TY - JOUR

T1 - Mercury exposure and risk assessment for Eurasian otters (Lutra lutra) in Denmark

AU - Dibbern, Miriam

AU - Elmeros, Morten

AU - Dietz, Rune

AU - Søndergaard, Jens

AU - Michelsen, Anders

AU - Sonne, Christian

PY - 2021

Y1 - 2021

N2 - Mercury (Hg) exposure may cause a wide range of adverse effects in mammals. A piscivorous apex predator, as the Eurasian otters (Lutra lutra) may accumulate and biomagnify heavy metals and pollutants. Here we investigate the Hg burden in 117 otters from Denmark to evaluate Hg concentrations and risks of health effects. Mercury concentrations ranged between 0.02 and 10.1 μg/g wet weight (ww) in liver tissue and 0.30–40.0 μg/g dry weight in fur. Concentrations in liver and fur in individual otters were highly correlated (P < 0.001). Generalized linear modelling showed that mercury concentrations in both liver and fur increased with age (liver: P < 0.002; fur P < 0.05) and with distance to the marine coastline i.e. towards freshwater habitats (P = 0.0526), and δ13C in muscle tissues (P < 0.001). No differences were detected between males and females (P > 0.59) and no correlation were detected between Hg concentration and trophic level (δ15N) (liver: P = 0.35; fur: P = 0.54). Mercury concentrations in the liver exceeded the No Risk threshold in 15% of the otters, and 25% had levels above the lowest observed effect level of 3.4 μg/g ww that may be associated with adverse effects on the central nervous system. The proportion exceeding these thresholds should therefore be monitored to document possible temporal and spatial trends in Hg exposure and the potential risk to the conservation status of the otter population.

AB - Mercury (Hg) exposure may cause a wide range of adverse effects in mammals. A piscivorous apex predator, as the Eurasian otters (Lutra lutra) may accumulate and biomagnify heavy metals and pollutants. Here we investigate the Hg burden in 117 otters from Denmark to evaluate Hg concentrations and risks of health effects. Mercury concentrations ranged between 0.02 and 10.1 μg/g wet weight (ww) in liver tissue and 0.30–40.0 μg/g dry weight in fur. Concentrations in liver and fur in individual otters were highly correlated (P < 0.001). Generalized linear modelling showed that mercury concentrations in both liver and fur increased with age (liver: P < 0.002; fur P < 0.05) and with distance to the marine coastline i.e. towards freshwater habitats (P = 0.0526), and δ13C in muscle tissues (P < 0.001). No differences were detected between males and females (P > 0.59) and no correlation were detected between Hg concentration and trophic level (δ15N) (liver: P = 0.35; fur: P = 0.54). Mercury concentrations in the liver exceeded the No Risk threshold in 15% of the otters, and 25% had levels above the lowest observed effect level of 3.4 μg/g ww that may be associated with adverse effects on the central nervous system. The proportion exceeding these thresholds should therefore be monitored to document possible temporal and spatial trends in Hg exposure and the potential risk to the conservation status of the otter population.

KW - Bioaccumulation

KW - Ecotoxicology

KW - Heavy metals

KW - Risk assessment

KW - Stable isotopes

U2 - 10.1016/j.chemosphere.2021.129608

DO - 10.1016/j.chemosphere.2021.129608

M3 - Journal article

C2 - 33486453

AN - SCOPUS:85099629705

VL - 272

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

M1 - 129608

ER -