The invasive red swamp crayfish (Procambarus clarkii) has become a major food resource for Eurasian otters (Lutra lutra) in the Iberian Peninsula. Crayfish accumulate large amounts of metals, and hence otters could be at risk of exposure and intoxication through crayfish consumption. We conducted a food safety risk assessment for otters inhabiting two historical mining areas in central Spain affected by lead (Pb) and mercury (Hg) pollution. Estimated daily intakes (EDI) of Pb and Hg were non-invasively calculated from the proportion of crayfish remains and metal levels in otter feces. We considered that the abdominal muscle and the carcass of crayfish differ significantly in relative weight, total metal content and bioavailability of metals to reduce the uncertainty of risk characterization. Fecal concentrations of Hg and Pb in the polluted areas were 1.878 and 6.554 μg/g d. w., respectively (13-fold and 7-fold higher compared to a non-polluted area). EDI of Hg and Pb in the polluted areas were 66.02 and 78.26 μg/kg-day, respectively (14- and 8-fold higher than in the reference area). EDI from the Hg area were above minimum levels susceptible to cause neurotoxicity in mustelids, and 6.3% were above levels susceptible to cause histopathological lessions. In the Pb area, 16.7% of EDI were consistent with levels causing reproductive effects. Metal exposure through crayfish consumption might prevent or slow the recovey of otters in these polluted environments, thus this factor should be considered in management strategies aimed to protect otter populations.
Keywords: Abandoned mines; Lutra lutra; Metal pollution; Non-invasive sampling; Procambarus clarkii.
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