What is it about?

We counted benthic Foraminifera assemblages in a Pleistocene profile from the Island of Rhodes in two different, but rather similar and often applied, size fractions. We then tested how large the difference in observed biodiversity would be, when the difference of used size fractions is only 25 μm.

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Why is it important?

Both the >125 μm and the >150 μm are often applied as "large" size fraction in benthic Foraminifera studies. In contrast to the "small" size fractions (e.g. >63 μm), where people expect assemblage patterns to differ because of the large difference in size fraction, many scientists consider the two "large" size fractions to be principally fully comparable due to the small difference between them. This was never tested so far, and if not true could render comparisons between studies using different size fractions invalid. We show that trends are the same between both size fractions, but differences in the details occur which are large enough to be important for studies who need a high degree of precision (e.g. bimonitoring studies).


We demonstrate that care must be taken for high-precision studies, even when the difference an employed size fractions is only 25 μm in benthic Foraminifera studies. We recommend to follow the suggestion by Schönfeld et al. (2012) and use the >125 μm size fraction whenever possible in the future.

Dr Manuel F. G. Weinkauf
Universite de Geneve

Read the Original

This page is a summary of: The Effect of Size Fraction in Analyses of Benthic Foraminiferal Assemblages: A Case Study Comparing Assemblages From the >125 and >150 μm Size Fractions, Frontiers in Earth Science, May 2018, Frontiers, DOI: 10.3389/feart.2018.00037.
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