The aim of the present study was to provide a current survey of the species of parasites found in the Upper Paraná River floodplain, as well as to investigate which strategies and mechanisms used by parasites, are favored and which environmental factors influence the parasite community in the studied environments. During a seven-year period from February 2000 to September 2007, 3,768 fish belonging to 72 species were collected and analyzed for the purpose of studying the parasite fauna. A total of 337 species of parasites were reported, including 12 new descriptions: one myxosporid, Henneguya paranaensis Eiras, Pavanelli and Takemoto Keywords: ichthyoparasites, biodiversity, helminthes, crustaceans, parasite ecology. Diversidade dos parasitos de peixes da planície de inundação do Alto Rio Paraná, BrasilResumo O objetivo do presente trabalho foi realizar um novo levantamento das espécies de parasitos encontradas na planície de inundação do Alto Rio Paraná, bem como investigar quais estratégias e mecanismos utilizados pelos parasitos são mais favorecidos e quais fatores ambientais estão influenciando a comunidade parasitária nos ambientes estudados.

A new environmental enrichment device, termed a “foraging/grooming board,” was presented to 8 individually housed rhesus monkeys for the explicit purpose of reducing the level of aberrant behaviors manifested by these animals. The device, consisting of a piece of plexiglass covered with artificial fleece, had particles of food treats rubbed into it and was attached to the outside of each animal's home cage. All animals foraged from the board to the point that a significant reduction in the level of abnormal behavior was noted. Most animals also groomed the fleece covering the board, utilizing the same motor patterns that would be directed toward grooming another monkey. These boards are inexpensive to construct and easy to sanitize, and do not require placing animal facility personnel at risk to maintain them.

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We examined 44 specimens of Metynnis lippincottianus (Cope, 1870) (Characidae), collected in the Upper Paraná River floodplain, Brazil, from March 2006 to December 2007. Of the total number of fishes, 32 (72.7 %) were infected by at least one species of helminth (endoparasites). One digenean, Dadayus pacupeva, and four nematode species, Spinoxyuris oxydoras, Contracaecum sp. (larval stage), Procamallanus (Spirocamallanus) inopinatus and Raphidascaris (Sprentascaris) mahnerti were identified. D. pacupeva and S. oxydoras showed the highest values of prevalence, mean intensity and abundance. The typical pattern of overdispersion or aggregation was observed for all endoparasites. Dominance by D. pacupeva and S. oxydoras was observed in the parasite community. Positive association between D. pacupeva and two nematode species (S. oxydoras and P.(S.) inopinatus) was observed, including positive and significant covariation between their abundances. These results suggest that species are coexisting without competition. There was no correlation between parasitism and sex for M. lippincottianus.

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The degradation and homogenization of natural habitats is considered a major cause of biotic homogenization. Many studies have been undertaken on the effects of dams on aquatic wildlife, in particular fish assemblages. But how do dams affect the parasitic fauna of such fish? The aim of the present study was to examine parasitic similarity, comparing the diversity and structure of parasite communities of Leporinus friderici (Characiformes, Anostomidae) in three upstream tributaries under the influence of the Jurumirim Dam on the Upper Paranapanema River in southeastern Brazil. The present study did not find any significant differences in parasite communities among populations of L. friderici in the three upstream tributaries. This result highlights that dams promote and facilitate the dispersal of organisms between localities, and therefore the spatial homogenization of parasite communities. Overall, the results suggest that fish parasite assemblages can provide suitable data for evaluating biotic homogenization caused by dams.

A parasitological study of two freshwater cichlid fish of the genus Cichla (C. kelberi and C. piquiti) from six different aquatic ecosystems in Brazil was performed. Based on the survey, a checklist of the component community of the metazoan parasites of each of the two peacock-bass fish species was produced. Fish were collected from May 2009 to April 2011 in six Brazilian aquatic ecosystems using gillnets of different mesh sizes or angling using standardized effort. In total, six groups of parasites were collected: Monogenea, Digenea, Cestoda, Nematoda, Copepoda and Branchiura. Among the groups of parasites found, nematodes presented the greatest number of species, with seven. The study lists new records of parasites in C. kelberi and C. piquiti, and new biogeography records of parasites in six different aquatic ecosystems in Brazil. The present paper collaborates with the study of conservation biology by adding new records of parasite species.

The gills of 41 Cichla piquiti and 39 C. kelberi from Itaipu and Lajes reservoirs, respectively, Brazil, were examined to describe the ectoparasite assemblages of these two non-native peacock-bass populations. All ectoparasite species of the two studied hosts (C. piquiti and C. kelberi) were dominant, but Ascocotyle sp. (metacercariae) was the prevalent (58.53%) and most abundant helminth species in C. piquiti hosts, while Sciadicleithrum ergensi was the dominant species in C. kelberi hosts. Gill ectoparasites of C. piquiti and C. kelberi showed a typical pattern of overdispersion or aggregation, which is commonly reported for many other freshwater fishes. Ectoparasite prevalence and abundance did not vary between host sexes of the two Cichla populations. The prevalence and abundance of Ascocotyle sp. were positively correlated with C. piquiti standard length (SL), but only the abundance of S. ergensi showed a positive correlation with C. kelberi SL. Although environmental differences between reservoirs might also have influenced the results, we anticipated that the presence of a close congener in Itaipu reservoir and the lack of other Cichla species in Lajes reservoir were the key factors to explain the contrasts between C. piquiti and C. kelberi gill ectoparasites. Overall, our results suggest that the trend of parasite species loss through the invasion process may have contributed to the establishment of non-native C. piquiti and C. kelberi populations in Brazilian reservoirs.