Abstract
Holocene sedimentary archives from Antarctic coastal embayments provide exceptional records of past ice–ocean interactions and marine biological productivity. Here we present a multiproxy study of sediment core BAY05-18c from Edisto Inlet (northern Victoria Land, Ross Sea), a fjord basin that preserves a high-resolution postglacial sedimentary sequence. Diatom assemblages reveal major changes in paleoceanographic conditions since ∼11 ka. An early Holocene well-laminated facies is characterized by high productivity, dominated by Chaetoceros resting spores and Corethron pennatum, indicating strong stratification, prolonged open-water seasons, and enhanced nutrient supply from glacial and sea-ice melt. This laminated interval reflects deglacial calving-bay conditions and parallels similar facies across Antarctic fjords and troughs. From ∼9.7 kyr BP, a massive and bioturbated diatomaceous mud marks reduced meltwater input, longer seasonal sea-ice cover, and weaker stratification. Mid-to late Holocene assemblages indicate persistently cool conditions with extended sea-ice duration, contrasting with warmer intervals recorded at other Antarctic coastal sites. Comparison with regional records suggests that Edisto Inlet oceanography was strongly influenced by the retreat history of the Ross Ice Shelf and local fjord geometry, which governed the formation and preservation of laminated diatom ooze. These results highlight the role of fjord morphology and freshwater fluxes in modulating Antarctic primary productivity and carbon export, providing analogs for ecosystem responses to ongoing ice retreat.