ABSTRACT The response of benthic foraminifer Pararotalia nipponica to heavy metal cadmium is observed in laboratory experiment. The results indicate that under a given set of conditions, heavy metal cadmium is deleterious to benthic foraminifera. Gradual increase in cadmium (Cd) concentration mainly affected normal growth and caused morphological abnormalities which were consistent from 4 µg/l to 14 µg/l. The intensity of deformation was severe exhibiting a peculiar change in coiling direction with increase in cadmium concentration. The presence of >50% deformed specimens at the lowest cadmium concentration (2 µg/l) indicates that the threshold of Cd concentration which is detrimental to P. nipponica is <2 µg/l
