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Identification of priority conservation areas is crucial for safeguarding freshwater ecosystems. Occurrence of unique populations and/or evolutionary significant units for key species is one of the most frequent reasons for protecting a region or location. In this study we have studied two of the most important fisheries resources of the Amazon basin, Curimata and Tambaqui, from different areas, in order to identify common zones of special diversity. Employing the Barcoding cytochrome oxidase I gene as a genetic tool, we have detected a clear differentiation of the populations inhabiting the Meeting of Waters and the rest of the basin for both species. This area corresponds to the confluence of the Solimões and the Negro rivers, of different physicochemical water characteristics, at the Brazilian city of Manaus in central Amazonas. The Meeting of Waters area (near Manaus) could be recommended as a potential area subject of special management, given its apparent role as a shelter for evolutionary significant units.

Nas últimas décadas a floresta amazônica vem sofrendo pressão de diversos setores com sua constante destruição, o que acaba ocasionando a busca por soluções para minimizar os impactos sofridos. O trabalho teve como objetivo geral caracterizar as principais técnicas utilizadas para uso do fogo na prática agrícola e a prevenção de queima controlada por agricultores familiares do município de Novo Progresso. A coleta de dados foi realizada através de uma entrevista semiestruturada com aplicação in loco. Constatou-se que 14% dos entrevistados não fazem uso do fogo na agricultura enquanto que a grande maioria dos produtores utilizam o fogo. Quanto as palestras de prevenção e combate a incêndios florestais, ministrados pela brigada de incêndios da região, 77% dos entrevistados participaram destas atividades, 18% nunca participaram, e 5% não foi possível adquirir dados a respeito do questionamento. Como medida de proteção ao fogo acidental, 95% dos produtores entrevistados fazem o uso de aceiro e 5% não adotam essa prática. A manutenção destes aceiros é feita com maquinas agrícolas por uma pequena parcela (10%) enquanto que 45% dos entrevistados fazem a limpeza manualmente e 45% não fazem nenhum tipo de manutenção. São necessários a presença e efetividade dos órgãos públicos da região, junto aos agricultores assentados, para a melhoria nas condições do uso do fogo nas práticas agrícolas.PALAVRAS-CHAVE: Agricultura, Assentamento, Incêndios.

Guanabara Bay is a semi-closed tropical bay located in the center of metropolitan Rio de Janeiro. The ecological integrity of this system has a spatial gradient, with better environmental conditions near the mouth than in the inner bay. The objectives of this study were to monitor the exposure of the pond perch Diplectrum radiale (Perciformes; Serranidae) to metal pollution, using metallothionein as a specific biomarker, and to detect spatial differences in metal contamination in this large water body. The effects of biological factors (allometric condition factor, size, weight, and reproductive stage) and spatial variations on MT levels were also investigated among sampling sites. The results revealed intraspecific sources of variation influencing MT expression. Therefore, it was not possible to use MT as a sensitive biomarker to distinguish heavy metal pollution among sites within this bay. The spatial heterogeneity of metal bioavailability and the probable mobility of individual fish contributed to those findings. However, the pond perch can still be considered a good target organism to evaluate the effects of metal contamination through comparison with other estuarine ecosystems on the Brazilian coast.

Acetylcholinesterase (AChE) is an important regulatory enzyme that controls the transmission of nerve impulses across cholinergic synapses. This study evaluated AChE activity as an effect biomarker for ecological risk assessment related to mercury contamination in fish from Guanabara bay, Rio de Janeiro State, Brazil. A total of 30 fishes were collected, 14 specimens of Genidens genidens and 16 specimens of Haemulon sp. at three sampling stations. AChE activity varied from 0.18 to 1.29 µmol min-1 mg-1 protein for G. genidens and a negative correlation between AChE activity in muscles and mercury concentrations in kidney was found (-0.55; p<0.05; n=14). For Haemulon sp. the enzyme activity showed a smaller range (0.06 to 0.22 µmol min-1 mg-1 protein) and a negative correlation between mercury concentrations in muscles and AChE activity was found (r =-0.570; p<0.05; n=16), suggesting a decrease on enzymatic response in specimens with higher mercury bioaccumulation.