Istrian and Dalmatian fishtanks as sea-level markers

Roman age fishponds along the Istrian and Dalmatian coast were studied with the aim of using the data as sea-level markers. Although the Adriatic fishponds do not display the architectural features (crepidines, channels, etc.) that can be observed in the Tyrrhenian ones and serve as precise sea-level markers, their structural elements can be used to define the sea-level rise. Fishponds at S. Bartolomeo and Fisine in Slovenja, Kupanja, near Parenzo, and at Katoro, near Umago, in Croatia, were studied and measured. The pool investigated in the island of Svršata Vela, on the Kornati Islands, represents a different feature. Located on the northwest coast of the island, adjacent to the southern part of the gulf, it is a single square pool, with dimensions clearly less than the Istrian fishtanks, similar to those associated with the Tyrrhenian villae maritimae. These data (the altitude of archaeological markers below sea level) were corrected for tide and pressure and compared with predictions derived from the SELEN glacio-hydro-isostatic model. Comparison with the predicted sea level allows calculation of tectonic rates that range between −0.63 and −0.89 mm/year since Roman times.