National Research Institute of Fisheries Science, Yokohama, Kanagawa 236-8648, Japan
Ingestion rate, digestion rate and phyto-pigment content in the digestive diverticula of Japanese pearl oyster, Pinctada fucata martensii, juveniles grazing six different micro-algae (Pavlova lutheri, Isochrysis aff. galbana clone T-Iso, Chaetoceros gracilis, Nitzschia closterium, Tetraselmis tetrathele, Dunaliella tertiolecta) were determined. Ingestion rates of the pearl oyster juveniles grazing T-Iso, P. lutheri, Ni. closterium, D. tertiolecta were almost the same (10.0×106~10.6×106 cells/h/ind). However the ingestion rate of T. tetrathele was slightly lower (6.6×106 cells/h/ind) while that of Ch. gracilis was slightly higher (12.8×106 cells/h/ind). Digestion rate and phyto-pigment contents in the digestive diverticula of the pearl oyster juveniles differed with the algal diet species. These results suggest that various algal diets cause differences in the ingestion rate, digestion rate and phyto-pigment content in the digestive diverticula of pearl oyster juveniles.