Effects of pentachlorophenol (PCP) on the oxygen consumption rate of the river puffer fish Takifugu obscurus

Laboratory bioassays were conducted to determine the effects of pentachlorophenol (PCP) on the oxygen consumption of the river puffer fish Takifugu obscurus. Oxygen consumption of 6 to 9 mo old puffer fish was measured with an automatic intermittent-flow-respirometer (AIFR). Oxygen consumption rate was significantly increased by exposing fish to concentrations of 50, 100, 200 and 500 ppb PCP. Following exposure to 50 or 100 ppb PCP, the instantaneous rate of oxygen consumption was considerably increased. T. obscurus exposed to 200 ppb PCP, however, exhibited a breakdown in the biorhythm of oxygen consumption presumably due to a strong physiological stress caused by the higher PCP concentrations. River puffer fish exposed to 500 ppb PCP died in 10 h.