[en] This study investigated transfer of radioactive substance through a food chain nutrioecologically. Concentration of radioactivity in predator organisms clearly increased significantly when feeding intensity was stressed. Feeding intensity depends on the density and the concentration of feed, and to what degree feeding condition used in this experiment is equivalent to GAMMA value can be estimated from parameter GAMMA which unifies both the density and the concentration. In contrast with this, if GAMMA value of predator in natural environment can be measured, the suggestion can be obtained as to what kind of feeding condition can be used in an experiment in order to conform feeding intensity to natural environment. Feeding interval did not affect the concentration of radioactivity in living thing when mean feeding intensity was equal at least within a range of this experiment condition. It was thought that result of this experiment was proper if there was not a difference in assimilation rate by feeding intensity. (Tsunoda, M.)