Acute physiological stress responses of juvenile coho salmon (Oncorhynchus kisutch) to sublethal concentrations of garlon 4®, garlon 3a® and vision® herbicides

Abstract

AbstractJuvenile coho salmon (Oncorhynchus kisutch) were exposed for 4 h to sublethal concentrations of the herbicides Garlon 4®, Garlon 3A®, and Vision®. Trials were performed in a closed‐system respirometer that measured oxygen consumption of fish prior to and during a 4‐h exposure. At the end of the exposure period, plasma glucose and lactate concentrations, hematocrit, and leucocrit were measured as indicators of acute physiological stress. There were no biologically significant indications of acute physiological stress in fish exposed to Garlon 4, Garlon 3A, or Vision at 5 to 80% of the 96‐h LC50 concentrations. The results suggest that threshold herbicide concentrations causing physiological stress in short‐term exposure (4 h) in juvenile coho salmon may be higher than the 96‐h LC50 value for those herbicides. It was concluded that sublethal concentrations of Garlon and Vision herbicides do not induce significant physiological stress responses in juvenile coho salmon during a 4‐h exposure period.