Effects of Ozone-Produced Oxidants on Ventilation of the Pearl Oyster, Pinctada fucata martensii

Abstract

To evaluate the effect of ozone-produced oxidants (OPO) on the ventilation of the pearl oyster, Pinctada fucata martensii, the ventilation volume (Vg), the gill cilia movement (SP) and observation of the surface structure of gills were examined after exposure to ozonated seawater for 24 hr. Vg was examined every 3 hr during exposure to the seawater of OPO 0.70 mgO₃/l. Also the day when Vg recovered to the level of the control after exposure (DY) was examined. In the 24 hr, Vg and SP decreased with an increase in the OPO concentration, and showed zero at 0.58 mgO₃/l or more. DY was under 23 days at 0.42 mgO₃/l or below, and 10-80 days at 0.58-0.70 mgO₃/l. However at 0.58-0.70 mgO₃/l, 20 % of the individuals used for the experiment died 5-76 days later. Every 3 hr, Vg decreased with time. DY was under 23 days within 12 hr and 25-80 days at 24 hr. From the observation, the damages of the gills were postulated to progress in order that the frontal cilia dispappeared, the lateral cilia dispappeared, the ciliary disc collapsed, and the gill filaments disappeared from the tip.