121 results on '"Zonneveld, Karin"'
Search Results
2. Climate change, society, and pandemic disease in Roman Italy between 200 BCE and 600 CE
- Author
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IVAU: Instituut voor Aardwetenschappen Utrecht, Geochemistry, Zonneveld, Karin A.F., Harper, Kyle, Klügel, Andreas, Chen, Liang, de Lange, Gert, Versteegh, Gerard J.M., IVAU: Instituut voor Aardwetenschappen Utrecht, Geochemistry, Zonneveld, Karin A.F., Harper, Kyle, Klügel, Andreas, Chen, Liang, de Lange, Gert, and Versteegh, Gerard J.M.
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- 2024
3. Deglacial export of pre-aged terrigenous carbon to the Bay of Biscay
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Queiroz Alves, Eduardo, Wong, Wanyee, Hefter, Jens, Grotheer, Hendrik, Tesi, Tommaso, Gentz, Torben, Zonneveld, Karin, Mollenhauer, Gesine, Queiroz Alves, Eduardo, Wong, Wanyee, Hefter, Jens, Grotheer, Hendrik, Tesi, Tommaso, Gentz, Torben, Zonneveld, Karin, and Mollenhauer, Gesine
- Abstract
The last deglaciation is the most recent relatively well-documented period of pronounced and fast climate warming and, as such, it holds important information for our understanding of the climate system. Notably, while research into terrestrial organic carbon reservoirs has been instrumental in exploring the possible sources of atmospheric carbon dioxide during periods of rapid change, the underlying mechanisms are not fully understood. Here we investigate the mobilization of organic matter to the Bay of Biscay at the mouth of the Channel River, where an enhanced terrigenous input has been reported for the last glacial-interglacial transition. A suite of biomarker and isotopic analyses on a high-resolution sedimentary archive provided the first direct evidence for the fluvial supply of immature and ancient terrestrial organic matter to the core location. In the light of what has been reported for other regions with present or past permafrost conditions on land, this result points to the possibility of permafrost carbon export to the ocean, caused by processes that likely furthered the observed changes in atmospheric carbon dioxide.
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- 2024
- Full Text
- View/download PDF
4. New physical and biological evidence of lateral transport affecting dinoflagellate cyst distribution in the benthic nepheloid layer along a land-sea transect off Figueira da Foz (Atlantic Iberian margin)
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García-Moreiras, Iria, primary, Hatherly, Melissa, additional, Zonneveld, Karin, additional, Dubert, Jesus, additional, Nolasco, Rita, additional, Santos, Ana Isabel, additional, Oliveira, Anabela, additional, Moita, Teresa, additional, Oliveira, Paulo B., additional, Magalhães, Jorge M., additional, and Amorim, Ana, additional
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- 2023
- Full Text
- View/download PDF
5. Deglacial export of pre-aged terrigenous carbon to the Bay of Biscay.
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Queiroz Alves, Eduardo, Wong, Wanyee, Hefter, Jens, Grotheer, Hendrik, Tesi, Tommaso, Gentz, Torben, Zonneveld, Karin, and Mollenhauer, Gesine
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ATMOSPHERIC carbon dioxide ,CARBON nanofibers ,GLOBAL warming ,GLACIAL erosion ,RIVER channels ,CARBON cycle ,RADIOCARBON dating - Abstract
The last deglaciation is the most recent relatively well-documented period of pronounced and fast climate warming, and, as such, it holds important information for our understanding of the climate system. Notably, while research into terrestrial organic carbon reservoirs has been instrumental in exploring the possible sources of atmospheric carbon dioxide during periods of rapid change, the underlying mechanisms are not fully understood. Here we investigate the mobilization of organic matter to the Bay of Biscay, located in the north-eastern Atlantic Ocean off the coasts of France and Spain. Specifically, we focus on the area that was the mouth of the Channel River during the last deglaciation, where an enhanced terrigenous input has been reported for the last glacial–interglacial transition. We conducted a comprehensive suite of biomarker analyses (e.g. n-alkanes, hopanes and n-alkanoic acids) and isotopic investigations (radiocarbon dating and δ13 C measurements) on a high-resolution sedimentary archive. The present study provides the first direct evidence for the fluvial supply of immature and ancient terrestrial organic matter to the core location. Moreover, our results reveal the possibility of permafrost carbon export to the ocean, driven by processes such as deglacial warming and glacial erosion. These findings are consistent with observations from other regions characterized by present or past permafrost conditions on land, which have shown that permafrost thaw and glacial erosion can lead to carbon remobilization, potentially influencing atmospheric carbon dioxide levels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Deglacial export of pre-aged terrigenous carbon to the Bay of Biscay
- Author
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Queiroz Alves, Eduardo, Wong, Wanyee, Hefter, Jens, Grotheer, Hendrik, Tesi, Tommaso, Gentz, Torben, Zonneveld, Karin, Mollenhauer, Gesine, Queiroz Alves, Eduardo, Wong, Wanyee, Hefter, Jens, Grotheer, Hendrik, Tesi, Tommaso, Gentz, Torben, Zonneveld, Karin, and Mollenhauer, Gesine
- Abstract
The last deglaciation is the most recent relatively well-documented period of pronounced and fast climate warming and, as such, it holds important information for our understanding of the climate system. Notably, while research into terrestrial organic carbon reservoirs has been instrumental in exploring the possible sources of atmospheric carbon dioxide during periods of rapid change, the underlying mechanisms are not fully understood. Here we investigate the mobilization of organic matter to the Bay of Biscay at the mouth of the Channel River, where an enhanced terrigenous input has been reported for the last glacial-interglacial transition. A suite of biomarker and isotopic analyses on a high-resolution sedimentary archive provided the first direct evidence for the fluvial supply of immature and ancient terrestrial organic matter to the core location. In the light of what has been reported for other regions with present or past permafrost conditions on land, this result points to the possibility of permafrost carbon export to the ocean, caused by processes that likely furthered the observed changes in atmospheric carbon dioxide.
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- 2023
- Full Text
- View/download PDF
7. (258-260) Proposals to eliminate contradiction between Articles 11.7 and 11.8 and to equate non-fossil with fossil names of dinophytes for purposes of priority
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Elbrächter, Malte, Gottschling, Marc, Hoppenrath, Mona, Keupp, Helmut, Kusber, Wolf-Henning, Streng, Michael, Tillmann, Urban, Versteegh, Gerard J. M., Zonneveld, Karin A. F., Elbrächter, Malte, Gottschling, Marc, Hoppenrath, Mona, Keupp, Helmut, Kusber, Wolf-Henning, Streng, Michael, Tillmann, Urban, Versteegh, Gerard J. M., and Zonneveld, Karin A. F.
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- 2023
- Full Text
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8. New physical and biological evidence of lateral transport affecting dinoflagellate cyst distribution in the benthic nepheloid layer along a land-sea transect off Figueira da Foz (Atlantic Iberian margin)
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European Commission, Fundação para a Ciência e a Tecnologia (Portugal), Xunta de Galicia, García-Moreiras, Iria, Hatherly, Melissa, Zonneveld, Karin, Dubert, Jesús, Nolasco, Rita, Santos, Ana Isabel, Oliveira, Anabela, Moita, Maria Teresa, Oliveira, Paulo B., Magalhães, Jorge M., Amorim, Ana, European Commission, Fundação para a Ciência e a Tecnologia (Portugal), Xunta de Galicia, García-Moreiras, Iria, Hatherly, Melissa, Zonneveld, Karin, Dubert, Jesús, Nolasco, Rita, Santos, Ana Isabel, Oliveira, Anabela, Moita, Maria Teresa, Oliveira, Paulo B., Magalhães, Jorge M., and Amorim, Ana
- Abstract
[Introduction] The production of resting cysts is a key dispersal and survival strategy of many dinoflagellate species. However, little is known about the role of suspended cysts in the benthic nepheloid layer (BNL) in the initiation and decline of planktonic populations. [Method] In September 2019, sampling of the dinoflagellate cyst community at different water depths in the water column and in the bottom sediments, and studies of spatio-temporal changes in physical properties (temperature, salinity, density and suspended sediment concentration), were carried out along a land-sea transect off Figueira da Foz (NW Portugal) to investigate the dinoflagellate cyst distribution and the factors (physical and biological) affecting it. A clustering analysis was used to compare the BNL and sediment cyst records with the cyst rain recorded by a sediment trap at a fixed station. Furthermore, Lagrangian particle experiments enabled simulating cyst trajectories in the BNL 5 and 10 days before sampling and assessing cross-shore, vertical and alongshore transport within the studied region. [Results] A well-developed BNL was present during the survey, which covered a change from active (14th of September) to relaxed (19th of September) upwelling conditions. Organic-walled dinoflagellate cysts were dominant in all samples, although calcareous dinoflagellate cysts consistently occurred (at low abundances). High proportions of full cysts were observed in the BNL, of which a significant portion was viable as shown by excystment experiments. Moreover, BNL cyst records collected on the 19th of September along the land-sea transect were similar to the sediment trap cyst record but greatly differed from sediment cyst records. The heterotrophic small spiny brown cysts (SBC) and cysts of the autotrophic yessotoxin-producer Protoceratium reticulatum notably increased during the survey, in the BNL and in the water column above. [Discussion] The comparison of the BNL, surface sediment and sed
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- 2023
9. Micro-Fourier transform infrared spectroscopy of degradation-resistant organic microfossils; Influence of preservation environment and phylogeny
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Versteegh, Gerard J. M., primary and Zonneveld, Karin A. F., additional
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- 2022
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10. Late Quaternary palaeoenvironmental evolution and sea level oscillation of Santa Catarina Island (southern Brazil).
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Kuhn, Lidia A., Zonneveld, Karin A. F., Souza, Paulo A., and Cancelli, Rodrigo R.
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RELATIVE sea level change ,SEA level ,LAGOONS ,COASTAL plains ,DINOFLAGELLATE cysts ,VEGETATION dynamics - Abstract
Sea level oscillation during the Quaternary played a major role in the geomorphology and vegetation dynamics of coastal areas in southern Brazil, encompassing ecosystems that often have a unique biodiversity. Understanding the natural evolution of these areas is essential for decision making regarding land use regulations towards sustainable development, as well as to preserve the uniqueness of the coastal ecosystems. The southern Brazil coastal plain is formed by marine, transitional and continental Quaternary deposits controlled by past variations of the sea level. These variations shaped the coastal landscape and influenced the development of different Atlantic rainforest formations, such as mangroves and restingas. In particular, the restinga formation corresponds to a specific ecosystem that covers sandy soils of marine and fluvial–marine origin formed during the Quaternary on the Brazilian coastal plain. In this contribution, we present high-resolution palynological and stable isotope data from a Holocene core retrieved from the coastal plain of Santa Catarina Island (southern Brazil). We were able to identify four different environmental zones for the last 6520 yr BP. The first zone (6520–2920 cal yr BP) is characterized by a lagoon with large marine-water influence. Notably, the observed dinoflagellate cyst association suggests that marine waters entering the region had their origin in the relatively warm and saline Brazil Current waters. During the second zone (2920–1520 cal yr BP), marine-water contribution to the lagoon decreased until it became disconnected from the sea. The third zone (1520–550 cal yr BP) was marked by the decrease of the water level until it dried out and led to the colonization of herbaceous vegetation over the palaeo-lagoon. The last zone (550 cal yr BP–recent) is characterized by the consolidation of the coastal-plain Atlantic rainforest (restinga vegetation). Our results form an example of the strong sensitivity of southern Brazilian ecosystem change caused by relative sea level variations. As such, this study might contribute to the debate about the potential effects of current climate change induced by global sea level variations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Dinoflagellate cysts production, excystment and transport in the upwelling off Cape Blanc (NW Africa)
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Zonneveld, Karin A. F., Grotheer, Hendrik, and Versteegh, Gerard J. M.
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Global and Planetary Change ,Ocean Engineering ,Aquatic Science ,Oceanography ,Water Science and Technology - Abstract
To extend the understanding of dinoflagellate cysts production, excystment and vertical/lateral transport in the water column, we compared upper water cyst export production with cysts associations and concentrations in the subsurface nepheloid layer, bottom nepheloid layer and deeper water column during active upwelling off Cape Blanc (NW Africa) in August 2020. Export production was collected by two drifting trap surveys; DTS1 in an active upwelling cell for 4 days and DTS2 in an offshore drifting upwelling filament for 2 days. Subsurface, bottom nepheloid layers and deeper waters were sampled by in-situ pumps along two transects perpendicular to the shelf break. During DTS1, light limitation hampered phytoplankton production which might have influenced cyst production negatively due to up- and downward movement of water masses. Cyst export production increased at the rim of the upwelling cell. For DTS2, upwelling filament cyst export production was up to 3 times lower than that of DTS1. Echinidinium delicatum had highest relative and absolute abundances in the active upwelling, Echinidinium zonneveldiae and Bitectatodinium spongium in the upwelling filament, and Impagidinium spp. and cysts of Gymnodinium microreticulatum/nolleri at the most distal stations. Comparison of concentrations of cysts with and without cell contents showed that the majority of cysts hatched before reaching deeper waters and displayed a dormancy period of less than 6 days. About 5% of the living cysts reached deeper waters and/or the ocean floor. Living cysts were transported offshore in the upwelling filament. In case ships exchange ballast waters in the studied region, they will take up laterally transported living cysts. Upon release of the ballast waters in the port of arrival, these cysts have the potential to become “invader species” that can threaten economy and/or health. Lateral transport of cysts was observed in the bottom nepheloid layer and in deeper waters (800 - 1200m depth) with a maximal extension of about 130km off the shelf break. Therefore, sediments in the region will contain a mixture of regionally and locally produced dinoflagellate cysts. This insight contributes to the improvement of environmental reconstructions of the Cape blanc upwelling system based on downcore cyst associations.
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- 2022
12. Performance of temperature and productivity proxies based on long-chain alkane-1, mid-chain diols at test: a 5-year sediment trap record from the Mauritanian upwelling
- Author
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Versteegh, Gerard J. M., Zonneveld, Karin A. F., Hefter, Jens, Romero, Oscar E., Fischer, Gerhard, Mollenhauer, Gesine, Versteegh, Gerard J. M., Zonneveld, Karin A. F., Hefter, Jens, Romero, Oscar E., Fischer, Gerhard, and Mollenhauer, Gesine
- Abstract
Proxies based on long-chain alkane-1, mid-chain diols (diol for short) are obtaining increasing interest to reconstruct past upper ocean temperature and productivity. Here we evaluate performance of the sea surface temperature proxies (long-chain diol index (LDI), diol saturation index (DSI), and diol chain length index (DCI)), productivity and upwelling intensity proxies (two diol indices DIR and DIW and the combined diol index (CDI)), and the nutrient diol index (NDI) as a proxy for phosphate and nitrate levels. This evaluation is based on comparison of the diols in sediment trap samples from the upwelling region off NW Africa collected at 1.28 km water depth with daily satellite derived sea surface temperatures (SSTs), subsurface temperatures, productivity, the plankton composition from the trap location, monthly phosphate and nitrate concentrations, wind speed, and wind direction from the nearby Nouadhibou airport. The diol-based SST reconstructions are also compared the long-chain-alkenone-based SST reconstructions. The alkenone SSTs correlate best with satellite SST (r2 D0.60). Amplitude and absolute values agree very well as do the flux-corrected time series averages. For the diol proxies the situation is more complicated. Diol proxies including 1,14 diols lag trade wind speed by 30 d. Since wind is nearly always from the NNE to NNW and induces the upwelling, we relate the variability in these proxies to upwelling-induced processes. Correlation with the abundance of upwelling species and wind speed is best for.
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- 2022
13. Late Quaternary palaeoenvironmental evolution and sea level oscillation of the Santa Catarina Island (southern Brazil).
- Author
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Kuhn, Lidia A., Zonneveld, Karin A. F., Souza, Paulo A., and Cancelli, Rodrigo R.
- Subjects
RELATIVE sea level change ,SEA level ,LAGOONS ,COASTAL plains ,SEAWATER ,DINOFLAGELLATE cysts - Abstract
Sea level oscillation during the Quaternary played a major role in the geomorphology and vegetation dynamics of coastal areas in southern Brazil, encompassing ecosystems that often have a unique biodiversity. Understanding the natural evolution of these areas is essential for decision-making of land use regulations towards sustainable development as well as to preserve the uniqueness of the coastal ecosystems. The southern Brazil coastal plain is formed by marine, transitional and continental Quaternary deposits controlled by relative past variations of the sea level. These variations shaped the coastal landscape and influenced the development of different Atlantic Rainforest formations, such as mangroves and restingas. In particular, the restinga formation corresponds to a specific ecosystem that covers sandy soils of marine and fluvial-marine origin formed during the Quaternary on the Brazilian coastal plain. In this contribution, we present high-resolution palynological and stable isotope data from a Holocene core retrieved from the coastal plain of the Santa Catarina Island (southern Brazil). We were able to identify four different environmental zones in the last 6500 yr BP. The first zone (6500-- 2820 cal yr BP) is characterized by a lagoon with large marine water influence. Notably, the observed dinoflagellate cyst association suggests that marine waters entering the region had its origin in the relatively warm saline Brazil Current waters. During the second zone (2820--1480 cal yr BP), marine water contribution to the lagoon decreased until it became disconnected with the sea. The third zone (1480--520 cal yr BP) was marked by the decrease of the water level until it dried out and led to the colonization of herbaceous vegetation over the palaeo-lagoon. The last zone (520 cal yr BP - recent) is characterized by the consolidation of the coastal plain Atlantic Rainforest (restinga vegetation). Our results form an example of the strong sensitivity of southern Brazilian ecosystem change caused by relative sea level variations. As such, it might contribute to the debate about potential effects of current climate change induced by global sea level variations. [ABSTRACT FROM AUTHOR]
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- 2023
- Full Text
- View/download PDF
14. Performance of temperature and productivity proxies based on long-chain alkane-1, mid-chain diols at test: a 5-year sediment trap record from the Mauritanian upwelling
- Author
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Versteegh, Gerard J. M., primary, Zonneveld, Karin A. F., additional, Hefter, Jens, additional, Romero, Oscar E., additional, Fischer, Gerhard, additional, and Mollenhauer, Gesine, additional
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- 2022
- Full Text
- View/download PDF
15. Distribution patterns of recent organic-walled dinoflagellate cysts in relation to environmental parameters in the Mediterranean Sea
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Elshanawany, Rehab, Zonneveld, Karin, Ibrahim, Mohamed I., and Kholeif, Suzan E.A.
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- 2010
16. Better molecular preservation of organic matter in an oxic than in a sulfidic depositional environment: evidence from Thalassiphora pelagica (Dinoflagellata, Eocene) cysts
- Author
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Versteegh, Gerard J. M., Houben, Alexander J. P., and Zonneveld, Karin A. F.
- Abstract
Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene (∼40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular cross-linking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature.
- Published
- 2020
17. Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008
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Romero, Oscar E., Baumann, Karl-Heinz, Zonneveld, Karin A. F., Donner, Barbara, Hefter, Jens, Hamady, Bambaye, Pospelova, Vera, and Fischer, Gerhard
- Subjects
fungi - Abstract
Continuous multiyear records of sediment-trap-gained microorganism fluxes are scarce. Such studies are important to identify and to understand the main forcings behind seasonal and multiannual evolution of microorganism flux dynamics. Here, we assess the long-term flux variations and population dynamics of diatoms, coccolithophores, calcareous and organic dinoflagellate cysts, foraminifera and pteropods in the eastern boundary upwelling ecosystem of the Canary Current. A multiannual, continuous sediment trap experiment was conducted at the mooring site CBeu (Cap Blanc eutrophic; ∼20∘ N, 18∘ W; trap depth is ca. 1300 m) off Mauritania (northwest Africa), between June 2003 and March 2008. Throughout the study, the reasonably consistent good match of fluxes of microorganisms and bulk mass reflects the seasonal occurrence of the main upwelling season and relaxation and the contribution of microorganisms to mass flux off Mauritania. A clear successional pattern of microorganisms, i.e., primary producers followed by secondary producers, is not observed. High fluxes of diatoms, coccolithophores, organic dinoflagellate cysts, and planktonic foraminifera occur simultaneously. Peaks of calcareous dinoflagellate cysts and pteropods mostly occurred during intervals of upwelling relaxation. A striking feature of the temporal variability of population occurrences is the persistent pattern of seasonal groups contributions. Species of planktonic foraminifera, diatoms, and organic dinoflagellate cysts typical of coastal upwelling, as well as cooler-water planktonic foraminifera and the coccolithophore Gephyrocapsa oceanica, are abundant at times of intense upwelling (late winter through early summer). Planktonic foraminifera and calcareous dinoflagellate cysts are dominant in warm pelagic surface waters, and all pteropod taxa are more abundant in fall and winter when the water column stratifies. Similarly, coccolithophores of the upper and lower photic zones, together with Emiliania huxleyi, and organic dinoflagellate cysts dominate the assemblage during phases of upwelling relaxation and deeper layer mixing. A significant shift in the “regular” seasonal pattern of taxa relative contribution is observed between 2004 and 2006. Benthic diatoms strongly increased after fall 2005 and dominated the diatom assemblage during the main upwelling season. Additional evidence for a change in population dynamics is the short dominance of the coccolithophore Umbilicosphaera annulus, the occurrence of the pteropod Limacina bulimoides and the strong increase in the flux of calcareous dinoflagellate cysts, abundant in warm tropical oligotrophic waters south of the study area after fall 2005. Altogether, this suggests that pulses of southern waters were transported to the sampling site via the northward Mauritania Current. Our multiannual trap experiment provides a unique opportunity to characterize temporal patterns of variability that can be extrapolated to other eastern boundary upwelling ecosystems (EBUEs), which are experiencing or might experience similar future changes in their plankton community.
- Published
- 2020
18. Use of selective degradation to separate preservation from productivity
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Versteegh, Gerard J.M. and Zonneveld, Karin A.F.
- Subjects
Atlantic Ocean -- Research ,Marine sediments -- Research ,Marine sediments -- Observations ,Geological research -- Methods ,Dinoflagellates -- Research ,Lipids -- Research ,Food chains (Ecology) -- Research ,Pollen -- Environmental aspects ,Diagenesis -- Research ,Earth sciences - Abstract
The assessment of diagenetic influences on the sedimentary record is problematic despite its crucial importance for accurate environmental reconstruction and understanding of biochemical cycles. We propose a general applicable method that uses differences in degradation rates of organic components to separate degradation and productivity. We demonstrate this method on a southeastern Atlantic sediment core covering the past 145 k.y. The new method solves discrepancies between existing organic matter, silica- and carbonate-based productivity reconstructions, and emphasizes the importance of bottom- and pore-water characteristics for transformation of the sedimentary record. Keywords: dinoflagellates, lipids, organic carbon, pollen, preservation, productivity.
- Published
- 2002
19. Better molecular preservation of organic matter in an oxic than in a sulfidic depositional environment: evidence from <i>Thalassiphora pelagica</i> (Dinoflagellata, Eocene) cysts
- Author
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Versteegh, Gerard J. M., primary, Houben, Alexander J. P., additional, and Zonneveld, Karin A. F., additional
- Published
- 2020
- Full Text
- View/download PDF
20. Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008
- Author
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Romero, Oscar E., primary, Baumann, Karl-Heinz, additional, Zonneveld, Karin A. F., additional, Donner, Barbara, additional, Hefter, Jens, additional, Hamady, Bambaye, additional, Pospelova, Vera, additional, and Fischer, Gerhard, additional
- Published
- 2020
- Full Text
- View/download PDF
21. Dynamics of sedimentation processes and their impact on biogeochemical reactions on the continental slope off Argentina and Uruguay (MARUM), Cruise No. SO260/Leg 1 & Leg2, Leg 1: January 12 - January 30, 2018, Buenos Aires (Argentina) - Montevideo (Uruguay), Leg 2: February 2 - February, 14, 2018, Montevideo (Uruguay) - Buenos Aires (Argentina), DosProBio
- Author
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Kasten, Sabine, Schwenk, Tilmann, Aromokeye, David A., Baques, Michele, Baumann, Karl-Heinz, Bergenthal, Markus, Bösche, Janina, Bozzano, Graziella, Brune, Rouven, Bülten, Jutta, Chiessi, Cristiano M., Coffinet, Sarah, Crivellari, Stefano, Dehning, Klaus, Dohrmann, Ingrid, Dröllner, Maximilian, Düßmann, Ralf, Durica, John T., Frederichs, Thomas, Garcia Chapori, Natalia, Gonzales, Lorena N., Hanebuth, Till J. J., Hilgenfeldt, Christian, Hüttich, Daniel, Jones, Christopher K., Klann, Marco, Klar, Steffen, Klein, Thorsten, Kockisch, Brit, Köster, Male, Lantzsch, Hendrik, Linowski, Erik, Long, Joshua H., Melcher, Anne-Christin, Ogunleye, Opeyemi J., Pereyra, Noelia, Rehage, Ralf, Riedinger, Natascha, Rosiak, Uwe, Schmidt, Werner, Schnakenberg, Annika, Spieß, Volkhard, Steinmann, Lena, Thieblemont, Antoine, Volz, Jessica, Warnke, Fynn, Warratz, Grit, Wenau, Stefan, Zonneveld, Karin A.F., Kasten, Sabine, Schwenk, Tilmann, Aromokeye, David A., Baques, Michele, Baumann, Karl-Heinz, Bergenthal, Markus, Bösche, Janina, Bozzano, Graziella, Brune, Rouven, Bülten, Jutta, Chiessi, Cristiano M., Coffinet, Sarah, Crivellari, Stefano, Dehning, Klaus, Dohrmann, Ingrid, Dröllner, Maximilian, Düßmann, Ralf, Durica, John T., Frederichs, Thomas, Garcia Chapori, Natalia, Gonzales, Lorena N., Hanebuth, Till J. J., Hilgenfeldt, Christian, Hüttich, Daniel, Jones, Christopher K., Klann, Marco, Klar, Steffen, Klein, Thorsten, Kockisch, Brit, Köster, Male, Lantzsch, Hendrik, Linowski, Erik, Long, Joshua H., Melcher, Anne-Christin, Ogunleye, Opeyemi J., Pereyra, Noelia, Rehage, Ralf, Riedinger, Natascha, Rosiak, Uwe, Schmidt, Werner, Schnakenberg, Annika, Spieß, Volkhard, Steinmann, Lena, Thieblemont, Antoine, Volz, Jessica, Warnke, Fynn, Warratz, Grit, Wenau, Stefan, and Zonneveld, Karin A.F.
- Published
- 2019
22. Postdepositional aerobic and anaerobic particulate organic matter degradation succession reflected by dinoflagellate cysts: The Madeira Abyssal Plain revisited
- Author
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Zonneveld, Karin A.F., Gray, Daniel D., Kuhn, Gerhard, Versteegh, Gerard J.M., Zonneveld, Karin A.F., Gray, Daniel D., Kuhn, Gerhard, and Versteegh, Gerard J.M.
- Abstract
We report on the succession of selective degradation of dinoflagellate cyst species that can be considered representative for discrete particulate organic matter (POM) classes of different degradability. The effects of anaerobic and aerobic degradation as well as bioturbation in a natural setting are documented in high resolution by means of palynological and geochemical analyses on Madeira Abyssal Plain A- and F-turbidites. These turbidites are unique as their initial ungraded sediments are affected by a downward penetrating oxydation front. Geochemical analyses document the presence of an active downward penetrating oxidation front in the A turbidite, and a palaeo-oxidation front in the F-turbidite. In this latter turbidite, several zones can be distinguished from top to bottom: an oxidised bioturbated zone, an oxidised but not-bioturbated zone, a visible paleooxidation front, and a narrow nitrogenous zone overlying unoxidised sediments. We are the first to report that anaerobic degradation within the nitrogenous zones in both turbidites affects cysts of some heterotrophic dinoflagellates. The cyst species affected (Echinidinium aculeatum, Echinidinium spp., cysts of Protoperidinium monospinum and Brigantedinium spp.) exponentially decrease in this zone that is further characterised by a strong decrease in sulphur content due to sulphide oxidation. Degradation rates are different for each species. These cysts of heterotrophic dinoflagellates consist of a nitrogen-rich glycan in contrast to the cellulosic cysts walls of phototrophic dinoflagellates. Therefore, our observation supports the hypothesis that the quality of organic matter plays an important role in OM degradation in oxygen deficient environments with N-rich OM being more labile than other components in these environments. All heterotrophic species are strongly affected by aerobic degradation with their cyst concentrations exponentially decreasing with increasing oxygen exposure. Degradation rates vary b
- Published
- 2019
23. Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals
- Author
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Nettersheim, Benjamin, Brocks, Jochen, Schwelm, Arne, Hope, Janet, Not, Fabrice, Lomas, Michael, Schmidt, Christiane, Schiebel, Ralf, Nowack, Eva C., De Deckker, Patrick, Pawlowski, Jan, Bowser, Samuel S., Bobrovskiy, Ilya, Zonneveld, Karin A. F., Kucera, Michal, Stuhr, Marleen, Hallman, Christian, Nettersheim, Benjamin, Brocks, Jochen, Schwelm, Arne, Hope, Janet, Not, Fabrice, Lomas, Michael, Schmidt, Christiane, Schiebel, Ralf, Nowack, Eva C., De Deckker, Patrick, Pawlowski, Jan, Bowser, Samuel S., Bobrovskiy, Ilya, Zonneveld, Karin A. F., Kucera, Michal, Stuhr, Marleen, and Hallman, Christian
- Abstract
The dawn of animals remains one of the most mysterious milestones in the evolution of life. The fossil lipids 24-isopropylcholestane and 26-methylstigmastane are considered diagnostic for demosponges—arguably the oldest group of living animals. The widespread occurrence and high relative abundance of these biomarkers in Ediacaran sediments from 635–541 million years (Myr) ago have been viewed as evidence for the rise of animals to ecological importance approximately 100 Myr before their rapid Cambrian radiation. Here we show that the biosynthesis of 24-isopropylcholestane and 26-methylstigmastane precursors is common among early-branching unicellular Rhizaria—heterotrophic protists that play an important role in trophic cycling and carbon export in the modern ocean. Negating these hydrocarbons as sponge biomarkers, our study places the oldest evidence for animals closer to the Cambrian Explosion. Cambrian silica hexactine spicules that are approximately 535 Myr old now represent the oldest diagnostic sponge remains, whereas approximately 558-Myr-old Dickinsonia and Kimberella (Ediacara biota) provide the most reliable evidence for the emergence of animals. The proliferation of predatory protists may have been responsible for much of the ecological changes during the late Neoproterozoic, including the rise of algae, the establishment of complex trophic relationships and the oxygenation of shallow-water habitats required for the subsequent ascent of macroscopic animals.
- Published
- 2019
24. The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions
- Author
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Mertens, Kenneth, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringue, Manuel, Dale, Barrie, De Schepper, Stijn, De Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkila, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurelie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, Andre, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, Zonneveld, Karin, Mertens, Kenneth, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringue, Manuel, Dale, Barrie, De Schepper, Stijn, De Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkila, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurelie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, Andre, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, and Zonneveld, Karin
- Abstract
We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973) Londeix et al. 2009, Spiniferites? rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica Baltes¸ 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail.
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- 2018
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25. The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions
- Author
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Marine palynology and palaeoceanography, Marine Palynology, Mertens, Kenneth Neil, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringué, Manuel, Dale, Barrie, De Schepper, Stijn, De Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkilä, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurélie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, André, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, Zonneveld, Karin, Marine palynology and palaeoceanography, Marine Palynology, Mertens, Kenneth Neil, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringué, Manuel, Dale, Barrie, De Schepper, Stijn, De Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkilä, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurélie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, André, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, and Zonneveld, Karin
- Published
- 2018
26. Intermittent development of forest corridors in northeastern Brazil during the last deglaciation: Climatic and ecologic evidence
- Author
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Bouimetarhan, Ilham, Chiessi, Cristiano M., González-Arango, Catalina, Dupont, Lydie, Voigt, Ines, Prange, Matthias, Zonneveld, Karin, Bouimetarhan, Ilham, Chiessi, Cristiano M., González-Arango, Catalina, Dupont, Lydie, Voigt, Ines, Prange, Matthias, and Zonneveld, Karin
- Abstract
The semi-arid northeastern (NE) Brazil vegetation is largely dominated by Caatinga, one of the largest and richest dry forests in the world. Caatinga is a strategic biome, since it has borders with Cerrado, Atlantic forests and the Amazon, acting as a potential corridor (or barrier) for biotic interchange between these regions during evolutionary times. Therefore, accurate reconstructions of past vegetation, ecological and hydrological changes in this area are critical to understanding the dynamics of biome boundaries that may play an important role in dispersal and diversification mechanisms and, more specifically, the link between the long-term climate variability and tropical biodiversity. Here, we present high-resolution palynological and elemental data from marine core GeoB16205-4 retrieved off the Parnaíba River mouth (NE Brazil) mainly covering the Younger Dryas (YD). We show that the YD interval was predominantly wet in NE Brazil, yet it was not homogenous and two distinct phases could be distinguished. A marked intensification of wet conditions between ∼12.3 and 11.6 cal kyr BP was recorded by the expansion of tropical rainforest and tree ferns. These results are in agreement with the transient TraCE-21k coupled climate model simulation. We infer that the second pluvial phase of the YD is related to a weak AMOC due to meltwater pulses in the North Atlantic, which forces a southward shift of the Intertropical Convergence Zone and its associated rainfall. Our records provide new evidence on the establishment of an “eastern forest corridor” in the nowadays semi-arid Caatinga allowing for past biotic interchanges of plant species.
- Published
- 2018
- Full Text
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27. The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments:a summary of round table discussions
- Author
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Mertens, Kenneth Neil, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringue, Manuel, Dale, Barrie, De Schepper, Stijn, de Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkila, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurelie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, Andre, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, Zonneveld, Karin, Mertens, Kenneth Neil, Van Nieuwenhove, Nicolas, Gurdebeke, Pieter R., Aydin, Hilal, Bogus, Kara, Bringue, Manuel, Dale, Barrie, De Schepper, Stijn, de Vernal, Anne, Ellegaard, Marianne, Grothe, Arjen, Gu, Haifeng, Head, Martin J., Heikkila, Maija, Limoges, Audrey, Londeix, Laurent, Louwye, Stephen, Marret, Fabienne, Masure, Edwige, Matsuoka, Kazumi, Mudie, Peta J., Penaud, Aurelie, Pospelova, Vera, Price, Andrea Michelle, Ribeiro, Sofia, Rochon, Andre, Sangiorgi, Francesca, Schreck, Michael, Torres, Vladimir, Uzar, Serdar, Versteegh, Gerard J. M., Warny, Sophie, and Zonneveld, Karin
- Published
- 2018
28. Better molecular preservation of organic matter in an oxic than in a sulfidic depositional environment: evidence from Thalassiphora pelagica (Dinoflagellata, Eocene) cysts.
- Author
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Versteegh, Gerard J. M., Houben, Alexander J. P., and Zonneveld, Karin A. F.
- Subjects
FOSSIL microorganisms ,ORGANIC compounds ,PYROLYSIS gas chromatography ,FOURIER transform infrared spectroscopy ,MASS spectrometry ,CARBONATES ,DINOFLAGELLATES ,DOLOMITE - Abstract
Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene (∼40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular cross-linking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
29. Species-specific sensitivity of dinoflagellate cysts to aerobic degradation: A five-year natural exposure experiment
- Author
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Gray, Daniel, Zonneveld, Karin A.F., Versteegh, Gerard J.M., Gray, Daniel, Zonneveld, Karin A.F., and Versteegh, Gerard J.M.
- Abstract
Post-depositional sedimentary dinoflagellate cyst associations undergo species-selective degradation under oxic conditions. However, there is little known about the temporal relationship between oxygen concentration and bulk dinocyst degradation rate over the time scale of several years, and if this degradation is mainly microbial or chemical. Whilst the overall sensitivity of heterotrophic dinoflagellate cysts is well documented, sensitivity differences within this group have not been studied. Here we examine the rates of cyst degradation of heterotrophic species over short temporal scales across an anoxic–oxic gradient. Sediment with a known dinoflagellate cyst association largely dominated by heterotrophic dinoflagellates, were connected to trap arrays at two different locations, Cap Blanc (NW Africa) and Gotland Basin (central Baltic Sea) and exposed to four different ambient oxygen concentrations representing a complete oxic gradient from 5.1 mL/L to sulphate bearing anoxic waters. Two treatments of either gauze or dialyse membrane in triplicate were established to investigate the effects of chemical or bacterial degradation. Cyst loss was significant at oxic settings, rapidly occurring within the first year of exposure (32%) whereas no significant degradation was observed for suboxic and anoxic exposures. Compiling the degradation rates of individual species under the different exposure settings reveals an overall species sensitivity ranking amongst cysts of heterotrophic species. Species of average resistance: Bitectatodinium spongium, Brigantedinium spp., Echinidinium spp., Echinidinium aculeatum, and Gymnodinium trapeziforme. Species more resistant than average: Stelladinium robustum and Trinovantedinium applanatum. We observe that oxic degradation of cysts of heterotrophic dinoflagellates is fast and selective with maximal cyst association changes during the first year of oxic exposure. These aspects have to be taken into account in palaeoenvironmental and
- Published
- 2017
30. Transport and preservation of organic-walled dinoflagellate cysts in nepheloid layers off Cape Blanc (N-W Africa)
- Author
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Zonneveld, Karin A. F., Versteegh, Gerard, Ebersbach, Friederike, Maeke, Mara, Zonneveld, Karin A. F., Versteegh, Gerard, Ebersbach, Friederike, and Maeke, Mara
- Abstract
For establishment of adequate environmental, oceanographic and climatic reconstructions based on fossil dinoflagellate cysts associations detailed information on selective transport and preservation is required. Here we present a comparison of export rain of dinoflagellate cysts with cyst associations in different intermediate nepheloid layers in the water column, the bottom nepheloid layer and surface sediments collected along two onshore-offshore transects off Cape Blanc (NW Africa) during active upwelling in November 2015. Highest cyst export production took place at the rim of a newly formed upwelling eddy/filament. Lateral transport of cysts up to 130 km off the shelf break was observed in a nepheloid layer varying in depth of 600 - 1300 m (shelf break - deep ocean) and in the bottom nepheloid layer. No indication of lateral transport could be documented in a second intermediate nepheloid layer deeper in the water column as well as in the more offshore part of the bottom nepheloid layer. The effects of lateral transport as registered from the water column was not reflected in underlying sediments. Selective degradation altering the cyst associations was not observed in the water column but the surface sediment cyst association differed considerable from that of the nepholoid layers and the upper water column. Comparison with long term sediment trap time series of cyst production in the region indicate that the surface samples are modified predominantly by species specific post depositional degradation rather than inter-annual variation in transport and/or production of cysts.
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- 2017
31. Selective dinoflagellate cyst degradation in Madeira Abyssal Plain (MAP) turbidites in an organic and inorganic geochemical context
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Versteegh, Gerard, Gray, Daniel, Kasten, Sabine, Zonneveld, Karin A. F., Versteegh, Gerard, Gray, Daniel, Kasten, Sabine, and Zonneveld, Karin A. F.
- Abstract
Assessment of selective preservation is of prime importance for the interpretation of proxies. Zonneveld et al. (1997) demonstrated strong selective changes in dinocyst assemblages as a result of aerobic degradation in the MAP F-turbidite. Based on two sets of 3 samples only, this did not allow much further differentiation. The present study relates palynological with geochemical changes at the transition from anoxic to oxic conditions in MAP turbidites with a high, 0.5-1 cm resolution. We now can understand why the geochemical processes already modify the peridinioid component of the dinoflagellate assemblage in the anoxic zone below the oxidation front, and why they lead to increasing cyst concentrations for some species close to the front. We demonstrate how taxon-specific differences in cyst degradation lead to successive dominance of Brigantedinium, Spiniferites and Impagidinium when degradation proceeds. We show the importance of knowledge of selective preservation by interpreting the assemblages with and without taking this process into account.
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- 2017
32. Which early Palaeozoic acritarchs might be dinoflagellate cysts?
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Servais, Thomas, Kroeck, David M., Mertens, Kenneth Neil, Versteegh, Gerard, Zonneveld, Karin A. F., Servais, Thomas, Kroeck, David M., Mertens, Kenneth Neil, Versteegh, Gerard, and Zonneveld, Karin A. F.
- Abstract
Small, organic-walled microfossils were usually attributed to the general term ‘hystrichospheres’ until the early 1960’s. After the discovery that many of these ‘hystrichospheres’ displayed morphological characteristics that are specific for dinoflagellates namely having a cingulum, a sulcus, an operculum and a para-tabulation, Evitt (1963) created the new term ‘acritarchs’ to classify all the remaining forms of unknown biological affinity and separate these from dinocysts. The acritarchs therefore include various kinds of organisms that have been affiliated to animal remains, fossil spores of various groups, and to several classes of (green) algae, including the prasinophycean, zygnematophycean or chlorophycean groups, for example. Although of unknown biological affinities by definition, many Palaeozoic acritarchs, in particular taxa from the Ordovician, Silurian and Devonian, have been compared morphologically to dinoflagellates. Such morphotypes have therefore been considered to be the resting cysts of phytoplankton since many years. The diversity of (planktonic) dinocyst-like taxa strongly increases in the late Cambrian, triggering probably the onset of the ‘Ordovician plankton revolution.’ These acritarchs are virtually impossible to differentiate from dinocysts, showing often the same process morphology (see Kröck et al., this conference). Furthermore, their palaeoecological distribution patterns, following inshore-offshore trends, is identical to those of dinoflagellates. Also, their biogeographical distribution is comparable to that of modern dinoflagellate taxa. We consider that some Palaeozoic acritarchs might therefore have been produced by dinoflagellate-like species, although they do not display all morphological criteria necessary to be recognized as a dinoflagellate cyst.
- Published
- 2017
33. Better molecular preservation of organic matter in an oxic than in a sulphidic depositional environment: evidence from of Thalassiphora pelagica (Dinoflagellata, Eocene) cysts.
- Author
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Versteegh, Gerard J. M., Houben, Alexander J. P., and Zonneveld, Karin A. F.
- Subjects
FOSSIL microorganisms ,PYROLYSIS gas chromatography ,ORGANIC compounds ,FOURIER transform spectroscopy ,DINOFLAGELLATES ,MOLECULAR structure ,CARBONATES ,DOLOMITE - Abstract
Anoxic sediments as compared to oxic settings encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to condensation reactions (such as vulcanisation) transforming the original biomolecules into geomolecules. For the oxic environment where the labile, reactive, component is rapidly removed, such transformation and condensation is much less likely so that one would expect a structurally much better preservation of the more refractory initial biomolecules. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thallasiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene (~ 40 Ma) sulphidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infra red analyses show that their macromolecular characteristics are strongly different. The cysts deposited in the sulphidic Rhine Graben show a strong contribution of long-chain aliphatic moieties and organic sulphur, absent in the material deposited on the oxic Kerguelen Plateau. Comparison with recent cyst walls suggests a much better molecular preservation for the oxic depositional environment, confirming our initial hypothesis. This leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
34. Variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008.
- Author
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Romero, Oscar E., Baumann, Karl-Heinz, Zonneveld, Karin A. F., Donner, Barbara, Hefter, Jens, Hamady, Bambaye, and Fischer, Gerhard
- Subjects
DINOFLAGELLATES ,EUPHOTIC zone ,DINOFLAGELLATE cysts ,FORAMINIFERA ,COCCOLITHUS huxleyi ,POPULATION dynamics ,MIXING height (Atmospheric chemistry) ,SOCIAL dominance - Abstract
Continuous multiyear records of sediment trap-gained microorganism fluxes are scarce. Such studies are important to identify and to understand the main forcings behind seasonal and multiannual evolution of microorganism flux dynamics. Here, we assess the long-term flux variations and population dynamics of diatoms, coccolithophores, calcareous and organic dinoflagellates, foraminifera and pteropods in the Eastern Boundary Upwelling Ecosystem (EBUE) of the Canary Current. A multiannual, continuous sediment trap experiment was conducted at the mooring site CB
eu (Cape Blanc eutrophic, ∼ 20° N, 18° W; trap depth = ca. 1,300 m) off Cape Blanc, Mauritania (northwest Africa), between June 2003 and March 2008. Throughout the study, the reasonably consistent good match of fluxes of microorganisms and bulk mass reflects the seasonal occurrence of the main upwelling season and the contribution of microorganisms to mass flux off Mauritania. A clear successional pattern of microorganisms, i.e. primary producers followed by secondary producers, is not observed. High fluxes of diatoms, coccolithophores, organic dinoflagellates cysts, and planktonic foraminifera occur simultaneously. Peaks of calcareous dinoflagellate cysts and pteropods mostly occurred during intervals of upwelling relaxation. A striking feature of the temporal variability of populations' occurrence is the persistent pattern of seasonal groups' contribution. Species of planktonic foraminifera, diatom, and organic dinoflagellate cysts typical of coastal upwelling as well as cooler water planktonic foraminifera and the coccolithophore Gephyrocapsa oceanica are abundant at times of intense upwelling (late winter through early summer). Planktonic foraminifera and calcareous dinoflagellate cysts dominant in warm pelagic surface waters and all pteropod groups are more abundant in fall and winter, when the mixed layer deepens. Similarly, coccolithophores of the upper- and lower photic zone, together with Emiliania huxleyi, and organic dinoflagellate cysts dominate the assemblage during phases of upwelling relaxation and deeper layer mixing. A significant shift in the regular seasonal pattern of species relative contributions is observed between 2004 and 2006. Benthic diatoms strongly increased after fall 2005 and dominated the diatom assemblage during main upwelling season. Additional evidence for a change in population dynamics are the short dominance of the coccolithophore Umbilicosphaera annulus, the occurrence of the pteropod Limacina bulimoides, and the strong increase in the flux of calcareous dinoflagellate cysts, abundant in tropical, warm oligotrophic waters south of the research area after fall 2005. Altogether, this suggests that pulses of southern waters were transported to the sampling site via the northward Mauritania Current. Our multiannual trap experiment provides a unique opportunity to characterize temporal patterns of variability that can be extrapolated to other EBUEs, which are experiencing or might experience similar future changes in the plankton community. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
35. Diagenesis in Madeira Abyssal Plain turbidites: New insights for inorganic geochemistry, organic geochemistry, palynology and their proxies
- Author
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Versteegh, Gerard, Gray, Daniel, Kuhn, Gerhard, Lipp, Julius, Zonneveld, Karin A. F., Kasten, Sabine, Versteegh, Gerard, Gray, Daniel, Kuhn, Gerhard, Lipp, Julius, Zonneveld, Karin A. F., and Kasten, Sabine
- Published
- 2016
36. Report and preliminary results of R/V POSEIDON cruise POS448. CAPRICCIO. Calabrian and Adriatic Past River Input and Carbon ConversIOn In the Eastern Mediterranean. Messina - Messina, 6 - 23 March 2013
- Author
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Zonneveld, Karin, Baumann, K.-H., Clotten, C., Donner, B., Gray, D., Iwanczuk, N., Lombrock, J., Theodor, M., Valk, O., and Versteegh, G.
- Subjects
550 Earth sciences and geology ,ddc:550 - Abstract
1 47 296
- Published
- 2013
37. Combined North Atlantic and anthropogenic forcing of changes in the marine environments in the Gulf of Taranto (Italy) during the last millennium.
- Author
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Menke, Valerie, Ehrmann, Werner, Milker, Yvonne, Brzelinski, Swaantje, Möbius, Jürgen, Mikolajewicz, Uwe, Zolitschka, Bernd, Zonneveld, Karin, Christian Emeis, Kay, and Schmiedl, Gerhard
- Abstract
This study examines the multi-decadal to centennial variability of benthic ecosystems, depositional environments and biogeochemical processes in the Gulf of Taranto (Italy) over the last millennium. Our study is based on sediment cores from two sites in the eastern Gulf of Taranto (Mediterranean Sea), and benthic foraminifera data of 43 surface sediment samples from the western Adriatic Sea reflecting modern conditions. We use the data to unravel relative contributions of natural and anthropogenic forcing to conditions at the sediment-water interface in a marine setting with a long history of human impacts in river catchments. High abundances of infaunal foraminifera in surface sediments trace the nutrient-rich Po river outflow and display an area of high organic matter deposition in the north-eastern Gulf of Taranto. Decreasing Ca / Ti ratios suggest increasing terrigenous fluxes at ~ 1300 AD driven by wetter conditions during persistent negative phases of the North Atlantic Oscillation (NAO). A strong NAO connection is also evident in high-resolution clay mineral data. The smectite / illite ratio reflects variable Po river runoff, and correlates well with NAO strength for the past 300 years. Benthic ecosystem variability as reflected by foraminifera is closely linked to the Northern Hemisphere temperature evolution during the past millennium. Spectral analysis reveals a quasi-periodic variability of ~ 50 to ~ 70 years suggesting an Atlantic Multidecadal Oscillation (AMO) forcing of Italian hydrology. Coeval with increasing anthropogenic activity, the effects of rising temperatures and nutrient discharge during the past 200 years further enhanced nutrient and organic matter fluxes. This is reflected by a substantial rise in the abundance of shallow to intermediate infaunal benthic foraminifera (SIIBF) and a concurrent decrease of Uvigerina mediterranea δ
13 C since at least 1800 AD. The SIIBF decrease in the youngest samples likely reflects environmental effects of stricter regulations on fertilizer use in Italy and the reduction of sediment transport due to the stabilization of river banks. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
38. Report and preliminary results of R/V POSEIDON Cruise P398, Las Palmas Lissabon, 1 16 April 2010. PAPOCA, Production and preservation of organic carbon in relationship to dust input and nepheloid layers in the upwelling area off NW Africa
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Zonneveld, Karin and participants, cruise
- Subjects
550 Earth sciences and geology ,ddc:550 - Abstract
1 33 282
- Published
- 2011
39. Report and preliminary results of R/V Poseidon Cruises P 366-1 and P 366-2, Las Palmas - Las Palmas - Vigo, 03 - 19 May 2008 and 22 - 30 May 2008. PERGAMOM Proxy Education and Research cruise off Galicai, Morocco and Mauretania
- Author
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Zonneveld, Karin and participants, cruise
- Subjects
550 Earth sciences and geology ,ddc:550 - Abstract
1 47 274
- Published
- 2010
40. Low- to high-productivity pattern within Heinrich Stadial 1: Inferences from dinoflagellate cyst records off Senegal
- Author
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Bouimetarhan, Ilham, Groeneveld, Jeroen, Dupont, Lydie, Zonneveld, Karin, Bouimetarhan, Ilham, Groeneveld, Jeroen, Dupont, Lydie, and Zonneveld, Karin
- Abstract
In order to investigate a possible connection between tropical northeast (NE) Atlantic primary productivity, Atlantic meridional overturning circulation (AMOC), and drought in the Sahel region during Heinrich Stadial 1 (HS1), we used dinoflagellate cyst (dinocyst) assemblages, Mg/Ca based reconstructed temperatures, stable carbon isotopes (δ13C) and geochemical parameters of a marine sediment core (GeoB 9508-5) from the continental slope offshore Senegal. Our results show a two-phase productivity pattern within HS1 that progressed from an interval of low marine productivity between ~ 19 and 16 kyr BP to a phase with an abrupt and large productivity increase from ~ 16 to 15 kyr BP. The second phase is characterized by distinct heavy planktonic δ13C values and high concentrations of heterotrophic dinocysts in addition to a significant cooling signal based on the reconstructions of past sea surface temperatures (SSTs). We conclude that productivity variations within HS1 can be attributed to a substantial shift of West African atmospheric processes. Taken together our results indicate a significant intensification of the North East (NE) trade winds over West Africa leading to more intense upwelling during the last millennium of HS1 between ~ 16 and 15 kyr BP, thus leaving a strong imprint on the dinocyst assemblages and sea surface conditions. Therefore, the two-phase productivity pattern indicates a complex hydrographic setting suggesting that HS1 cannot be regarded as uniform as previously thought.
- Published
- 2013
41. Atlas of modern dinoflagellate cyst distribution based on 2405 data points
- Author
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Zonneveld, Karin A.F., Marret, Fabienne, Versteegh, Gerard J.M., Bogus, Kara, Bonnet, Sophie, Bouimetarhan, Ilham, Crouch, Erica, de Vernal, Anne, Elshanawany, Rehab, Edwards, Lucy, Esper, Oliver, Forke, Sven, Grøsfjeld, Kari, Henry, Maryse, Holzwarth, Ulrike, Kielt, Jean-François, Kim, So-Young, Ladouceur, Stéphanie, Ledu, David, Chen, Liang, Limoges, Audrey, Londeix, Laurent, Lu, S.-H., Mahmoud, Magdy S., Marino, Gianluca, Matsouka, Kazumi, Matthiessen, Jens, Mildenhal, D.C., Mudie, Peta, Neil, H.L., Pospelova, Vera, Qi, Yuzao, Radi, Taoufik, Richerol, Thomas, Rochon, André, Sangiorgi, Francesca, Solignac, Sandrine, Turon, Jean-Louis, Verleye, Thomas, Wang, Yan, Wang, Zhaohui, Young, Marty, Zonneveld, Karin A.F., Marret, Fabienne, Versteegh, Gerard J.M., Bogus, Kara, Bonnet, Sophie, Bouimetarhan, Ilham, Crouch, Erica, de Vernal, Anne, Elshanawany, Rehab, Edwards, Lucy, Esper, Oliver, Forke, Sven, Grøsfjeld, Kari, Henry, Maryse, Holzwarth, Ulrike, Kielt, Jean-François, Kim, So-Young, Ladouceur, Stéphanie, Ledu, David, Chen, Liang, Limoges, Audrey, Londeix, Laurent, Lu, S.-H., Mahmoud, Magdy S., Marino, Gianluca, Matsouka, Kazumi, Matthiessen, Jens, Mildenhal, D.C., Mudie, Peta, Neil, H.L., Pospelova, Vera, Qi, Yuzao, Radi, Taoufik, Richerol, Thomas, Rochon, André, Sangiorgi, Francesca, Solignac, Sandrine, Turon, Jean-Louis, Verleye, Thomas, Wang, Yan, Wang, Zhaohui, and Young, Marty
- Published
- 2013
42. Atlas of modern dinoflagellate cyst distribution based on 2405 data points
- Author
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Zonneveld, Karin A F, Marret, Fabienne, Versteegh, Gerard J.M., Bogus, Kara, Bonnet, Sophie, Bouimetarhan, Ilham, Crouch, Erica, de Vernal, Anne, Elshanawany, Rehab, Edwards, Lucy, Esper, Oliver, Forke, Sven, Marino, Gianluca, Neil, Helen, Young, Martin, Zonneveld, Karin A F, Marret, Fabienne, Versteegh, Gerard J.M., Bogus, Kara, Bonnet, Sophie, Bouimetarhan, Ilham, Crouch, Erica, de Vernal, Anne, Elshanawany, Rehab, Edwards, Lucy, Esper, Oliver, Forke, Sven, Marino, Gianluca, Neil, Helen, and Young, Martin
- Abstract
Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organic-walled dinoflagellate cyst species. The synthesis is based on the integration of literature sources together with data of 2405 globally distributed surface sediment samples that have been prepared with a comparable methodology and taxonomy. The distribution patterns of individual cyst species are being compared with environmental factors that are known to influence dinoflagellate growth, gamete production, encystment, excystment and preservation of their organic-walled cysts: surface water temperature, salinity, nitrate, phosphate, chlorophyll a concentrations and bottom water oxygen concentrations. Graphs are provided for every species depicting the relationship between seasonal and annual variations of these parameters and the relative abundance of the species. Results have been compared with previously published records; an overview of the ecological significance as well as information about the seasonal production of each individual species is presented.The relationship between the cyst distribution and variation in the aforementioned environmental parameters was analysed by performing a canonical correspondence analysis. All tested variables showed a positive relationship on the 99% confidence level. Sea-surface temperature represents the parameter corresponding to the largest amount of variance within the dataset (40%) followed by nitrate, salinity, phosphate and bottom-water oxygen concentration, which correspond to 34%, 33%, 25% and 24% of the variance, respectively. Characterisations of selected environments as well as a discussion about how these factors could have influenced the final cyst yield in sediments are included.
- Published
- 2013
43. The use of dinoflagellate cysts to separate human-induced from natural variability in the trophic state of the Po River discharge plume over the last two centuries
- Author
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Zonneveld, Karin A.F., Chen, Liang, Elshanawany, Rehab, Fischer, Helmut W., Hoins, Mirja, Ibrahim, Mohammed I., Pittauerová, Daniela, Versteegh, Gerard J.M., Zonneveld, Karin A.F., Chen, Liang, Elshanawany, Rehab, Fischer, Helmut W., Hoins, Mirja, Ibrahim, Mohammed I., Pittauerová, Daniela, and Versteegh, Gerard J.M.
- Published
- 2012
44. The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic-matter based alteration, productivity and temperature proxies
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Bogus, Kara A., Zonneveld, Karin A.F., Fischer, David, Kasten, Sabine, Bohrmann, Gerhard, Versteegh, Gerard J.M., Bogus, Kara A., Zonneveld, Karin A.F., Fischer, David, Kasten, Sabine, Bohrmann, Gerhard, and Versteegh, Gerard J.M.
- Abstract
A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. In this study, we used surface samples collected along two meter-scale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the studied alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in the oxygen regime. Several export production indices, a cholesterol-based stanol/stenol index and dinoflagellate lipid- and cyst-based ratios, showed significant (more than 20%) change only over the lateral oxygen gradients. Therefore, these compounds do not exclusively reflect surface water productivity, but are significantly altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol tetraether-based TEX86 sea surface temperature indices and indices based on phytol, phytane and pristane, did not show any trends related to oxygen. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX86, TEX86L, and TEX86H proxies. The phytol-based ratios were likely affected by the sedimentary production of pristane. Our results demonstrate the selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments along a short lateral oxygen gradient and suggest that some of the investigated proxies may be useful tracers of changing redox conditions at the sediment-water interface.
- Published
- 2012
45. Aerobic degradation of organic carbon inferred from dinoflagellate cyst decomposition in Southern Ocean sediments
- Author
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Kupinska, Monika, Sachs, Oliver, Sauter, Eberhard J., Zonneveld, Karin A.F., Kupinska, Monika, Sachs, Oliver, Sauter, Eberhard J., and Zonneveld, Karin A.F.
- Abstract
Organic carbon (OC) burial is an important process influencing atmospheric CO2 concentration and global climate change; therefore it is essential to obtain information on the factors determining its preservation. The Southern Ocean (SO) is believed to play an important role in sequestering CO2 from the atmosphere via burial of OC. Here we investigate the degradation of organic-walled dinoflagellate cysts (dinocysts) in two short cores from the SO to obtain information on the factors influencing OC preservation. On the basis of the calculated degradation index kt, we conclude that both cores are affected by species-selective aerobic degradation of dinocysts. Further, we calculate a degradation constant k using oxygen exposure time derived from the ages of our cores. The constant k displays a strong relationship with pore-water O2, suggesting that decomposition of OC is dependent on both the bottom- and pore-water O2 concentrations.
- Published
- 2012
46. Average process length variation of the marine dinoflagellate cyst Operculodinium centrocarpum in the tropical and Southern Hemisphere Oceans: Assessing its potential as a palaeosalinity proxy
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Verleye, Thomas, Mertens, Kenneth N, Young, Martin, Dale, Barrie, McMinn, A, Scott, Louis, Zonneveld, Karin A F, Louwye, Stephen, Verleye, Thomas, Mertens, Kenneth N, Young, Martin, Dale, Barrie, McMinn, A, Scott, Louis, Zonneveld, Karin A F, and Louwye, Stephen
- Abstract
The study investigates the morphological variability of the dinoflagellate cyst Operculodinium centrocarpum (resting cyst of Protoceratium reticulatum) in core-top samples distributed over the Southern Hemisphere and the tropics in relation to sea-surface temperature (SST) and sea-surface salinity (SSS) at the corresponding sites. The process lengths show a moderate inverse relationship to summer SST (sSST) (R 2=0.44) and sSSS/sSST (R 2=0.4), however, lateral transport of cysts probably produced noise in the plots. After excluding tropical and Southern Hemisphere sites considered to have been affected by long distance lateral transport, the relationship between process length and density follows the equation sD=0.8422x+1016.9 (R 2=0.55) with a Root Mean Square Error=0.63kgm -3, while the negative correlation with sSST increases up to R 2=0.79. Next to salinity, this study thus highlights the importance of a second factor, temperature, affecting process length in the topics and the Southern Hemisphere oceans.
- Published
- 2012
47. Report and preliminary results of R/V Poseidon Cruises P 366-1 [POS366/1] and P 366-2 [POS366/2], Las Palmas - Las Palmas - Vigo, 03-19 May 2008 and 22-30 May 2008. PERGAMON Proxy Education and Research cruise off Galicai, Morocco and Mauretania
- Author
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Zonneveld, Karin and Zonneveld, Karin
- Published
- 2010
48. NW African climate variations during the last 47,000years: Evidence from organic-walled dinoflagellate cysts
- Author
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Holzwarth, Ulrike, Meggers, Helge, Esper, Oliver, Kuhlmann, Holger, Freudenthal, Tim, Hensen, Christian, Zonneveld, Karin A.F., Holzwarth, Ulrike, Meggers, Helge, Esper, Oliver, Kuhlmann, Holger, Freudenthal, Tim, Hensen, Christian, and Zonneveld, Karin A.F.
- Abstract
NW African climate shows orbital and millennial-scale variations, which are tightly connected to changes in marine productivity. We present an organic-walled dinoflagellate cyst (dinocyst) record from a sediment core off Cape Yubi at about 27°N in the Canary Basin covering the time period from 47 to 3 ka before present (BP). The dinocyst record reflects differences in upwelling intensity and seasonality as well as the influence of fluvial input. Sea-level changes play an important role for the upwelling pattern and productivity signals at the core site. Within the studied time interval, four main phases were distinguished. (1) From 45 to 24 ka BP, when sea-level was mostly about 75 m lower than today, high relative abundances of cysts of heterotrophic taxa point to enhanced upwelling activity, especially during Heinrich Events, while relatively low dinocyst accumulation rates indicate that filament activity at the core location was strongly reduced. (2) At sea-level lowstand during the LGM to H1, dinocyst accumulation rates suggest that local filament formation was even more inhibited. (3) From the early Holocene to about 8 ka BP, extraordinary high accumulation rates of most dinocyst species, especially of Lingulodinium machaerophorum, suggest that nutrient supply via fluvial input increased and rising sea-level promoted filament formation. At the same time, the upwelling season prolongated. (4) A relative increase in cysts of photoautotrophic taxa from about 8 ka BP onwards indicates more stratified conditions while fluvial input decreased. Our study shows that productivity records can be very sensitive to regional features. From the dinocyst data we infer that marine surface productivity off Cape Yubi during glacial times was within the scale of modern times but extremely enhanced during deglaciation.
- Published
- 2010
- Full Text
- View/download PDF
49. Process length variation in cysts of a dinoflagellate, Lingulodinium machaerophorum, in surface sediments: investigating its potential as salinity proxy.
- Author
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Mertens, Kenneth, Ribeiro, Sofia, Ilham, Bouimetarhan, Caner, Hulya, Combourieu-Nebout, Nathalie, Dale, Barrie, de Vernal, Anne, Ellegaard, Marianne, Filipova, Mariana, Godhe, Anna, Goubert, Evelyne, Grøsfjeld, Kari, Holzwarth, Ulrike, Kotthoff, Ulrich, Leroy, Suzanne A.G., Londeix, Laurent, Marret, Fabienne, Matsuoka, Kazumi, Mudle, Peta J., Naudts, Lieven, Peña-Manjarrez, José Luis, Persson, Agneta, Popescu, Speranta-Maria, Pospelova, Vera, Sangiorgi, Francesca, van der Meer, Marcel T.J., Vink, Annemiek, Zonneveld, Karin A.F., Vercauteren, Dries, Vlassenbroeck, Jelle, Louwye, Stephen, Mertens, Kenneth, Ribeiro, Sofia, Ilham, Bouimetarhan, Caner, Hulya, Combourieu-Nebout, Nathalie, Dale, Barrie, de Vernal, Anne, Ellegaard, Marianne, Filipova, Mariana, Godhe, Anna, Goubert, Evelyne, Grøsfjeld, Kari, Holzwarth, Ulrike, Kotthoff, Ulrich, Leroy, Suzanne A.G., Londeix, Laurent, Marret, Fabienne, Matsuoka, Kazumi, Mudle, Peta J., Naudts, Lieven, Peña-Manjarrez, José Luis, Persson, Agneta, Popescu, Speranta-Maria, Pospelova, Vera, Sangiorgi, Francesca, van der Meer, Marcel T.J., Vink, Annemiek, Zonneveld, Karin A.F., Vercauteren, Dries, Vlassenbroeck, Jelle, and Louwye, Stephen
- Abstract
A biometrical analysis of the dinoflagellate cyst Lingulodinium machaerophorum [Deflandre, G., Cookson, I.C., 1955. Fossil microplankton from Australia late Mesozoic and Tertiary sediments. Australian journal of Marine and Freshwater Research 6: 242–313.] Wall, 1967 in 144 globally distributed surface sediment samples revealed that the average process length is related to summer salinity and temperature at a water depth of 30 m by the equation (salinity/temperature) = (0.078low asteriskaverage process length + 0.534) with R2 = 0.69. This relationship can be used to reconstruct palaeosalinities, albeit with caution. The particular ecological window can be associated with known distributions of the corresponding motile stage Lingulodinium polyedrum (Stein) Dodge, 1989. Confocal laser microscopy showed that the average process length is positively related to the average distance between process bases (R2 = 0.78), and negatively related to the number of processes (R2 = 0.65). These results document the existence of two end members in cyst formation: one with many short, densely distributed processes and one with a few, long, widely spaced processes, which can be respectively related to low and high salinity/temperature ratios. Obstruction during formation of the cysts causes anomalous distributions of the processes. From a biological perspective, processes function to facilitate sinking of the cysts through clustering.
- Published
- 2009
50. Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names
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Elbrächter, Malte, Gottschling, Marc, Hildebrand-Habel, Tania, Keupp, Helmut, Kohring, Rolf, Lewis, Jane, Meier, Sebastian, Montresor, Marina, Streng, Michael, Versteegh, Gerard, Willems, Helmut, Zonneveld, Karin, Elbrächter, Malte, Gottschling, Marc, Hildebrand-Habel, Tania, Keupp, Helmut, Kohring, Rolf, Lewis, Jane, Meier, Sebastian, Montresor, Marina, Streng, Michael, Versteegh, Gerard, Willems, Helmut, and Zonneveld, Karin
- Abstract
Calcareous dinoflagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decades with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaeopyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated during the past decade. Over the years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellates, and non-calcareous relatives derived from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate specialists, we outline major subjects that are in need of re-investigation and -evaluation (an Agenda for Calcareous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates in a nomenclatural synopsis, with species names indicating their types and information on type locality and stratigraphy. We evaluate the status of these names—whether validly published and, if so, whether legitimate—,a crucial first step for any revisionary work in the future.
- Published
- 2008
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