Heavy metals and metalloid levels in the tissues of yellow-legged gulls (Larus michahellis) from Spain: sex, age, and geographical location differences

In the present study, mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se), and arsenic (As) were measured in liver, kidney, and feathers of adult, juvenile, and chick seagulls (Larus michahellis) collected from the northwest of Spain. Age, sex, and the geographical location of samples were considered variables that can infuence metal bioaccumulation, for which concentrations were determined by means of ICP-MS. The mean concentrations (dry weight) found in seagulls were 7.01±0.37 mg Hg/kg, 22.82±2.83 mg Cd/kg, 7.36±1.36 mg Pb/kg, 18.64±0.63 mg Se/kg, and 10.64±0.59 mg As/kg. Regarding the diferent factors analyzed, Hg was the only metal showing sex-related diferences, being signifcantly higher (p<0.05) the concentrations found in feathers of males (1.26±0.12 mg/kg) than those in females (0.99±0.11 mg/kg). A highly signifcant (p<0.01) increase in levels of some metals was found in liver related to the increase of age: Hg (adults (A) 3.33±0.22 mg/kg vs chicks (C) 1.76±0.28 mg/kg), Cd (A 4.74±0.62 mg/kg vs C 1.79±0.2), Pb (A 0.65±0.12 mg/kg vs juveniles 0.4±0.11 mg/kg), and Se (A 7.56±0.43 mg/kg vs C 5.24±0.53 mg/kg). Positive correlations between Cd-Hg and Se–Hg were found in liver (p<0.001), kidney (p<0.001), and feathers (p<0.05 and p<0.001, respectively). The associa tions found may refect antagonistic interactions between Se and Cd on Hg toxicity. The results suggest that L. michahellis can reveal local contamination around the foraging and breeding sites and can be a very useful monitoring instrument for assessing heavy metal contamination and sentinel species of environmental health