TOXICITY AND BEHAVIORAL EFFECTS OF CADMIUM IN PLANARIAN (Dugesia japonica Ichikawa et Kawakatsu)

摘要

Acute toxicity tests of a freshwater Planarian {Dugesia japonica Ichikawa et Kawakatsu) exposed to cadmium were conducted according to the American Society for Testing and Materials (ASTM) guidelines. The 24, 48, 72 and 96-h LC_(50) values were calculated as 4.92, 2.25, 1.52 and 1.45 mg Cd~(2+)/L, respectively. When compared with different phyla or classes of freshwater animals, the rank of Dugesia japonica in species sensitivity was in the 43-44 and 39-40 ranges for 24- and 48-h LC_(50), respectively. D. japonica had moderate sensitivity. A mobility assay was carried out to explore the behavioral effects of Cd~(2+) on D. japonica. At sub-toxic concentrations, Cd~(2+) decreased D. japonica locomotor behavior in a concentration-dependent manner. The mobility IC~(50) for adult D. japonica at 24,48,72 and 96 h were calculated to be 3.07, 2.66, 1.35 and 1.37 mg Cd~(2+) /L for measured concentrations, respectively. Locomotion of newborns was seriously impaired and cannot be used to calculate the mIC~(50). Results showed that D. japonica can be regarded as a useful bioindicator species for the detection and evaluation of Cd~(2+) effects upon freshwater invertebrates. Acute toxicity on D. japonica and mobility assay for adult D. japonica can be used as biomarkers for Cd~(2+) exposure in a freshwater environment.