Metal(loid) exposure assessment and biomarker responses in captive and free-ranging European brown bear (Ursus arctos)

Maja Lazarus,Tatjana Orct,Agnieszka Sergiel,Lana Vranković,Vlatka Filipović Marijić,Dubravka Rašić,Slaven Reljić,Jasna Aladrović,Tomasz Zwijacz-Kozica,Filip Zięba,Jasna Jurasović,Marijana Erk,Robert Maślak,Nuria Selva,Đuro Huber

doi:10.1016/j.envres.2020.109166

Abstract

We investigated the level of five non-essential metal(loid)s (As, Cd, Hg, Tl, Pb) and nine essential metals (Mg, Ca, Mn, Fe, Co, Cu, Zn, Se, Mo) in hair and blood components of captive and free-ranging European brown bear populations in Croatia and Poland. Metal(loid) associations with biomarkers of oxidative stress (superoxide dismutase, SOD; glutathione-peroxidase, GSH-Px; malondialdehyde, MDA) and metal exposure (metallothionein, MT) were estimated in this top predatory mammal. Lead was the most abundant non-essential metal(loid) in both blood and hair, with 4 of 35 individuals having blood levels over 100 μg/L. A positive association was found between Pb level and SOD activity in blood. Free-ranging bears had higher blood SOD activity, Mn, Zn and Cd levels, hair Co, Cd, Tl and Pb compared to captive individuals, while the opposite was true for Mg and hair Ca thereby reflecting habitat and diet differences. With increasing age, animals showed lower levels of SOD activity and certain essential metals. Females had higher SOD activity and blood levels of some essential metals than males. Hair showed a higher Fe and Co level when sampled during the growth phase and was not predictive of non-essential metal(loid) blood levels. The established metal(loid) baseline values will enable future risk assessment in both captive and wild European brown bear populations.

Highlights

The Dinarides and Carpathians are two of the few European habitats hosting three large carnivore species, of which the brown bear (Ursus arctos) is the most spread-out occurring in 22 European countries (Chapron et al 2014)
Adverse health effects of toxic metal(oid)s were demonstrated through impairment of homeostasis of essential elements leading to their deficiency or excess state (Goyer 1997, 2019)
Sex, status, country and date of sampling as factors potentially influencing the element levels in bear blood and hair

Summary

Introduction

The Dinarides and Carpathians are two of the few European habitats hosting three large carnivore species, of which the brown bear (Ursus arctos) is the most spread-out occurring in 22 European countries (Chapron et al 2014). Toxic metal(oid)s (arsenic, cadmium, lead, and mercury) are among the health stressors (Tchounwou et al 2012) recognized to adversely impact large terrestrial mammals Oxidative stress-related toxic effects of metals are induced through the depletion of major antioxidants (e.g., glutathione, metallothionein), changes in activity of antioxidative enzymes (e.g., glutathione-peroxidase, superoxide-dismutase) and free radical levels which can damage biomolecules (DNA, proteins, membrane lipids) (Stohs and Bagchi 1995, Ercal et al 2001). Small proteins metallothioneins (MTs) regulate level of essential metals (e.g., Zn, Cu) and detoxify non-essential metals (e.g., Cd, Hg) binding them to its sulfhydryl groups (Kägi 1991, Isani and Carpené 2014). Adverse health effects of toxic metal(oid)s were demonstrated through impairment of homeostasis of essential elements leading to their deficiency or excess state (Goyer 1997, 2019)

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