Mercury isotopes of key tissues document mercury metabolic processes in seabirds

Seabirds accumulate significant amounts of mercury (Hg) due to their long-life span together with medium high trophic position in marine food webs. Hg speciation and isotopic analyses total different tissues (pectoral muscles, liver, brain, kidneys, blood feathers) were assessed investigate detoxification mechanisms. Three species contrasted ecological characteristics studied: the Antarctic prion (zooplankton feeder), white-chinned petrel (pelagic generalist consumer) southern giant (scavenger on seabirds mammals). The difference mass-dependent fractionation (MDF, ?202Hg) values between liver muscles (up 0.94 ‰) all three strongly suggests hepatic demethylation isotopically lighter methylmercury (MeHg) subsequent redistribution heavier fraction MeHg towards muscles. Similarly, higher ?202Hg feathers 1.88 relative proportion (94–97%) than (30–70%) likely indicate potential muscle preferential excretion (isotopically heavier) growing during moult. extents these key processes dependent species-specific strategies levels dietary exposure. We also found mass-independent (MIF, ?199Hg) internal tissues, possibly integration times exposure permanently active organs inert as feathers. isotope variations reported this study show evidence propose a powerful approach for deep investigation metabolic seabirds.