The Late Glacial and Early Holocene environmental history of shallow lakes in Estonia, revealed from subfossil ostracod data

Abstract

The Late Glacial and Early Holocene shallow lake history in Estonia is documented from the freshwater ostracod subfossil record. Three cores studied consist of Late Glacial and Holocene sediments: gyttja, calcareous mud and peat, with ostracod subfossils being well preserved in the calcareous mud. 18 freshwater ostracod species were recorded in the cores: the most common species are Metacypris cordata, Limnocythere inopinata, Cyclocypris ovum, Cypridopsis vidua, and Candona candida. Changes in the ostracod succession of the lakes can be interpreted in the context of environmental changes that were not contemporaneous but were related to the evolution of particular water bodies. Darwinula stevensoni and Metacypris cordata do not appear together in the Late Glacial and Early Holocene lacustrine sediment records of Estonia. M. cordata appears as the water body evolves or by lowering of the water level. The appearance of Scottia pseudobrowniana in the sediments refers to the stage of an overgrown lacustrine system. M. cordata appeared in southeastern Estonia at the end of the Late Glacial (~12 800 cal. BP), when the calcareous mud started to form. The earliest subfossil record of M. cordata from southwestern Estonia is from the Early Holocene.