수온급변에 노출된 참돔의 생존과 생리적 반응

Survival and physiological response of Pagrus major exposed to sudden change of water temperature

This experiment was conducted to estimate the effects of sudden changes in water temperature (WT) on survival and physiological responses (hematocrit: Ht, hemoglobin: Hb, serum cortisol and glucose levels, and osmolality) of red seabream, Pagrus major. All the fishes were acclimated for 2 weeks at 25℃ before experiment initiation, thereafter exposed to each WT regime (13, 16 and 19℃) in a flow through recirculation culture system with 12 tanks (water vol. 200 L/tank). The WT was decreased from 25℃ to 13, 16 and 19℃ within 6 hours (2, 1 and 0.5℃/hour), and then was increased to 25℃ within 6 hours after maintenance for 42 hours in each WT regime. The cumulative survival rates of the fish exposed to the experimental WT regime of 13℃ and 16℃ during whole experiment were shown 0% and 88%, respectively. The blood Hct and Hb of 16℃-exposure fish were significantly decreased and were significantly increased in the level of serum cortisol and glucose as compared with those in the control. The Hct, Hb, cortisol and glucose levels of the fish exposed to 16℃ were recovered after back to initial temperature of 25℃. The serum cortisol and glucose levels of all fish groups were significantly increased by lowering WT, and were shown the hypercortisolism and hyperglycemia in the 13℃-exposure fish group.