Basin elevation and salinity changes: late Holocene development of two freshwater lakes at the Karelian White Sea coast, northwest Russia as reflected in their sediments

Abstract

In this paleolimnological multi-proxy study, anthropogenic influences and salinity changes of the northwest Russian lakes Erchovskye Ozero East (ESE) and Erchovskye Ozero West (ESW) were assessed using diatoms, pollen and other microfossils from 210 Pb-dated sediment cores. Both lakes are situated on the Fennoscandian Shield in direct vicinity to the White Sea coast, a region that is still subject to isostatic land uplift processes today. The analyses showed that both lakes evolved from typical saltwater-dominated coastal waters to freshwater lakes within the last two centuries. Salinity was found to be the determining environmental factor for the aquatic biota whereas no significant anthropogenic influences on the lakes could be detected. The decreasing salinity in both lakes was caused by basin elevation and isolation due to isostatic rebound of the Fennoscandian Shield. A hypothetical land uplift rate of 5.7 mm yr -1 was calculated based on data from the sediment cores analysed.