Relict Anthropogenic Ecosystem from the Middle Ages: History of a Salt Marsh from Transylvania (Sic, N Romania)

A paleoecological study was performed on a sediment core recovered from a former artificial lake - the Reedbed of Sic near Cluj-Napoca, Romania - in order to explore the history of water management and nearby salt mining, and its impact on the environment. From the Roman period, the area served as a recipient of salty wastewaters. The most significant shift in the sediment composition and macrofossil assemblages took place after 1000 AD, suggesting a significant upturn in salt mining. The impact of mining-related activities was further increased in the Middle Ages when, according to documentary sources, fishponds and watermills were constructed in the area. They led to the stabilisation of the water level in the lakebed, and enhanced the appearance of reed beds and the spread of secondary salt marsh vegetation. This biotop was later invaded by the Entzia macrescens, an agglutinated foraminiferal taxon, known mostly from the high intertidal marshes worldwide. In the investigated marshland, the dominance of halophytic species reached their acme in the seventeenth century, which coincides with the acme of mining activities. This medieval - early Modern Age industrial ecosystem survived the abandonment of salt mines and fishponds, being preserved until today.