Sedimentological and biostratigraphical analyses of short sediment cores from Hagelseewli (2339 m a.s.l.) in the Swiss Alps

André F. LOTTER, Wolfgang HOFMANN, Christian KAMENIK, Andrea LAMI, Christian OHLENDORF, Michael STURM, Willem O. VAN DER KNAAP, Jacqueline F.N. VAN LEEUWEN
  • Wolfgang HOFMANN
    Affiliation not present
  • Christian KAMENIK
    Affiliation not present
  • Andrea LAMI
    Affiliation not present
  • Christian OHLENDORF
    Affiliation not present
  • Michael STURM
    Affiliation not present
  • Willem O. VAN DER KNAAP
    Affiliation not present
  • Jacqueline F.N. VAN LEEUWEN
    Affiliation not present

Abstract

Several short sediment cores of between 35 and 40 cm from Hagelseewli, a small, remote lake in the Swiss Alps at an elevation of 2339 m a.s.l. were correlated according to their organic matter content. The sediments are characterized by organic silts and show in their uppermost part a surprisingly high amount of organic matter (30-35%). Synchronous changes, occurring in pollen from snow-bed vegetation, the alga Pediastrum, chironomids, and grain-size composition, point to a climatic change interpreted as cooler or shorter summers that led to prolonged ice-cover on the lake. According to palynological results the sediments date back to at least the early 15th century A.D., with the cooling phase encompassing the period between late 16th and the mid-19th century thus coinciding with the Little Ice Age. Low concentrations of both chironomid head capsules and cladoceran remains in combination with results from fossil pigment analyses point to longer periods of bottom-water anoxia as a result of long-lasting ice-cover that prevented mixing of the water column. According to our results aquatic biota in Hagelseewli are mainly indirectly influenced by climate change. The duration of ice-cover on the lake controls the mixing of the water column as well as light-availability for phytoplankton blooms.

Keywords

diatoms, pollen, chironomids, cladocera, chrysophyte cysts, grain-size analysis

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Submitted: 2011-12-09 16:56:36
Published: 2000-09-01 00:00:00
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Copyright (c) 2000 André F. LOTTER, Wolfgang HOFMANN, Christian KAMENIK, Andrea LAMI, Christian OHLENDORF, Michael STURM, Willem O. VAN DER KNAAP, Jacqueline F.N. VAN LEEUWEN

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