Holocene evolution of Portus Pisanus, the lost harbour of Pisa.

The ancient harbour of Pisa, Portus Pisanus, was one of Italy's most influential seaports for many centuries. Nonetheless, very little is known about its oldest harbour and the relationships between environmental evolution and the main stages of harbour history. The port complex that ensured Pisa's position as an economic and maritime power progressively shifted westwards by coastal progradation, before the maritime port of Livorno was built in the late 16th century AD. The lost port is, however, described in the early 5th century AD as being "a large, naturally sheltered embayment" that hosted merchant vessels, suggesting an important maritime structure with significant artificial infrastructure to reach the city. Despite its importance, the geographical location of the harbour complex remains controversial and its environmental evolution is unclear. To fill this knowledge gap and furnish accurate palaeoenvironmental information on Portus Pisanus, we used bio- and geosciences. Based on stratigraphic data, the area's relative sea-level history, and long-term environmental dynamics, we established that at ~200 BC, a naturally protected lagoon developed and hosted Portus Pisanus until the 5th century AD. The decline of the protected lagoon started at ~1350 AD and culminated ~1500 AD, after which time the basin was a coastal lake.

Middle East coastal ecosystem response to middle-to-late Holocene abrupt climate changes.

The Holocene vegetation history of the northern coastal Arabian Peninsula is of long-standing interest, as this Mediterranean/semiarid/arid region is known to be particularly sensitive to climatic changes. Detailed palynological data from an 800-cm alluvial sequence cored in the Jableh plain in northwest Syria have been used to reconstruct the vegetation dynamics in the coastal lowlands and the nearby Jabal an Nusayriyah mountains for the period 2150 to 550 B.C. Corresponding with the 4.2 to 3.9 and 3.5 to 2.5 cal kyr BP abrupt climate changes (ACCs), two large-scale shifts to a more arid climate have been recorded. These two ACCs had different impacts on the vegetation assemblages in coastal Syria. The 3.5 to 2.5 cal kyr BP ACC is drier and lasted longer than the 4.2 to 3.9 cal kyr BP ACC, and is characterized by the development of a warm steppe pollen-derived biome (1100-800 B.C.) and a peak of hot desert pollen-derived biome at 900 B.C. The 4.2 to 3.9 cal kyr BP ACC is characterized by a xerophytic woods and shrubs pollen-derived biome ca. 2050 B.C. The impact of the 3.5 to 2.5 cal kyr BP ACC on human occupation and cultural development is important along the Syrian coast with the destruction of Ugarit and the collapse of the Ugarit kingdom at ca. 1190 to 1185 B.C.