As aves antárticas estão livres de hemoparasitos? Um estudo de caso de pinguins (Pygoscelis spp.) e de skuas (Catharacta spp.) antárticos da Baía do Almirantado, Ilha Rei George, Antártica.

Abstract

Parasitism is an important selective pressure in populations, as well as competition and predation. Blood parasites can affect the color of plumage, sexual selection and reproductive success in birds. Antarctic birds have been mentioned in literature absent of blood parasites. Admiralty Bay is located at King George Island, Antarctic Peninsula, and is the largest bay on the region, harboring different avian species during the reproductive period. Among them, are the two most common skuas of Antarctica, the brown-skua (Catharacta lonnbergi) and the south-polar-skua (Catharacta maccormicki), and tree penguins species, the Chinstrap (Pygoscelis antarctica), the Gentoo (P. papua) and the Adelie (P. adeliae). Skuas and penguins are seabirds that migrating during the southern winter, and may be potential reservoirs and transmitters of parasites. However, negative results of blood parasiteshave been found in several seabirds and also to the Antarctic region. The objective of this study was to investigate the presence of blood parasites in Antarctic penguins and skuas at Admiralty Bay. Blood smears and blood samples for molecular analyses to research Plasmodium/Haemoproteuswere collected in two reproductive periods, from December 2010 to March 2011 and from December 2011 to March 2012. A total of 185 bird samples were collected, including 120 penguins and 65 skuas. Skuas were negative for parasites. The tree species of penguins were positives to Plasmodium/Haemoproteusby molecular analysis, including two P. papua, two P. antarctica and tree P. adeliae. Only one positive penguin by molecular technique, a P. papua, was positive in blood smears, diagnosed with Plasmodium sp. There was no significant difference between male and female individuals of the parasitizedspecies, as well as between adults and chicks. Parasitized birds (n = 7) were categorized as underweight (n=5) and overweight (n=2).The present study is the first to report blood parasites in the Antarctic region and is also the first record of the presence of blood protozoa for the three penguin species analyzed. The absence of blood parasites in Antarctic birds has been justified by the absence of potential vectors in the region. Therefore, it is possible that the parasitized penguins acquired infectionwhen they disperse during southern winter. However, antarctic skuas are migratory birds, and they can reach regions with recognized potential vectors, but have never been diagnosed with blood parasites, what was reinforced by data of the present study. In this case, it is believed that skuas may have a competent immune system, or that the absence of these parasites in these birds is justified by phylogenetic constraints between the host-parasite. Nevertheless, little is known about the existence of vectors in the Antarctica, migratory routes of birds in the region and parasite-host specificity. The inedited results found in this study should therefore serve as a starting point to understand the host-parasite interactions, and to contribute to the preservation of the Antarctic environment.