Use of fish otoliths as a temporal biomarker of field uranium exposure

Sandra Mounicou (1) , Sandrine Frelon (2) , A. Le Guernic (2) , Yvan Eb-Levadoux (2) , V. Camilleri (2) , L. Fevrier (3) , S. Pierrisnard (3) , L. Carasco (3) , R. Gilbin (3) , K. Mahé (4) , H. Tabouret (1) , Gilles Bareille (1) , O. Simon (2)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 IRSN/PSE-ENV/SRTE/LECO - Laboratoire d'écotoxicologie des radionucléides
3 IRSN/PSE-ENV/SRTE/LR2T - Laboratoire de recherche sur les transferts des radionucléides dans les écosystèmes terrestres
4 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer

This study aimed to determine uranium (U) pollution over time using otoliths as a marker of fish U contamination. Experiments were performed in field contamination (~20 μg L−1: encaged fish: 15d, 50d and collected wild fish) and in laboratory exposure conditions (20 and 250 μg L−1, 20d). We reported the U seasonal concentrations in field waterborne exposed roach fish (Rutilus rutilus), in organs and otoliths. Otoliths were analyzed by ICPMS and LA-ICP SF MS of the entire growth zone. Concentrations were measured on transects from nucleus to the edge of otoliths to characterize environmental variations of metal accumulation. Results showed a spatial and temporal variation of U contamination in water (from 51 to 9.4 μg L−1 at the surface of the water column), a high and seasonal accumulation in fish organs, mainly the digestive tract (from 1000 to 30,000 ng g−1, fw), the gills (from 1600 to 3200 ng g−1, fw) and the muscle (from 144 to 1054 ng g−1, fw). U was detected throughout the otolith and accumulation varied over the season from 70 to 350 ng g−1, close to the values measured (310 ng g−1) after high exposure levels in laboratory conditions. U in otoliths of encaged fish showed rapid and high U accumulation from 20 to 150 ng g−1. The U accumulation signal was mainly detected on the edge of the otolith, showing two U accumulation peaks, probably correlated to fish age, i.e. 2 years old. Surprisingly, elemental U and Zn signatures followed the same pattern therefore using the same uptake pathways. Laboratory, caging and field experiments indicated that otoliths were able to quickly accumulate U on the surface even for low levels and to store high levels of U. This study is an encouraging first step in using otoliths as a marker of U exposure.

Mots clés: Roach; Accumulation; Laser ablation; ICP-MS

Domaines: Biodiversité et Ecologie; Autre; Océanographie

Sandra Mounicou, Sandrine Frelon, A. Le Guernic, Yvan Eb-Levadoux, V. Camilleri, et al.. Use of fish otoliths as a temporal biomarker of field uranium exposure. Science of the Total Environment, 2019, 690, pp.511-521. ⟨10.1016/j.scitotenv.2019.06.534⟩. ⟨hal-02289346⟩