Iguacu River Research Articles

As chuvas do baixo rio Iguaçu (Sudoeste do Paraná) no período de 1976 a 2016

A Bacia Hidrográfica do Baixo Rio Iguaçu está localizada no Sudoeste do estado do Paraná e no decorrer dos anos, passou a apresentar importância significativa, sobretudo no que se refere à agropecuária, abastecimento urbano e geração de energia. Contudo, ainda são raras as pesquisas científicas que abordam a área analisada. Frente a isso, o presente trabalho, objetiva caracterizar o regime pluviométrico do Baixo Rio Iguaçu no período de 1976 até 2016. Para tanto, no regime de precipitações, utilizou-se de parâmetros estatísticos de tendência central e o método de interpolação krigagem, a fim de espacializar os dados de chuva de 31 estações pluviométricas. Os resultados destacam a influência do El Niño e da Oscilação Decadal do Pacífico no regime de chuvas da área estudada.

Environmental assessment of Neotropical streams using fish as bioindicators: a multibiomarker and integrated approach

Freshwater ecosystems are among the most threatened habitats on Earth, due mainly to anthropogenic pollutants made up of complex mixtures. The Iguacu River is world famous for the Iguacu Falls and highlighted by its endemism. Unfortunately, it is considered the second most polluted urban river in Brazil. We aimed to perform an environmental evaluation of Neotropical streams in the Iguacu River basin, using a multibiomarker approach from a land use and landscape perspective. A set of biomarkers in the fish Psalidodon bifasciatus was analyzed using an Integrated Biomarker Response (IBR) index and correlated with surrounding land uses. Agricultural and urban sites presented more alterations compared to references sites, with elevated protein carbonyls at agricultural sites, increased DNA damage and depletion of glutathione S-transferase at urban sites and decreased glutathione associated with higher histopathological indices at urban and agricultural sites. The IBR shows a consistent increase in negative effects in anthropized areas, with similar values at agricultural and urban sites. The multibiomarker approach, associated with a well-elaborated sample design and a statistical analysis, is an ideal method to obtain more conclusive results about the effects of human activities, revealing the effective result of exposure in the real world.

Parasites of Cambeva davisi (Siluriformes: Trichomycteridae) from the Cascavel stream, Neotropical area

The aim of the present study was to record the occurrence of parasites in Cambeva davisi (= Trichomycterus davisi) (Siluriformes: Trichomycteridae) from the Cascavel Stream, in the Iguacu River basin, municipality of Cascavel, state of Parana, Brazil, and present a review of the parasites reported infecting trichomycterids belonging to Cambeva and Trichomycterus species from the Neotropical region. Eighty-one fish specimens were collected using the electrofishing technique, with three standardized passes with a duration of 40 min, with extensions of 50 m for each site. In the laboratory, the fish were necropsied, and parasitological and histological analyses were conducted. Two parasite species were found and identified as nymphs of Sebekia oxycephala (Pentastomida) (Prevalence [P] = 8.54%) and Minilernaea floricapitella (Crustacea: Lernaeidae) (P = 1.23%), both representing new records of distribution and host-parasite relationships for genus Cambeva. The presence of the nymphs of S. oxycephala did not result in harmful histological changes or a significant inflammatory process in infected organs. Twenty-one taxa of parasites have been described parasitizing trichomycterids belonging to Trichomycterus (sensu stricto) and Cambeva from the Neotropical region. Nymphs of S. oxycephala have already been reported in freshwater fish belonging to 10 different orders, and M. floricapitella has been found parasitizing Brazilian fishes belonging to two orders. The nymphs of S. oxycephala did not cause histopathological changes and the new records of distribution and host-parasite relationships reported here enrich knowledge of the parasitic fauna of freshwater fish from the Neotropical region.

HPLC-MS/MS Method for Quantification of Pharmaceuticals in Subtropical Rivers and Water Treatment Plants in Brazil

A multiclass analytical method for the investigation of 25 pharmaceuticals in the main rivers of the four largest hydrographic basins and an industrial water treatment plant in Curitiba, Brazil was developed and validated. The analysis of the pharmaceuticals was done using SPE-HPLC-MS/MS. The LoD and LoQ concentrations were 10–100 ng L–1 and 20–200 ng L–1, respectively. The extraction and quantitation of the 25 compounds proved to be precise and accurate. Surface water samples collected during the spring of 2019 (n=16) were analyzed. Caffeine, lidocaine, sulfamethoxazole, and carbamazepine were the main compounds present in the river samples. Sulfamethoxazole was the antibiotic found in the highest concentrations. Other antibiotics, psychiatric drugs, anti-inflammatories, analgesics, antiretrovirals, and antidiabetics were also frequently detected and quantified. It was also observed that the treatment employed at the treatment station did not efficiently remove all pharmaceutics investigated. The results of this study indicate an intense anthropogenic influence in the Iguacu basin, mainly due to the presence of domestic sewage. The lack of sanitation has a negative impact on the water quality of the Iguacu River, which is highly degraded due to the influence of the tributaries of the Metropolitan Region of Curitiba.

Do advantages in resource exploration lead to better body condition?

The colonization of novel reservoirs tends to support opportunistic species that undergo mass proliferation after the reservoir is formed. It is common that in this process, a species will change its diet based on resource availability. This is the case in the Salto Caxias reservoir, Iguacu River, where five Astyanax species presented changes in their diets after damming. The present study aimed to evaluate possible changes in the feeding activity and condition factor of five sympatric species of Astyanax in the Salto Caxias reservoir in different areas impacted by damming. Sampling was carried out before and after damming the Salto Caxias reservoir. The fish feeding activity and nutritional status were inferred by the mean stomach repletion index and the mean condition factor, respectively. Most of the studied species showed a general decrease in feeding activity and condition factor. Both studied regions, the upstream region and the dam region, presented changes in the analyzed factors. These observations suggest that regardless of diet changes, nutritional status is negatively impacted in altered environments. The nutritional deficit occurs (i) if the diet is altered due to adaptive limitations on the use of the available resources and (ii) if the diet remains unaltered due to the scarcity of the preferred feeding resource. Such decreases might lead to reductions in the population size due to limitations on growth and reproduction until the environment feeding resources can sustain those populations.

STATISTICAL CONTROL OF THE PROCESS APPLIED TO THE MONITORING OF THE WATER QUALITY INDEX

ABSTRACT Analyzing the physical-chemical and biological characteristics allows the evaluation of the water quality of a water body. Thus, the objective of this study was to determine the water quality index of the Passauna and Piraquara rivers, as well as to apply statistical quality control methodologies to evaluate the data resulting from the monitoring of water quality. Therefore, a database with physico-chemical and microbiological parameters of the Passauna and Piraquara rivers, a watershed of the Iguacu River, belonging to the cities of Araucaria and Piraquara, respectively Parana, Brazil, was used to carry out the research. The water quality index was determined with the time series and, subsequently, these data were submitted to the statistical control of the process, with the control charts of individual Shewhart, EWMA and CUSUM, in addition to the development of the process capacity index. The WQI detected that the rivers remained in average quality until the year 2000, however, from that year it was possible to see a decreasing trend in the water quality of the evaluated rivers. The control charts of Shewhart, EWMA, CUSUM and the process capability index were able to identify the decreasing trend in water quality, demonstrating that they are fast and efficient techniques for the evaluation of water quality control.

Comparative Cytogenetics Among Three Sympatric Hypostomus Species (Siluriformes: Loricariidae): An Evolutionary Analysis in a High Endemic Region

ABSTRACT The karyotypes of three armored catfish species (Loricariidae) from the Iguacu river, southern of the Brazil, were compared using different techniques: C-banding, Ag-NOR and fluorescence in situ hybridization (FISH), which used 5S and 18S rDNAs and total Cot-1 fraction as probes. Hypostomus commersoni and Hypostomus derbyi presented 2n = 68 chromosomes, with karyotype formulae 12m+12sm+14st+30a and 12m+12sm+10st+34a, respectively; whereas Hypostomus myersi presented 2n = 74 chromosomes and 12m+16sm+12st+34a. The chromosomal localization of the Ag-NORs, 5S and 18S rDNAs differed in number of sites and chromosomal localization among the studied species. The total Cot-1 probe permitted the visualization of the repetitive DNA fraction in karyotypes of each species. Cross-hybridizations using total Cot-1 probe revealed that these species have repetitive DNAs in common. However, this does not occur in H. commersoni in relation to the other species. The apparent karyotype similarity suggests a close relationship between the sympatric H. commersoni and H. derbyi species, but the small differences detected in the examined chromosomal markers indicate evolutionary divergence due to gene flow restriction among them. Hence, the present findings indicate different composition of repetitive sequences among studied species, which permit to infer its role in chromosomal differentiation of Hypostomus.

<b>Comparison of nuclear abnormalities in <i>Astyanax bifasciatus</i> Cuvier, 1819 (Teleostei: Characidae) of two sections of rivers from the middle Iguaçu

Most changes in water bodies are result of human activities that have the potential to undermine the environmental integrity of aquatic ecosystems. Changes in genetic material can be evidenced by the frequency of nuclear abnormalities in fish blood cells, in response to genotoxic agents even at low concentrations. Thus, we aimed at comparing the frequencies of nuclear abnormalities of fish kept in acclimation, with fish collected in Timbo river (Santa Cruz do Timbo, Santa Catarina State), under low anthropogenic interference, and fish collected in Iguacu river (Uniao da Vitoria, Parana State), a polluted river. The highest frequency of changes in nuclear morphology of fish erythrocytes was found in the urbanized area around the Iguacu river, while, the fish collected in areas with preserved riparian forest surrounding the Timbo river and acclimated fish showed no morphological changes. Our results suggest that genotoxic compounds in the Iguacu river are acting as stressors to aquatic communities, especially fish. In addition, the absence of nuclear abnormalities in fish from the Timbo river suggests that rivers without significant environmental changes can serve as reference point for comparative studies of genetic modifications for the species studied.

Contrasting fish size distributions between Neotropical run-of-river and storage reservoirs

The spectrum size has been used to assess environmental disturbances and to understanding the energy flow in ecosystems. The objective of this work was to investigate if the operation regimes of reservoirs, including run-of-river and storage systems, interfere with the biomass spectra of fish fauna. We tested the hypothesis that the run of river reservoirs present higher proportions of large individuals than storage system. Samplings of fish fauna were carried out between January 2005 and December 2007 at six Neotropical reservoirs belonging to the sub-basin Iguacu River and Coastal basin in Sao Jorge River, Brazil. The spectrum calculation was performed using the Pareto type I continuous distribution model. Reservoirs operated under run-of-river regime had significantly higher values than those operated under storage regimes. This study has elucidated some impacts of reservoir operating regime on biomass spectra and indicated differences in size spectra of fish assemblages among the sampled reservoirs. Therefore, it is important to incorporate management plans that take dam operating mode into account so that conservation of aquatic fauna, especially fish, is more effective.

Ausência do mexilhão dourado invasor em um reservatório perto de Curitiba, Brasil: um possível caso de invasão malsucedida

Although most cases of non-native species introductions do not result in the final phases of the invasion process or in negative impacts, there are few reports of failure through their different stages, especially for unintentional introductions. However, unsuccessful invasion cases may help understand which factors are predominant during the invasion process. The golden mussel, Limnoperna fortunei, is an invasive species in South America. Since its first record in Rio de la Plata watershed, it has spread and caused several ecological and economic impacts in different hydrographic basins. Based on larval sampling through conventional and molecular techniques and visual census by scuba diving, we report the absence of this invasive species after its occurrence recorded in 2003, at the Piraquara I reservoir, Upper Iguacu River basin, Brazil. It is the only potential record of juvenile individuals of this species in a reservoir environment without their population establishment and spreading. Understanding the causes of failures in the invasion process may be crucial to avoid their negative impacts. In this context, the accuracy of non-native species records in new environments is fundamental; recording invasion failure of non-native species may be as important as reporting new occurrences.Keywords: Bivalvia, alien species, ecosystem engineers, invasiveness, naturalization, propagule pressure.

Vitellogenin levels and others biomarkers show evidences of endocrine disruption in fish species from Iguaçu River - Southern Brazil

The adverse effects of endocrine disrupting chemicals (EDCs) on aquatic wildlife and human health represent a current issue of high public concern. Even so, they are still poorly studied in aquatic environments of South America. The aim of the present study was to investigate the impact of EDCs in five cascading reservoirs from the Iguaçu River, evaluating reproductive endpoints in three native fish species (Astyanax bifasciatus, Chrenicicla iguassuensis and Geophagus brasiliensis). Additionally, a polyclonal antiserum anti-vitellogenin from G. brasiliensis and a capture ELISA assay were developed for detection of estrogenic or anti-estrogenic activities in male and female fish, respectively. Vitellogenin (VTG) levels in male fish from the Iguacu River was observed, as well as decreased levels of vitellogenin and estradiol in the plasma of female fish. These findings were associated with immature gonads and lower gonadosomatic index in G. brasiliensis adult females from the Foz do Areia (FA) Reservoir. Additionally, both endemic species (Astyanax bifasciatus and Chrenicicla iguassuensis) displayed immature gonads and histological changes, such as degeneration of germ cells, in other studied reservoirs. The current results suggest that these reproductive responses may be associated with the bioavailability of EDCs in the Iguaçu River. These impacts are likely related to chemicals released by human activities, especially from sewage and industrial sources and agricultural production, detected in previous studies. Overall, the FA reservoir was potentially the most affected by chemicals with endocrine properties, and further studies are necessary to identify and quantify these chemicals.

Metal Bioavailability in Contaminated Estuarine Sediments from a Highly-Impacted Tropical Bay

The aim of this study is to assess possible spatial variability of trace metal (Cd, Cu, Pb and Zn) bioavailability along the main channel of a highly eutrophic tropical estuary (Iguacu River estuary, Guanabara Bay, Brazil). Metal potentially-bioavailable concentrations (soluble in 1 mol L-1 HCl) and strongly-bound concentrations (soluble in concentrated HNO3) were sequentially extracted and determined by a Coupled Plasma Optical Emission Spectrometry (ICP OES). These sediments generally have high trace metal contents associated to weakly-bound fractions, while Zn was the most bioavailable metal (approximately 83% of Zn concentrations were weakly-bound to sediments) while Cu showed the greatest heterogeneity of proportion between weakly- and strongly-bound fractions. The employed sampling strategy combined results from sediments taken along and across the estuarine channel, evidencing that care is required when using only a single sampling transect along estuarine channels, particularly for metals sensitive to changes in geochemical partitioning during sediment transport and redistribution, as evidenced by the Cu concentrations in this work.

Distribution and Characterization of Sex Hormones in Sediment and Removal Estimate by Sewage Treatment Plant in South Brazil

Sex hormones are a group of endocrine disruptors excreted by humans and animals. These compounds have been detected in surface waters and sewage treatment plant (STP), all over the word. Due their physicochemical properties significant amount is deposited in the sediment of surface waters acting as reservoirs able to contaminate the water column. Although these compounds have origin in different sources, it is widely accepted that the main source of these contaminants is STP effluents. Despite toxicity and high input of this compound in the aquatic systems, little information is available on their concentration in the sediment and how these compounds are distributed in the environment. In this study, natural and synthetic female sex hormones (estrone - E1, 17β-estradiol - E2, 17α-Ethinylestradiol – EE and progesterone - PG) were monitored in the sediment of three rivers from the Iguacu river basin, South Brazil. Also, a removal estimate of these compounds by the local STP was performed. The results showed significant concentrations of hormones, mainly E2, in the sediment samples and an inefficient removal by the STP, resulting in some cases, in the increasing of estrogens. An assessment of the sediment-water partition coefficient (Kd) showed high mobility in the environment for the estrogens, in contrast to the higher affinity for the sediment of the progesterone.

Lazer nos rios urbanos da Tríplice Fronteira: transformações, contradições e significados

A discussão sobre os rios urbanos, na sua interface com o lazer, foi o tema desta pesquisa, com foco na cidade brasileira de Foz do Iguaçu – localizada na Tríplice Fronteira que reúne, ainda, Puerto Iguazú (Argentina) e Ciudad del Este (Paraguai). O objetivo geral foi identificar e discutir as apropriações sociais e vivências de lazer realizadas nos rios urbanos Paraná e Iguaçu, e suas margens. Procurou-se entender suas transformações e contradições e, ainda, de que maneira os moradores significam esses ambientes fluviais. A metodologia desta pesquisa qualitativa contou com estudo bibliográfico, observações e entrevistas com 23 moradores de Foz do Iguaçu. Nesse trabalho, verificou-se que as apropriações e vivências de lazer tornaram-se pontuais à medida que as mudanças urbanísticas e no meio natural praticamente desprezaram um sentido integrativo entre a cidade e o ambiente fluvial. Restam, no entanto, nos rios e nas suas margens, práticas como pesca por lazer e esportes de aventura, que imprimem múltiplos significados, por meio de vivências lúdicas, contemplativas, espirituais e interativas com as águas. Houve, no município, uma opção pelo olhar privilegiado voltado ao turista, fato que impacta diretamente nos espaços públicos e democráticos de lazer, para os moradores, como os localizados nos rios e suas margens.

Genetic structure and diversity of migratory freshwater fish in a fragmented Neotropical river system

Over the past few decades, South American Rivers, including the Parana River system, have been intensely impacted by dam constructions. To mitigate adverse impacts, fish passages were incorporated into two large dams on the Parana River (Itaipu and Porto Primavera) to reestablish longitudinal connectivity, which is very important for conserving populations of migratory fish species. The aim of this study was to estimate genetic diversity, population differentiation and gene flow, using microsatellites markers and mitochondrial haplotypes (d-loop), in populations of Prochilodus lineatus, a long distance migratory species commonly found in Parana River basin drainages. Samples were obtained from six locations in the Upper and Middle Parana River: Porto Primavera Reservoir, downstream of the Porto Primavera Reservoir, four tributaries of this reservoir (Pardo, Peixe, Verde and Aguapei Rivers) and in the Iguacu River, downstream of the Itaipu dam. High genetic diversity was observed in all samples, as expected for species with large population sizes and high migration rates. However, the influence of other factors, such as secondary contacts, fish passages and restocking were also suggested. In general, evidence of spatial population structuring was not found, even though there were two large dams in the study area. This could also be attributed to the brief period that has elapsed since the dams were built, the influence of migratory and reproductive patterns and the possible contributory effects of the fish passages. Furthermore, the absence of population structuring also corroborates existing information that emphasizes the importance of unimpeded tributaries for conserving migratory fish populations in fragmented watersheds.

Geochemical fractionation of metals and semimetals in surface sediments from tropical impacted estuary (Guanabara Bay, Brazil)

A three-step sequential extraction procedure, which was based on the BCR method, was used to analyse Guanabara Bay sediment samples to evaluate the potential mobility of some metals and metalloids. Zn and Cd were found to be the most labile metals because these were recovered in the first extraction stage and were associated with the non-residual fraction of the sediment. In contrast, Cr, Cu, Ni, and Hg were the least labile metals, and 62 to 84 % of the concentrations of these metals were found in the organic residual fraction of the sediment samples. The spatial distribution of the metal concentrations in Guanabara Bay led to the identification of various sources of contamination. The continental sources, which were related to Fe and Al, were distributed in the northern and central sectors, although lower concentrations were found in the mouths of the rivers that flow into the estuarine system of Guanabara Bay. The urban emission sources are related to the discharges of the Sao Joao de Meriti River, which exhibit significant levels of Ba, Cd, Ni, Zn, and Hg. The Sao Joao de Meriti River and harbour activities also show a predominance of Pb and Cu. The system formed by the Iguacu River and the Sarapui River is mainly characterised by V and Cr. The metals associated with biogeochemical processes, such as As and Mn, were found in the central sector of Guanabara Bay.

Determinação de anti-inflamatórios na água e sedimento e suas relações com a qualidade da água na bacia do Alto Iguaçu, Curitiba-PR.

Environmental contamination by emerging pollutants has been explored in different studies in the environmental area. This is due, in the most part, by the low efficiency of municipal wastewater treatment and the high chemical consumption. The watershed of the Alto Iguacu located in the Metropolitan Region of Curitiba has a high population density in your surroundings and, consequently, has some problems in water quality of its rivers. Considering this aspect, this study comprehended the evaluation of emerging contaminants in five rivers inside this watershed. Contamination by anti-inflammatory ibuprofen, paracetamol and diclofenac in surface water and sediment was evaluated for a year, a total of four sampling campaigns. Ibuprofen was found only in the first sampling, but in high concentrations in the Belemriver(729 ng.L-1). Diclofenac had been widely detected in water and it reached concentrations of 285 ng.L-1 in the third sampling in the Iguacu river. Unlike the rest, paracetamol was often quantified in the water, being the Iguacu and Belem rivers with more presence of this drug. It was also determined in sediments, especially in Bariguiriver, being founded 6,896 µg g-1. The presence of these compounds in the sampled rivers confirms an anthropogenic interference with the Alto Iguacu watershed, which suffers from unplanned urbanization

Environmental fragility of Iguaçu river watershed, Paraná, Brazil

The aim of this study was to analyze the environmental fragility of Iguacu River watershed, Parana. Regarding fragility potential, most watersheds fell under...

Length-weight and length-length relationships and length at first maturity for freshwater fish species of the Salto Santiago Reservoir, Iguaçu River Basin, Brazil

Summary Length-weight (LWR) and length-length (LLR) relationships were estimated for 20 species and lengths at first maturity (L50) for six species of freshwater fishes caught in the Salto Santiago Reservoir, Iguacu River Basin, Brazil. In nine species significant differences were found in the LWR between sexes. Average b-value for species with no differences between sexes in LWR was 3.12 (SE = ±0.05). Average b-value in LLR was 0.823. First references on LWRs and L50 are presented for 13 and four fish species, respectively, as well as the new maximum total lengths for eight species.

Cytogenetic analysis in three species from genusAstyanax(Pisces; Characiformes) with a new occurrence of B chromosome inAstyanax paranae

Cytogenetic studies were carried out in three species from genus Astyanax: Astyanax paranae (Tagacaba Stream and Taua Stream), Astyanax altiparanae (Iguacu River and Maringa Stream) and Astyanax fasciatus (Maringa Stream). Both populations of A. paranae featured 2n = 50 chromosomes, although with different karyotype formulae and Ag-nucleolar organizer regions systems. Using the FISH technique in the Tagacaba population, it was possible to detect rDNA genes in 14 chromosomes and bitelomeric marking in one chromosome. The constitutive heterochromatin pattern also showed differences between the two populations. Moreover, the Tagacaba population showed macrochromosome B in 50% of analyzed females. Both A. altiparanae populations featured 2n = 50 chromosomes, but also differed in karyotype formula. Both populations featured multiple-NOR systems and quite similar constitutive heterochromatin patterns. For the A. fasciatus population from Maringa Stream, the diploid number was 2n = 46 chromosomes with karyotype ...