Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring

The Antarctic Peninsula’s coastal benthic ecosystems are shaped by glacial meltwater-driven sedimentation and turbidity, yet high-resolution biodiversity studies across depth gradients remain scarce. Benthic megafauna and seaweeds were surveyed in Collins Bay, King George Island, using ROV video transects (10–80 m depth) and analysed for biodiversity and community composition in relation to environmental factors. Our results show that glacial proximity and bathymetry shape the benthic communities, with biodiversity increasing with both depth and distance from the glacier. Unexpectedly, species richness was high in shallow glacier-proximal areas, possibly due to a nutrient pump by wind-driven upwelling events enhancing local productivity and resource availability. Functional diversity followed a depth-related trend and interestingly showed sessile filter-feeders being dominant in deeper glacial-proximal habitats, while mobile taxa were more abundant further from the glacier. The prevalence of diverse seaweed assemblages highlights the role of primary productivity in structuring these communities. Site-specific differences in species composition suggest that small-scale environmental variability plays a stronger role than large-scale oceanographic processes. These findings highlight the need for continued monitoring, as glacial retreat will likely reshape these ecosystems, altering biodiversity patterns and functional composition in the coming decades.