Soil and vegetation patterns associated with contrasting Antarctic fur seal use in maritime Antarctica

Marine vertebrates influence Antarctic terrestrial ecosystems by transferring marine-derived nutrients to coastal environments and modifying habitats through physical disturbance. Ice-free coastal areas in Maritime Antarctica are primarily vegetated by mosses and lichens, with only two native angiosperm species present. Antarctic fur seal recovery and expansion have increased their presence in ice-free areas, but their influence on soil processes and vegetation structure remains poorly understood. This study investigated how fur seal occupation influences soil properties, plant community composition, and functional-group responses along a gradient of biogenic influence at Lions Rump, King George Island. Soil and vegetation data were collected in 78 plots (26 per site) distributed across three areas representing different levels of fur seal occupation. Soil variations were evaluated through multivariate analyses, while vegetation responses were assessed using species composition, functional groups, and redundancy analysis (RDA). Sites differed markedly in soil conditions and vegetation structure. The area with lower observed fur seal occupation showed higher plant diversity and vegetation cover, whereas the site with intense occupation presented more acidic soils, higher phosphorus and potassium contents, and lower species richness. Differences in observed fur seal occupation were associated with variation in soil properties and vegetation structure, with distinct responses among functional groups: algae were particularly prominent at the site with intense use, whereas bryophyte cover was lower and only crustose lichen taxa were recorded. These patterns suggest that biogenic nutrient inputs and physical disturbance associated with fur seal use may contribute to soil-vegetation heterogeneity, generating distinct ecological conditions across coastal Antarctic environments.