Yvonne Milker

Dr. Yvonne Milker


Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 November 2017 in PLOS ONE
Verified
Journal Article
Open access
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YMYvonne Milker
Yvonne Milker
MWManuel F. G. Weinkauf
Manuel F. G. Weinkauf
JTJürgen Titschack
Jürgen Titschack
AFAndre Freiwald
Andre Freiwald
SKStefan Krüger
Stefan Krüger
GSGerhard Schmiedl
Gerhard Schmiedl
We present paleo-water depth reconstructions for the Pefka E section deposited on the island of Rhodes (Greece) during the early Pleistocene. For these reconstructions, a transfer function (TF) using modern benthic foraminifera surface samples from the Adriatic and Western Mediterranean Seas has been developed. The TF model gives an overall predictive accuracy of ~50 m over a water depth range of ~1200 m. Two separate TF models for shallower and deeper water depth ranges indicate a good predictive accuracy of 9 m for shallower water depths (0–200 m) but far less accuracy of 130 m for deeper water depths (200–1200 m) due to uneven sampling along the water depth gradient. To test the robustness of the TF, we randomly selected modern samples to develop random TFs, showing that the model is robust for water depths between 20 and 850 m while greater water depths are underestimated. We applied the TF to the Pefka E fossil data set. The goodness-of-fit statistics showed that most fossil samples have a poor to extremely poor fit to water depth. We interpret this as a consequence of a lack of modern analogues for the fossil samples and removed all samples with extremely poor fit. To test the robustness and significance of the reconstructions, we compared them to reconstructions from an alternative TF model based on the modern analogue technique and applied the randomization TF test. We found our estimates to be robust and significant at the 95% confidence level, but we also observed that our estimates are strongly overprinted by orbital, precession-driven changes in paleo-productivity and corrected our estimates by filtering out the precession-related component. We compared our corrected record to reconstructions based on a modified plankton/benthos (P/B) ratio, excluding infaunal species, and to stable oxygen isotope data from the same section, as well as to paleo-water depth estimates for the Lindos Bay Formation of other sediment sections of Rhodes. These comparisons indicate that our orbital-corrected reconstructions are reasonable and reflect major tectonic movements of Rhodes during the early Pleistocene.

5 December 2013 in Natural Hazards and Earth System Sciences
Verified
Journal Article
Open access
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YMYvonne Milker
Yvonne Milker
MWM. Wilken
M. Wilken
JSJ. Schumann
J. Schumann
DSD. Sakuna
D. Sakuna
PFPeter Feldens
Peter Feldens
GSG. Schmiedl
G. Schmiedl
We have investigated the benthic foraminiferal fauna from sediment event layers associated with the 2004 Indian Ocean tsunami and former storms that have been retrieved in short sediment cores from offshore environments of the Andaman Sea, off Khao Lak, western Thailand. Species composition and test preservation of the benthic foraminiferal faunas exhibit pronounced changes across the studied sections and provide information on the depositional history of the tsunami layer, particularly on the source water depth of the displaced foraminiferal tests. In order to obtain accurate bathymetric information on sediment provenance, we have mapped the distribution of modern faunas in non-tsunamigenic surface sediments and created a calibration data set for the development of a transfer function. Our quantitative reconstructions revealed that the resuspension of sediment particles by the tsunami wave was restricted to a maximum water depth of approximately 20 m. Similar values were obtained for former storm events, thus impeding an easy distinction of different high-energy events.


1 October 2023 in Journal of Foraminiferal Research
Verified
Journal Article
Open access
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YMYvonne Milker
Yvonne Milker
JSJoachim Schönfeld
Joachim Schönfeld
SMStefan Meng
Stefan Meng
CWClaudia Wrozyna
Claudia Wrozyna
MSMartin Schneppmüller
Martin Schneppmüller
GSGerhard Schmiedl
Gerhard Schmiedl
Benthic foraminifera have rarely been reported from saline springs in Germany. To fill this gap, we investigated live (Rose Bengal stained) and dead benthic foraminifera from saline ponds, springs, and meadows in central Germany. For foraminiferal investigations, we collected surface samples along transects with changes in vegetation at Sülldorf in Saxony-Anhalt, in Artern and close to Auleben, Luisenhall, and Esperstedt in Thuringia. We found live and dead foraminifera at all investigated saline locations. We observed seven different agglutinated species that commonly inhabit coastal salt marshes (Trochamminita irregularis, Trochamminita salsa, Entzia macrescens, Miliammina fusca, Siphotrochammina lobata, Haplophragmoides manilaensis, and Haplophragmoides wilberti), one agglutinated species, Entzia sp., which has not been described to date, and one calcareous species, Gordiospira arctica, which has earlier been described from shallow-water settings at high northern latitudes. We hypothesize that foraminifera have been repeatedly transported to the inland saline habitats in central Germany by migratory birds on their routes from northern and southern Europe probably since the early Holocene. Future genetic investigations of the species in central Germany and comparisons with sequenced specimens from other localities will provide a better understanding of their provenance and phylogenetic position.

21 November 2014
Verified
Book Chapter
Closed access
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YMYvonne Milker
Yvonne Milker
RRRima Rachmayani
Rima Rachmayani
MWManuel F. G. Weinkauf
Manuel F. G. Weinkauf
MPMatthias Prange
Matthias Prange
MRMarkus Raitzsch
Markus Raitzsch
MKMichal Kučera
Michal Kučera

23 March 2020 in EGUsphere
Verified
Preprint
Open access
DBDorothea Bunzel
Dorothea Bunzel
YMYvonne Milker
Yvonne Milker
KMKatharina Müller-Navarra
Katharina Müller-Navarra
HAHelge Wolfgang Arz
Helge Wolfgang Arz
GSGerhard Schmiedl
Gerhard Schmiedl
Salt marshes are of substantial importance for the adaptation of coastal regions to present-day and predicted future climate changes, and accompanied sea-level fluctuations. This gives the motivation to investigate salt-marsh archives from the southern North Sea region, which provide an exceptional archive to understand the response of coastal systems to climate variability of the recent past. For this study, well-stratified sediment sequences from two different salt-marsh systems were analysed by scanning XRF spectroscopy. The study sites are affected by both natural processes and anthropogenic interventions on different time scales. To address the complex interplay between storm surges, human-induced coastal management, and coupled internally forced atmosphere-ocean mechanisms during the last century, this study focuses on the ln(Zr/Rb) ratio as proxy for the relative particle-size distribution, and the Br/Corg ratio as an indicator for the marine versus terrestrial organic matter input to the sediment. Additional information about local changes in the sedimentary organic matter quality is provided by the alteration of ln(Br/Cl) ratios. The ln(Zr/Rb) records reveal periodic fluctuations at inter-annual, inter-decadal to multi-decadal time scales, suggesting a close link of sediment accretion to the atmospheric-ocean climate oscillation over the North Atlantic and Europe, which is accompanied by variations in the wind field, precipitation and river runoff. By contrast, the Br/Corg ratios exhibit a long-term increase starting from the mid-twentieth century towards recent times, resembling the observed increasing trend in North Sea storminess. Abrupt drops in the ln(Br/Cl) records coincide with relatively coarser sand layers, indicating impacts by regional storm surges during winter, while intervals of comparable higher ln(Br/Cl) values represent times of generally calm weather conditions of periods with less frequent storm surges. Our results imply that past regional to super-regional climate changes have been transferred into the sedimentary salt-marsh archives of the southern North Sea region.