Paleoceanographic changes during the Late-Holocene in the Adriatic Sea (Central Mediterranean)

Sub-millennial scale variability during the last 6000 years is recognized in the planktic and benthic foraminifera records from sediment cores retrieved from the Central Adriatic shelf and the Southern Adriatic deep basin. The ?18O shift of benthic foraminifer B. marginata suggests an increase of dense water production around 500 years BP with the onset of the modern routing of the North Adriatic Dense Water occurring before the end of Mediterranean Sapropel S1. After 5500 years BP, the northward intrusion of the salty Levantine Intermediate Water (LIW) in the Mid Adriatic slope basin (MAD) is recorded by the ?18O of intermediate-water dweller G. bulloides. During the late Holocene, short-lived episodes of increased runoff are indicated by ?18O values of G. bulloides in the MAD with concurrent drops in G. sacculifer concentration, suggesting either increased fresh water input impacting the entire water column (thereby forcing the LIW to a deeper level) or reduced LIW formation failing to intrude the MAD slope basin. Repeated abundance peaks of the planktic foraminifer Globigerinoides sacculifer represent warm-dry intervals, among which the Medieval Warm Period, the Roman Age, the late Bronze Age and the Copper Age. Moreover, the Little Ice Age (LIA) is approximated at the base by the Last Occurrence of G. sacculifer (550 years BP), and its two main (coldest) phases are recorded on all the shelf cores by two peaks of the benthic foraminifer Valvulineria complanata.