Mercury in Feathers and Blood of Gulls from the Southern Baltic Coast, Poland
2017
Szumiło-Pilarska, Emilia | Falkowska, Lucyna | Grajewska, Agnieszka | Meissner, Włodzimierz
Gulls were assessed as sentinels of contamination in the coastal zone of the Southern Baltic, research material being obtained from dead birds collected on Polish beaches and near fishing ports in 2009–2012. In feathers and blood of four gull species: herring gull (Larus argentatus), common gull (Larus canus), black-headed gull (Chroicocephalus ridibundus), and great black-backed gull (Larus marinus), concentration of total mercury (HgT) was assayed, taking into account the type of feathers, sex, and age. Stable isotopes (δ¹⁵N, δ¹³C) were used as tracers of trophic position in the food web. In the study, feathers and blood were compared as non-invasive indicators of alimentary exposure introducing mercury into the system. In order to do that, the correlations between mercury concentrations in the blood, feathers, and the birds’ internal tissues were examined. The strongest relations were observed in the liver for each species R ²Cₒₘₘₒₙ Gᵤₗₗ = 0.94, p = 0.001; R ²Bₗₐcₖ₋ₕₑₐdₑd Gᵤₗₗ = 0.89, p = 0.001; R ²Gᵣₑₐₜ Bₗₐcₖ₋bₐcₖₑd Gᵤₗₗ = 0.53, p = 0.001; R ²Hₑᵣᵣᵢₙg Gᵤₗₗ = 0.78, p = 0.001. While no correlation was found with feathers, only developing feathers of juvenile herring gulls were found to be a good indicator immediate of exposure through food (R ²ₘᵤₛcₗₑ = 0.71, p = 0.001; R ²ₖᵢdₙₑyₛ = 0.73, p = 0.001; R ²ₕₑₐᵣₜ = 0.89, p = 0.001; R ²ₗᵤₙgₛ = 0.86, p = 0.001; R ²bᵣₐᵢₙ = 0.83, p = 0.001). Additionally, based on studies of herring gull primary feathers, decrease of mercury concentration in the diet of birds over the last two decades is also discussed.
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