Gas supersaturation — Impact on the design and operation of aquatic systems

Abstract

Exposure to gas supersaturation can have a significant impact on aquatic animals held in culture systems, resulting in gas bubble trauma (GBT) due to the formation of gas bubbles in the tissues and vascular system. Typically, most research on gas supersaturation has been conducted on salmonid species which were exposed to acutely lethal levels. The chronic effects of sublethal gas supersaturation levels that may be present in many hatcheries are not well identified due to the low levels of gas supersaturation involved, a delay of 1–2 months before the start of mortality, a lack of typical clinical signs of gas bubble trauma and significant seasonal variation in the gas levels of many surface waters. Gas bubble trauma can be produced by influent water that is supersaturated or by production of gas supersaturation within the hatchery. Prevention of gas bubble trauma in hatcheries will require degassing of influent water and some process waters, design of aquatic systems to prevent production of gas supersaturation, and proper operation of the water system and water quality maintenance processes.