Abstract
In palynology and other laboratory-based disciplines, methodological literature often lags the development and adoption of new practices. Here we highlight the lack of literature on the application of heavy liquid density separation for pollen preparations, a technique that has become common practice in recent years. In a study of Holocene-age sediments from Lake Pupuke, northern New Zealand, we found that the density of the heavy liquid used to separate pollen from the minerogenic fraction, within the range of reported practice, affected pollen counts. When a relatively low density was used (2.0 g/cm3), buoyant pollen grains such as Prumnopitys taxifolia and Dacrydium cupressinum were overrepresented, whereas small, compact pollen grains such as Libocedrus and Metrosideros were underrepresented. This result raises wider concerns, as heavy liquid densities reported in the literature range from 1.88 to 2.40 g/cm3. We draw attention to this problem and recommend steps that palynologists can take to ensure that their enumerated pollen assemblages are representative and do not lead to spurious interpretations.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Augustinus PC, Reid M, Andersson S, Deng Y, Horrocks M (2006) Biological and geochemical record of anthropogenic impacts in recent sediments from Lake Pupuke, Auckland City, New Zealand. J Paleolimnol 35:789–805
Borcard D, Legendre P, Drapeau P (1992) Partialling out the spatial component of ecological variation. Ecology 73:1045–1055
Borcard D, Gillet F, Legendre P (2011) Numerical ecology with R. Springer, New York
Campbell JFE, Fletcher WJ, Hughes PD, Shuttleworth EL (2016) A comparison of pollen extraction methods confirms dense-media separation as a reliable method of pollen preparation. J Quat Sci 31:631–640
Faegri K, Iversen J (1989) Textbook of pollen analysis. Wiley, Chichester
Heyng AM, Mayr C, Lücke A, Striewski B, Wastegård S, Wissel H (2012) Environmental changes in northern New Zealand since the Middle Holocene inferred from stable isotope records (δ15N, δ13C) of Lake Pupuke. J Paleolimnol 48:351–366
Heyng AM, Mayr C, Lücke A, Wissel H, Striewski B (2014) Late Holocene hydrologic changes in northern New Zealand inferred from stable isotope values of aquatic cellulose in sediments from Lake Pupuke. J Paleolimnol 51:485–497
Heyng AM, Mayr C, Lücke A, Moschen R, Wissel H, Striewski B, Bauersachs T (2015) Middle and Late Holocene paleotemperatures reconstructed from oxygen isotopes and GDGTs of sediments from Lake Pupuke, New Zealand. Quat Int 374:3–14
Hopkins JL, Wilson CJN, Leonard GS, Timm C, McGee LE, Smith IEM, Smith EGC (2017) Multi-criteria correlation of tephra deposits to source centres applied in the Auckland Volcanic Field, New Zealand. Bull Volcanol 79:55
Horrocks M, Augustinus PC, Deng Y, Shane P, Andersson S (2005) Holocene vegetation, environment, and tephra recorded from Lake Pupuke, Auckland, New Zealand. N Z J Geol Geophys 48:85–94
Legendre L, Legendre P (1998) Numerical ecology. Elsevier, Amsterdam
Leslie AB (2010) Flotation preferentially selects saccate pollen during conifer pollination. N Phytol 188:273–279
Moar NT (1993) Pollen grains of New Zealand dicotyledonous plants. Manaaki Whenua Press, Lincoln
Moar NT, Wilmshurst JM (2011) Standardizing names applied to pollen and spores in New Zealand Quaternary palynology. N Z J Bot 49:201–229
Moore PD, Collinson M, Webb JA (1991) Pollen analysis. Blackwell Scientific, Oxford
Munsterman D, Kerstholt S (1996) Sodium polytungstate, a new non-toxic alternative to bromoform in heavy liquid separation. Rev Palaeobot Palynol 91:417–422
Newnham RM, Lowe DJ, Gehrels M, Augustinus P (2018) Two-step human–environmental impact history for northern New Zealand linked to late-Holocene climate change. Holocene 28:1093–1106
Oksanen J, Blanchet FG, Kindt R, Legendre P, Minchin PR, O’Hara RB, Simpson GL, Solymos P, Stevens MHH, Wagner H (2016) vegan: community ecology package (R package version 2.3-3). https://CRAN.R-project.org/package=vegan
Peres-Neto PR, Legendre P, Dray S, Borcard D (2006) Variation partitioning of species data matrices: estimation and comparison of fractions. Ecology 87:2614–2625
Pocknall DT (1981) Pollen morphology of the New Zealand species of Dacrydium Selander, Podocarpus L’Heritier, and Dacrycarpus Endlicher (Podocarpaceae). N Z J Bot 19:67–95
R Core Team (2015) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/
Simpson GL (2007) Analogue methods in palaeoecology: using the analogue package. J Stat Softw 22:1–29
Simpson GL, Oksanen J (2016) Analogue: analogue matching and modern analogue technique transfer function models (R package version 0.17-0). https://CRAN.R-project.org/package=analogue
Stephens T, Atkin D, Augustinus PC, Shane P, Lorrey A, Street-Perrott A, Nilsson A, Snowball I (2012a) A late glacial Antarctic climate teleconnection and variable Holocene seasonality at Lake Pupuke, Auckland, New Zealand. J Paleolimnol 48:785–800
Stephens T, Atkin D, Cochran U, Augustinus PC, Reid M, Lorrey A, Shane P, Street-Perrott A (2012b) A diatom-inferred record of reduced effective precipitation during the Last Glacial Coldest Phase (288–180 cal kyr BP) and increasing Holocene seasonality at Lake Pupuke, Auckland, New Zealand. J Paleolimnol 48:801–817
Striewski B, Mayr C, Flenley J, Naumann R, Turner G, Lücke A (2009) Multi-proxy evidence of late Holocene human-induced environmental changes at Lake Pupuke, Auckland (New Zealand). Quat Int 202:69–93
Striewski B, Shulmeister J, Augustinus PC (2013) Late Holocene climate variability from Lake Pupuke maar, Auckland, New Zealand. Quat Sci Rev 77:46–54
van den Bos V, Rees A, Newnham R, Vandergoes M, Wilmshurst J, Augustinus P (2018) Holocene temperature, effective precipitation and seasonality in northern New Zealand linked to Southern Hemisphere summer insolation. Quat Sci Rev 201:77–88
Wardle P (1991) Vegetation of New Zealand. Cambridge University Press, Cambridge
Wickham H (2009) ggplot2: elegant graphics for data analysis. Springer, New York
Zabenskie S (2006) Post-glacial climatic change on Boothia Peninsula, Nunavut, Canada. Thesis submitted to the Faculty of Graduate and Postdoctoral Studies of the University of Ottawa
Acknowledgements
We thank Drs. Xun Li and Marcus Vandergoes for their recommendations regarding appropriate heavy liquid density; without their advice, the problematic effects of using a low-density liquid may never have been discovered. We also thank two anonymous reviewers for their helpful comments, and the editors for giving us the opportunity to improve our manuscript during the review process. Vandergoes and Li, along with authors Newnham and Rees are key investigators of the Lakes380 Research Programme, funded by New Zealand’s Ministry for Business, Innovation and Employment Endeavour Fund. This paper benefited from and is a contribution to the Lakes380 Programme. Postgraduate study of VB was funded through Marsden Fund Project 14-UOA-040.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
van den Bos, V., Newnham, R., Rees, A. et al. Density separation in pollen preparation: How low can you go?. J Paleolimnol 63, 225–234 (2020). https://doi.org/10.1007/s10933-020-00112-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10933-020-00112-6