February 1st to 5th 2016
Olhão, Portugal
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Thermal stress biomarkers in the widespread tropical and subtropical sergeant-major fish: temperature as a major environmental stressor in a warming ocean

Scientific Exhibition
Future Oceans
Wednesday, February 3, 2016 -
18:30 to 20:00

Madeira, C. 1 Mendonça, V. 2 Flores, A.A.V. 3 Cabral, H.N. 4 Diniz, M. 5 Vinagre, C. 6

1MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
2MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
3CEBIMAR - Centro de Biologia Marinha, Universidade de São Paulo, Rodovia Manoel Hipólito do Rego, km 131.5, São Sebastião, Brazil
4MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
5UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica
6MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa

Tropical and subtropical reef associated organisms have been recognized as being among the most vulnerable organisms towards environmental change, namely due to climate warming and consequent habitat loss. The study of their physiological responses under environmental stress seems to be a key issue for assessing ecosystem health in these areas but this knowledge is still missing for most species. This study investigates the effect of increased temperature (29°C – control, 32°C – thermal stress) over one experimental month (samplings at 0, 7, 14, 21 and 28 days) in the response of heat shock protein 70kDa (Hsp70) and ubiquitin (Ub) in different body tissues - gills, muscle and skin (including scales) – of a common shallow water fish Abudefduf saxatilis. Results show significantly increased levels of both proteins in gills under increased temperature exposure, suggesting the cellular stress response was activated, but there was nevertheless an accumulation of irreversible damaged proteins, which explains why ubiquitin showed an increase at 32°C. Muscle showed an increase in Hsp70 levels at 32°C but no significant differences were found for ubiquitin, suggesting in this tissue Hsp70 production was enough to cope with stress. No significant differences between temperature treatments were found for skin tissue. This may present an interesting opportunity for ecotoxicology studies, as it suggests skin and scales might be a good target tissue for chemical pollution analyses, given that temperature will not be a confounding factor. Significant differences were found for biomarker levels along time and among different tissues. Muscle and especially skin showed the lowest levels of the biomarkers tested when compared to the gills. It was concluded that this fish species can be used as an indicator for thermal stress, and it is proposed it should be included in standard biomonitoring programs in tropical and subtropical areas, given its vast geographical range.
keywords: 
sergeant-major fish, thermal stress biomarkers, climate warming, environmental assessment, ecosystem health

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