Iguacu River Basin Research Articles

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.

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.

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.

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.

Long-Term Runoff Modeling Using Rainfall Forecasts with Application to the Iguaçu River Basin

This work presents the development of a rainfall-runoff model for the Iguacu River basin in southern Brazil. The model was developed to support the operation planning of hydroelectric power plants and is intended to predict the natural flow based on meteorological rain forecasts. A recurrent fuzzy system model was employed with parameters estimated by a genetic algorithm using observed rainfall as input. The model performs well using observed rainfall as input; however, its performance using predicted rainfall as input decays with the forecasting horizon, illustrating the effect of meteorological prediction errors. The prototype implementing the model has been used for dispatch planning by the Brazilian Electric System Operator.

Occurrence of the non-native fish Salminus brasiliensis (Cuvier, 1816), in a global biodiversity ecoregion, Iguaçu River, Paraná River basin, Brazil

We register here the first occurrence of the “dourado” Salminus brasiliensis (family: Characidae) in Salto Santiago Reservoir in the Iguacu River basin, Parana State, Brazil, a global biodiversity ecoregion with an extremely rich endemic ichthyofauna. The single specimen captured, an adult female measuring 480-mm total length, was taken with gillnet in January 2008. No additional S. brasiliensis were captured during general fish surveys conducted at four sites in the reservoir even though multiple types of gear were used (gill and trammel nets and long-line fishing) over a period of nearly two years (bimonthly from July 2006 to September 2008). The presence of S. brasiliensis, a large, predacious freshwater species native to other parts of Brazil, may be related to its use as a sport fish, and the single specimen taken from the reservoir may have escaped from ponds built by aquaculturists for recreational angling. Before appropriate management measures are taken, additiona l field work is needed to determine the status and distribution of S. brasiliensis in the Iguacu basin and to assess possible negative effects of the introduction on native fishes.

Relações entre a distribuição das espécies de diferentes estratos e as características do solo de uma floresta aluvial no Estado do Paraná, Brasil

Entre os fatores que influenciam a distribuição de espécies nas comunidades vegetais localizadas em regiões ribeirinhas, as características do solo são consideradas os mais importantes. No presente estudo, foram avaliadas a composição florística, a diversidade e a estrutura de três estratos da vegetação e suas relações com as características do solo em um fragmento de floresta aluvial na bacia do rio Iguaçu, no estado do Paraná. Buscou-se verificar se a estrutura e a diversidade da floresta nos diferentes estratos podem ser explicadas por fatores edáficos e hídricos. Caracterizaram-se os parâmetros estruturais e a composição florística de três estratos da vegetação % de regeneração (20 cm < altura < 1,30 m; 80 sub-parcelas de 1 m×1 m), intermediário (perímetro à altura do peito - PAP < 15 cm, altura > 1,30 m; 20 sub-parcelas de 5 m×5 m) e superior (PAP > 15 cm, 20 parcelas de 10 m×10 m) - e correlacionaram-se as abundâncias das espécies com os parâmetros do solo e do lençol freático de cada parcela. A floresta caracterizou-se por baixa diversidade (H' = 2,36 no estrato de regeneração, 2,49 no estrato no estrato intermediário e 1,59 no estrato superior) e alta similaridade florística entre estratos (índices de similaridade de Sørensen > 0,65). As relações entre a distribuição espacial das espécies e as características do solo foram distintas entre estratos: no estrato superior correlacionou-se com a profundidade do lençol freático e o teor de matéria orgânica; no intermediário, com profundidade do lençol e teor de alumínio, porém no estrato inferior nenhum dos fatores ambientais analisados explicou a distribuição das espécies. Os resultados sugerem que a estrutura e a composição florística destas comunidades aluviais refletem os diferentes níveis de interação ao longo do ciclo de vida dos indivíduos.

Comentários sobre a distribuição geográfica de Astyanax altiparanae Garutti & Britski, 2000 (Osteichthyes, Characidae) na bacia do rio Iguaçu

Garutti (1995) made a revision of some Astyanax (Osteichthyes, Characidae) species and the species called tambiu from the upper Parana River basin, formerly identified as Astyanax bimaculatus , was considered new. Garutti & Britski (2000) later described it as Astyanax altiparanae (Pisces, Characiformes). However, they did not analyze specimens from the Iguacu River basin at that time. The Iguacu River, affluent to the Parana River, has a high degree of endemism in its ichthyofauna because of the geographic isolation caused by the falls near its mouth. Thus, there were still many doubts regarding the specific status of the population from the Iguacu River basin, also called A. bimaculatus before Garutti’s studies. To verify if the population from the Iguacu River belongs to the A. altiparanae species, we compared specimens from both basins and concluded that they belong to the same species, widening their geographic distribution.

Avaliação de Cheias Considerando Distribuições Sazonais

This paper aims at estimating of design floods based on seasonal probability distributions and their comparison with a classical annual series frequency analysis. The study is developed for the Iguacu river basin in South Brazil. Initially the evidence of seasonal diversity is analyzed and appropriate seasons are defined. Then several classical probability distributions (Gumbel, GEV, lognormal, exponential and log Pearson III) are fitted to the observed data at selected gauging stations. Goodness of fit is analyzed by means of the PPCC test proposed by Filliben (1975). This test shows that the lognormal distribution (LN2) best fits the data both for seasonal and annual maxima and hence this distribution was selected for further analysis. The annual flood may be estimated either by the classical approach of annual maximum series or by assuming that it is the maximum of independent random variables, corresponding to the seasonal floods. The floods corresponding to each of these approaches as well as that corresponding to each season are compared for selected return periods

Aspectos da história natural de Astyanax scabripinnis Jenyns (Teleostei, Characidae) em um riacho de floresta com araucária no sul do Brasil

Neste trabalho é descrita a estrutura populacional, os hábitos alimentares e a reprodução de Astyanax scabripinnis Jenyns, 1842, baseado em coletas realizadas mensalmente entre outubro de 1998 e setembro de 1999, em um riacho das cabeceiras do rio Iguaçu. A distribuição de freqüência por classe de comprimento revelou valores diferentes entre machos (5,4-6,7 cm) e fêmeas (6,1-8,1 cm). Foram encontradas diferenças significativas para os valores do fator de condição entre os sexos, o que pode implicar em diferentes taxas de crescimento. O período reprodutivo ocorreu entre outubro e março, como já descrito para outros caracídeos da mesma região. Fragmentos de insetos terrestres, restos de vegetais superiores e larvas de insetos aquáticos foram os principais itens consumidos, indicando uma pronunciada dependência da alimentação com os itens alóctones importados da vegetação ripária. Possíveis implicações das variações sazonais dos parâmetros físicos, químicos e hidrológicos sobre a história natural de A. scabripinnis são discutidas.

Cianobactérias perifíticas nos reservatórios de Segredo e Iraí, Estado do Paraná, Brasil

In order to evaluate spatial-temporal distribution of periphytic cyanobacterial community, as well as the influence of abiotic factors on these organisms, samples were collected in two reservoirs: Segredo and Irai, located within the Iguacu river basin, State of Parana. Samplings were collected in summer (April) and winter (September), 2002, in upper, intermediary and lower regions. A total of 66 cyanobacterial species were registered, with fifty species occurring in Irai Reservoir and thirty-eight in Segredo Reservoir. Irai showed higher values of cyanobacteria density (25 to 101 x ind 10 3 cm -2 ) when compared with Segredo (1 to 14 x ind 10 3 cm -2 ). We believe that cyanobacteria composition and density resulted from several factors, with preponderance of the effects of abiotic variables differences (nitrogen, phosphorus and temperature) along the longitudinal axis and along the different seasons, as well as the morphometric and hydrodynamic effects.

Resposta do álamo (<i>Populus deltoides</i> Marsh) à adubação nitrogenada em dois sítios do município de São Mateus do Sul, Paraná.

Os plantios de álamo realizados na região de São Mateus do Sul, PR, não tem o desenvolvimento esperado, pela ausência de informações a respeito de clones ideais, pragas, doenças e nutrição. Diante da carência de estudos sobre fertilização de povoamentos de álamo para as condições em que a espécie é plantada no Brasil e visando a melhorar a produtividade dos plantios de álamo na região de São Mateus do Sul, PR, foi instalado um experimento testando cinco doses de N e mais um formulado NPK em dois sítios diferentes. As avaliações mostraram um pequeno efeito da adubação sobre o crescimento em circunferência à altura do peito (CAP) e altura total (Ht). Também houve correlação positiva entre os parâmetros de crescimento com P, Ca e pH do solo, e os teores de P, Ca e B da folha, indicando a influência desses elementos sobre o crescimento das plantas, sugerindo a necessidade de adequação da fertilidade do solo, via corretivos da acidez e adubação, antes da implantação das mudas.

Copper speciation in Iguaçu river basin, at Curitiba's metropolitan region, Brazil, by ligand competition using DPASV

Copper concentrations and speciation in two different sites located in the Iguacu River Basin, Brazil, were evaluated during a 10-months period, in this work. Results showed a seasonal influence on copper levels with a major contribution of non-point sources during the rainy season, when concentrations of copper were similar in both Irai and Iguagu Rivers. During the dry season the discharge of raw sewage was the primary source of copper for the sampling point located downstream the city of Curitiba, in the Iguacu River, which exhibited higher metal concentrations. Speciation results also showed different patterns. Higher copper contents were found in the particulate phase in Iguacu River, whereas labile copper concentrations were relatively greater in Irai River waters.

Cytogenetic Characterization and NOR Polymorphism in <i>Astyanax</i> sp. C (Tetragonopterinae, Characidae) from the First Plateau of the Iguaçu River (Paraná State, Brazil)

The characids belong to the greater freshwater fish family of the world with around 700 recognized species. Whithin this group the genus Astyanax includes several species with unclear phylogenetic relationships, showing a wide karyotypic diversity. In the highly endemic Iguacu river basin these problems are also observed being distinguished 6 unnamed Astyanax species (A to F). In the present work were cytogenetically studied 2 populations of A. sp. C from the first plateau of the Iguacu river (Parana State, Brazil). Fishes of both populations are similar in chromosome number, having 2n=50, however were evidenced clear differences in C-banding and nucleolar organizing regions (NORs) patterns. With the use of the restriction enzyme Alu I were obtained the same results as C-bands. These results indicate the complexity of Astyanax and the importance of further taxonomic revisions joining morphological, cytogenetic and molecular approachings.

Identification of Astyanax altiparanae (Teleostei, Characidae) in the Iguaçu River, Brazil, based on mitochondrial DNA and RAPD markers

Astyanax fishes are among the most important food-web components of South America rivers. In the Iguacu River basin, the Astyanax genus is represented mainly by endemic species. For millions of years, that hydrographic basin has been geographically isolated from the Parana River basin by the Iguacu Falls. Recently, a species from the Upper Parana River basin identified as Astyanax bimaculatus was revised and described as a new species named Astyanax altiparanae Garutti & Britski, 2000. Fauna endemism and geographic isolation triggered interest in investigations to evaluate the identification and genetic relatedness among two A. altiparanae populations from the Upper Parana River basin and the population identified as A. bimaculatus in the Iguacu River, upstream from the Iguacu Falls. Mitochondrial DNA sequences and RAPD markers revealed high genetic diversity within each population, as well as low genetic distance, high gene flow, and high mitochondrial DNA similarity among all three populations. In conjunction with morphological similarities, these results demonstrated that the population presently known as Astyanax bimaculatus in the Iguacu River should actually be stated as Astyanax altiparanae. Furthermore, it could be inferred that the A. altiparanae population is not endemic and most likely it was recently introduced in the Iguacu River basin, maintaining the ancestral genetic identity.