Antarctic environments are characterised with potentially high levels of ultraviolet radiation (UVR) damaging to living organisms. Aquatic organisms have different strategies to minimise their negative effects, e.g. behavioural (migrating to deeper aquatic layers) or biochemical (photoprotection or enzymatic repair of the incurred damages). The calanoid genus Boeckella has a high level of plasticity with regard to UVR, which ensures its wide distribution in different regions of Antarctica. Here we present a specific photoprotective reaction in the population of Boeckella poppei on the Livingston Island, Maritime Antarctica. In non-ovigerous females, we observed uniform distribution of carotenoids in the body, while these pigments were almost entirely concentrated in the oval sacs of mature females. We consider this a mechanism to protect the eggs from the teratogenic influence of the high level of UVR in Antarctic environments. Another mechanism for avoidance of the effects of UVR we observed was the migration of specimens of B. poppei towards the deeper zone of the Antarctic glacial lake Todorina buza. 5th Balkan Scientific Conference on Biology – Book of Abstracts, © Plovdiv University Press, 2021, eISBN 978-619-202-644-8