Abstract
ABSTRACT Drought can be viewd as a perturbation in running waters and fish are often trapped in isolated pools, where deterioration of water quality may be stressful. We investigated how this extreme condition influences response of oxidative stress biomarkers. The response of the characid Astyanax elachylepis was assessed during the dry and rainy seasons in intermittent and perennial (control) sites in streams from Brazilian savannah (Cerrado). We predicted that the biomarkers would be enhanced in the dry season in intermittent streams only due the environmentally harsh conditions in the few isolated pools that remain filled with water. As predicted, fish from the intermittent stream in the dry season presented higher gill MDA values, indicating greater stress. In the liver, MDA values were higher in the dry season for both intermittent and perennial streams, suggesting a generalized seasonal response. As expected, some antioxidant response enzymes changed in the intermittent sites during the dry season. Therefore, oxidative stress biomarkers vary seasonally, with greater increase in intermittent sites. These evidences contribute for the understanding of the spatio-temporal variation of the fish responses and fish resistance to perturbations by drought in tropical environments.
Highlights
Drought can be viewd as a perturbation in running waters influencing water availability and biota responses (Lake, 2003)
We investigated the response of fish caught in Brazilian savanna (Cerrado) streams along a reach of 300 meters in two streams: 13o17’34”S; 48o38’32”W, and 13o21’49”S; 48o35’57”W located in Cental-West Brazil, Montividiu river drainage (Fig. 1), Araguaia-Tocantins ecoregion
The glutathione peroxidase (GPx) activity was higher in the intermittent-dry condition (Fig. 2), while glutathione S-transferase (GST) activity was higher in the perennialdry condition (Fig. 2)
Summary
Drought can be viewd as a perturbation in running waters influencing water availability and biota responses (Lake, 2003). The cells have antioxidant defense systems, such as the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST), which intercept oxidant species avoiding oxidative damage to macromolecules (Van der Oost et al, 2003) These biomarkers of oxidative stress are known to exhibit strong seasonal variation (Sheehan, Power, 1999; Aras et al, 2009; Hunt von Herbing et al, 2015), due to intrinsic (metabolic changes along ontogeny and reproductive cycles) and extrinsic (changes in environmental conditions) factors (Lau, Wong, 2003; Hermes-Lima et al, 2015). Changes in dissolved oxygen scielo.br/ni | sbi.bio.br/ni
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