MEPS 160:109-120 (1997)  -  doi:10.3354/meps160109

Although a number of measurements have been made on radiocesium concentrations in aquatic organisms, no clear agreement has been reached on the factors affecting accumulation of these radionuclides. Natural variations in the concentration of the long-lived artificial radionuclide ¹³⁷Cs in marine organisms and factors affecting variations in marine fishes were investigated through long-term and systematic measurements in coastal waters of Japan from 1984 to 1995. Concentrations of ¹³⁷Cs were measured in more than 30 species of crustaceans, cephalopods and teleosts considered representative of the marine biotic community. A clear positive correlation (p < 0.05) was found between mean weight and concentration of ¹³⁷Cs in 276 fish samples. However, different relationships between ¹³⁷Cs concentration and weight of fish were observed in different species. Within 16 studied species ¹³⁷Cs concentration increased with growth for 4 species, while no specific correlation was observed in the remaining species. These different patterns depended on a change of food habits with growth. Analysis of 6066 stomach contents of fish samples together with ¹³⁷Cs concentrations in the stomach contents demonstrated that ¹³⁷Cs concentration increased with rising trophic level and that the biomagnification factor (¹³⁷Cs in predator/¹³⁷Cs in prey) was 2.0 (95% confidence interval 1.8 to 2.2). From the yearly change of ¹³⁷Cs in 24 marine fish species, a mean effective environmental half-life of ¹³⁷Cs of 13 ± 3 yr (range 10 to 17 yr) was calculated.

Trophic level · Food habits · Marine organisms · Bioaccumulation · ¹³⁷Cs · Size-dependence · Environmental half-life