Are cladoceran fossils in lake sediment samples a biased reflection of the communities from which they are derived? |
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| Authors: | G R Kattel R W Battarbee A Mackay H J B Birks |
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| Institution: | (1) Environmental Change Research Centre, University College London, Pearson Building, Gower Street, London, WC1E 6BT, UK;(2) School of Geography and Environmental Science, University of Auckland, Private Bag 92019, Auckland, New Zealand |
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| Abstract: | A study on the taphonomy of Cladocera was carried out in a small (9 ha), oligotrophic mountain loch, Loch Coire Fionnaraich
(LCFR) in northwest Scotland. Four approaches were used. First, the fossil assemblage of Cladocera in the core-top sample
taken from the deepest basin (14 m) of the loch were compared with the fossil assemblages of Cladocera in surface sediments
along eight depth transects with samples taken at 2, 5, 8 and 11 m, respectively. The results of the deposition of remains
of individual Cladocera and of the PCA ordination showed that littoral Cladocera were dominant in the 2 m-depth samples, while
the planktonic Cladocera dominated the deeper water (8, 11 m and core-top) samples. Second, the fossil assemblages of Cladocera
in the core-top sample were compared with the assemblages in a sediment trap sample. The core-top sample showed a better representation
of the cladoceran taxa present in the loch than the trap sample, but rare taxa were missing in the core sample. Third, the
fossil assemblages of Cladocera in the core sample were compared with the contemporary assemblages in the source samples derived
from seasonal sampling across all habitats (macrophyte, sand, boulder) over 2 years. Only a small proportion of Cladocera
in the source samples was represented by the fossil assemblages in the core sample. Finally, ‘integrated’ approach samples
(spatial, trap, source and core together) were compared using PCA. The Cladocera in the core-top sample were closely related
to the trap and surface sediment samples, but weakly related to the source samples. The overall results indicate that biases
may occur whilst reconstructing the past environmental change based on the fossil assemblages of Cladocera in the core sample
taken from the deepest basin of the lake. |
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| Keywords: | Cladocera Taphonomy Representation Scottish loch Core sample Trap sample Source sample Surface sediment sample |
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