Edisto Inlet as a sentinel for the Late Holocene environmental changes over the Ross Sea: insights from foraminifera turnover events

Abstract. Identifying key environmental changes is important to understand the processes that govern the Earth’s climate system and all its interacting components. Micropaleontological proxies are one of the most used proxies, being able to connect abundances of species to changes in the physiochemical characteristics of the environment. In this context, foraminifera have been extensively used due to their preservation potential. However, little attention has been paid to the properties of the whole foraminiferal community that, in turn, can be used to depict a comprehensive view of the environment. In this study we focused on the laminated marine sediment core TR17-08 collected in the Edisto Inlet (Ross Sea, Antarctica), and the turnover events that characterized the foraminiferal fauna over the last 3.6 kyrs BP. Using the Rate-of-Change analysis, three turnover events with long term effects on the fauna were recognised at 2.7–2.5 kyrs BP, at 1.2–1.0 kyrs BP and at 0.7 kyrs BP. Through the analysis of the most common benthic foraminiferal species, it was possible to connect them to specific changes in the environment. In addition, by comparing the TR17-08 records with other proxies from nearby cores we identify a switch from a multi-year landfast ice (3.5–2.7 kyrs BP) to a seasonal sea-ice dominated environment (2.5–1.5 kyrs BP). Other Victoria Land Coast sites reported this change in the sea-ice type over the Late Holocene, suggesting that the increase in the seasonal sea-ice environment is connected to entrance of mCDW. Our study also suggests an increase in the presence of mCDW in the fjord after 2.7–2.5 kyrs BP. Lastly, the presence of expanded laminated sequence at the bottom of the Inlet makes this site an exceptional record for studying the evolution of the Late Holocene environmental conditions over the Ross Sea.