The Paraná River basin has about 600 fish species. In the Upper Paraná, 310 fish species were recorded, with 52 species were registered in the streams and headwaters of the Paranapanema River. The aim of this study was to characterize the stream fish communities in the Upper Paranapanema River basin. Samplings were conducted with electrofishing during the dry season in the year of 2014. The collection effort consisted of 30 streams stretches. As a result, 41 species of stream fish were recorded in the Upper Paranapanema River basin, distributed in 26 genera, 11 families and 7 orders. Thirty-nine percent of the species can be considered rare, 41% intermediate and 20% common. We captured approximately eight species by stream stretch and the estimated richness (Schao2) was 40 ± 6 species. Around 40% of the individuals had less than 50 mm in length.

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Bees are valuable bioindicators, providing information regarding environmental conditions through different kinds of analyses. Therefore, the effect of cadmium on the morphology of ovaries of Bombus morio workers was used to study a concentration considered environmentally safe (1 ppb) in Brazil. Workers of the same estimated age exposed for 48 h to 1 ppb cadmium showed extensive morphological changes in the germarium and vitellarium compared with the control group. Bees exposed to cadmium showed death of or damage to entire vitellogenic follicles, with chromatin condensation and fragmentation of nurse cell nuclei. In the germarium, the intercellular bridge connecting the primary oocyte to the developing nurse cells was broken. The nurse cells formed a cluster of cells with compacted chromatin, detached from an isolated primary oocyte. In some cases, the cytoblasts were absent from the germarium, leaving an empty space surrounded by collapsed peritoneal sheaths. We further propose that such a hazardous impact of 1 ppb cadmium on the ovaries of B. morio workers is not only mainly due to cadmium itself as an endocrine disruptor, indirect oxidative stress promoter, cytoskeleton destabilizer and mutagenic trace metal, but by disruption of the trophocytes, where perivitelline space filled with eosinophil material in the control group, was totally empty in exposed bees, suggesting interruption of trophocyte vitellogenin production.