Environmental drivers of biodiversity and community structure in marine soft sediments of the Vestfold Hills, East Antarctica

Abstract We present a synthesis of marine soft sediment macrofaunal communities from the Vestfold Hills, East Antarctica, spanning historical data (1978–1982) and recent surveys from 47 locations (2010–2021). We examined relationships between environmental conditions, such as sediment properties and sea-ice duration, and community structure and biodiversity. Macrofaunal biodiversity was high, with 148 taxa identified in recent surveys. Community composition varied significantly between locations, influenced primarily by sediment grain size. Sediments ranged from mud to coarse sands, with organic content varying from < 1% to 15%, and locations were classified into four sediment categories: muds, very fine sands, fine sands and medium/coarse sands. Significant differences in community structure were found between sediments groups, but the considerable variability within groups suggests additional influences from factors such as sea ice, depth and stochastic processes. Crustaceans, including amphipods, ostracods and tanaids, dominated communities across all locations. Macrofaunal abundance was highest in muds and very fine sands and declined significantly in coarser sediments. Species-level abundance patterns showed high heterogeneity, with some trends linked to sediment grain size. Areas with abundant large sessile epifauna were associated with higher sediment biodiversity. This study highlights the complexity of environmental factors shaping macrofaunal communities in Antarctic coastal ecosystems.