Assessing helminth infection in some reproductive colonies of Southern Giant Petrel (Macronectes giganteus) from Antarctica

The host/parasite relationship is a key tool for understanding the role of parasitism in the feeding ecology of Antarctic seabirds. Especially, birds with extensive migratory routes through isolated regions are particularly sensitive to new infections. Although research on parasitic diSseases in Antarctic birds is sparse and information is fragmentary, an increasing number of studies are currently underway in this area. The present study aims to provide new information on parasitic helminths in the Southern Giant Petrel Macronectes giganteus in some nesting areas from South Shetland Island and Antárctic Península, integrating different parasitological techniques. A total of 126 faecal samples, 16 regurgitates and six dead individuals (five adults and one chick) were analysed for helminth parasites. Members of four helminth groups (Cestoda, Digenea, Nematoda, Acanthocephala) represented the parasitic diversity of the Southern Giant Petrel in the studied localities. All dead birds analysed (P = 100%) harboured helminth parasites, additionally P = 49.2% of the faecal samples and P = 6.25% of the regurgitated individuals presented at least one of the different helminth groups found in the viscera. The combination of three diagnostic techniques allowed us to determine the presence of nine helminth species (Cosmocephalus obvelatus, Stegophorus macronectes, Stegophorus diomedeae, Contracaecum sp., Parorchites zederi, Tetrabothrius heteroclitus, Diphylobotrium sp., Corynosoma shackletoni, and Renicolidae). In addition, juvenile specimens of Tetrameres sp. and Anisakis sp. were found in the eviscerated host. We discuss the trophic relationships of the hosts and their influence in the helminth infestations. This study provides new knowledge about the parasitic diversity of the Southern Giant Petrel in its nestling areas with new records of helminth species in Antarctica.