Aquatic Sciences

, Volume 62, Issue 2, pp 125–141

Do diatoms in the Swiss Alps reflect the length of ice-cover?

  • André F. Lotter
  • Christian Bigler

DOI: 10.1007/s000270050002

Cite this article as:
Lotter, A. & Bigler, C. Aquat. sci. (2000) 62: 125. doi:10.1007/s000270050002

Abstract:

Diatom analyses in the water column, sediment traps, surficial sediments as well as in a short sediment core from Hagelseewli (2339 m asl, Swiss Alps) give information about the present-day seasonal cycle of diatom blooms, taphonomic processes in the lake basin and the lake's history. Analyses of surficial sediments show that water depth and thus light and nutrient availability is the most important factor influencing the production and distribution of diatom assemblages in Hagelseewli, and that periphytic diatom valves deposited in the deeper part of the basin originate from the shallow, littoral parts and are transported to the central part by processes such as lateral currents or sediment focussing. The lake is characterised by a very short period (2-3 months) of open water. Water-column and sediment-trap data revealed that planktonic diatoms bloom during and after the ice break-up, whereas mainly periphytic Fragilaria species entered the traps during the ice-covered period. These results suggest that plankton development is strongly inhibited by the ice-cover, with longer periods of ice-cover favouring Fragilaria species in Hagelseewli. The diatom analysis of a short sediment core that includes the last five centuries revealed several changes in the proportion of planktonic diatoms to Fragilaria species. The colder phases of the Little Ice-Age correspond to phases of lower concentration of planktonic diatoms. The highest, statistically significant amount of variance in the downcore diatom data is explained by winter precipitation, which directly influences the length of the ice-cover but inversely influences the light regime.

Key words: Diatoms, sediment traps, ice-cover, surface sediments, climate change.

Copyright information

© Birkhäuser Verlag, 2000

Authors and Affiliations

  • André F. Lotter
    • 1
  • Christian Bigler
    • 1
  1. 1.Geobotanical Institute, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland CH
  2. 2.Climate Impacts Research Centre, Abisko Naturvetenskapliga Station, Box 62, SE-98107 Abisko, Sweden SE