The use of biomarkers for assessing effects of pollutant stress on fish species from a tropical river in Southeastern Brazil/O uso de biomarcadores para avaliar efeitos de estresses de poluentes sobre especies de peixes em um rio tropical no sudeste do Brasil

• Published in: Acta scientiarum. Biological sciences Vol. 39; no. 4; p. 431
• Main Authors: Morado, Claudio Nona, Araujo, Francisco Gerson, Gomes, Iracema David
• Format: Journal Article
• Language: English
• Published: Universidade Estadual de Maringa 01.10.2017
• Subjects: Brasil
• ISSN: 1679-9283; 1807-863X
• DOI: 10.4025/actascibiolsci.v39i4.34293

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. Biomarcadores sao medidas dentro de um organismo que respondem a efeitos ambientais e sao utilizadas em programas de bioavaliacao, ja que refletem alteracoes fisiologicas induzidas pela exposicao a poluentes. O indice hepatossomatico (IHS) e o fator de condicao (FC) das especies Geophagus brasiliensis, Hypostomus affinis e Hypostomus auroguttatus foram calculados em um rio tropical durante duas estacoes (seca e cheia). Peixes de locais menos alterados apresentaram menores FC e IHS, enquanto os de locais proximos de descargas de poluentes apresentaram maiores FC e IHS. Maiores IHS e menores FC ocorreram durante a estacao seca, comparados com a estacao chuvosa. E sugerido que especies adaptadas as condicoes estressantes levam vantagem da disponibilidade de alimentos proxima as descargas organicas ou nichos nao ocupados por especies menos tolerantes, aumentado o FC. Os valores mais elevados do IHS foram diretamente associados ao estresse ambiental, enquanto os valores mais elevados FC estao relacionados com a disponibilidade de recursos alimentares derivados de descargas organicas ou outras fontes. FC e IHS sao simples e de baixo custo, portanto, adequados como ferramentas no controle da poluicao, mas cuidados devem ser tomados ao relacionar suas mudancas as medicoes fisiologicas ou a qualquer poluente especifico para evitar efeitos de interferencia. Palavras-chave: fator de condicao, indice hepatossomatico, peixes, monitoramento, rios.