Abstract

This study was performed to obtain the basic data on physiological responses of low water temperature stress of the cultured Pacific abalone, Haliotis discus hannai. Abalones were exposed at low water temperatures of $7^{\circ}C$ and $4^{\circ}C$. We have investigated survival rate, superoxide dismutase (SOD) activity and total protein (TP) in the abalone by the exposure times (0, 3, 6, 12, 24, 72, 120, 168 and 216 hours). Survival rate of the abalone at $7^{\circ}C$ experiment was 90.8%, whereas at $4^{\circ}C$ experiment was 0% after exposure 10 days. SOD activity was significantly increased until 12 hours after exposure to $4^{\circ}C$, and then was recovered to starting level after 24 hours. However, there was no significant difference between control ($12^{\circ}C$) and $7^{\circ}C$ experiments. TP was significantly increased until 216 hours after 24 hours at $4^{\circ}C$ experiment, but $7^{\circ}C$ experiment showed no significant differences compared to control ($12^{\circ}C$) experiment. Therefore, H. discus hannai was acclimated in low water temperature stress at $7^{\circ}C$, but at $4^{\circ}C$, all abalone died possibly because they exceed the limits of defense ability to too low temperature.