Low mercury contamination in Mediterranean gull Larus melanocephalus chicks in Greece

Abstract

Mercury (Hg), a toxic heavy metal harmful to animals, commonly occurs in Mediterranean ecosystems. Mediterranean gull Larus melanocephalus numbers have declined considerably in Greece since the 1990s. Mediterranean gull chicks’ back feathers were therefore collected from three Greek colonies in different years between 1999 and 2009 to assess Hg pollution in this larid. Hg concentrations varied with arithmetic means ranging between 815 ng g−1 dry weight (dw) (Lafri Lagoon in 2000) and 1264 ng g−1 dw (Evros Delta in 2000), and values were independent of chick age, although significant among-year and among-site variations were found. Hg concentrations in Greek Mediterranean gull chick feathers were generally low and in fact lower than those associated with adverse effects in other bird species. Comparisons with other studies revealed that Hg concentrations in Mediterranean gulls from Greece were mostly lower than those found in other gull species elsewhere in the world. This study presents the first data on Hg contamination in the Mediterranean gull. The results might be useful in understanding and evaluating the birds’ exposure to this highly toxic pollutant and its impact on both local populations and the wider ecosystem.