Evaluation of body size and temperature on ¹³⁷Cs uptake in marine animals

Highlights: • The bioaccumulation of ¹³⁷Cs in marine prey species was found to be directly related to animal body size and hence their surface: volume ratios. • Bioconcentration factors of ¹³⁷Cs were highest in the smallest animal Acartia tonsa and lowest in Palaemonetes vulgaris. • Temperature did not significantly affect the bioaccumulation of ¹³⁷Cs in the experimental animals except in mollusc larvae. - Abstract: ¹³⁷Cs bioaccumulation and retention in seven different marine animal species, including crustaceans, mollusc larvae, and fish larvae were compared under different temperature conditions (10 °C, 18 °C and 25 °C). Replicate animals were experimentally exposed to 0.5 nM ¹³⁷Cs dissolved in filtered seawater for 3 days, and their ¹³⁷Cs contents were periodically measured using gamma spectrometry. Among the seven species, ¹³⁷Cs bioconcentration factors ranged from 14 to 239 at the end of the exposure periods. Following uptake, the¹³⁷Cs loss rate constants from the animals ranged from 5 to 50% d⁻¹ and were unaffected by temperature or animal size. The ¹³⁷Cs bioconcentration factors were directly related to animal size and hence their surface: volume ratios, consistent with the conclusion that Cs sorption from the aqueous phase is the principal uptake mechanism in these animals. With the exception of gastropods, temperature had no major influence on Cs uptake and efflux in the experimental species.