Experimental study of iodine uptake by phytoplankton

Sato, Yuhi; Otosaka, Shigeyoshi  ; Suzuki, Takashi  

It is known that iodine is a biophilic element. However, uptake processes of iodine by phytoplankton are less well understood. The present study evaluated phytoplanktonic uptake of iodine under light or dark conditions, by using cultivated cultures and natural population of phytoplankton. Cultivated cultures were incubated with iodate for 10 hours. Diatom, haptophyceae, and cryptophyceae accumulated significant amount of iodine whereas cyanobacteria did not show accumulation. Although haptophyceae and cryptophyceae incorporated iodine only under the light condition, diatom accumulated under light and dark conditions. The natural population incubation, which was conducted under sunlight and dark conditions in natural seawater, showed a significant accumulation of iodine into phytoplankton under both light and dark conditions. These results indicate that species of phytoplankton and physiological activities can affect dynamics of iodine in a diurnal scale.