High Temperature, pH, and Hypoxia Cause Oxidative Stress and Impair the Spermatic Performance of the Amazon FishColossoma macropomum

The control of abiotic parameters is fundamental for fish survival, growth and reproduction. These factors have a direct effect on sperm quality. Thus, this study evaluated the effect of different temperatures (29, 31, 33, and 35 degrees C), pHs (4 and 8), and hypoxia (1 mgO(2)L(-1)) on sperm motility ofColossoma macropomum(tambaqui). The results indicated a longer duration of sperm motility at 29 degrees C (50.1 +/- 2.70 s) that progressively decreased when exposed to 35 degrees C (31.2 +/- 1.31 s) and hypoxia at pH 4 (27.4 +/- 1.42 s) and pH 8 (30.44 +/- 1.66 s;p< 0.05), respectively. Sperm oxygen consumption increased in hypoxia at both pH (pH 4 = 61.22; pH 8 = 54.74 pmol s(-1)). There was an increase in the activity of glutathione-S-transferase (GST) and superoxide dismutase (SOD), as well as in lipid peroxidation levels (LPO) and DNA damage in sperm exposed to higher temperatures and hypoxia. The pH 4 and pH 8 under normoxia did not affect the quality ofC. macropomumsperm. These results suggest that water warming and acidification, consequences of climate changes, significantly affect the reproduction ofC. macropomum, reducing the quality of spermatozoids during fertilization.