期刊
MARINE MICROPALEONTOLOGY
卷 101, 期 -, 页码 127-145出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.marmicro.2013.02.002
关键词
Planktonic foraminifera; Test size; Stable isotopes; Ecology; Photosymbiosis; Metabolic fractionation; Water column; Thermal structure; Carbon gradient; Western tropical Indian Ocean
类别
资金
- Netherlands Organisation for Scientific Research (NWO)
- NERC
- Royal Society
- NERC [NE/F523293/1] Funding Source: UKRI
- Natural Environment Research Council [NE/F523293/1] Funding Source: researchfish
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. (C) 2013 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据