メジナおよびアゴハゼの成長に伴うCdの毒性および蓄積性の変化

抄録

The Cd toxicity and its accumulation for two species of marine fish were examined at various growth stages. Girella Glarella punctata and goby Chasmichtys dolichognatus fish. The 96-h LC₅₀ for girella at the first growth stage when the mean body weight was 0.18g was 15.7mg/l and this value was considerably lower compared with 25.1, 27.1 and 29.7mg/l in the later three stages. Cd accumulated in juveniles weighing about 0.2-0.3g in the highest concentration for 96h while the concentration in thefish weighing over about 1.0g remained constant. Goby was found to enhance prominently the tolerance to Cd, i.e. the 96-h LC₅₀ increased from 5.5mg/l at 0.021g of mean body weight to 30.5mg/l at 0.211g. The Cd concentration in exposed gobies decreased markedly with the growth in the early juvenile stage and remained a constant level in adult.
Those results indicate that girella and goby enhanced markedly their tolerance to Cd in their early juvenile stages, and they had a particular period when this metal was highly concentrated in acute exposure.