Change search
ReferencesLink to record
Permanent link

Direct link
Planktonic foraminifera stable isotopes and water column structure: Disentangling ecological signals
Stockholm University, Faculty of Science, Department of Geological Sciences.
Show others and affiliations
2013 (English)In: Marine Micropaleontology, ISSN 0377-8398, Vol. 101, 127-145 p.Article in journal (Refereed) Published
Abstract [en]

Differential carbon and oxygen stable isotope (delta C-13 and delta O-18) fractionation between planktonic foraminifera test calcite and sea water related to ecology and life stage confound the potential for reconstructing palaeo-water column temperature and carbon gradients. Multi-species analysis and strict selection of test sizes are useful methods for identifying these fractionation processes, also known as 'vital effects', in fossil taxa. However, there are a limited number of species with adequate size-controlled data sets, needed for ground truthing the approach in the modern. Here we report delta C-13 and delta O-18 measurements made on twelve species of modern planktonic foraminifera across a range of fourteen tightly constrained size windows from a tropical Indian Ocean core top sample. This data set includes more test size windows per species, especially from the smallest (identifiable) test size-classes, and a wider range of species than previously attempted. We use the size controlled delta O-18 calcite trajectories to infer depth habitats and calculate species-specific calcification temperatures. The temperatures are then used to constrain species-specific calcification depths along the modern vertical temperature profile in the western tropical Indian Ocean. By overlaying the per species delta C-13 calcite trajectories on local water column delta C-13(DIC) profiles, we estimate if and when (i.e. at which test sizes) the planktonic foraminifera species investigated approach ambient delta C-13(DIC) values. The profiling shows significant size-controlled delta C-13 deviation from seawater values in all species at some life/growth stage, which we attribute to (i) metabolic fractionation in tests <150-300 mu m (juveniles of all species and small adults), and; (ii) photosymbiont fractionation, affecting large tests (>similar to 300 mu m) of mixed layer photosymbiotic taxa. For most species there is a size-window where these effects appear to be at a minimum, and/or in balance. Exceptions are Globigerinita glutinata, a small (<200 mu m) surface living species, Globigerina bulloides, which is highly opportunistic, and deep living Globorotalia tumida and Globorotaloides hexagonus, the latter two species being affected by various unexplained delta C-13 vital effects. Use of our refined guidelines for test-size selection should improve the potential for making realistic reconstructions of water column delta C-13(DIC) in a modern tropical stratified setting and potentially in the distant geological past when there are no living analogues present.

Place, publisher, year, edition, pages
2013. Vol. 101, 127-145 p.
Keyword [en]
Planktonic foraminifera, Test size, Stable isotopes, Ecology, Photosymbiosis, Metabolic fractionation, Water column, Thermal structure, Carbon gradient, Western tropical Indian Ocean
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:su:diva-92816DOI: 10.1016/j.marmicro.2013.02.002ISI: 000321536700011OAI: diva2:642518


Available from: 2013-08-22 Created: 2013-08-20 Last updated: 2013-08-22Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Coxall, Helen K.
By organisation
Department of Geological Sciences
In the same journal
Marine Micropaleontology
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 28 hits
ReferencesLink to record
Permanent link

Direct link