抄録
T. obscurus from the mouth of Susami and Tonda rivers and brackish water pond in Onzan park and T. brevispinis from the lower of Tonda river in Wakayama prefecture were transferred directly from freshwater to seawater.
Within 24 hours after the transfer, both species showed loss of body weight, decrease in muscle water content, increase in plasma osmolarity and increase in Na+ and Cl- concentrations of both plasma and muscle. No remarkable changes were observed in K+ concentrations of both plasma and muscle except for that of the muscle of T. obscurus from Onzan.
After 168 hours, Cl- concentrations in the muscle of both species increased remarkably as compared to those of the freshwater specimens. With the exception of CI-, almost all measureditems in T. obscurus returned to nearly same levels as those in freshwater. On the other hand, in T. brevispinis, loss of body weight, decrease in muscle water content, increase in Na+ and K+ concentrations of both plasma and muscle were observed as compared to those under freshwater conditions.
