries has had serious consequences for biodiversity. In freshwater aquatic environments, organisms suffer from various degradation processes, which involve pollution, environmental fragmentation, introduction of invasive species, among others. The construction of dams and reservoirs for energy production is among one of the biggest reasons for the degradation of these environments, as this fragments the water body, preventing connectivity between sites, in addition to transforming the lotic environment into a lentic one, completely changing the dynamics of the local. As an aggravating factor, there are reservoir cascades, which consist of a sequence of reservoirs built on the same river, enhancing the negative effects of a single reservoir. In highly fragmented environments, physical-chemical changes occur, which harm the local biological communities. Thus, in this work, analyzes of the spatial and temporal beta diversity of fish were carried out in a very fragmented river in northeastern Brazil, the São Francisco River. For spatial beta diversity, we calculated the Local Contribution to Beta Diversity (LCBD), taxonomic and functional, at 28 points along the six reservoirs and in a lotic stretch downstream of the reservoirs, up to the mouth. We performed a beta regression model to verify the relationship between LCBD values and environmental variables collected in the same period. As a result, we found that the points of the initial reservoirs and the points closest to the mouth of the river were the ones that most contributed to beta diversity, both taxonomic and functional, and turbidity was the variable that was most positively associated with LCBD values. For the temporal beta diversity analysis, we used five reservoirs, and compared the beta diversity between pairs of months over years. A correlation was also made between the results of temporal beta diversity and the variation of environmental variables. There was no relationship between environmental variables and temporal beta diversity. However, it was possible to observe that the reservoirs that operate as a trickle of water had the most unstable and unpredictable temporal beta diversity values, while the reservoir that operates as an accumulation followed the pattern of seasonal variation of the dry-flood dynamics. We recommend the proper management of the reservoirs of a waterfall, monitoring the variations in the parameters and regulating the flow and water level according to the expected natural variations, mainly the initial ones that function as sources of species and functional traits, and also the preservation of the rivers tax. We conclude that deeper studies covering other periods must be carried out, to complement the existing data and provide greater assertiveness in decision-making and conduction of reservoir operations.
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Redescrição de Platanichthys platana (Regan, 1917) (Clupeiformes, Clupeidae) com comentários sobre a distribuição geográficaA taxonomic and biogeographic review for the genus Platanichthys was necessary. In recent years, they have been identified as being of the species Platanichthys platana specimens collected in rivers and lakes of other hydrographic basins besides the then known ones. The species considered the smallest sardine in Brazil, always found in continental and coastal environments, including estuarine regions, began to be captured in waters of regions more in brazil, thus raising the hypothesis that these new specimens are a new species of the genus, until the monospecific moment. A total of 478 specimens identified as Platanichthys platana, from seven different hydrographic basins of South America (Baixo Paraíba do Sul, São João, Ribeira de Iguape, Alto Paraná, Guaíba, Atlântico Sul and La Plata), were analyzed. 40 morphometric analyses were performed, 21 non-overlapping (truss), and 13 additional morphological analyses. The differences observed between the analyzed populations didn’t support the hypothesis of being a new species for the genus Platanichthys, but after the analysis of all the material, it was possible to better determine its geographical distribution is to elaborate a better diagnosis for characterization and differentiation of the species in relation to other similar Clupeideos.
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Human-induced pressures driving biodiversity and functioning o freshwater ecosystems.Many studies have shown that human-induced pressures are causing species loss across many trophic groups, with potential negative effects ability of ecosystems to maintain functions and provide services to human well-being. However, evidence for this prediction is still lacking in freshwater ecosystems. In this document, we report the results of four studies that investigated the effects of human-induced disturbance on (i) biodiversity, (ii) ecosystem functioning, and (iii) biodiversity-ecosystem functioning relationships. These studies were conducted in different freshwater ecosystems and encompassed multiple spatial and temporal scales. In the first study, we used a 12-year data set from a shallow lake displaying shifts between three alternative states (clear, turbid and shaded). We investigated how the biodiversity (taxonomic and functional) of fish and zooplankton, ecosystem multifunctionality (provision of multiple ecosystems functions simultaneously) and their relationships were affected by shifts between alternative states. Biodiversity of fish and zooplankton and multifunctionality enhanced during clear-water state, but decreased during turbid and shaded states. The relationship between biodiversity and multifunctionality was strongly positive during the clear state, but weakened after the lake shifted to turbid and shaded states. In the second study, we used a dataset of 72 lakes from four large Brazil wetlands to examine how increased human pressure (human footprint) affected the relationship between the biodiversity (taxonomic and functional) of seven groups of aquatic organisms and multifunctionality. The biodiversity of most organismal groups was positively associated with multifunctionality. However, increased human pressure has weakened these relationships, and for some groups these relationships have become negative. In the third study, we used a dataset of 61 streams from two Neotropical biomes (Amazonian rainforest, Uruguayan grasslands) to investigated how increased cover human land-uses (agriculture, pasture, urbanization and afforestation) affected the biodiversity (taxonomic and functional) of fish, arthropods and macrophytes, and the consequences of this for animal biomass production. In both biomes, the biodiversity of animal and plant assemblages decreased with increasing cover of land-uses. Land-uses reduced animal biomass through direct and indirect pathways mediated by declines in biodiversity. In the fourth study, we investigate how increasing human pressure affects fish diversity and the consequences of this for energy flux in fish food webs over 17 years in a subtropical river (Uruguay River). Human pressure was associated with temporal declines in diversity and energy flux in all fish trophic compartments, and the relationship between diversity and energy flux weakened over time. Collectively, these studies reveal that human-induced disturbances reduce the biodiversity of various groups of organisms in different types of aquatic ecosystems. The decline in biodiversity, in turn, reduces the ability of these ecosystems to sustain multiple functions.
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Dormant structures of aquatic microfauna: ecological aspects and perspectives on different climate temperature scenarios.Dormancy is a biological process that allows communities to survive in adverse environmental conditions. The production of dormant structures is one of the main strategies performed by aquatic microfauna (ciliates, rotifers, cladocerans, copepods and ostracods). This study aimed to evaluate the dormant structures of aquatic microfauna, addressing different ecological aspects such as hatching time, dispersal, fungal influence and viability of the structures at different temperatures. The hatching experiments were performed with sediment and aquatic macrophytes of lakes from the upper Paraná River floodplain, Brazil. The results evidenced that ostracod resting eggs have similar hatching times among taxonomically close species and that the functional traits of the species (e.g. body size and presence of spines) influence the hatching time. In addition, dried roots of the free floating macrophyte (Eichhornia crassipes) shelter and disperse ostracod resting eggs. While, for all dormant aquatic microfauna a positive effect was observed between the presence of fungi in the sediment and species richness of the dormant communities, which did not negatively influence the viability of the dormant structures. The results also showed that the increase in temperature reduced significantly the species richness of the dormant microfauna and led to homogenisation of the egg bank. Based on the results, we highlight the importance of dormant structures in the recolonisation of environments and the high potential for dispersal by biotic vectors (plants), however this is also a warning for the invasion process. In addition, climate change responsible for temperature increase is a threat to the dormant structures of aquatic microfauna, thus it necessary to create mitigation measures for the conservation of the egg bank.
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Efeitos da invasão de espécies de Cichla nos padrões taxonômicos e funcionais da assembleia de peixes da planície de inundação do alto rio ParanáInvasive species cause loss of diversity in introduced sites. Species of the genus Cichla, popular tucunaré or peacock bass, are known for their voracious behavior that makes them a target in sport fishing and a predator with great negative impacts on introduced sites. There is a visible controversy around the species, since the scientific literature points out more and more impacts and the legislation seek ways to increase introductions, generating propagule pressure and prohibiting fishing in invaded places. In addition, mostpapers are punctual and in anthropized places such as reservoirs. Thus, we investigated how the abundance of Cichla individuals affects the assemblage of a floodplain over a time series. We investigated the effects of Cichla on taxonomic attributes of the assemblage (richness, evenness, diversity, abundance, and body length) and on species composition (beta diversity). In addition, the effects of Cichla on functional indices of the assemblage (functional richness, functional equitability, functional divergence, and functional dispersion) are investigated. Cichlaimpacts were evident in changes in beta and functional diversities. Cichla helped in the fauna homogenization process, increasing nestedness and reducing turnover. Additionally, it increased species with similar and more common traits and reduced species with rare traits, reducing dispersion, evenness, richness and functional divergence, it is worth noting that some results appeared with a delay, that is, some impacts make some time to appear in the invaded assembly.Our results showed that Cichlaspecies are capable of changing diversity patterns even in natural environments with great diversity of habitats and species, causing ecological losses that can lead to large economic and ecosystem losses.
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Parâmetros populacionais de peixes oportunistas da planície de inundação do alto rio Paraná : influências do El Niño Southern Oscillation - ENSO.The occurrences of El Niño - Southern Oscillation – ENSO climate events promote alterations in the global hydrological cycle, so that the precipitation pattern results in periods of extreme drought and floods in certain continental regions. The irregularity of rainfall inconstantly changes the hydrometric level of aquatic bodies, the flood pulse and the river discharge, which in turn alter the limnological variables, the primary productivity and the availability of resources and habitat for the aquatic organisms, possibly affecting their growth and reproduction patterns. Therefore, the population parameters (such as sex ratio, size at first sexual maturity, weight-length ratio and somatic growth) of the short-lived icthyofauna (CVC) in the upper Paraná River floodplain (PIARP) were evaluated and compared in different climate periods (El Niño, La Niña and Neutral) through statistical modeling, under Bayesian perspective. The population parameters were estimated for the Hyphessobrycon eques species, for it was one of the selected species that presented traits of opportunistic strategy, being so characterized as a short life cycle species. The results found partially corroborated with the predictions, that the highest sex ratio found was for the La Niña period (2.7 females for one male), followed by Neutral (2.3) and El Niño (1.3) periods. For the first maturity sizes (L50), estimated for both sexes, they were smaller in the La Niña period (23.87mm for females and 23.35mm for males), followed by the El Niño period (25.89 mm for females and 28.75mm for males) and Neutral period (25.97mm females/ 29.92mm males). The weight-length ratio showed that the male body shape (α) had a slightly higher body biomass (α) average than females in the Neutral and La Niña periods. However, in the El Niño period, the opposite of the other periods was observed. The estimated parameters for the female body shape (α) were higher in Neutral, followed, respectively, by the El Niño and La Niña period, though, for males, the body shape (α) was higher in Neutral, followed by the La Niña and El Niño period. The estimated median lengths for the ages are moderately longer in males than females. Furthermore, the estimated median lengths are relatively longer in extreme periods (La Niña and El Niño) for the initial ages (3 and 6 months) when compared to the Neutral period, both for males or females. For females, the estimated median lengths are comparably longer in the El Niño period than in the La Niña period, while the opposite is observed for males. For that reason, the reproductive tactics of H. eques presented in the La Niña period can be a population level’s response, used for the optimization of the reproductive success and for the maintenance of the species in the environment.
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Alterações na assembleia de peixes antes e após a construção de barragens com trecho de vazão reduzida no rio das Antas, Rio Grande do Sul, Brasil.The demand for electricity around the world has led several countries to construct and to plan more damming in rivers. Nowadays, even small and medium sized rivers are considered for the construction of dams, forming small to medium sized reservoirs, including a reduced flow stretch, once turbines are usually located downriver far from the dam. The purpose of this study was to investigate the effects of small to medium sized reservoirs on fish assemblages, using a Before-After Control-Impact (BACI) design, which includes sampling before and after dammings. Reservoirs were in the cascade of the Antas River (Castro Alves, Monte Claro and 14 de Julho dams and associated reservoirs). Specifically, alterations in the selected attributes (abundance, species richness, Shannon diversity index and evenness) and in the structure of fish assemblages were evaluated. Samples were conducted before and after reservoir filling, in three sampling stations of each reservoir, one located downstream (along the reduced flow stretch), another in the reservoir (lentic area) and the other above the reservoir (lotic stretch). For the collected data, in the three reservoirs, there were variation in abundance, species richness and Shannon diversity Index, always with greater values after the formation of the reservoirs. There were also variations for the sampling sites, with greater values of abundance and species richness downstream the dams. Variations in the structure of fish assemblages, due to the formation of the reservoirs, were also relevant. These variations were more intense in the station located below the dams, followed by the one located inside the reservoir and the one located upstream. The alterations appeared to be lessened because the hydrologic regime of the Antas River works as waves, in which, several times, the wave may pass over the dam, increasing water level downstream. The increases in species richness in the sites sampled seem to be a result of distinct processes. In the reduced flow stretch downstream dams, the increase may be attributed to the accumulation of fish due the obstacle represented by the dam. For the stations inside the reservoirs, the increases are due to samplings in the littoral zone during the trophic upsurge period; fish are known to inhabit the littoral, especially small characids. Finally, for the stations located upstream may be a result of the intense fish movements in this stretch.
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Resposta à inundação de plantas jovens de Albizia niopoides (Spruce ex Benth.) Burkart.Floodplains provide a unique environment, periodic floods cause low rates of diffusion and solubility of oxygen in the soil and represent the main restriction to plant community development. Among the strategies presented by plants that allow them to survive these flooding events are morphophysiological and anatomical adjustments, reducing the damage caused by oxygen deficiency. This study was conducted with the objective of experimentally observing the adaptive strategies of survival to the flooding, thus, young plants of Albizia niopoides (Spruce ex Benth.) Burkart were submitted to water saturation conditions. The following treatments were submitted to the plants: flooded (only the soil submerged in water), submersion (plants totally under the water) and the control group (maintained at field capacity). For morphological evaluation, we collected data from shoot height, root length, biomass (leaves, stem and root). For the anatomical analysis of the root, we measured the diameter of the vascular cylinder of the root and the total diameter of the root, in addition to data about chlorophyll a and b, carotenoids and total chlorophyll. Analyzes were performed 15, 30 and 60 days after the start of the treatments. Results were statistically compared by mean tests (ANOVA, Kruskal-wallis and t-test). In general, the control group presented higher growth averages in the parameters: shoot height, root length, biomass of leaves and root, diameter of the central cylinder of the root and total diameter of the root, compared to the other treatments, in all studied periods. The values of chlorophyll a, b and total and carotenoids showed little variation at 15 days after the beginning of treatments and only at 30 days the control and flooded groups obtained higher values, compared to the totally submerged, indicating changes in the metabolism of plants kept in submersion. Anatomical analysis showed greater development in the control group, with roots in advanced secondary tissue growth and reduced total root diameter in treatments when it was in hypoxia. We observed The presence of lenticels and adventitious roots in the flooded plants. At 60 days after the start of treatments, subjects in the submerged treatment were dead. Flooding represented a negative effect on the growth of individuals as well as substrate flooding. The death of plants under submersion treatment indicates that Albizia niopoides does not tolerate long periods of total submersion, while the morphoanatomical characteristics developed suggest that the plant is considered tolerant to the stress caused by the flooding of the substrate.
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Diversidade taxonômica, funcional e filogenética de protistas ciliados em uma planície de inundação Neotropical: determinantes dos padrões espaciais e temporais da diversidade β e sincronia de comunidade.Patterns of species richness are driven by biotic and abiotic factors and the way in which they operate at spatial and temporal scales. In continental aquatic environments, communities may differ in important aspects such as taxonomic, functional and phylogenetic structure, and the detection of biodiversity may vary between these different facets. For the development of this study, to test important ecological theories, we used the spatial and temporal database of ciliate protists from the upper Paraná River floodplain, from a long-term ecological program - PELD. The spatial and temporal β diversity was verified in three facets of biodiversity (taxonomic, functional and phylogenetic) of the ciliate community, and the contribution of different environmental predictors, using data on composition (presence/absence) and structure (abundance) of the community. It was found that different facets of diversity are influenced by different environmental predictors, but with more evident results for the functional and phylogenetic facets, especially when using data on the structure of the ciliate community. The synchrony between ciliate species in time and space was also evaluated, and the relation of this synchrony with the facets of diversity. Significant relationships were observed between ciliate synchrony and phylogenetic distance, but not for community functional distance. It is concluded that systematic and more precise advances in the community are needed to further improve knowledge about phylogenetic proximities of species and ecosystem functions performed by ciliate protists in limnic environments. Therefore, studies with functional and phylogenetic characteristics of ciliate species are recommended, in future research with application in other ecological theories, with significant contributions in the field of ecology, taxonomy and conservation of this community.
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Priorização espacial para conservação e restauração da interação entre peixes frugívoros e floresta na bacia Paraná-Paraguai.Interactions between frugivorous fish and forests contribute to seed dispersal and the structuring of plant communities in riverine habitat and floodplain forests. However, fish-forest interactions that contribute to maintaining biodiversity are threatened by climate and landscape changes. The objective was to identify areas suitable for the conservation and restoration of fish-forest interaction and related ecosystem services in the Parana-Paraguay River basin, integrating climatically suitable areas for Myloplus tiete and Piaractus mesopotamicus, two species of frugivorous habit, native to the basin, and at risk of becoming extinct. The predictions show a reduction in climate-environmental suitability for the two species at different times (present, 2050, and 2080) and different carbon emission scenarios and low availability of vegetation cover. By multiplying the values of climate suitability with the availability of vegetation, generated the Environmental Optimum Index, which allowed us to identify areas for conservation and restoration. The models demonstrated priority areas for conservation concentrated in the southern portion of the Pantanal and the headwater regions of the upper Parana River basin. At the same time, classified the restoration areas concentrated in the mouth region between the Tietê and Paranapanema rivers. It reinforces the essential that decision-makers prioritize the investment of limited resources for the conservation and restoration of riparian landscapes and develop efficient policies and practices to integrate biodiversity conservation, ecosystem services, and social well-being.
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Macrófitas aquáticas na Região Neotropical: riqueza e qualificação das espécies.Aquatic macrophytes are macroscopic photosynthetic organisms that encompass several taxonomic groups of plants, with broad limnological characteristics that colonize from marshes to submerged areas, playing a fundamental role in structuring wetlands and affecting aquatic biodiversity. The Neotropical Region, covering from the south of Mexico to the south of Argentina, is characterized for being one of the most biodiverse regions in the world, with a unique biota, many endemic species and a great diversity of environments. As one of the wetlands with the greatest potential in this ecozone and the world, the Paraná-Paraguay basins stand out. The objectives of this thesis were to quantify and qualify the species of aquatic macrophytes that occur in the Neotropical Region and in the Paraná-Paraguay basins, carry out an analysis of hotspots for the Paraná-Paraguay basins and provide current information and indicators of areas of high richness of aquatic macrophytes. A conservation efficiency analysis is also available that correlates areas considered hotspots and the protected areas present in these basins. Data from systematic searches in important bibliographic bases were used to compose the lists and geographic coordinates. A total of 1616 spp. for the Neotropics and 979 species for the Paraná-Paraguay basins. The families with the highest number of species were Cyperaceae Juss. and Poaceae Barnhart in both regions studied. Species richness for the Paraná-Paraguay basins was recorded using occurrence points, with 5 locations with values from 71 to 139 species and 50 locations from 1 to 11 species, with the Lower Paraná River having the lowest number of occurrences and the Lower Paraguay River the largest amount. Sixteen sub-basins considered as hotspots were registered, and these areas coincided with the areas of greatest richness. Approximately 6% of the total ecological hotspot areas are being conserved within protected areas. In conclusion, the results obtained in both surveys reaffirm the high number of species present in these wetlands, highlighting the need for further systematic and taxonomic studies of aquatic macrophytes, seeking to precisely detail these megadiverse regions.
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Efeito temporal na parasitofauna do bagre invasor Trachelyopterus galeatus (Linnaeus, 1766) de uma planície Neotropical.Aquatic environments have been anthropically influenced over the years, mainly with the construction of dams and hydroelectric plants. However, few studies evaluate how the parasitic fauna can be influenced in the long term by these environmental changes. Possible changes in the composition of endoparasites of the invasive fish Trachelyopterus galeatus in the upper Paraná River floodplain were investigated over a 27-year study period. 79 fish were analyzed in period 1 (1993) and 31 in period 2 (2019/2020). In the first period, the fish showed higher values in the variables weight (g) and standard length (cm), when compared to period 2. A total of five species of endoparasites were found, three per period. Although the richness was the same, the composition of endoparasites differed between the periods, as only one species of digenetic (Microrchis oligovitellum) parasitized the host in both periods of study. It was found that both the development of the fish and its endoparasites were affected over time. It is noteworthy that the beginning of operation of the Porto Primavera dam, located upstream of the plain, occurred between the two sampling periods (1999), and caused several environmental changes, possibly being the main responsible for these changes in the parasitofauna. Most endoparasites require intermediate hosts to complete their life cycles. Therefore, a modified environment may lose diversity and ecological interactions, as it affects the populations they use during the transmission process between hosts. This may explain the difference found in the infracommunities of T. galeatus parasites, emphasizing, through the results obtained, the importance of including these organisms in studies that evaluate environmental impacts caused by anthropic actions
