ABSTRACT. Biomarkers are measurements within an organism that respond to environmental effects and are used as tools in bioassessment programs since they reflect physiological changes induced by exposure to pollutants. The hepatosomatic index (HSI) and the condition factor (CF) in three fish species Geophagus brasiliensis, Hypostomus affinis and Hypostomus auroguttatus were used to assess effects of pollutant stress in a tropical river during two seasons (dry and wet). Fish from the least disturbed sites had the lowest condition factor (CF) and the lowest HSI, whereas those from sites near pollutant discharges had the highest CF and HSI. Higher HSI and lower CF occurred during the dry season. It is suggested that species adapted to stressful conditions take advantage on food availability from organic loads or unoccupied niches by lesser tolerant species, increasing CF. We concluded that higher HSI values were directly associated with environmental stress whereas the higher CF values are related to availability of food resources derived from organic loads or other sources. CF and HSI are simple and cost-effective, thus suitable as routine screening tools in pollution monitoring, but caution should be taken in relating changes in physiological measurements and any specific pollutant to prevent misinterpretation.Keywords: condition factor, hepatosomatic index, fishes, monitoring, rivers.O uso de biomarcadores para avaliar efeitos de estresses de poluentes sobre espécies de peixes em um rio tropical no sudeste do Brasil RESUMO. Biomarcadores são medidas dentro de um organismo que respondem a efeitos ambientais e são utilizadas em programas de bioavaliação, já que refletem alterações fisiológicas induzidas pela exposição a poluentes. O índice hepatossomático (IHS) e o fator de condição (FC) das espécies Geophagus brasiliensis, Hypostomus affinis e Hypostomus auroguttatus foram calculados em um rio tropical durante duas estações (seca e cheia). Peixes de locais menos alterados apresentaram menores FC e IHS, enquanto os de locais próximos de descargas de poluentes apresentaram maiores FC e IHS. Maiores IHS e menores FC ocorreram durante a estação seca, comparados com a estação chuvosa. É sugerido que espécies adaptadas às condições estressantes levam vantagem da disponibilidade de alimentos próxima às descargas orgânicas ou nichos não ocupados por espécies menos tolerantes, aumentado o FC. Os valores mais elevados do IHS foram diretamente associados ao estresse ambiental, enquanto os valores mais elevados FC estão relacionados com a disponibilidade de recursos alimentares derivados de descargas orgânicas ou outras fontes. FC e IHS são simples e de baixo custo, portanto, adequados como ferramentas no controle da poluição, mas cuidados devem ser tomados ao relacionar suas mudanças às medições fisiológicas ou a qualquer poluente específico para evitar efeitos de interferência.Palavras-chave: fator de condição, índice hepatossomático, peixes, monitoramento, rios.
The Funil Reservoir receives a large amount of xenobiotics from the Paraíba do Sul River (PSR) from large number of industries and municipalities in the watershed. This study aimed to assess environmental quality along the longitudinal profile of the Paraíba do Sul River-Funil Reservoir system, by using biomarkers and bioindicators in a selected fish species. The raised hypothesis is that Funil Reservoir acts as a filter for the xenobiotics of the PSR waters, improving river water quality downstream the dam. Two biomarkers, the ethoxyresorufin-O-deethylase activity (EROD), measured as fluorimetricly in S9 hepatic fraction, and the micronuclei frequency (MN), observed in erythrocytes of the cytoplasm, and three bioindicators, the hepatosomatic index (HSI), gonadosomatic index (GSI) and condition factor (CF) were used in Pimelodus maculatus, a fish species widely distributed in the system. Four zones were searched through a longitudinal gradient: 1, river upstream from the reservoir; 2, upper reservoir; 3, lower reservoir; 4, river downstream of the reservoir. EROD activity and HSI and GSI had significant differences among the zones (P<0.05). The upper reservoir had the lowest EROD activity and HSI, whereas the river downstream of the reservoir had the highest EROD and lowest GSI. The river upstream from the reservoir showed the highest HSI and GSI. It is suggested that the lowest environmental condition occur at the river downstream of the reservoir, where it seems to occur more influence of xenobiotics, which could be associated with hydroelectric plant operation. The hypothesis that Funil reservoir acts as a filter decanting pollution from the Paraíba do Sul River waters was rejected. These results are novel information on this subject for a native fish species and could be useful for future comparisons with other environments.Keywords: biomonitoring, EROD, fishes, pollutants, reservoirs. Biomarcadores e bioindicadores da condição ambiental usando uma espécie de peixe (Pimelodus maculatus
Movimentos antivacinas, negacionismo da ciência personificado na negação das mudanças climáticas, pseudociências como terraplanismo e curas milagrosas são questões extremamente comuns no atual mundo da pós-verdade. Como ensinar e aprender Biologia neste cenário? Os alunos de hoje possuem essa preocupação ao pesquisar sobre Biologia pela Internet? A presente pesquisa surgiu a partir desses questionamentos, cujo objetivo principal é buscar compreender a relação que os alunos do ensino médio têm com as fake news. Para tal, foi realizado um levantamento, por meio de questionário com 7 perguntas, sendo 3 abertas e 4 fechadas, em turmas do ensino médio normal e regular do Colégio Estadual Presidente Dutra. O questionário buscou investigar as frequências com as quais os entrevistados empregavam diferentes estratégias de verificação de conteúdo em seu processo de aprendizagem de Biologia. Os resultados do estudo se mostraram relativamente positivos, ao considerar que cerca de 60% dos alunos, sempre ou quase sempre, checam as fontes das informações sobre Biologia que acessam ao fazer pesquisas, trabalhos ou estudos. No entanto um número considerável de alunos declarou nunca consultar um especialista a respeito das informações que consomem, evidenciando que há a necessidade de que as escolas se preparem, e que tenham professores atualizados para que sejam também agentes de alfabetização digital dos alunos.
The Paraíba do Sul River (PSR) drainage basin in Southeastern Brazil covers one of the most industrialized and densely populated regions of the country. The impact of chemical contamination on the PSR basin seems to be more pronounced in its middle reach where a number of potentially polluting plants are located. In this study, we used hepatic EROD activity-a biomarker of exposure to CYP1A-inducing pollutants (e.g. PAHs, PCDD/Fs, PCBs)-and the incidence of micronucleated erythrocytes (Mn) in the peripheral blood-a biomarker of effects of DNA-damaging agents (e.g. PAHs)to evaluate the effects of pollution on two native fish species, Geophagus brasiliensis and Pimelodus maculatus. Results showed that the incidence of Mn and EROD in G. brasiliensis and P. maculatus from the two most downstream sites (Três Rios Town and Piabanha River) were markedly higher than the incidence of Mn and EROD recorded in fish from the most upstream site (Funil Reservoir). Our findings are consistent with the view that CYP1A-inducing activity and increased DNA-damage are found in fish caught in sampling sites located downstream of the stretch where there are several industries that are potential sources of PAHs and CYP1A-inducing contaminants.
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