Climate change is impacting marine benthic communities substantially at high latitudes through changes in the cryosphere, ocean physical and chemical properties, and a myriad of flow-on effects. Changes to sea ice duration in coastal waters result in changes in subtidal light penetration, physical disturbance, and sediment deposition. This drives a complex restructuring of marine benthic communities and their ecological functioning, yet the long-term trajectories of polar benthic communities remain poorly understood.
We present a dataset on benthic communities and their ecological functioning from the Windmill Islands region of East Antarctica collected during three field trips spanning 18 years, one of the longest field-based records available for this region. We analyse how patterns of biodiversity, community composition and functional diversity are shaped by sea ice cover, habitat (complexity and substrate composition) and temporal change.
Sites with shorter sea ice duration had lower biodiversity and ecological functioning, with shifts from rich invertebrate-dominated communities to simpler, fleshy algae-dominated assemblages corresponding with more ice-free duration. Structurally-complex rocky boulder habitats supported higher biodiversity, while increased sedimentation at some sites simplified epifaunal community structure. We observed substantial benthic community shifts over the 18-year period, where simplified algal bed or epifaunal soft sediment communities replaced diverse, functionally rich communities at some sites.
Our findings add to a growing body of evidence that climate-related environmental change can precipitate rapid reorganisation of marine communities, with cascading effects on biodiversity and ecosystem functioning, and the potential for acceleration through tipping points. Such transformations have profound implications for the persistence of ecological patterns and processes, undermining ecosystem resilience and complicating conservation and management efforts under ongoing climate change.