Late Glacial and Holocene environmental history of a buried ice-wedge system, Barrow, Alaska

Abstract

The DFG funded project (RI 809/17-1) aims to reconstruct environmental changes in the Eurasian Arctic during the Late Quaternary interstadial and interglacial periods basing on microfossils records from permafrost sequences of NE-Siberia. We present the testate amoebae records from the Cape Mamontovy Klyk (Laptev Sea coast) covering the last 50 14C ka.Testate amoebae (Protozoa: Rhizopoda, Testacea) are one cell microorganisms with a distinct organic shell (testa). They are common in wet environments such as wetlands but they are also frequent in soils, especially in high organic content soils. Their well-defined ecological preferences for habitats and good preservation of fossil shells provide a basis for the rhizopod analysis as a method for reconstruction of environmental changes and climate in the past. The analysis show that differences of Pleistocene and the Holocene climatic conditions are well reflected in the testate amoebae records. The main characteristic of Mamontovy Klyk fossil rhizopod complexes is the dominance of eurybiotic soil genera (e.g. Centropyxis, Cyclopyxis, Plagiopyxis and Phryganella). Fluctuations in species abundances and diversity well reflect alternating of warm-wet and cold-dry periods during the Late Pleistocene, in particular the Karginsky interstadial ca 50-30 14C ka BP and Sartan stadial 30-10 ka 14C BP. It is obvious that climate changes were more drastic during the Pleistocene. These changes were at least partly responsible for the disappearance of some rare rhizopod species (e.g. Argynnia sp., Paraquadrulla irregularis). Considering the species diversity as a result of ecological and climatic conditions, we assume that habitat and climatic conditions during the periods with higher species diversity (e.g. Karginsky interstadial), were more favourable than during the Sartan stadial.