Interspecific comparison of radiocesium trophic transfer in two tropical fish species.

The trophic transfer of radiocesium ( ¹³⁴ Cs) was investigated in two tropical fish, the silver moony Monodactylus argenteus and the spotted scat Scatophagus argus. Juveniles of both species were exposed to dietary ¹³⁴ Cs using the pulse-chase feeding methodology. The food was brine shrimp (Artemia salina) previously exposed to the dissolved radiotracer. Depuration kinetics of ¹³⁴ Cs were followed for 45 d. Results showed that Cs was similarly efficiently assimilated by both species (AE > 50%). The estimated trophic transfer factors in the two species ranked from 1 to 2, suggesting that ¹³⁴ Cs could be biomagnified in both omnivorous species. In complement, dissections of 7 body compartments were carried out at three different times in order to highlight ¹³⁴ Cs organotropism. ¹³⁴ Cs organotropism was similar in both species: more than 50% of ¹³⁴ Cs was quickly distributed in the muscles and skeleton (after 3 days of depuration), which is likely related to the analogous behavior between Cs and K, an essential element for muscle contractions and bone formation.
(Copyright © 2018 Elsevier Ltd. All rights reserved.)