Trace metals in feathers and leukocyte differentials in chicks of three seabird species from the Beagle Channel, Argentina

Abstract

Seabirds are long lived mesopredators and are therefore very good indicators of trace metal exposure in the environment. In January 2023, the concentrations of Cu, Zn, Fe, Cd, Ni and Pb were measured in feathers of imperial cormorant Leucocarbo atriceps, kelp gulls Larus dominicanus and dolphin gulls Leucophaeus scoresbii chicks from colonies close (< 3km) and far (80km) from Ushuaia city, within the Beagle channel. In addition, the proportion of granulocytes (heterophiles and eosinophils) to lymphocytes (G/L) were analyzed for these individuals. Cu did not differ amongst species and locations (7.05 ± 0.88 µgg-1). Zn was slightly higher for kelp gulls close to Ushuaia than further away (153.2 ± 10.6 µgg-1 vs. 136.8 ± 1.2µgg-1) and Fe differed amongst species and the interaction between species and locations, being higher for cormorants close to Ushuaia (46.84 ± 6.75 µgg-1). Cd, Ni and Pb were not detectable (<0.83 µgg-1) except for Pb in one dolphin gull close to Ushuaia (outlayer). The G/L ratio was lower for kelp gulls close to Ushuaia than further away (G/L = 0.99 ± 0.70 vs. G/L= 0.58 ± 0.40). The present study is the first to detect trace metal presence in kelp gull, dolphin gull and imperial cormorant chick feathers within the Beagle Channel. Future studies must include other tissues and age classes in order to have a better understanding of exposure of trace metals on seabirds in this region.