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

Abstract

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. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Reading the biomineralized book of life: expanding otolith biogeochemical research and applications for fisheries and ecosystem-based management

“…Aquatic ecosystems are increasingly threatened by human-mediated sources of contaminants (Guédron & Acha 2021;Schwarzenbach et al 2006). Elevated levels of metal contaminants have been measured in archival tissues such as otoliths, fin rays, and eye lenses, to monitor elevated exposures and corroborate water quality concerns (e.g., Dove & Kingsford 1998;Mounicou et al 2019;Selleslagh et al 2016;Sun et al 2019). Contaminants such as selenium have also been measured in otoliths from several species and systems to evaluate increased exposure.…”

Loss of Coilia nasus habitats in Chinese freshwater lakes: An otolith microchemistry assessment

“…We previously conducted a comparative study on element composition profiles of Na, Mn, Fe, Ni, Cu, Sr, Ba, and Ca in otolith cores of C. nasus from the Yangtze River, Yellow Sea, and Poyang Lake using LA-ICPMS analysis. The results of the study suggested a natal homing capability of this species; the Poyang Lake, Yangtze River, and Yellow Sea seemed to be the natal lake, migration pathway, and feeding ground, respectively, for this species [ 48 ]. As indicated by Arostegui and Quinn [ 65 ], based on studies of salmonid fish of the North American, Asian, European, and African ranges, lakes provide spawning, rearing, and refuge habitats and support life-history variants, reproductive ecotypes, and trophic morphs.…”

“…In addition, otoliths are acellular and metabolically inert [ 45 , 46 ] and are not resorbed or otherwise chemically altered via biogenic processes. Consequently, otolith microchemistry provides reasonable timeline representations of the chemical composition of the waters in which fish live during the course of their lives [ 47 , 48 ]. Otoliths have previously been used to determine fish natal habitats, population connectivity, and distribution areas [ 49 , 50 ].…”

Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry Imaging in Biology

“…Other targeted structures to reveal past element exposure events include bones and otoliths. Fish otoliths are stable and durable structures that serve as a temporal biomarker for environmental monitoring and investigation of migration patterns. ,, Ishii et al analyzed bones of lead-exposed birds to measure the lifetime exposure of Pb. Bones had up to 90% of the Pb burden (approximately 90%) and were correlated to levels in other soft tissues.…”