Palaeocladocerans as indicators of environmental, cultural and archaeological developments in Eifel maar lakes region (West Germany) during the Lateglacial and Holocene periods

The use of subfossil cladocerans is rare for understanding environmental, cultural and archaeological developments of lakes in Europe. In 2007, we collected a 12-m long sediment core from Lake Schalkenmehrener Maar (SMM), Germany for the analyses of subfossil cladocerans. Dating of core was based on tephrochronology, radiocarbon and pollen stratigraphy. Pollen-based chronostratigraphy indicated a decline of species richness and abundance of chydorids during the Lateglacial (ca. 14500 cal yr BP) with dominant cold preferring taxa Acroperus harpae Baird and Alona affinis Leydig. During the early Bolling, the abundance of cladocerans increased commensurate with growth of birch (Betula L.) and pine (Pinus L.) trees. Except a spike of Bosmina coregoni Baird during the Younger Dryas, cladoceran assemblages remained stable from the Bolling to the mid-Atlantic period. During the Neolithic (ca. 4300 BC), the abundance of B. coregoni increased sharply with reciprocal decrease in Daphnia. However, as soon as Daphnia was dominant (ca. 4250 BC), a reciprocal decline in abundance of B. coregoni occurred. The mid-Holocene change in cladoceran abundance coincided with the use of hardwood forest. This situation ended at ca. 4000 BC and remained unchanged throughout the Neolithic and Bronze Age (ca. 3000-1200 BC). Low Daphnia abundance indicated reduced water quality in the Hunsruck-Eifel culture (ca. 800 BC). A spike of B. coregoni at ca. AD 150 indicates construction of the Roman Villa Rustica and extensive farming. However, reoccurrence of Daphnia at ca. AD 470 indicates the retreat of the Romans from the Eifel region. From the early Frankish rule (ca. AD 500) to the Medieval period (ca. AD 1500), species richness reduced but abundance of B. coregoni increased indicating a switch in lake ecosystem. The loss of species richness and the lack of precise evidence of the human activity in the region in the past have impeded the restoration of the ecosystem of the Lake SMM.