Multidisciplinary study of the sediments from the Imperial harbour of Rome

The ancient port built along the Tyrrhenian coast by Roman Emperor Claudius (1st Cent. AD), and enlarged by Emperor Trajan (beginning of 2nd Cent. AD) was Rome’s principal maritime port from the middle of the first century onwards. The remains of the port and of the town raised in the close vicinity are ca. 3 km away from the present coastline, in the Tiber delta. Historical sources report that the imperial harbour was excavated both in terra firma and in lagoons. The harbour town named Portus developed together with the port itself and expanded in the following centuries. This study applies detailed pollen, microcharcoal, plant macroremains and ostracod analyses together with radiocarbon dating of the sediments recovered from two cores drilled in the area of the Claudius harbour. The chronological framing of the cores was carried out using radiocarbon dates, archaeological evidences and historical sources. They cover different periods of time, probably slightly overlapping or not overlapping at all. The dock core shows the first phases of the harbour activities, recording first a marine and then a brackish environment. The plant landscape is typical of a coastal environment and appears rather preserved. The human presence is clear, but not of great impact outside the port area. The channel core (spanning a time period more recent than that of the dock core) records mainly a brackish water environment and a strong human impact related to the presence of Portus, the port town. Plant macroremain and microremain analyses indicate that anthropic indicators (cultivated, ruderal and weed taxa) as well as strong fire use/occurrence, are increasing in the first centuries AD. The combined use of the different paleolimnological analyses allowed to disentangle between natural and human induced changes in the port management of the landscape.