Effect of low salinity on the ventilation volume and the ciliary movement were examined in the Purplish bifurcate mussel Septifer virgutus. The ventilation volume was measured by using a direct measurement method. The ciliary movement was shown indirectly by the transportation velocity of a piece of vinyl film (2.0mm diameter, 0.3mm thickness) put on the gill surface. The ventilation volume at 20℃ declined with decrease in salinity, and the ventilation stopped at 21.0 psu. The ventilation volumes in 30 psu were the same as those in 35 psu. The transportation velocities in 25psu were the same as those in 34 psu, and the velocities were zero mm/min in 10 psu at 13.0, 21.0 and 25.0℃, and in 13 psu at 29.5℃ when the salinity decreased. From the results for salinity tolerance, the Purplish bifurcate mussel is suspected not to be distributed over an inner bay where the salinity offten declines to low levels.
Purplish bifurcate mussel
ciliary movement
salinity
ventilation
water temperature