Abstract:The drainages of the Iguaçu River basin, as well as the main channel of the river, have peculiar characteristics resulting from geomorphological processes in this area, including the formation of the Iguaçu River Falls. This slope in the lower portion of the basin is a biogeographical barrier to many organisms. In this study was inventoried the fish fauna of streams of the lower Iguaçu River basin, evaluating possible differences in the species composition upstream and downstream of this biogeographical barrier. Sampling were conducted between 2004 and 2013, in five streams, three upstream and two downstream of the Iguaçu River Falls, using electrofishing. The nMDS analysis was run to investigate possible groupings of similar fauna between the streams sampled. The scores of this test were tested as to the significance of groupings with the Hotelling T 2 test. The indicator value method (IndVal) was used to detect the distribution of species among the groups of the streams upstream and downstream of the Iguaçu River Falls. We collected 18,908 individuals of six orders, 11 families, and 40 species. Siluriformes and Characiformes had the highest species richness; Cyprinodontiformes presented the highest abundance. Considering the species recorded, 21 are considered natives to the Iguaçu River basin, including 15 endemic, wich were found only in streams upstream of the falls. Additional 18 species were verified only in the streams downstream of such barrier. Four species were common to both stretches. The axis 1 of the nMDS separated two groups: streams upstream (S1, S2 and S3) and streams downstream of the Iguaçu River Falls (S4 and S5). The indicator species analysis also indicated a distinction between the groups of streams, that were significantly different (Hotelling's T 2 = 234.36, p ˂ 0.0001). The number of endemic species in the streams upstream of the Falls (15 spp.) evidences a significant effect of isolation promoted by the Iguaçu River Falls, and confirms the role of this barrier in the vicariant processes and endemism typical of this basin. These results emphasize the importance of conserving these ecosystems, once the extinction of species in this region means the irreversible loss of them. Resumo: As drenagens da bacia do rio Iguaçu, bem como o canal principal do rio, possuem características peculiares resultantes de processos geomorfológicos dessa área, incluindo a formação das Cataratas do rio Iguaçu. Esse desnível na porção inferior da bacia constitui uma barreira biogeográfica para muitos organismos. Neste trabalho inventariamos a fauna de peixes de riachos na porção do baixo rio Iguaçu, avaliando possíveis diferenças na composição de espécies acima e abaixo dessa barreira biogeográfica. Entre 2004 e 2013, foram amostrados cinco riachos, sendo três localizados acima das Cataratas do Iguaçu e dois abaixo, por meio de pesca elétrica. Para investigar possíveis padrões de agrupamentos de fauna similares entre os riachos amostrados foi
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 Iguaçu River basin, municipality of Cascavel, state of Paraná, 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.
Os zoológicos são ambientes não formais de ensino com grande potencial educativo. Esse trabalho buscou promover a Educação Ambiental (EA) em espaços não formais, utilizando o zoológico como local de estudo. Para isso, uma colônia de férias foi organizada para 19 crianças (9 a 12 anos). A pesquisa teve uma abordagem qualitativa e a constituição dos dados se deu através de questionários pré e pós, submetidos a análise de conteúdo. Os resultados demonstraram uma carência no conhecimento sobre o real papel dos zoológicos e suas atribuições. Após as atividades, foi identificado uma maior criticidade com os temas estudados, demonstrando que existem várias possibilidades para se trabalhar a EA em zoológicos.
Studies on the size spectrum allow indirect inferences of how the energy flows from one organism to another. Assuming that the bottom-up is more intense than the top-down mechanism along the cascade of reservoirs, which limits the growth and development of individuals, we investigated the effect of a cascade of reservoirs in a neotropical basin on the stock and distribution of the population of Oligosarcus longirostris, a species at the top of the food chain. Samples were conducted quarterly in five reservoirs, from March 2004 to December 2008. Stock size was estimated by catch per unit effort (CPUE); to establish the size spectra slopes of fish, we used Pareto I model, and data was analyzed using univariate analysis of variance followed by Tukey's test. There was a higher proportion of smaller individuals in the first reservoir of the cascade, with a decline in this proportion along the succession of reservoirs in the cascade. It can be concluded that there is an effect of the reservoir cascade on the abundance and size of individuals of Oligosarcus longirostris.
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