Trace elements in three marine birds breeding on Reunion Island (Western Indian Ocean) Part 1 : Factors influencing their bioaccumulation

International audienceThis work aims to use seabirds as bioindicators of trace element levels in the tropical waters and food webs of the Western Indian ocean. The accumulation patterns of selected toxic (Cd and Hg) and essential (Cu, Fe, Mn, Se and Zn) elements were determined in liver, kidney and pectoral muscles of three species of 162 marine birds collected in Reunion Island between 2002 and 2004. These pelagic seabirds belong to the following species : Barau's Petrel (Pterodroma baraui), Audubon's Shearwater (Puffinus lherminieri bailloni) and the White-tailed Tropicbird (Phaethon lepturus). Mercury levels were also measured in breast feathers. Highest mean kidney Cd and liver Hg levels (respectively 27.79±13.78 μg.g−1 d.w. and 24.31 ±14.13 μg.g−1 d.w.) were found in the squid-eating Barau's Petrel. Barau's Petrel feather Hg levels fell in the 0.6-2.7 μg.g−1 d.w. range previously reported for other petrels and shearwaters. The values of the other elements were also in the same range as those previously reported in the published literature concerning related seabirds, although Se and Zn burdens in the Reunion birds were amongs the highest values. Levels of Zn, Fe and, to a lesser extent, Cu appeared to be regulated in seabird tissues. Uptake and pathways of metabolism and storage seemed to be similar for the five essential elements. The reproductive status of the bird did not seem to affect elemental levels which, moreover, were not significantly different between males and females. However, trace elements in sampled birds varied according to the tissue considered, the age of the animal and its species. The diet was seemingly a major influencing factor. The health status also appeared to have an impact on elemental levels