The Palaeoenvironmental study of the Alimini Piccolo Lake enables a reconstruction of Holocene sea-level changes in south-east Italy

Based on multiproxy investigations of a 250 cm long sediment core (ALI1), a reconstruction of palaeoenvironmental dynamics for the Alimini Piccolo lake (south Adriatic coast of Apulia, Italy), is proposed. Our results indicate that shortly before 5500 cal. yr BP a marsh environment established. From 5400 cal. BP the marsh progressively became a lagoon and did not change until 3320 cal. BP, when Alimini Piccolo evolved into a shallow, sheltered, freshwater basin. Around 1400 cal. yr BP the basin became again a lagoon. Changes of the deposition environments and the chronological framework defined in the ALI1 sequence allowed speculation about local relative sea-level motions through the mid–late Holocene. Using proxy-data (molluscs, foraminifers, ostracods and plant macro-remains) as environment and bathymetry indicators, we reconstruct the elevation of the basin bottom (above or below sea level) through time. Plant macro-fossils have proved to be an especially reliable source of data for sea-level reconstruction. The resulting relative sea-level curve is characterised by a slow rise between 5500 and 3900 cal. yr BP, a drop culminating around 2500 cal. yr BP and a new, steeper rise continued to the present position. Our model differs from other curves (tectonically and isostatically corrected) proposed for a number of Mediterranean coastal sites where Holocene sea-level changes have been described with a continuously rising curve, steep before 7000–6000 yr BP, more gradual between 6000 yr BP and the present. On the other hand, our reconstruction seems to agree with evidence on sea-level position during the Roman age, found in several Apulian sites (Salento coastland) by means of geomorphological and archaeological investigations.