No abstract

We investigated blood gas, hematological and biochemical parameters and gill morphology and morphometry of Lophiosilurus alexandri juveniles submitted to hypoxia for 48 hours followed by recovery for 48 hours. A total of 48 juveniles (360.0 ± 141.6 g) were distributed among eight tanks (120 L) and subjected to hypoxia condition (water with dissolved oxygen at 2.12 ± 0.90 mg L − 1 ) or normoxia (at 5.60 ± 0.31 mg L − 1 ). Blood gas values (pH, PvCO 2 , PvO 2 , sO 2 , HCO 3 − , stHCO 3 − and base excess) in hypoxia were signi cantly different from normoxia, while lactate and the electrolytes (K + , Na + , Cl − , Ca 2+ and HCO 3 − ) there was no signi cant change among treatments. The erythrocytes differed signi cantly between hypoxia and normoxia at 24 h of recovery, while for hemoglobin and hematocrit there were no signi cant differences. There was a signi cant difference in glucose, triglycerides, and cholesterol for both normoxia and hypoxia, while plasma protein remained unchanged. All gill components (epithelial cells, erythrocytes, pillar cells, mucus cells, chloride cells, undifferentiated cells, and blood capillary lumen) differed signi cantly between hypoxia and normoxia. A reduction in the length of the primary lamella was observed in the hypoxia and recovery treatments, when compared to normoxia. The secondary branchial lamella showed no signi cant difference for both treatments. In general, juveniles of L. alexandri adapted well to hypoxia exposure for 48 h, as they were able to adjust most of their physiological variables to survive this stress condition and return to normoxia within 48 h.

We investigated blood gas, hematological and biochemical parameters and gill morphology and morphometry of Lophiosilurus alexandri juveniles submitted to hypoxia for 48 hours followed by recovery for 48 hours. A total of 48 juveniles (360.0 ± 141.6 g) were distributed among eight tanks (120 L) and subjected to hypoxia condition (water with dissolved oxygen at 2.12 ± 0.90 mg L− 1) or normoxia (at 5.60 ± 0.31 mg L− 1). Blood gas values (pH, PvCO2, PvO2, sO2, HCO3−, stHCO3− and base excess) in hypoxia were significantly different from normoxia, while lactate and the electrolytes (K+, Na+, Cl−, Ca2+ and HCO3−) there was no significant change among treatments. The erythrocytes differed significantly between hypoxia and normoxia at 24 h of recovery, while for hemoglobin and hematocrit there were no significant differences. There was a significant difference in glucose, triglycerides, and cholesterol for both normoxia and hypoxia, while plasma protein remained unchanged. All gill components (epithelial cells, erythrocytes, pillar cells, mucus cells, chloride cells, undifferentiated cells, and blood capillary lumen) differed significantly between hypoxia and normoxia. A reduction in the length of the primary lamella was observed in the hypoxia and recovery treatments, when compared to normoxia. The secondary branchial lamella showed no significant difference for both treatments. In general, juveniles of L. alexandri adapted well to hypoxia exposure for 48 h, as they were able to adjust most of their physiological variables to survive this stress condition and return to normoxia within 48 h.