Radiocesium uptake, trophic transfer, and exposure in three estuarine fish with contrasting feeding habits

This study investigated the effects of different environmental factors on ¹³⁷Cs uptake in three subtropical estuarine fish, and the trophic transfer of ¹³⁷Cs in the fish from different preys. Our data showed that salinity, potassium, and temperature had appreciable effects on the dissolved uptake of ¹³⁷Cs in the fish, but no conclusive relationship was found between the effects of salinity and potassium concentration on the uptake. The dietary assimilation of ¹³⁷Cs was 51–55% in the omnivorous fish Siganus fuscescens when fed with macroalgae or bivalve tissues, and was much lower than those in carnivorous fish Sebastiscus marmoratus and Jarbua terapon (70–79%). Dietary pathway dominated the ¹³⁷Cs accumulation in the omnivorous and carnivorous fish, both of which exhibited strong potential to biomagnify ¹³⁷Cs from their preys. Using the biokinetic model, we demonstrated that salinity and temperature only had minor effects on the overall accumulation of ¹³⁷Cs in carnivorous species living in estuarine environment. Modeling calculation suggested that it would take 37–80 days for the fish to reach 95% of steady-state concentration, and lower somatic growth increased the time to reach steady-state in the fish.