A comparison of Holocene testate amoeba assemblages and paleohydrological records from pollen slides and wet-sieved peat
Date
2021
Authors
Magnan, Gabriel
Lacourse, Terri
Garneau, Michelle
Journal Title
Journal ISSN
Volume Title
Publisher
The Holocene
Abstract
In this study, we compared new testate amoeba records produced by the conventional water-based
wet-sieving method to testate amoeba data from previous palynological analyses of two Holocene
peat profiles from British Columbia, Canada. We used 132 paired samples from the same peat cores
to compare the composition of testate amoeba assemblages between the two methods and evaluate
the potential of palynological testate amoeba records as quantitative paleohydrological proxies in
peatlands. Our results suggest that the palynological treatments (acetolysis, 10% KOH and 150 μm
sieving) substantially reduce test concentrations, diversity and richness in most pollen-slide samples.
The smaller sieve size used in the palynological treatment (i.e. 150 μm) removed only a small fraction
of the total tests, but could introduce a species-specific bias in assemblage composition. However,
major shifts between wet and dry conditions, as shown by the water table depth (WTD)
reconstructions using wet-sieved samples, were relatively well captured by the palynological datasets
in most instances. The palynological assemblages with counts of >50 tests (n = 30) provided WTD
estimates similar to those inferred from the wet-sieved samples as the most dominant hydrophilous
and xerophilous taxa were relatively well represented in the pollen-slide samples in the two studied
peat cores. Testate amoeba data from pollen slides can provide useful paleohydrological information
particularly when combined with other paleoenvironmental proxies. Nonetheless, if the goal is to
generate quantitative paleohydrological reconstructions, we recommend that testate amoeba
analyses be conducted using the wet-sieving method, as testate amoeba concentrations, diversity and
richness are typically much lower in samples prepared with palynological treatments.
Description
Keywords
non-pollen palynomorphs, paleohydrological records, peat profiles, pollen slides, testate amoebae, water table depth, wet-sieving method
Citation
Magnan, G., Lacourse, T., & Garneau, M. (2021). A comparison of Holocene testate amoeba assemblages and paleohydrological records from pollen slides and wet-sieved peat. The Holocene, 31(1), 73-82. https://doi.org/10.1177/0959683620961520.