engleski

Relative sea-level change in the Central Adriatic during the last 1.5 ka years

On the particularly exposed sites on rocky coasts of the Central Adriatic islands (Vis, Ravnik and Biševo) in Croatia, biogenic littoral rims built by the coralline rhodophyte Lithophyllum byssoides (formerly known as L. lichenoides) were found. They were mapped, measured and sampled for 14C dating. The presence of thick and well-developed Lithophyllum rims, considered to be precise (±10 cm) sea-level indicator (Laborel, 1986 ; Laborel et al., 1994), points directly to the rising sea-level environment. Here we present new sea-level reconstruction for the past 1.5 ka years based on this biological indicator. The obtained results revealed four phases of sea-level changes. The sea-level was near stable from around 1400 till 1170 cal BP, in the Dark Ages Cold Period (DACP), then during the Medieval Climate Anomaly (MCA) 1170 till 620 cal BP the sea-level increased at a rate of 0.71 mm/yr. During the Little Ice Age (LIA) 620 till 310 cal BP it was near stable again. Later, the sea-level started to rise at a much speedier rate particularly during the Current Warm Period (CWP). These data were compared with predictions derived from a glacio-hydro-isostatic model associated with the Last Glacial cycle (Lambeck et al., 2004 ; Lambeck and Purcel, 2005). If the isostatic-eustatic component is separated, this area reveals almost stable tectonic conditions during the past 1500 years. Our results show that large algal rims grew during near-stable sea-level conditions that occurred during two relatively colder periods in the past 1500 years. They also reveal that well-developed (up to 1.8 m wide) upper levels of algal rims were formed during the 300 years of stabilisation during the LIA, which also corresponds to the time needed for the formation of the tidal notch that is widespread and slightly submerged today. The obtained results have been also compared with archaeological markers, e. g. submerged port remains of the ancient Issa harbour on the island of Vis (Faivre et al., 2010) and other available data along the Croatian coast.

sea-level change; algal rims; coralline algae; Adriatic Sea; Croatia; Vis; Biševo

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