Benthic foraminifera turnover events as indicator of environmental shifts over the Late Holocene in an Antarctic fjord (Ross Sea)

Micropaleontological proxies are one of the most used types of proxy, 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 Edisto Inlet (Ross Sea, Antarctica) and the turnover events that characterized the foraminiferal fauna over the last 3.6 kyrs BP. Using Rate-of-Change analysis, turnover events connected to long terms faunal changes were recognised and further linked to environmental transitions undertaken by the fjord. In addition, by comparing the TR17-08 records with other proxies from nearby cores we identify a switch from multi-year landfast ice (3.5-2.7 kyrs BP) to a seasonal sea-ice dominated environment (2.5-1.5 kyrs BP). Other sites over the Victoria Land coast report 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 modified Circumpolar Deep Water (mCDW). Our study also suggests an increase in the influence 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 make this site an exceptional record for studying the evolution of the Late Holocene environmental conditions over the Ross Sea.