Holocene freshwater diatoms: palaeoenvironmental implications from south Kamchatka, Russia

• Published in: Boreas
• Main Authors: Hoff, Ulrike, Dirksen, Oleg, Dirksen, Veronika, Kuhn, Gerhard, Meyer, Hanno, Diekmann, Bernhard
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Kamchatka
• Online Access: http://dx.doi.org/10.1111/bor.12019; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12019; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12019

H olocene palaeolimnological conditions were reconstructed by analysing fossil diatom assemblages within a lacustrine sediment core from L ake S okoch, southern K amchatka ( R ussia). Sediments of this proglacial lake cover the past 9400 years and hence represent almost the whole H olocene history. The biosiliceous muddy sample material was analysed for several geochemical and biological parameters, such as the total organic carbon and biogenic silica content, and the diatom community (quantitative and qualitative changes). Based on changes in the relative abundances of the most frequent species A ulacoseira subarctica , S taurosira martyi and S tephanodiscus alpinus and a depth‐constrained cluster analyses ( CONISS ), five diatom assemblage zones could be identified. The oldest stage recovered lies between 9400 and 9000 cal. a BP and reflects the initial lake stage after the retreat of local glaciers, with a high detrital sediment supply, shallow‐water conditions and a high diatom diversity. The next zone (9000–6200 cal. a BP ) shows a more mature lake system with accumulating biogenic remains and higher water levels during climate amelioration. This is followed by the most obvious change in the diatom assemblage, delineated by an occurrence of S . alpinus , between 6200 and 2700 cal. a BP . Wet conditions in spring probably led to an enhanced fluvial runoff and eutrophic to hypertrophic conditions. The end of this period might reflect climate deterioration related to the N eoglacial epoch of the H olocene. Between 2700 and 1600 cal. a BP the sediments of L ake S okoch reveal oligotrophic water conditions in a windy high‐energy environment. The youngest interval, between 1600 cal. a BP and the P resent, indicates shallow‐water conditions and a very short growing season, which might reflect the L ittle I ce A ge. The results may offer a baseline for the interpretation of H olocene palaeoenvironmental changes in K amchatka and their relation to regional climate change from a palaeoecological perspective.