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Given the recent climate changes and their impact on the Antarctic Peninsula ecosystems, the emergence of invasive species, and increased tourism activity in this region, monitoring changes in the habitats of species native to the Antarctic Peninsula region is necessary. One such species is the Antarctic midge Belgica antarctica (Chironomidae). This insect is endemic to the Antarctic Peninsula and adjacent islands. Thorough studies of changes in the range of this species have not been performed in recent decades. In this study, we present the area of Belgica antarctica according to the collections of biological samples during 2007–2021 (XII, XIV, XVI, XXIV, and XXV Ukrainian Antarctic Expeditions). This Antarctic midge was recorded at 26 localities on the Antarctic Peninsula and 212 localities on 55 surrounding islands between 66°08′38.4′′ S, 65°43′37.1′′ W (Cape Evensen, Stresher Peninsula, opposite the Marie Island, west coast of Graham Land) and 62°11′44.7′′ S, 58°57′40.6′′ W (King George Island, South Shetland Islands) from south-west to north-east.

Patterns of the rockcod Notothenia coriiceps infection with helminths were analysed to understand the dynamics of helminth communities in Antarctic fish and to test their stability over time. The study was performed using helminth samples (30,951 specimens in total) collected from 183 N. coriiceps in 2014–2015 and 2020–2021 in the vicinity of the Ukrainian Antarctic station (UAS) "Akademik Vernadsky", Galindez Island, Argentine Islands, West Antarctica. Overall, 25 helminth taxonomical categories (nine trematodes, four cestodes, five nematodes, and seven acanthocephalans) were distinguished and analysed. A direct comparison of the helminth taxonomic categories' prevalences and intensities showed that nine significantly changed their infection parameters during the six years between the samples. Seven of them (Pseudoterranova sp., Contracaecum sp., Ascarophis nototheniae, monolocular metacestodes, bilocular metacestodes, Metacanthocephalus rennicki, and Diphyllobothrium sp.) were found to have a significant impact on the differences between helminth infracommunities in 2014–2015 and 2020–2021. The range of changes in meteorological parameters (water and air temperature and water salinity) was not sufficient to significantly impact the helminth community’s patterns; most community patterns showed a stable trend and observed fluctuations were close to the steady trend. Slight but significant changes in the infection patterns observed in this study might have been caused by changes in the populations of intermediate, paratenic, and definitive hosts of helminths (marine invertebrates, mammals, and birds), which participate in helminth transmission in Antarctic ecosystems.

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