Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies
The composition of planktonic foraminiferal (PF) calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions rec...
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ftcopernicus:oai:publications.copernicus.org:cp56030 2023-05-15T18:01:08+02:00 Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies Jonkers, Lukas Kučera, Michal 2018-09-27 application/pdf https://doi.org/10.5194/cp-13-573-2017 https://cp.copernicus.org/articles/13/573/2017/ eng eng doi:10.5194/cp-13-573-2017 https://cp.copernicus.org/articles/13/573/2017/ eISSN: 1814-9332 Text 2018 ftcopernicus https://doi.org/10.5194/cp-13-573-2017 2020-07-20T16:23:43Z The composition of planktonic foraminiferal (PF) calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions recorded by sedimentary assemblages. PF seasonality changes with temperature in a way that minimises the environmental change that individual species experience and it is not unlikely that changes in depth habitat also result from such habitat tracking. While this behaviour could lead to an underestimation of spatial or temporal trends as well as of variability in proxy records, most palaeoceanographic studies are (implicitly) based on the assumption of a constant habitat. Up to now, the effect of habitat tracking on foraminifera proxy records has not yet been formally quantified on a global scale. Here we attempt to characterise this effect on the amplitude of environmental change recorded in sedimentary PF using core top δ 18 O data from six species. We find that the offset from mean annual near-surface δ 18 O values varies with temperature, with PF δ 18 O indicating warmer than mean conditions in colder waters (on average by −0.1 ‰ (equivalent to 0.4 °C) per °C), thus providing a first-order quantification of the degree of underestimation due to habitat tracking. We use an empirical model to estimate the contribution of seasonality to the observed difference between PF and annual mean δ 18 O and use the residual Δ δ 18 O to assess trends in calcification depth. Our analysis indicates that given an observation-based model parametrisation calcification depth increases with temperature in all species and sensitivity analysis suggests that a temperature-related seasonal habitat adjustment is essential to explain the observed isotope signal. Habitat tracking can thus lead to a significant reduction in the amplitude of recorded environmental change. However, we show that this behaviour is predictable. This allows accounting for habitat tracking, enabling more meaningful reconstructions and improved data–model comparison. Text Planktonic foraminifera Copernicus Publications: E-Journals Climate of the Past 13 6 573 586 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The composition of planktonic foraminiferal (PF) calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions recorded by sedimentary assemblages. PF seasonality changes with temperature in a way that minimises the environmental change that individual species experience and it is not unlikely that changes in depth habitat also result from such habitat tracking. While this behaviour could lead to an underestimation of spatial or temporal trends as well as of variability in proxy records, most palaeoceanographic studies are (implicitly) based on the assumption of a constant habitat. Up to now, the effect of habitat tracking on foraminifera proxy records has not yet been formally quantified on a global scale. Here we attempt to characterise this effect on the amplitude of environmental change recorded in sedimentary PF using core top δ 18 O data from six species. We find that the offset from mean annual near-surface δ 18 O values varies with temperature, with PF δ 18 O indicating warmer than mean conditions in colder waters (on average by −0.1 ‰ (equivalent to 0.4 °C) per °C), thus providing a first-order quantification of the degree of underestimation due to habitat tracking. We use an empirical model to estimate the contribution of seasonality to the observed difference between PF and annual mean δ 18 O and use the residual Δ δ 18 O to assess trends in calcification depth. Our analysis indicates that given an observation-based model parametrisation calcification depth increases with temperature in all species and sensitivity analysis suggests that a temperature-related seasonal habitat adjustment is essential to explain the observed isotope signal. Habitat tracking can thus lead to a significant reduction in the amplitude of recorded environmental change. However, we show that this behaviour is predictable. This allows accounting for habitat tracking, enabling more meaningful reconstructions and improved data–model comparison. |
format |
Text |
author |
Jonkers, Lukas Kučera, Michal |
spellingShingle |
Jonkers, Lukas Kučera, Michal Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
author_facet |
Jonkers, Lukas Kučera, Michal |
author_sort |
Jonkers, Lukas |
title |
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
title_short |
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
title_full |
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
title_fullStr |
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
title_full_unstemmed |
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
title_sort |
quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-13-573-2017 https://cp.copernicus.org/articles/13/573/2017/ |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-13-573-2017 https://cp.copernicus.org/articles/13/573/2017/ |
op_doi |
https://doi.org/10.5194/cp-13-573-2017 |
container_title |
Climate of the Past |
container_volume |
13 |
container_issue |
6 |
container_start_page |
573 |
op_container_end_page |
586 |
_version_ |
1766170485386641408 |