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Reconstructing calcification in ancient coccolithophores: Individual coccolith weight and morphology of Coccolithus pelagicus (sensu lato)
journal contribution
posted on 2023-05-17, 11:57 authored by Cubillos, JC, Henderiks, J, Beaufort, L, Howard, WR, Gustaaf HallegraeffGustaaf HallegraeffWe have adapted an existing method to estimate coccolith calcite weight using birefringence (Beaufort, 2005) to suit the large coccoliths of Coccolithus pelagicus, which are only partially birefringent under crosspolarised light microscopy. Fossil and sediment trap material from the South Tasman Rise region of the Southern Ocean was used for calibration and validation. Our approach was tested with only the coccolith central area (CA) considered for measurement, to avoid relying on the less robust proximal shields. Thus our results are relative and intend to quantify intra-specific variations in volumetric calcite weight, expressed as a Weight Index (WI). Our results were overall consistent with mass estimation based on distal shield lengths. However, the WI approach clearly has the advantage in exploring allometric scaling between coccolith size and weight, as well as in measuring the degree of calcification in similarly sized morphotypes. Combining WI and morphometry data (distal shield length, DSL), we demonstrate subtle, but statistically significant changes in shape and thus calcification degree both within and between the tested Coccolithus populations. Most strikingly, it appears that modern Coccolithus populations in the Southern Ocean are, on average, more heavily calcified than their fossil counterparts.
Funding
Australian Research Council
History
Publication title
Marine MicropaleontologyVolume
92-93Pagination
29-39ISSN
0377-8398Department/School
Institute for Marine and Antarctic StudiesPublisher
Elsevier Science BvPlace of publication
Po Box 211, Amsterdam, Netherlands, 1000 AeRights statement
Copyright 2012 Elsevier B.V.Repository Status
- Restricted