Effects of photocatalytic reactions on marine plankton: Titanium dioxide powder as catalyst on the body surface

Photocatalytic effects of TiO2 powder on marine plankton were examined by the use of either brine shrimp Artemia salina or noxious red tide flagellate Chattonella antiqua as a probe. After UV (365 nm) irradiation for ca. I hour, A. salina stopped moving and the body surface was completely covered by TiO2 powder. Similar photoirradiation of C. antiqua, on the other hand, induced deformation of the body from spindle to round shape within 20 minutes. The deformed C. antiqua recovered to normal shapes, when the cells were kept in the same conditions but without UV irradiation for more than 40 minutes. On the prolonged U-V irradiation (more than 100 minutes), however, the cells burst and came to annihilation. The photocatalytic reactions of TiO2 on the body surface are thus concluded to induce fatal damages to these microorganisms.