Acute but not chronic hyperoxia increases metabolic rate without altering the cardiorespiratory response in Atlantic salmon alevins

• Published in: Aquaculture
• Main Authors: Polymeropoulos, ET, Elliott, NG, Frappell, PB
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2018
• Subjects: Biological Sciences; Physiology; Comparative Physiology; Atlantic salmon; Salmo salar
• Online Access: https://doi.org/10.1016/j.aquaculture.2018.12.041; http://ecite.utas.edu.au/129902

Hyperoxia has been shown to affect growth, survival and cellular homeostasis in fish. Previous findings onchronic hypoxia (low environmental O 2 ) exposure in Atlantic salmon alevins indicate that re-exposure to normoxicconditions after hypoxia exposure (relative hyperoxia) elevates metabolism above normal. Hence, we hereinvestigated whether acute hyperoxia above normoxic conditions also alters O 2 ) uptake and whether chronichyperoxia affects O 2 ) uptake under normoxic and hypoxic conditions. To this end, the effects of acute and chronichyperoxia exposure on metabolic rate and cardiorespiratory function (heart rate and ventilation rate) in Atlanticsalmon ( Salmo salar ) alevins incubated at 4 C were investigated, and how it is affected by an increase in ambienttemperature (4 C and 8 C). Hyperoxia (1518 days at 28 kPa) reared alevins display advanced development compared with normoxiaincubated animals. While acute hypoxia generally leads to metabolic depression (≈70%, 21 kPa compared with5 kPa), acute hyperoxia (28 kPa) causes hypermetabolism (≈30% compared with normoxia at 4 C and ≈20% at8 C). Chronic hyperoxic rearing on the other hand did not alter metabolic rate at 4 C or 8 C in acute hyperoxia,normoxia or hypoxia. Heart rates and ventilation rates were also unaltered with acute hyperoxia and wereunaffected by chronic hyperoxia exposure. It is shown that acute hyperoxia increases O 2 ) uptake above normoxicconditions but chronic hyperoxia does not result in long term physiological changes. This adds further proof thatO 2 ) uptake is not limited by O 2 ) transport capacity but by O 2 ) availability at this developmental stage in salmonids.