Ecological Indicators 63 (2016) 324–331 Contents lists available at ScienceDirect Ecological Indicators jo ur nal ho me page: www.elsevier.com/locate/ ecolind Are fish in hot water? Effects of warming on oxidative stress metabolism in the commercial species Sparus aurata Diana Madeira a,∗ , Catarina Vinagre b , Mário S. Diniz a,∗ a UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal b MARE, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal a r t i c l e i n f o Article history: Received 5 June 2015 Received in revised form 16 October 2015 Accepted 1 December 2015 Keywords: Anti-oxidant enzymes Oxidative damage Biomarkers Thermal stress Sea bream Climate change a b s t r a c t Climate change is disturbing marine biological processes, and impacting goods and services provided to society. Physiological studies are a major contributor to the improvement of biological forecasting in the context of climate change. Oxidative stress biomarkers are useful tools to assess the metabolic status and health of organisms, improving management of wild and cultured populations. The aims of this study were to assess the health status and vulnerability of Sparus aurata juveniles toward ocean warming and heat wave events by (1) exposing fish to a thermal ramp from 18 ◦ C until their Critical Thermal Maximum (≈35 ◦ C) and (2) quantifying oxidative stress biomarkers in several organs, i.e. lipid peroxidation (LPO), catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), and cytochrome CYP1A. Fish showed signs of oxidative stress in every tissue tested (gills, muscle, liver, brain and intestine), the most affected being muscle and liver, which showed greater increases in LPO. In gen- eral, antioxidant enzymes increased their activity: CAT increased in every organ tested, GST increased in every organ except brain (no change) and SOD increased in every organ except intestine (no change) and brain (decrease, probably due to enzyme denaturation). Muscle showed the greatest stress response with a massive increase in GST. Hepatic CYP1A decreased upon warming suggesting that temperature influences detoxifying mechanisms and may affect fish health. These results are significant in the con- text of climate change and associated impacts on fisheries and aquaculture because over-induction of oxidative stress due to warming can induce health problems, mortality and shortened lifespan. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction One of the main concerns of contemporary society is climate change. Climate projections predict significant changes in ocean chemistry and increases in air and ocean temperature by 2100 (IPCC, 2001, 2007, 2014; Santos et al., 2002). This has led to a great interest in thermal eco-physiology because temperature is an extremely important factor in aquatic environments, especially considering that most of the inhabiting organisms are ectothermic and cannot regulate their body temperatures. Temperature starts to exert its influence at the kinetic level, impelling biochemical reactions and metabolic rates (Kordas et al., 2011). Its effect builds up to the upper levels of biological organization (i.e. community and ecosystem functioning) by affecting the energy available for growth, foraging and reproduction, which ultimately sets ∗ Corresponding author. Tel.: +351 21 2948500; fax: +351 212948554. E-mail addresses: dianabmar@gmail.com (D. Madeira), cmvinagre@fc.ul.pt (C. Vinagre), mesd@fct.unl.pt (M.S. Diniz). ecological patterns which are related to distribution, abundance of species and biological interactions (Hutchins, 1947; Hochachka and Somero, 2002; Kordas et al., 2011). In fact, changes in communities and ecosystems have already been detected and attributed to climate change (Walther et al., 2002; Perry et al., 2005; Peck et al., 2012). According to IPCC (2001), southern Europe is one of the regions where warming is expected to be most severe, with predicted air temperature increases up to 4–7 ◦ C by 2100 in the Iberian Peninsula (Santos et al., 2002 – SIAM Project). More specifically, climate change models predict a +2–3 ◦ C increase in Portuguese waters (Miranda et al., 2002) and +3–4 ◦ C in the Mediterranean (Fischer and Schär, 2010). In this context, species inhabiting these areas, which are already warm, will be exposed to even higher temperatures, especially considering that heat waves will also increase in frequency, duration and intensity (IPCC, 2007). Therefore, it is relevant to understand the physiolog- ical and molecular responses deployed by fish to cope with ocean warming. Several parameters and end-points have been used in the field of eco-physiology to detect changes on the health of wild and cultured http://dx.doi.org/10.1016/j.ecolind.2015.12.008 1470-160X/© 2015 Elsevier Ltd. All rights reserved.