Abstract Isopods of the suborder Cymothoida include ectoparasite species that cause physical damage and affect the development of the host by feeding on blood and tissues. On fishes, these parasites attach themselves to the skin, fins, gills, and oral cavity using claws on articulated legs. The ability to remain hidden in cavities even after the fish is caught enables isopods to be transported to new areas along with the host, making these parasites potential co-invaders. Understanding the role and environmental impact of parasites is essential, although research on parasitism in the context of biological invasions lags in comparison to general research on such invasions. Previous records indicate only two species of parasitic isopods in the São Francisco River basin. However, the present study reports the first record of two other species (Braga patagonica and Braga nasuta) on Pygocentrus piraya and in the basin itself. This demonstrates a lack of knowledge regarding fish parasites in the region, despite the presence of other parasites. Collaborations with research groups conducting fish sampling in the basin can contribute to expanding knowledge on these parasites and the training of human resources in fish parasitology. The present study provides important information on the presence of unidentified parasitic isopods on fishes in the São Francisco River basin, underscoring the need for further studies and expanding the geographic distribution of these parasites, as well as the host list for these isopods. tissues skin fins gills legs coinvaders. coinvaders co invaders. invaders co-invaders essential However nasuta itself region parasitology

Resumo Diante da toxicidade do mercúrio para o ser humano e para o meio ambiente, o objetivo deste trabalho foi avaliar a sua bioacumulação em 13 espécies de peixes com diferentes hábitos alimentares, capturados no reservatório de Três Marias, bacia do rio São Francisco, no período de março de 2012 a abril de 2013. Os resultados obtidos revelam que as espécies com hábito alimentar carnívoro apresentaram as maiores concentrações médias de mercúrio em músculo, com destaque para Serrasalmus brandtii (pirambeba) e Pygocentrus piraya (piranha), com concentrações de 0,4147 ± 0,2744 μg g-1 e 0,1774 ± 0,2980 μg g-1, respectivamente. Considerando as concentrações médias, todas as espécies estudadas apresentaram teores de mercúrio abaixo dos limites máximos de 0,5 μg g-1 em peixes não predadores e de 1,0 μg g-1 em peixes predadores, estabelecidos pela Agência Nacional de Vigilância Sanitária. Levando em conta cada espécie, os valores mínimos e máximos de mercúrio nos tecidos muscular e hepático demonstraram uma ampla dispersão. Em 4% dos espécimes de pirambeba e 7% de piranha, os teores de mercúrio em músculo ultrapassaram o limite estabelecido pela ANVISA para peixes predadores, e, portanto, sendo impróprios para o consumo humano. As demais espécies não apresentaram amostras de músculo com teor de Hg acima do estabelecido em lei. Devido ao seu hábito alimentar carnívoro e sua ampla distribuição na bacia do rio São Francisco, Serrasalmus brandtii pode ser considerada como biomonitor, capaz de bioacumular mercúrio, indicando, assim, o nível de contaminação desse metal no ambiente aquático em que vive.

Abstract The objective of this work was to evaluate the bioaccumulation of mercury in 13 species of fish with different eating habits, captured in the Três Marias Reservoir, São Francisco Basin, from March 2012 to April 2013. The results obtained showed that the species with carnivorous eating habit presented the highest average concentrations of mercury in muscle, especially Serrasalmus brandtii (pirambeba) and Pygocentrus piraya (piranha), with concentrations of 0.4147 ± 0.2744 μg g-1 and 0.17774 ± 0.2980 μg g-1, respectively. Considering the average concentrations, all the species studied showed levels of mercury below the maximum limit of 0.5 μg g-1 in non-predatory fish and 1.0 μg g-1 in predatory fish, established by the Agência Nacional de Vigilância Sanitária. Taking each species into account, the minimum and maximum values of mercury in the muscular and hepatic tissues showed a wide dispersion. In 4% of the specimens of pirambeba and 7% of piranha, the contents of mercury in muscle exceeded the limit established by ANVISA for predatory fish, and therefore, were unfit for human consumption. The other species did not present muscle samples with Hg content above that established by law. Due to its carnivorous eating habit and its wide distribution in the São Francisco Basin, Serrasalmus brandtii can be considered a biomonitor, capable of bioaccumulating mercury, thus indicating the level of contamination in the aquatic environment in which it lives.

Surface sediments from the River São Francisco were analyzed to investigate the impact, due to the presence of metals (Cd, Cu, Pb, Zn) in wastes from a metallurgical industry in the city of Três Marias/MG, Brazil. The concentrations and geochemical associations of Pb, Zn and trace metals associated with the minerals employed in zinc production were measured. Sediments close to discharge locations were highly contaminated with Pb (332-512 μg g-1) and Zn (7872-10780 μg g-1), with values decreasing rapidly due to dilution and hydraulic sorting. Evaluation of toxicity according to the Consensus-based Sediment Quality Guidelines indicated for Cd, Pb and Zn a high probability of adverse effects on aquatic biota at these sites.