Effect of dietary calcium on the absorption of radiocalcium from seawater in japanese flounder paralichthys olivaceus

Abstract

Abstract : The present study was undertaken to know the absorption of 45Ca from seawater in Japanese flounder in presence of dietary Ca. Juveniles of Japanese flounder were fed diets with calcium (Ca) supplement from Ca-lactate or without Ca supplement for 2 weeks, then exposed to seawater containing 45CaCl2. Overall 45Ca absorption from seawater was higher in this species. Absorption rate was rapid initially and become slower with the exposure time increased. After a 23 hours exposure, absorption of 45Ca was not affected by dietary Ca supplementation. It is considered that 45Ca absorption in Japanese flounder do not depend on dietary Ca supplement and this species may need both dietary and environmental calcium for their normal growth and other physiological processes.