Effect of Cold Shock on the Physiological Responses of the Cultured mullet, Mugil haematocheilus in Winter

Physiological responses of mullet Mugil haematocheilus to cold shock in winter were investigated. The experimental mullets were initially acclimated at $10.0^{\circ}C$ and then the water temperature was reduced to $-1.2^{\circ}C$ for cold shock experiment. The stress responses was monitored for nearly 50 hours. The parameters monitored include survival rate, plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose (GLU), total protein (TP), electrolytes $(Na^+,\;K^+,\;Cl^-)$, cortisol and thyroid hormones $(TT_4,\;TT_3,\;FT_4\;and\;FT_3)$. With the exception of the TP and electrolytes, most parameters changed significantly during the cold shock. The survival rate did not change from $10^{\circ}C\;to\;-0.6^{\circ}C$, but decreased significantly below $-1.0^{\circ}C$, and was zero at $-1.2^{\circ}C$. The plasma AST and ALT concentrations increased remarkably from $2.5^{\circ}C\;to\;0.5^{\circ}C$ and from $2.5^{\circ}C\;to\;1.5^{\circ}C$, respectively, and then declined rapidly as the temperature decreased to $-1.2^{\circ}C$. The plasma GLU concentration did not change until -0.5'E, and then the concentration increased significantly at $-1.2^{\circ}C$. The plasma cortisol concentration increased remarkably from $2.5^{\circ}C\;to\;-0.5^{\circ}C$, and then declined at $-1.2^{\circ}C$. The plasma thyroid hormones showed two changes during the cold shock. Both plasma 74 concentrations increased remarkably from $2.5^{\circ}C$\;to\;0.5^{\circ}C$, then declined rapidly until $-1.2^{\circ}C$, while both plasma 73 concentrations decreased significantly from $10^{\circ}C\;to\;2.5^{\circ}C$, and then remained significantly lower than the concentration at $10^{\circ}C$.

월동기 저수온 충격에 따른 양식산 가숭어 Mugil haematocheilus의 생리생화학적 반응