PUB - Publikationen an der Universität Bielefeld

Parasitic infections can play a major role in the dynamics of animal populations by influencing the development and survival of juveniles. Understanding how intrinsic and extrinsic factors shape individual parasitisation and affect long-term consequences of infections is therefore of prime importance for conservation management. Galapagos sea lions (Zalophus wollebaeki) provide a good model system to assess the impact of environmental and behavioural differences on parasitisation. Their environment is characterised by seasonal changes in sea surface temperatures (SST), and the slow transition to independence in juveniles goes along with major behavioural changes. The present study focused on infections with Philophthalmus zalophi, a digenetic trematode, which is regularly found in the ocular cavity of young sea lions. Long-term data on P. zalophi infections were collected from a sea lion colony located in the centre of the Galapagos archipelago (0A degrees 45'S, 90A degrees 160'W, 2007-2014). The probability to become infected differed between age classes and was influenced by the SST at the time of capture. About 16 % of the animals infected during the peak of infections developed severe clinical signs which had long-term consequences for juvenile survival. The transition to independence appeared to be a particularly sensitive period when negative consequences of previous parasitic infections exerted the greatest influence on juvenile survival. Our results suggest that the prevalence of infections and thus the negative implications for juvenile survival may increase with broad-scale climatic changes.