Rising threats to Antarctic penguins: Prevalence and implications of Ixodes uriae infestations.

Abstract

Antarctica is increasingly affected by climate change, with rising temperatures and prolonged summers creating favourable conditions for parasitic vectors such as the seabird tick Ixodes uriae. These ticks pose a threat to Antarctic wildlife and the health of personnel stationed in the region. This study investigated trends in tick prevalence among penguin colonies and the factors influencing their distribution. Fieldwork was conducted over two austral summer seasons (2022/23 and 2023/24) across the Antarctic Peninsula, focusing on accessible colonies in the South Shetland Islands. Ticks were collected from beneath stones within rookeries of Pygoscelis penguins (Adélie, chinstrap, and gentoo). Prevalence was compared with prior surveys, and colony characteristics such as size and species composition were evaluated. All developmental stages of ticks were identified in surveyed colonies. Female ticks infested both adults and chicks, whereas nymphs and larvae were predominantly found on chicks. The prevalence of ticks was highest during the guard phase of host species, with gentoo (58%) and chinstrap (50%) penguins exhibiting the greatest infestations, while Adélie colonies showed lower prevalence (28%). Tick abundance ranged from 1 to over 2,000 individuals per stone. Significant increases in tick prevalence were observed compared to earlier studies, particularly among chinstrap penguins (from 26% to 32%). Additionally, ticks were detected in new locations, including Cierva Cove, Penguin Island, Yalour Island, Lions Rump, Turret Point, and Patelnia/Uchatka Point. As I. uriae is a competent vector for various pathogens, including Borrelia, Babesia, Rickettsia, and viruses such as H5N1, these findings highlight potential risks to penguin fitness and survival. Future research should focus on the prevalence of vector-borne pathogens and their impacts on Antarctic ecosystems to inform conservation strategies. This study received funding from the Polish National Science Centre (Grant No. 2022/44/C/NZ6/00142) and The Spanish National Research Council (Grant No. PERPANTAR: PID2019-8597R. Keywords: Antarctica, climate change, Ixodes uriae, penguins, Pygoscelis, ticks