Abstrakt
Sediment cores were taken from 294 lakes in 12 different remote mountain areas in Europe (from Greenland to Finland in the north and from Spain to Bulgaria in the south) for the analyses of Cladocera reamins. Surface samples (0-0.5 cm) were analysed to examine the contemporary distribution of Cladocera.
These were compared with sub-samples from the pre-industrial period (depth}15 cm)) to assess changes in species composition over time. In total, the remains of 42 different Cladocera taxa were identified in the surface sediment.
The number of taxa per lake decreased from north to south, which also corresponded to a gradient of increasing altitude. Multivaraite statistical analyses showed that the taxa assemblages were primarily determined by biogeographical factors.
Dispersal limitations at high altitudes may be the most important factor for the difference in species diversity among distcrict. Comparisons between the top and the ottom section of the sediment cores revealed similar taxa numbers, but most cores, although only marginally, differed in taxa assemblages.