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THE MICROPALAEONTOLOGICAL SOCIETY’S FORAMINIFERA AND NANNOFOSSIL GROUPS’
JOINT SPRING MEETING 2008
BIOINDICATORS OF
PAST AND PRESENT ENVIRONMENTS
15th to 17th May 2008
Tübingen, Germany
Hosted by the Department of
Micropalaeontology, Institute of Geosciences, University Tübingen
The TMS Spring Meeting is kindly supported by
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HYDRO‐BIOS Apparatebau GmbH was founded in 1960 and is manufacturing precise instruments, which are in use on every continent and are exported to approximately 80 countries all over the world. The manufacturing and sales programme includes equipment for use in oceanography, hydrobiology, limnology as well as instrumentation for water pollution investigation in the fields of public health, environmental protection and ecology. Scientific Committee: Kate Darling, Karl Heinz Baumann, Daniela Schmidt, and Tom Dunkley‐Jones (Chairs & Secretaries, TMS Foraminifera and Nannofossil Groups) Organisation Committee: Michal Kucera, Petra Heinz, Ralf Aurahs, Gabi Trommer, Michael Siccha, Lea Numberger and Anne Schulze
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MEETING PROGRAMME Wednesday, 14th May 18:00 – 21:00 Registration & Icebreaker Reception in the paleontological museum Thursday, 15th May 8:00 Registration 8:50 Welcome by Michal Kucera
9:00 SCHULZ, KAI Coccolithophorid calcification in a high CO2 ocean: from organism to ecosystem
9:30 Nomaki, Hidetaka Particulate versus dissolved organic matter uptake by deep‐sea benthic foraminifera revealed by in situ 13C‐labeling experiments
9:50 Bouchet, Vincent Combining benthic foraminifera and macrofauna for assessing a foraminifera biotic index
10:10 Goineau, Aurélie Live (stained) benthic foraminifera from the Rhône prodelta: environmental controls and interannual variability
10:30 Coffee Break 11:00 Margreth, Stephan
Benthic Foraminifera as bioindicators for active cold‐water coral mounds: Results from the Porcupine and Rockall Banks in the North Atlantic
11:20 Milker, Yvonne Distribution of Recent and subrecent shallow‐water benthic foraminifera in the Western Mediterranean Sea: Development of a transfer function for quantitative sea level reconstructions
Chair: Daniela Schmidt
11:40 de Nooijer, Lennart Foraminiferal calcification and the role of intracellular pH
12:00 –
14:30
Lunch Break Poster Session 1
14:30 GROENEVELD, JEROEN Salinity influence on planktonic foraminiferal Mg/Ca: A case study from the Red Sea
15:00 Kısakürek, Basak Calcium isotope fractionation in foraminifera
15:20 Hathorne, Ed Test surface coatings of planktonic foraminifera investigated with single pulse laser ablation (LA) ICP‐MS
15:40 Morard, Raphaël Morphometric and stable isotope (δ13C, δ18O) analyses of planktonic foraminiferal cryptic species: new perspectives for paleoceanographic reconstructions
16:00 Aurahs, Ralf Distribution patterns of cryptic and pseudo‐cryptic species in Globigerinoides ruber and Globigerinoides conglobatus in the north‐eastern Atlantic and Mediterranean Sea
Chair: Karl‐Heinz Baumann
16:20 Tea Break
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16:40 Rigual Hernández, Andrés Seasonal evolution of the foraminifer fluxes in the Northwest Mediterranean based on the study of a 12‐year‐long sediment trap record
17:00 Wit, Jos Seasonality in the Mediterranean Sea: A calibration study using paired single specimen D18O and Mg/Ca measurements of G. ruber alba
17:20 Zarrieß, Michelle Productivity and ventilation variability off NW Africa during the last 30,000 years
17:40 Owen, Nick Assemblages of foraminifera at the continental slope off Western Ireland – influence of variations in bottom current strength and positioning
19: 30 Conference Dinner at the “Kelter”
Friday, 16th May Chair: Tom Dunkley Jones
9:00 BEAUFORT, LUC Effect of ocean carbonate chemistry on Isochrysidales (Coccolithophore) calcification: studies from present and past oceans
9:30 Simón‐Baile, Débora Stable Isotope record in Pleistocene Coccoliths Recovered in Western Mediterranean and North‐Western Africa
9:50 Stolz, Katharina Coccolith assemblages and coccolith isotope signals as a proxy for the reconstruction of the Last Glacial in the North Atlantic
10:10 Saavedra‐Pellitero, Mariem Coccolithophorid assemblage variations in ODP site 1233 (South Pacific) covering the last 70 kyr, focusing on Termination I
10:30 Coffee Break 11:00 Mejía‐Molina, Alejandra
Relationship between coccolithophore assemblage and dust supply during Heinrich Events in the Eastern tropical Atlantic
11:20 Lupi, Claudia Pleistocene climate events in the SW Pacific Ocean: biotic and geochemical evidences
11:40 Ivanova, Elena Carbonate microfossil assemblages of the Eastern Equatorial Pacific: evidence of bioproductivity and circulation changes over the last 250 kyr
12:00 –
14:30
Lunch Break Poster Session 2
Chair: Petra Heinz
14:30 BORNEMANN, ANDRE Stable isotope studies on Cretaceous planktic foraminifera from Demerara Rise – implications for depth habitat, photosymbiosis and paleotemperature reconstructions
15:00 Speijer, Robert 3D‐imaging and quantification of foraminifera with high‐resolution X‐ray CT
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15:20 Holcová, Katarína Can Island biogeography work also in paleobiogeography?
15:40 Benjamini, Chaim Pre‐ vs. post‐Suez symbiont‐bearing larger foraminifera in the Mediterranean – Refugia vs. Lessepsian migration
16:00 Ashckenazi‐Polivoda, Sarit Paleobiological Implication of the Latest Cretaceous Oil Shale Sequence in Israel as Inferred from Foraminifera
16:20 Tea Break 16:40 Vestergaard – Laursen, Gitte
A case story of a multi‐disciplinary approach from deep‐water clastic deposits Offshore Nigeria; Methodology and Applications
17:00 Stassen, Peter Foraminiferal response to abrupt warming during the PETM, a reconstruction of a coastal paleoenvironment in Tunisia
17:20 Giraldo Gómez, Victor Manuel Paleoenvironmental reconstruction with foraminifera during the middle – late Albian of the Villeta Formation (Tetuan Member) in the Upper Magdalena Valley, Colombia
17:40 Casellato, Cristina Calpionellid and Calcareous Nannofossil Evolution and Calcification across Tithonian‐Berriasian Interval (Thetys Ocean)
18:00 Closing remarks & farewell Saturday, 17th May 9:00 Field Trip
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POSTER SESSIONS Session 1: Thursday, 15th May 1 Alcántara‐Carrió,
J. (Diz*) Combined analysis of grain size, mineralogy and foraminifera content to determine the sediment source area and geomorphological evolution for a costal Aeolian environment
2 Arieli, Ruthie
The effect of thermal pollution on benthic foraminiferal assemblages, in the Mediterranean shore face adjacent to Hadera power plant (Israel)
3 Ní Fhlaithearta, Shauna
Variations in bottom water trace metal concentrations during the deposition of sapropel S1, as derived from benthic foraminifera
4 Broggy, Teresa
Coiling ratios of Globorotalia truncatulinoides in the western Mediterranean Sea during the Holocene
5 Diz, Paula
Taphonomic effects on the benthic foraminiferal paleoecological record of the Ría de Vigo (NW Spain)
6 Drinia, Hara
Benthic foraminiferal assemblages in the Plio‐Pleistocene restricted environment of the Kritika Member (Rhodes Island, Greece)
7 Geslin, Emmanuelle
Oxygen Respiration rates of benthic foraminifera measured under laboratory conditions using oxygen microelectrodes
8 Harbers, Almuth
Time series observations of planktonic foraminifera in the NE Atlantic Ocean (Porcupine Seabight)
9 Hoffmann, Ramona
Coccolithophorid and calcareous dinoflagellate species fluxes in the vicinity of the Azores Front (33°N 22°W) during 2003/2004: a sediment trap investigation
10 Kaminski, Michael
Integrated foraminiferal and nannofossil biostratigraphy and paleoecology of the Campanian of the Eastern Carpathians, Romania (Dambovita Valley)
11 Kitazato, Hiroshi
Roles of agglutinated foraminifera in benthic ecosystem; evidences and speculations
12 Koho, Karoliina
Sedimentary labile organic carbon and redox control on species distribution of benthic foraminifera: A case study from Lisbon‐Setúbal Canyon
13 Leiter, Carola
Benthic Foraminifera of the Benguela Upwelling System as potential denitrifyers
14 Linshy, V. N.
Benthic foraminifera as bio indicators of marine pollution
15 Lončarić, N. (Howa*)
Seasonal record of foraminiferal export fluxes in the Bay of Biscay
16 Mojtahid, Meryem
Benthic foraminifera as bio‐indicators of drill cutting disposals
17 Moller, Tobias
Biometric Analysis of phenotypic variation in recent Neogloboquadrina pachyderma in the 18northern Atlantic Ocean, its usability as a proxy for SST and its application to glacial Atlantic Ocean
18 Numberger, Lea
Habitats of Globigerinoides ruber (d’Orbigny) in the eastern Mediterranean Sea since the Marine Isotopic Stage 12
19 Retailleau, Sophie
Living planktic foraminifera in hemi‐pelagic environments
20 Scherrer, Sandra
Combining morphological with genetic characters: Single cell analysis on coccolithophores from plankton filter samples
21 Schönfeld, Joachim
Time series observations of planktonic foraminifera in the NE Atlantic Ocean (Porcupine Seabight)
22 Schweizer, Magali
Molecular identification of an Ammonia species (Foraminifera, Rotaliida) from the Kiel Fjord (Germany)
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23 Schweizer, Magali
How similar are morphological and genetic diversities recognizable on a typical plankton filter?
24 Toyofuku, Takashi
A new model of foraminiferal calcification pathways in shallow benthic foraminifera: miliolids vs. hyaline species
25 Trattenero, Iacopo
The evolutive turnover of benthic foraminifera in the images Site 97‐2114 (SW Pacific Ocean) During the middle Pliestocene Transition
26 Trommer, Gabriele
Multi‐proxy reconstruction of Holocene paleoceanography in the Red Sea
27 Van Kerckhoven, Liesbeth
Causes of Cenozoic evolution of deep‐sea benthic foraminifera
28 Polovodova, Irina
Foraminiferal test abnormalities as proxies of environmental change in SW Baltic Sea
Session 2: Friday, 16th May 1 Cetean,
Claudia Integrated foraminiferal and nannofossil biostratigraphy and paleoecology of the Campanian of the Eastern Carpathians, Romania (Dambovita Valley)
2 Abdolalipour, Samere
Benthonic and planktonic foraminiferal transformation in Campanian‐ Maastrichtian boundary in Jorband Section‐ North of Iran
3 Asgharian, Masoud (Abdol.*)
Planktonic foraminifera response to sudden global warm temperature in late Maastrichtian, Ziyarat Kola, Alborz Mountain, Iran
4 Dunkley Jones, Tom
Exceptionally well‐preserved calcareous nannofossils from the Paleogene of coastal Tanzania – an update
5 Daniel, Thomas
Micropalaeontological reconstruction of Holocene environmental changes in the archaeological excavation site Stralsund Ozeaneum, southern Baltic Sea
6 Gressier, Vincent
The 13C positive excursion of the Valanginian/Hauterivian interval. Comparison of bulk carbonate, photic zone and diagenetic records in Vocontian Basin (SW France)
7 Hermoso, Michael
Nannofloral Assemblage Change During the Early Toarcian Anoxic Event in the Paris Basin and Biogeochemical Insights
8 Mancin, Nicoletta
Paleobathymetry of the Southalpine foreland basin (Cenozoic, NE Italy) inferred from Micropaleontological and geometrical data
9 Peryt, Danuta
Palaeoenvironmental Inferences from Campanian Foraminiferal and Ostracod Assemblages from the Miechów Trough, Southern Poland
10 Sprong, J. (Speijer*)
Upper Danian lower Selandian stratigraphy and paleoenvironment along a paleobathymetric transect in the Nile Valley Basin (Eastern Desert, Egypt)
11 Alonso‐García, Montserrat
North Atlantic paleotemperatures during the mid‐Pleistocene transition based on foraminifer assemblages
12 Barry, Darren
Planktonic Foraminiferal Test Size during Sapropel S5
13 Baumann, Karl‐Heinz
Variations in upper water‐column dynamics in the North Atlantic during the last 20,000 years as revealed by coccolithophorid assemblages
14 Chistyakova, Natalia
Reconstruction of the postglacial environments in the South‐Western Barents Sea by variations in benthic and planktic foraminiferal assemblages and stable isotopes
15 Halligan, Sean
Holocene Climate Variability in the Western Mediterranean Sea
16 Hernández‐Almeida, Ivan
North Atlantic Climate change during the Mid‐Pleistocene (MIS 19 to MIS 31) based on foraminifer and isotopes studies in IODP Site 1314
17 Holcová, Katarína
Succession of the Bryozoa‐rich communities in the Middle Miocene of the Central Paratethys
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18 Meier, Sebastian
The laminated sapropel S5 from ODP core 971C ‐ deciphering the seasonal productivity signal during sapropel formation
19 Mourik, Anja
The Middle Miocene Climate Transition in the central Mediterranean: changing paleoenvironments as revealed by benthic foraminifera
20 Ufkes, Els
Changes in SE Atlantic watermass distribution during the MidLatePleistocene
21 Álvarez, Garcia
Identification of two ENSO‐like events in the Gulf of California?
22 Barras, Christine
Calibration of 18O from deep‐sea benthic foraminiferal shell as a temperature proxy: laboratory results
23 Egoroff, Grégoire
Exploiting the calcareous nannoplankton biogeochemistry: an asset for palaeoceanographical studies
24 Fink, Christina
Geochemical and isotopic signals (Sr/Ca‐ratios, stable δ13C‐ and δ18O‐isotopes) in coccolith carbonate of different grain‐size fractions in South Atlantic surface sediments
25 Friedrich, Oliver
Influence of planktic foraminiferal morphotypes, shell size, and weight on Mg/Ca ratios
26 Phuong Nguyen, T.M. (Speijer*)
Experimental dissolution studies on lower Eocene foraminiferal assemblages from Egypt
27 Steinke, Stephan
Test surface coatings of planktonic foraminifera investigated with single pulse laser ablation (LA) ICP‐MS
28 van Raden, Ulrike
Mg/Ca ratios of Globigerina bulloides and Globorotalia inflata from Core Top and Plankton Tow Samples in the Western Mediterranean Sea
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PRESENTATIONS ABSTRACTS North Atlantic paleotemperatures during the mid‐Pleistocene transition based on foraminifer assemblages Alonso‐García, M.1, Sierro, F. J.1, Kucera, M.2 and Flores, J. A.1 1 Departamento de Geología (Paleontología), Universidad de Salamanca, Pz. de la Merced s/n, 37008 Salamanca, Spain, [email protected] 2 Institut für Geowissenschaften, Eberhard‐Karls Universität Tübingen, Sigwartstrasse 10, DE‐72076 Tübingen, Germany IODP Site 1314 was drilled in southern Gardar Drift (56° 21.8’ N, 27° 53.3’ W) during Expedition 306 “North Atlantic Climate” to study ice sheet‐ocean‐atmosphere interactions on millennial timescales during the late Neogene‐Quaternary. This study encompasses Marine Isotope Stage (MIS) 19 to 12 (ca. 800‐400 ka), covering the so‐called Mid Pleistocene Transition (MPT, [1]) when the Earth’s climate response to orbital forcing underwent a significant change in cyclicity, shifting from dominant obliquity (40 ka) to eccentricity cycles (100 ka). In each sample, a minimum of 300 individuals of planktic foraminifers (> 150 μm) were counted to calculate the species relative abundances. The amount of IRD (Ice Rafted Debris), benthic foraminifers, diatoms and radiolarians were also determined. The alternation of cold and warm planktic foraminifer assemblages, IRD abundance and the paleomagnetic record helped us to develop a preliminary age model for the sequence. Paleotemperatures were calculated using Artificial Neural Networks (ANN, [2]) and Modern Analog Technique (MAT, [3]), both based on the MARGO North Atlantic calibration dataset [4]. Sea surface temperature (SST) reconstructions produced by both methods are similar and depict annual SST around 4°C during glacial periods, and 12°C during interglacial periods. Statistical analyses of the assemblage composition show that although the fossil assemblages appear to have good analogs in the calibration dataset, the mid‐Pleistocene foraminiferal faunas of the North Atlantic were different from the present day, particularly during the interglacials. A comparison with the MARGO LGM dataset shows that even the glacial faunas during the investigated period deviated from the last ice‐age pattern. We speculate that either the oceanographic situation at that time was distinctly different from the present‐day configuration or some of the foraminifer species shifted their ecological habitats. Identification of two ENSO‐like events in the Gulf of California? Álvarez, M C 1, a, Flores, J A 1, Sierro, F J 1, Molina‐Cruz, A 2. 1 Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca, Spain. (e‐mail: [email protected]) 2 Lab. de Ecología de Foraminíferos y Micropaleontología, Inst. de Ciencias del Mar y Limnología (ICMYL), UNAM, 04510 México D.F., Mexico. a present address: Facultad de Ciencias Experimentales, Universidad Católica de Valencia, 46003 Valencia, Spain. We are showing the Coccolithophore record from a gravity core (PCM‐00/Est.C) located in the Gulf of California. The coccolithophore assemblage was dominated by small placoliths as well as a typical subtropical assemblage. Nevertheless, specific variations in relative abundance and paleoproductivity (N ratio) reveal two different paleoceanographic and paleoclimatic settings during the last 11 Ka. Constant dominance in the coccolithophore record of “small” Gephyrocapsa and high paleoproductivity was the main feature during Holocene, related with an active upwelling and prevailing Southeastern winds. In contrast with this context, we recognised two different instances around 11 Ka and 6 Ka B.P. The coccolithophore assemblage highlight was the development of Florisphaera profunda together with the fall down in the paleoproductivity values. Both features reveal a deep nutricline/thermocline position and a strong stratification in the water column. These oceanographic conditions are similar to those prevailing during an ENSO (El Niño Southern Oscillation) event in the tropical Pacific, suggesting that the influence of the ENSO oscillations reaches the Gulf of California.
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Combined analysis of grain size, mineralogy and foraminifera content to determine the sediment source area and geomorphological evolution for a costal Aeolian environment J. Alcántara‐Carrió1, P. Diz2, S. Fernández‐Bastero2, C. Álvarez1 and I. Alonso3 1 Inst. Medio Ambiente y Ciencias Marinas. Univ. Católica de Valencia. Valencia, Spain. 2 Dpto. Geociencias Marinas. Universidad de Vigo, Pontevedra, Spain. 3 Dpto. Física. Universidad de Las Palmas de Gran Canaria. Las Palmas G.C., Spain. [email protected] The Jandia Isthmus (Fuerteventura, Canary Islands) is a complex aeolian system influenced by climatic changes during the Quaternary. Grain size, mineralogical and micro‐paleontological analyses (foraminifer content) has been carried to determine the main source area of sediments for the present aeolian environments. Specially useful have been the application of the Rietveld method to quantify the mineralogical composition obtained from the analysis of XRD powder diffraction patterns and the use of foraminifers as natural tracers of the aeolian dynamics. Combination of all these techniques indicate that erosion of the Upper Pleistocene aeolian deposits that partially cover the isthmus surface is the process that presently supplies most of the aeolian sediments blowing across the isthmus. Moreover, foraminifer content of Upper Pleistocene sediments is not similar to Pliocene one. Consequently, this study also permits to deduce the previous coastal geomorphology and sedimentary dynamics, that is, the existence of backshore surfaces westward the present shoreline during both Pliocene and Upper Pleistocene, acting as source area for their respective aeolian deposits. Calpionellid and Calcareous Nannofossil Evolution and Calcification across Tithonian‐Berriasian Interval (Thetys Ocean) G.Andreini2, C.E.Casellato*1, E.Erba1, G.Parisi2 1 Dep. of Earth Sciences, Univ. of Milan, Milan, Italy 2 Dep. of Earth Sciences, Univ. of Perugia, Perugia, Italy *coresponding author e‐mail address: [email protected] The Tithonian‐Berriasian interval is characterized by the appearance of calpionellid and by a major calcareous nannofossil speciation episode: several genera and species first appear and evolve, showing an increase in diversity, abundance and calcification degree. Monte Pernice and Torre de Busi sections (Southern Alps, Italy) have been analyzed for calcareous nannofossil and calpionellid biostratigraphy, relative and absolute abundances and to reconstruct biogenic calcite palaeofluxes. Calcareous nannofossils have been investigated on simple smear slides and ultra‐thin sections (7‐8 μm thick) calpionellids on the same thin sections (20‐30 µm thick). All nannofossil specimens have been counted on 1 mm2 of ultra‐thin section; all calpionellid specimens on 1 cm2 of thin sections to reconstruct paleofluxes. In the Tithonian‐ Berriasian interval all known calcareous nannofossil Zones and corresponding Subzones (Bralower et al., 1989) have been recognized. Chitinoidella, Crassicollaria and Calpionella Zones have been identified (Remane, 1986; Pop, 1994b; Reháková & Michalík, 1997; Andreini et al., 2007). Quantitative calpionellid and nannofossil analyses point out major changes during the Tithonian – Berriasian interval: nannolith taxa (F.multicolumnatus, C.mexicana, P.beckmannii) increase in abundance, size and calcification degree in discrete steps across the Lower Tithonian, coeval with the occurrence of first calcified calpionellids (Tintinopsella). Nannoconids and calcified calpionellids (Crassicollaria, Calpionella, Remaniella) increase across the Tithonian/Berriasian boundary reaching lithogenetic abundances: the rise in high‐calcified nannoconids roughly corresponds with the Acme of C. alpina spherical forms. The diversification and biomineralization of highly‐calcified microplankton produced a major increase in pelagic carbonate sedimentation due to the onset of paleoenvrionmental conditions favourable to calcification.
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The effect of thermal pollution on benthic foraminiferal assemblages, in the Mediterranean shore face adjacent to Hadera power plant (Israel) Arieli, R. N.1, Abramovich, S. 1, Almogi‐Labin, A.2 & Herut, B. 3 1Deparment of Geological and Environmental Sciences, Ben Gurion University, Israel 2Geological Survey of Israel 3Israel Oceanographic & Limnological Research, Israel [email protected]
So far, few studies have looked at the consequences of global warming on marine living organisms at the Levantine basin of the East Mediterranean. In this study, we have used the thermal pollution of a power plant at the Mediterranean coast of Israel as an analog for the expected future trend of sea surface temperature (SST) rise. We have performed a sequence of 11 sampling campaigns at 5 stations located along a temperature gradient of approximately 10°C, from the discharge site of the heated cooling seawater to a few kilometres south, were temperatures are normal. The large natural variations in seawater temperature (16‐30°C) enable us to examine the seasonal impact at relatively extreme conditions, which are intensified during summer, when the temperature anomaly becomes a threat to the environment. Thus, the main objectives of this study were to examine the response of the benthic foraminifera, known as sensitive indicators of environmental changes, to the locally elevated SST and compare it with the response of other groups such as crustaceans, ostracods and molluscs. The SST varied between winter, 27°/18°C and summer, 35°/29°C along the transect. The preliminary results show that the maximal abundance of foraminifera, ostracodes and crustaceans occur in winter while that of the molluscs in summer. The total standing stocks (TSS) of foraminifera are negatively correlated with SST anomaly. This may indicate that foraminiferal reproduction rate and life span are temperature dependant. Unlike the working hypothesis that predicted increasing numbers in heated stations during winter when SST is optimal, the numerical abundance was continuously low all year, indicating that the local assemblage did not adjust yet to the sharp changes in SST. The species diversity varied between the 5 stations indicating that some species have adapted to the elevated temperatures better than others. Planktonic foraminifera response to sudden global warm temperature in late Maastrichtian, Ziyarat Kola, Alborz Mountain, Iran Masoud Asgharian1*, Behrouz Darvishzade2 1Faculty of geology, University of Tehran, Tehran, Iran 2Faculty of science, University of Bualisina, Hamadan, Iran [email protected] Near the end of Maastrichtian between 65.45‐ 65.10 Ma, an abrupt global warming occurred and recorded in many parts of the world. This warm event and its environment effects are documented here based on quantitative analysis of plankton foraminifera at Ziyarat‐ Kola in Central Alborz. Decreasing in diversity and relative abundance of number of species accompanied by dwarfing (small size of species), indicate changing in water mass stratification, species vertical migration and high stress environment conditions. A noticeable result for sudden global warming is unusual increasing of adult large size species in 63‐ 150μm sieves such as Globotrncana arca, Globigerinelloides subcarinatus, Rugoglobigerina rugosa, Pseudoguembelina hariaensis. Here, High stress environment is indicated by increasing at abundancy of opportunitist species Guembelitria spp. In the warming period, G. arca, P. hariaensis, Pseudotextularia elegans, Pseudotextularia nuttali increased accompanied by decreasing of ecological specialists such as globotruncanids that declined at the climax of a rapid warm event about 350 kyr before the K‐T boundary. At the same time, Laeviheterohelix dentata a long ranging dominant species, decrease considerably reflecting the high stress environmental conditions. In these time, palynological studies also shows the 25% increased of fungi spores that proved warm period dominated in the Ziyarat Kola section. Keywords: Late Maastrichtian; global warming; planktonic foraminifera; Alborz Mountain
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Paleobiological Implication of the Latest Cretaceous Oil Shale Sequence in Israel as Inferred from Foraminifera Ashckenazi‐Polivoda S 1,2, Abramovich S.1, Schneider‐Mor A.1, Feinstein S.1 and Almogi‐Labin A.2. 1 The Department of Geological and Environmental Sciences, Ben‐Gurion University of the Negev 2 The Geological Survey of Israel, Jerusalem [email protected] The development of a thick (~45 m) organic rich (oil shale) sequence, in the earliest Maastrichtian at ~70 Ma, signifies a major change in the dynamics of the Late Cretaceous southern Tethys upwelling system. The mechanisms that drive such change and the paleoenvironmental history of this upwelling regime are still not well understood and are of great scientific interest. High‐resolution records of planktic and benthic foraminifera were used for reconstructing the paleoecological and paleoceanographic conditions that led to the formation of the oil shale deposits in the Negev Israel, as an example of the extensive deposits found all over the Levant. Our new planktic foraminiferal biostratigraphy indicates that the oil shale sequence spans only ~1 m.y. from ~70‐69 Ma (early Maastrichtian), revealing high sedimentation rates of ~4.5 cm/kyr. Both, planktic and benthic foraminiferal assemblages record major changes at the lower transition with the Phosphate Member and at the upper transition with the Marl Member. The Phosphate Mbr. is characterized by the dominance of specializing buliminids, known to be associated with dysoxic to nearly anoxic conditions at the sea floor. Planktic foraminifera are rarely present in this interval, but abruptly appear in great quantities and high diversity at the base of the OSM. At the same time, the buliminis are replaced by rotaliids, suggesting an increase in bottom water aeration. The intermediate dwellers, keeled globotruncanids, appear shortly above the base of the OSM, supporting our notion that this transition involves a probable deepening and increasing ventilation of the intermediate water. The OSM to Marl Mbr. transition marks another important paleoenvironmental change as indicated by changes in assemblage composition and additional increase in planktic foraminiferal abundance and diversity. These changes represent a further increase in bottom water aeration, water column deepening and the probable ending of the enhanced upwelling activity in this region. Distribution patterns of cryptic and pseudo‐cryptic species in Globigerinoides ruber and Globigerinoides conglobatus in the north‐eastern Atlantic and Mediterranean Sea Aurahs, R. 1, Grimm, G. W.1, Moller, T.1, Treis, Y1. Hemleben, V.², Hemleben, C. 1, Kucera, M.1 1 IfG, Department of Micropalaeontology, Eberhard Karl Universität Tübingen 2Department of General Genetics, ZMBP, Eberhard Karl Universität Tübingen Sigwartstrasse 10, 72076 Tübingen; ralf.aurahs@uni‐tuebingen.de Earlier work on plankton samples and sediment traps has shown that in the temperate regions of the Atlantic Ocean, G. ruber pink dominates surface waters during the warm season, while G. ruber white prevails in relatively constant numbers throughout the year. This simple seasonal pattern forms the basis for the interpretation of paleoproxies based on this species. However, it has been shown that the white variety of G. ruber consists of several morphotypes with distinct geochemical signals in their shells. Molecular genetic analyses of a ~1000 base pair SSU rDNA fragment have revealed the existence of several genetic types as well as the paraphyletic nature of the G. ruber white morphotaxon. Our analyses of specimens identified as G. ruber white from the north‐eastern Atlantic and Mediterranean Sea show that these specimens represent both the G. ruber senso stricto Type Ia (sister taxon to G. ruber pink) and the Types IIa1 and IIa2 which are in fact closer related to Globigerinoides conglobatus. In this context, the pattern of geographical and seasonal distribution of G. ruber white becomes far more complex. Here we discuss our results on the distribution patterns of the genetic types of G. ruber and G. conglobatus, with emphasis on Type IIa1, IIa2 and their sister type IIb, in the Canary region and Mediterranean Sea. The distribution of these genotypes shows patterns of geographical exclusion and co‐occurrence at different locations in our study area. The data suggest that the distribution of planktonic foraminifera is in some cases not simply a function of physical parameters, but possibly of niche competition between closely related taxa. Further, phylogenetic
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reconstruction based on SSU rDNA, combined with morphometric measurements and the ecological data presented here strongly suggest that the individual genetic types represent reproductively isolated entities akin to true biological species. Molecular data provide a superior taxonomic resolution that may allow a better assessment of ecological demands and distribution patterns of these “cryptic species” and in this way of the individual morphospecies. Calibration of 18O from deep‐sea benthic foraminiferal shell as a temperature proxy: laboratory results Christine Barras1, 2, Emmanuelle Geslin1, Elisabeth Michel2, Jean‐Claude Duplessy2, Frans Jorissen1 1 Laboratoire des Bio‐Indicateurs Actuels et Fossiles (BIAF), Angers, France and Laboratoire d’Etude des Bio‐Indicateurs Marins (LEBIM), Ile D’Yeu, France christine.barras@univ‐angers.fr 2 Laboratoire des Sciences du Climat et de lʹEnvironnement (LSCE), Gif‐sur‐Yvette, France The relations between the isotopic composition of the foraminiferal shell and the specific physico‐chemical parameters of the environment in which the organism calcifies are still poorly understood. In fact, the calcification process is influenced by numerous interfering factors, which are hard to distinguish in natural environments. To better understand the effect of one single environmental parameter (temperature) on the isotopic composition of deep‐sea benthic foraminiferal shells, we developed, in the laboratory of Angers, a methodology to stimulate reproduction and obtain growth of the deep‐sea foraminifera under stable physico‐chemical conditions. We realise experiments with Bulimina marginata at temperatures from 4 until 19°C in order to investigate its effect on the oxygen isotopic (18O) composition of the foraminiferal calcite. We observed that the 18O signature of these benthic foraminifera is clearly influenced by individual size. The temperature: 18O calibration equation obtained from foraminifera that calcified the totality of their test in stable conditions is close to previously published paleotemperature equations. Planktonic Foraminiferal Test Size during Sapropel S5 Darren Barry, Angela Hayes Department of Geography, Mary Immaculate College, University of Limerick, Ireland One of the most intriguing aspects of Mediterranean palaeoclimate is the occurrence of sapropelic sediments. The exact environmental conditions that led to these events are not yet fully understood. This research focuses on the deposition of an Eemian sapropel S5 with a view to reconstructing the palaeoenvironmental and palaeoecological conditions associated with this depositional event. Specifically, the research aims to assess the size variation of individual planktonic foraminiferal species prior to, during and after the deposition of sapropel S5 to provide an insight into the growth of individual species in such an extreme physical environment. The project will be initiated by obtaining sediment from ODP core 971A (latitude 24.68° N, longitude 33.72° E, water depth 2026 m) from the western side of the eastern Mediterranean. Sapropel thickness, in this core, is recorded at approximately 23 cm, allowing for a sufficiently high resolution analyses. The diameter of species specific planktonic foraminifera will be recorded throughout the sapropel and also at intervals prior to and after deposition. The data will be considered in context with two further S5 sapropels from spatially diverse cores which are still to be determined. It is hoped that the results will be compared to similar data for Holocene sapropel S1 which occurs nearly 80,000 years later.
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Variations in upper water‐column dynamics in the North Atlantic during the last 20,000 years as revealed by coccolithophorid assemblages Baumann, K.‐H. and Meggers, H. Department of Geosciences, University of Bremen, Germany, baumann@uni‐bremen.de A coccolith‐based micropalaeontological investigation of ODP Sites 980 and 984 from the Feni and Gardar contour drifts of the northern North Atlantic was conducted in order to reconstruct the pattern and timing of surface circulation changes in the area during the last 20,000 years. In addition, sea‐surface palaeotemperature records from both sites were generated at high resolution based on the widely used alkenone palaeothermometer. The down‐core variations in coccolith assemblage composition indicate that changes in properties of surface waters in the northern North Atlantic occurred stepwise during the Termination I. Sparse occurrences of coccolithophores together with a higher number of reworked pre‐Quaternary species are observed before about 13,500 cal yr BP, indicating harsh environmental conditions and the influence of melt‐water. The stepwise increase of North Atlantic Drift water influence from 13,500 to about 10,000 cal yr BP was associated with the increase in absolute numbers of coccolithophores in the whole area and coincides with maximum Northern Hemisphere summer insolation. A considerable cooling of the surface waters as indicated by a prominent change in the relative abundances of the dominant coccolith species occurred after about 5000 cal yr BP. In addition, a successive increase in millennial‐scale perturbations of the surface hydrology towards the Neoglaciation (the last ca. 5000 years) is documented by changes in accumulation of the species, in particular of Emiliania huxleyi. These successive decreases in the numbers of E. huxleyi, as previously described by Giraudeau et al. (2000, EPSL 179), is in phase with recorded Holocene advection of cool, ice‐bearing waters from the Greenland‐Iceland seas to the North Atlantic. These long‐term reorganisations of the surface hydrology are interpreted as the response of the North Atlantic to the combined forces of the solar insolation and the waning Laurentide ice sheet. Effect of ocean carbonate chemistry on Isochrysidales (Coccolithophore) calcification: studies from present and past oceans Luc Beaufort CEREGE, CNRS and Aix‐Marseille University, Aix en Provence, France. The calcite weight of Isochrysidales coccoliths and coccospheres from samples taken in water and sediment samples from the 3 oceans was estimated using automated pattern recognition and automated morphometry software. The calcite estimates made from more than 150 water samples collected in the photic zone (more than 1000 individuals measured per sample) indicates that the variability in the degree of calcification of Isochrysidales (weight of their coccoliths and coccospheres) strongly depends on environmental parameters (alkalinity, temperature and concentration in CO3). In area of high alkalinity, high temperature, and high concentration in CO3 the Isochrysidales secretes the heaviest coccospheres. Isochrysidales coccolith weight was estimated in 7 cores covering the last 35 Ka (3 from the Atlantic, 3 from the Pacific and 1 from the Indian Ocean). All records exhibit highest coccolith weight during the last glacial maximum. When all the records are stacked, the pattern of calcite weight mirrors strongly that of the CO2 concentration in Vostock ice core. This cannot be due to dissolution for two reasons: (1) dissolution in the Atlantic and IndoPacific oceans at glacial/interglacial scale present opposite histories. (2) Laboratory experiments show little effect of dissolution on the weight of the coccoliths. Therefore the weight variability observed at Glacial/Interglacial time scale is the results of a change in the secretion of Isochrysidales, certainly related to changes in the environment parameters described in the modern ocean study. Because the last glacial maximum was obviously not time of higher oceanic temperature, only changes in the oceanic carbonate chemistry produces the observed variations of Isochrysidales calcification. This study provides a new case on the threat that future increase in atmospheric CO2 and consequent ocean acidification induces on oceanic biological calcification.
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Pre‐ vs. post‐Suez symbiont‐bearing larger foraminifera in the Mediterranean – Refugia vs. Lessepsian migration Chaim Benjamini 1, Ahuva Almogi‐Labin 2 1 Ben Gurion University and Ramon Science Center, [email protected] 2 Geological Survey of Israel, [email protected] Specialized symbiont‐bearing larger foraminifera populated Mediterranean coasts until possibly as late as the Late Miocene. Extinction is primarily attributed to climate change, with the Messinian crisis providing a coup de grâce. Subsequent Plio‐Pleistocene introductions are of Atlantic origin, mainly cool or deep‐water species. However, symbiont‐bearing larger foraminifera sporadically reappear; e.g., Amphistegina in the Italian Pliocene, and soritids in the Pliocene, and in Pleistocene beds attributed to interglacials. The 1869 opening of the Suez gateway led to ʹLessepsianʹ reintroductions into the eastern Mediterranean, e.g., Amphistegina lobifera, Amphisorus hemprichii, Heterostegina depressa, and Borelis. A counterclockwise migration around the eastern Mediterranean has been demonstrated. Samples taken prior to that date should not include these new arrivals. SYNTHESYS grant GB‐TAF‐3920 enabled us to examine old collections at the NHM for symbiont‐bearing larger foraminifera from the Mediterranean. Amphistegina lessonii, A. radiata, A. papillosa (?), A. bicirculata, Operculina ammonoides, Neorotalia calcar, Calcarina spengleri, and soritids, are present in material collected from shore sands and dredgings taken in the 1850’s off Tunisia, Malta, Italy and Crete. These foraminifera cannot have entered via the Suez route, most are absent from the eastern Atlantic, and no reasonable ancient trade route could have introduced them. These results suggest a warm water Mediterranean refugia for symbiont‐bearing species, located on the arch between the Western Mediterranean and Levantine basins. This may be a Miocene relict assemblage that somehow survived the Messinian vicissitudes. If so, this finding requires expansion of the biogeography of modern Indo‐Pacific foraminifera, a reconsideration of Late Miocene and Messinian events in the Mediterranean, and possibly a surviving Miocene gene pool which would have diverged from congeneric or even conspecific forms many millions of years ago. Stable isotope studies on Cretaceous planktic foraminifera from Demerara Rise – implications for depth habitat, photosymbiosis and paleotemperature reconstructions André Bornemann1, Richard D. Norris2 1 Universität Leipzig, Institut für Geophysik und Geologie, Talstraße 35, D‐04103 Leipzig, Germany (e‐mail: a.bornemann@uni‐leipzig.de) 2 Scripps Institution of Oceanography ‐ University of San Diego, Geoscience Research Division, 9500 Gilman Drive, La Jolla, CA 92093‐0244, USA
Stable isotope data from species‐specific planktic foraminiferal tests offer a powerful tool for paleoceanographic and paleoecologic reconstructions of recent and past oceans. In particular size‐dependent isotope changes provide information about the ontogeny of the studied species, photosymbiotic activity, calcification‐rate dependent kinetic fractionation, as well as life habitat and/or diet. The study interval covers the Turonian to Santonian (83.5–93.5 Ma) interval, which represents one of the warmest periods in Earth’s history with tropical sea surface temperatures above 35°C. Isotopic information on the ecology of planktic foraminifera and absolute temperature estimates from this period are rare, because sediments of this age are mostly preserved as chalk or limestone with uncertain geochemical overprints. We present δ13C and δ18O data from sieve size fractions of monospecific samples of exceptionally well preserved planktic foraminifera recovered during Ocean Drilling Program Leg 207 (Demerara Rise, western tropical Atlantic). Our results suggest that the selected species (Hedbergella delrioensis, Heterohelix globulosa, Marginotruncana sinuosa, Whiteinella baltica) grew primarily in surface waters and did not change their depth habitat substantially during their life cycle. Comparison of size‐related ontogenetic trends in δ13C in Cretaceous and modern foraminifera further suggests that detection of dinoflagellate photosymbiosis using δ13C is confounded by physiological effects during the early stages of foraminifer growth, raising doubts about previous interpretations of photosymbiosis in small foraminifera species. We propose that obligate
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photosymbiosis involving dinoflagellates may not have evolved until the Campanian or Maastrichtian since our survey of Cenomanian‐Coniacian species does not find the δ 18O and δ 13C size‐related trends observed in modern foraminifer‐dinoflagellate symbioses. Last but not least, we compare δ18O‐derived sea‐surface temperatures (SST) with SST estimates based on the newly developed TEX86 paleothermometer and compiled a tropical paleotemperature record for the entire Turonian to Santonian interval. Combining benthic foraminifera and macrofauna for assessing a foraminifera biotic index Vincent M.P. Bouchet* 1, 2, Pierre‐Guy Sauriau1, 3 and Jean‐Pierre Debenay 4 1 ELA, CNRS, Ifremer, Place Gaby Coll, BP 5, 17137, L’Houmeau, France 2 BIAF, Université d’Angers, 2 bld Lavoisier, 49000, Angers, France 3 LIENSS, CNRS, Université de La Rochelle, 2 av Olympe de Gouges, 17042 La Rochelle, France 4 IRD, UR055 Paleotropique, Centre de Nouméa, BP A5, 98848, Nouméa cedex, New Caledonia * Presenting author: [email protected] According to the Pearson and Rosenberg’s paradigm (1), soft‐bottom macrofauna has been classified into five ecological groups (EG) depending on their sensitivity to organic matter enrichment from EG I constituted by species very sensitive to organic enrichment to EG V of first order opportunistic species (2, 3, 4). To date very few authors have used both macrofauna and foraminifera in soft‐bottom environmental studies; they mainly used the two taxa side‐by‐side and not combined them. However, benthic foraminifera and macrofauna may be complementary tools in terms of life span, generation time and organic matter sensitivity. They both appeared useful to assess the ecological status of benthic environments. The aim of our study was to determine the effects of oyster farming on benthic communities living on intertidal mudflats in the Pertuis Charentais (SW France), using both macrofauna and foraminifera. We used canonical correspondence analysis to summarize the relationships between a set of measured environmental factors from the sediment (mean grain size, Eh, OM%, POC, PON, Chl a, phaeopigments, POC:Chl a) and the responses of both benthic foraminifera and macrofauna. We highlighted analogies and significant correlations between some foraminiferal and macrofaunal species and sediment data, allowing us to classify these foraminifera species using the five EGs previously defined for the macrofauna. For example, both the foraminifera Rosalina cf. vilardeboana and the amphipod Urothoe poseidonis were significantly correlated to positive values of Eh and low organic matter content. We thus classified Rosalina cf. vilardeboana in the EG I that included Urothoe poseidonis. Similarly, Cribroelphidium excavatum, Haynesina germanica and Eggereloides scabrus were classified in the EG III as does the polychaete Streblospio shrubsolii, and C. gunteri in the EG IV with the polychaete Tharyx multibranchiis. This attempt needs to be further tested and validated but constitutes the first step towards a biotic index based on foraminifera. Coiling ratios of Globorotalia truncatulinoides in the western Mediterranean Sea during the Holocene Teresa Broggy1, Angela Hayes1, Michal Kucera2 1 Department of Geography, Mary Immaculate College, University of Limerick, Ireland 2 Institut für Geowissenschaften, Eberhard Karls Universität Tübingen, Germany This research focuses on Globorotalia truncatulinoides, an extant species of planktonic foraminifera, and its potential use as a biostratigraphic marker in the western Mediterranean Sea during the Holocene. The test of G. truncatulinoides is constructed of trochospirally arranged chambers and the species exhibits alteration between sinistral and dextral coiling. The principle aims of this research are to asses the use of G. truncatulinoides as a biostratigraphic marker based on the coiling ratio and secondly, to investigate possible environmental correlations linked to the observed coiling direction changes. The latter is done by reconstructing a sea surface temperature record across the interval in which the coiling direction changes. Sediments from four geographically distant cores, M40/4 82‐2‐SL (latitude 42.31° N; longitude 3.78° E; water depth 1070 m), M40/4‐80‐SL (latitude: 40.96° N longitude 11.01° E; water depth 1881 m), ODP 975B (latitude 38.89° N, longitude 4.5° E; water depth 2415.5 m), ODP 974B
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(latitude: 40°21.362´N. Longitude: 12°8.516´W; water depth 3453.9 m) were obtained to conduct this research. An average sampling resolution of 2 cm was used and a minimum of 100 specimens of the target species were counted from each interval. Preliminary results indicate a consistent pattern of change in coiling direction. Current results indicate one correlated change from sinistral to dextral coiling in all four cores and a second change in coiling direction, from dextral to sinistral in cores 975B and M40/4‐80‐SL. The significance of the coiling change ranged between 96% sinistral and 97% dextral, however the dominance in dextral coiling of the species is concurrent with an overall reduction in the total species. Integrated foraminiferal and nannofossil biostratigraphy and paleoecology of the Campanian of the Eastern Carpathians, Romania (Dambovita Valley) Claudia G. Cetean1, Ramona Balc1, Michael A. Kaminski2, Sorin Filipescu1 1 Babes‐Bolyai University, Department of Geology, M. Kogalniceanu 1, 400084, Cluj Napoca, Romania, email:[email protected] 2 Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, U.K. As part of a project which aims to establish an integrated biostratigraphy of the Upper Cretaceous red beds from the southern part of the Eastern Carpathians, Romania, we investigated a Campanian succession from the Izlaz Valley, Cotenesti (Dambovita Valley). Planktonic foraminifera, calcareous nannoplankton, and agglutinated foraminifera were used to determine the age of the Plaiu Formation (Lower to Upper Campanian), the deposits underlain by it (Lowermost Campanian), and the Lower Member of the Gura Beliei Formation (Upper Campanian). For the Gura Beliei Formation (Upper Campanian‐Paleocene), the paleodepth of deposition was estimated to be around 2000m (Stefanescu, 1995) and the mean sediment accumulation rate 3 mm/ky (Melinte & Jipa, 2005). We estimate for this Lower to Upper Campanian succession from Dambovita Valley a mean accumulation rate of 4mm/ky and a middle slope paleodepth. In the Lower Campanian, the lowermost part of the Globotruncanita elevata Zone and middle part of the Globotruncana ventricosa Zone, two levels of red glauconitic sands/sandstones were found in the grey marl succession of the Izlaz Valley section. These clastic sediments may reflect short but abrupt sea levels falls that can be well correlated with the sea levels falls and positive δ13C excursions documented by Jarvis (2002) from Europe and Tunisia as the Santonian – Campanian Boundary Event and the Middle Campanian Event. High resolution sampling of the Lower‐Upper Campanian succession from the Cotenesti locality (Globotruncanita elevata to Globotruncanella havanensis Zones) resulted in the recovery of rich benthic foraminiferal assemblages. In the Lower Campanian grey shales foraminiferal diversity is low, and an increase in infaunal agglutinated foraminifera can be observed together with high numbers of spherical radiolarians. The low diversity of foraminifera and increased numbers of radiolarians are documented in land sections in the Tethys and ODP sites in the North Atlantic, implying low oxygen levels of bottom waters as a result of enhanced primary productivity. The diversity of foraminiferal assemblages increases in the uppermost part of the Lower Campanian, reaching a maximum in the variegated marls of the Lower Member of Gura Beliei Formation in the Upper Campanian. Although agglutinated foraminifera dominate, there are two high‐stand intervals in which the proportion of calcareous benthics increases from 25% to almost 50%. Changes in the tubular agglutinated morphogroup induced by high sea levels can be observed, with an increase in finely agglutinated forms such as Rhizammina, Bathysiphon and Kalamopsis, in contrast to times of low sea level when coarsely agglutinated tubular forms such as Dendrophrya dichotomica and Arthrodendron dominate the morphogroup. Agglutinated foraminiferal morphogroups provide additional information about paleoecological changes in the Eastern Carpathian basins during the Campanian.
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Reconstruction of the postglacial environments in the South‐Western Barents Sea by variations in benthic and planktic foraminiferal assemblages and stable isotopes Chistyakova, N.O. 1, Ivanova, E.V. 1, Risebrobakken, B. 2 1 Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia [email protected] 2 Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway The distribution and abundance of benthic and planktic foraminiferal species and stable isotopes has been studied in sediment core PSh 5159N/R (71°22’ N, 22°39’ E, w.d. 420 m) from the Ingøydjupet Depression, on the Atlantic water pathway to the Barents Sea. The age model is based on 15 AMS‐14C dates, and the average time resolution of the study is ~ 100 years over the last 14 ka. A strong dominance of typical arctic shelf species, C. reniforme and E. clavatum, during the deglaciation (before 14.2 cal. ka BP), points to severe environments with a long sea‐ice season. Bølling‐Allerød (~ 14.2 – 12.6 cal. ka) is characterized by an increased saline but chilled Atlantic Water inflow, as indicated by the dominance of M. barleeanus and relatively high abundance of the “atlantic” species: C. teretis, P. bulloides, T. angulosa. High amount of the arctic species and a prominent increase in percentage of S. loeblichi indicate a return of sea ice cover conditions over the Younger Dryas (~12.6 – 11.5 cal. ka). The earliest Holocene is marked by the dominance of “atlantic” benthic and boreal planktic (mainly T. quinqueloba and N. pachyderma dex.) species, and by a strong depletion of oxygen and carbon isotope values of N. pachyderma sin. These changes are related to increased Atlantic Water input, relatively warm conditions in surface and subsurface water layer after the insolation maximum, and possibly to a nearby front location. Foraminiferal‐based summer sea‐surface temperatures are about 12°C as compared to ~ 6°C at YD. Rather minor changes in the investigated proxies are found through the Middle Holocene. On the contrary, pronounced variations in foraminiferal assemblages, oxygen isotope values of N. pachyderma sin. and benthic species in the Late Holocene, especially through the last ~ 2 cal. ka, imply unstable bottom and subsurface water conditions. Micropalaeontological reconstruction of Holocene environmental changes in the archaeological excavation site Stralsund Ozeaneum, southern Baltic Sea Thomas Daniel & Peter Frenzel Institute of Geosciences, University of Jena, Burgweg 11, D‐07743 Jena email address of corresponding author: [email protected] In summer 2006, sediment profiles of the harbour island of the Hanse town Stralsund have been made available by an excavation pit for a new building (Ozeaneum) of the Meeresmusem. An archaeological excavation provided numerous artifacts, dating from the first mesolithic settlement to the middle of the 19th century. Among many metal objects and other artefacts which document the wide going trading connections of Stralsund and military conflicts, there were excavated the remnants of two piers. The wooden piers protected sediments of the litorina transgression and later ones from erosion. These profiles of the Semlower Bridge and the Kingsbridge were studied micropalaeontologically and sedimentologically in detail. The aims were a reconstruction of changing environmental conditions in a transgressive environment, a documentation of the Holocene evolution of brackish fauna and flora at the southern Baltic Sea coast and a correlation with profiles of the excavation Stralsund Mischwassserspeicher, which allows the reconstruction of a more precise local sea level curve. Anthropogenic effects in the vicinity of the town like eutrophication and habitat destruction and their impacts on the littoral ecosystem could be identified by studying the subfossil associations. The most important studied taxa are foraminifers, ostracods, molluscs and botanical macro remains. Especially trochamminid foraminifers like Balticammina pseudomacrescens and Haplophragmoides manilaensis proved to be significant proxies for the past sea level. Other foraminiferal taxons like Cribroelphidum albiumbilicatum, C. williamsoni, C. gunteri and several endobenthic molluscs delivered references for risen water depth and storm events. The appearance of Milliammina fusca allowed the depth estimation for the wave base. As a result of the numerous discovered remnants of charophytes and other submerged plants, the past phytal communities could be reconstructed. The investigations
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queue to the continuation of the interdisciplinary project SINCOS (Sinking Coasts – Geosphere, Ecosphere and Anthroposphere of the Holocene Southern Baltic Sea) to Holocene transgression, environmental and settlement history of the southern Baltic Sea. Benthonic and planktonic foraminiferal transformation in Campanian‐ Maastrichtian boundary in Jorband Section‐ North of Iran. ¹Darvishzad, B., ²*Abdolalipour, S ¹Faculty of science, University of Bualisina, Hamadan, Iran ²Faculty of geology, University of Tehran, Tehran, Iran [email protected] Study of Planktonic and benthonic foraminifera reveals the environmental changing in Campanian‐ Maastrichtian boundary in Jorband section in northern flanks of Alborz Mountains. In this study, 10 biozones of plankton foraminifera related to Campanian and Maastrichtian recognized and the first appearance of Planoglobulina carseyae indicated the C M boundary. Increases species richness of rugoglobigerinids, heterohelicids and globigerinelloids come along with lesser population of warm water markers (such as Rugoglobigerina milamensis and R. pennyi) coincided with the onset of major cooling in surface and bottom waters in latest Campanian and early Maastrichtian. Absent of deep‐sea dwellers such as Laeviheterohelix glabrans, Gublerina cuvillieri, Globotruncanella havanensis and abundant of heterohelicids, epifauna and shallow dwellers infouna show the Jorband area took place on the shallow water in late Campanian and early Maastrichtian. Foraminiferal calcification and the role of intracellular pH L.J. de Nooijer, T. Toyofuku, K. Oguri, H. Nomaki, H. Kitazato Institute for Research on Earth Evolution, Japan Agency for Marine‐Earth Science and Technology In reconstructing past oceanic temperature, pH and trace metal concentrations, the chemical composition of foraminiferal calcite has proven to be among the most useful tools to do so. In particular, the magnesium concentration of foraminiferal CaCO3 (expressed as its Mg/Ca ratio) has become a popular tool to reconstruct paleo‐sea water temperatures. The partition coefficient of Mg in calcite of many species, however, differs greatly from those obtained from inorganic coprecipitation experiments. This indicates that before and during foraminiferal calcite precipitation, there is a strong control of the individual on the incorporation of magnesium and this effect is known as the ʹvital effectʹ. To apply foraminiferal calcite‐based proxies correctly and with higher precision than is currently possible, a better understanding of the cellular control on biomineralization is necessary. To precipitate calcite from seawater, foraminifera vacuolize sea water (the mother solution) and have to concentrate Ca2+ and (bi)carbonate from the mother solution. In addition, the inhibiting properties of Mg2+ need to be overcome before calcite can be precipitated. Mg‐removal is likely to prevail in species that produce calcite with a low Mg concentration and in species (e.g. miliolids) that produce calcium carbonate with a relatively high Mg concentration, raising the pH during calcite precipitation may be an alternative strategy to promote calcite precipitation. HPTS is a fluorescent probe that is non‐toxic and membrane‐impermeable that can visualize the pH of (vacuolized) sea water. Results show that foraminifera decrease the pH of the mother solution after sea water uptake and increase the pH by at least 1 unit in vesicles that participate in calcification. In hyaline species these vesicles are consumed during chamber formation and produce a zone of high pH in which the new chamber is formed. The observed increase in pH at the site of calcification potentially results in corrections for the application of paleoceanographic proxies like oxygen and boron isotopes, as well as foraminiferal Mg/Ca ratios.
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Taphonomic effects on the benthic foraminiferal paleoecological record of the Ría de Vigo (NW Spain) Paula Diz1, 2 and Guillermo Francés2 1 Laboratoire dʹEtude des Bio‐indicateurs Actuels et Fossiles (BIAF), Université dʹAngers, Angers, France. [email protected] 2 Departamento de Xeociencias Mariñas e O.T., Universidade de Vigo, Vigo, Spain Understanding the factors playing a role in the formation of dead assemblages is essential for an accurate interpretation of the fossil record in a particular region. The comparison of dead and live benthic foraminiferal assemblages (>63 μm) along the muddy central axis of the Ría de Vigo (NW Spain) reveals that there are major differences in the relative abundance of species. Some of them could be attributed to: 1) species‐specific production patterns, 2) low preservation potential of particular species and 3) transport of allochthonous foraminifera from nearby areas. Epifaunal, thin shelled, upwelling‐related species (e.g. N. stella, N. turgida, L. scottii, B. translucens) are almost absent from the surface and subsurface dead assemblages. This is probably the result of their low preservation potential rather than their opportunistic behaviour. High local bottom currents actively transport dead shells of epifaunal‐attached and free‐living benthic foraminiferal forms (Cicicides spp., E. crispum) and estuarine species (A. beccarii and H. germanica) to low energy settings of the ría. The study of subsurface assemblages reveals that, in the innermost areas of the ría, there is a downcore loss of calcareous and agglutinated forms (E. scaber) likely as a consequence of establishment of reducing conditions into the sediment. Benthic foraminiferal assemblages in the Plio‐Pleistocene restricted environment of the Kritika Member (Rhodes Island, Greece) H. Drinia1, E. Koskeridou1, P. Moissette2, J.‐J. Cornée2 1University of Athens, Faculty of Geology and Geoenvironment, dept. of Hist. Geology‐Paleontology, Athens, Greece, Email: [email protected] 2UMR CNRS 5125 Paléoenvironnements and Paléobiosphère, Université Claude Bernard Lyon I, 27 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France An attempt for palaeoenvironmental reconstruction of the Late Pliocene‐Early Pleistocene Kritika Member (Rhodes Formation) has been made based on the results of statistical analysis. A Hierarchical Cluster Analysis (Q‐mode) was carried out on benthic foraminiferal assemblages in order to single out distinct groups of samples corresponding to different palaeoenvironments. In addition, components of PCA were interpreted as the main ecological parameters conditioning the assemblage composition. On this basis, five biofacies corresponding to five environmental settings were recognized: Biofacies 1 is defined by the dominance of the monospecific assemblage of Ammonia tepida (> 90.0%), indicating a brackish lagoon and marsh environment. Biofacies 2 also exhibits a restricted affinity characterized by higher frequencies of H. depressula (~60%), a very strong development of plano‐convex foraminifera and small numbers of Miliolidae. These features are clear indications of brackish water lagoon evolving into shallow‐marine environment with fresh water influence. Biofacies 3 is characterized by abundant Miliolidae and Ammonia beccarii, representing a marine coastal environment (infralittoral zone). In part, the relatively high abundance of Buliminidae and Bolivinidae indicate influence from deeper water, high food input and low oxygen levels (infralittoral/upper circalittoral environment). The predominant epiphytal assemblage of Biofacies 4, mainly represented by C. lobatulus, points to a more wide‐spread occurrence of submarine vegetation in the littoral realm. The higher diversity of this biofacies compared to the others, indicates that the environment is stable, characterized by better conditions. Biofacies 5 is represented only in one sample and consists of Fursenkoina acuta, Bolivina, Bulimina, Cassidulina, indicative of increased amounts of organic matter and decreased oxygen concentrations, associated with the influence of fresh‐water (fluvial) discharge. The micropalaeontological and lithological features of the studied section enabled us to recognize the palaeoenvironmental succession that is constituted by lagoon, marsh and marine environments, with evidence of continued interaction between continental and marine processes.
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Exceptionally well‐preserved calcareous nannofossils from the Paleogene of coastal Tanzania – an update Dunkley Jones, T.1, Bown, P. R.1 and Tanzania Drilling Project scientists (1) Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT; UK. [email protected] The clay‐rich sediments of the Paleogene Kilwa Group of coastal Tanzania have been shown to host an extraordinary diversity of calcareous nannofossils largely due to the preservation of small and fragile taxa that are normally lost during taphonomic and diagenetic dissolution and breakage in other environments (Bown et al. 2008). The palaeobiological and evolutionary information gained from this long‐lived (~20Myr) Konservat‐Largerstätte is still being processed but recent results will be presented including: 1) a significant increase in the known global diversity of calcareous nannofossils throughout much of the Paleogene; 2) the documentation of a previously unknown Paleogene lower photic zone assemblage, including members of the extant genera Gladiolithus, Algirosphaera and Solisphaera; 3) improved constraints on the early Paleogene origination of the modern families Syracosphaeraceae and Rhabdosphaeraceae including a deep‐time origin for the modern genera Syracosphaera, Rhabdosphaera and Acanthoica; 4) an unprecedented long‐time series record of holococcolith diversity, including a record of holococcolith‐production in response to oceanographic perturbations through the Eocene‐Oligocene transition; and 5) new high‐resolution records of the response of the calcareous phytoplankton to rapid global change during the Paleocene‐Eocene Thermal Maximum and Eocene‐Oligocene transition (Pearson et al. 2008). The potential environmental and sedimentary controls on the preservation of this assemblage will be discussed with reference to taphonomic processes in the modern ocean. Exploiting the calcareous nannoplankton biogeochemistry: an asset for palaeoceanographical studies Grégoire Egoroff1, Fabrice Minoletti1*, Vincent Gressier1 and Michaël Hermoso2. 1 UPMC Univ. Paris 06, JE2477 Biominéralisations et Paléoenvironnements, F‐75005, Paris, France. 2 University of Oxford, Department of Earth Sciences Parks Road, Oxford, OX1 3PR, UK * Corresponding author: [email protected] The geochemistry of calcareous microfossils offers valuable datasets for reconstructing the thermal and trophic structure of uppermost water column. Despite considerable refinement in respect to bulk carbonate analyses, culture studies have highlighted the importance of isotopic disequilibria between seawater and coccolith calcite. In order to generalize the use of coccolith geochemistry in palaeoceanography, it is of primary importance to know if vital effects calculated by nannoplankton culture studies are transposable to ʹnaturalʹ assemblages found in modern pelagic sediments. We investigated Arabian Sea top‐cores of which we separated the various carbonate producers: planktonic foraminifera by hand‐picking, coccoliths and calcispheres by microfiltering steps. We obtained monogenetic assemblages that afford geochemical analyses (carbon and oxygen stable isotopes and Sr/Ca ratio) at the species level. Furthermore, since the physico‐chemical parameters of the seawater are known for each calcification depth, as given by the World Ocean Atlas database (www.nodc.noaa.gov), it is possible to meaningfully compare both seawater and calcite geochemistry with specific vital effects provided by nannoplankton culture studies. For example, we obtained pure fraction of Thoracosphaera sp. calcispheres and Calcidiscus leptoporus coccoliths. The isotopic offsets between seawater and measured biogenic calcite composition seem to be in accordance with isotopic fractionation calculated from culture studies. Coupled with this biogeochemical approach; the microseparation of key‐taxa thriving in surficial and deep watermasses, could enable further understanding in the evolution of whole water column through Cenozoic times.
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Geochemical and isotopic signals (Sr/Ca‐ratios, stable δ13C‐ and δ18O‐isotopes) in coccolith carbonate of different grain‐size fractions in South Atlantic surface sediments Christina Fink*, Karl‐Heinz Baumann Faculty 05: Geosciences, University of Bremen, P.O. Box220440, 28334Bremen, Germany *Corresponding author. E‐mail address: cfink@uni‐bremen.de Coccolithophores are unicellular, marine algae and therefore directly dependent on the surface water conditions in world oceans. They are one of the main open ocean primary producers and one of the most dominant carbonate contributors to pelagic sediments. Therefore, these organisms influence the chemical composition of surface water on their parts, by calcification and photosynthetic mechanisms in different ways. As photosynthetic organisms, their chemistry and stable isotope composition can provide a sensitive tool for understanding photic zone processes. The chemistry of coccoliths serves both, as a record of changes in the chemistry of the ocean and a record of environmental and biological conditions like temperature and productivity. Nevertheless, their effect on and response to the climate system is one of the big questions facing our field today, since coccolith geochemistry has hardly been explored. In this study, the geochemical and isotopic signals of coccoliths in different grain size fractions (<5μm, >5μm and <20μm) from 14 surface sediment samples from equatorial to South Atlantic are investigated. The core‐top samples are aligned along a north‐south transect from about 20°N to 40°S at about 20°W. With this study, we try to assess the relationships between geochemistry and isotopic composition of coccoliths and environmental parameter influence; we also seek to evaluate the influence of vital effects of different species due to different grain size fractions. The investigations show great variability between the different grain size fractions. Even if the absolute values show a great difference the general trends are similar: The δ18O‐ratios in these samples show a decreasing trend with increasing temperature, while δ13C‐ and Sr/Ca‐ratios are influenced by a mixture of processes, such as temperature, nutrient‐ and probably freshwater supply. Influence of planktic foraminiferal morphotypes, shell size, and weight on Mg/Ca ratios Oliver Friedrich, Ralf Schiebel, Matthew Cooper, Paul Wilson National Oceanography Centre Southampton, School of Ocean and Earth Science, European Way, Southampton, SO14 3ZH, UK Email of the corresponding author: [email protected] To understand past changes in climate and oceanography, it is essential to determine temperature and salinity of ocean surface and deep waters. Mg/Ca ratios in foraminiferal calcite have been of increasing use in the past decade as proxy for seawater paleotemperature. To use the Mg/Ca‐paleothermometer effectively calibration is needed in order to assess the accuracy and precision of the technique. One striking feature of recent investigations has been the existence of differences in resulting calibrations between different species. Thus, the use of species‐specific calibrations provides the most desirable way to employ the Mg/Ca paleotemperature technique. However, we do not know the extent to which calibrations are applicable across foraminiferal morphotypes and little is known about the effect of shell size and weight on Mg/Ca ratios. To increase our understanding of how these factors influence planktic foraminiferal Mg/Ca ratios, we analyzed three different species Globigerina bulloides, Globorotalia inflata, and Globorotalia truncatulinoides in samples from the North Atlantic Ocean Azores‐Front Current‐System. Thereby, G. truncatulinoides has been analysed for the dextral and sinistral morphotypes. Planktic foraminiferal tests were picked from the 100 to 750 μm size interval in 50 μm steps and subsequently weighed, photographed and analysed for their morphometry using automatic microscopy and image analysis software. After weighing and photographing Mg/Ca ratios were measured by inductively coupled plasma‐optical emission spectrometry. Our results allow clarification of the relationship between Mg/Ca and shell size, weight, and morphotypes, and accuracy and precision of the Mg/Ca‐paleothermometer.
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Oxygen Respiration rates of benthic foraminifera measured under laboratory conditions using oxygen microelectrodes Geslin E.1, Risgaard‐Petersen N.2, Jorissen F.1 1 BIAF, University of Angers, 2 Bd lavoisier, F – 49 045 Angers, and LEBIM, Marine station of Yeu Island, France. emmanuelle.geslin@univ‐angers.fr 2 Center for Geomicrobiology, Institute of Biological Sciences, University of Aarhus, Denmark Oxygen respiration rates of benthic foraminifera are not well documented because of the difficulties of their measurements. However the determination of the respiration rates of benthic foraminifera is important in order: 1) to understand the metabolism between different species showing various sizes and various microhabitat in the sediment; 2) to determinate the mineralization rate of organic carbon and to estimate the contribution of benthic foraminifera in the mineralization of organic matter (data not available yet). Benthic foraminifera from 2 different natural environments were used: three species from the intertidal zone of Yeu island (France) and twelve species from the Rhône prodelta (France). Living foraminifera were placed in a small tube where the oxygen gradients were determined using oxygen microelectrodes. Respiration rates were calculated according to the oxygen fluxes around the foraminiferal specimens. Biovolume were estimated according to the shape of the species (for example, Ammonia is assimilate to a half sphere) and the volume of the shell walls. The results show a large range of respiration rates according to the species (around 0.080 to 6 nmol. cell‐1. day ‐1) and a clear correlation with the biovolume of the foraminifera. No clear relation between respiration rates and microhabitat is observed. The comparison with previous published data shows that our estimations are lower for the small size species. For example, the respiration rate estimations published recently by Nomaki et al. in 2008 show a range of 0.9 to 6.4 nmol. cell‐1. day‐1. As show by Risgaard‐Petersen et al. in 2006, some foraminiferal species are able to respirate nitrate. In the future, we want to determine the nitrate respiration rates of the previous studied species in order to determine which species are able to use the denitrification processes. Then, we want to study the capacities of the foraminifera to switch between oxygen and nitrate respiration rates and to determine if there is a relation between these two kinds of respiration. Paleoenvironmental reconstruction with foraminifera during the middle – late Albian of the Villeta Formation (Tetuan Member) in the Upper Magdalena Valley, Colombia Giraldo, V. M. & Caicedo, C. Consorcio ASEXPRO, ICP ( ECOPETROL) [email protected], [email protected] This work summarizes the results of the micropaleontologic study on cuttings and core samples from two boreholes located in the Upper Magdalena Valley (UMV) basin in the central region of Colombia, corresponding to the Tetuan Member of the Villeta Formation. These results are focused on the paleoenvironmental analysis of planktic and benthic foraminifera during the middle – late Albian. The preservation of the samples is bad to regular due to the diagenetic, tectonic and metamorphic processes in the area. Low abundance of benthic foraminifera which were grouped in morphogroups, together with high values of the infaunal genera as Praebulimina and Haplophragmoides, indicate low oxygen (dysoxic) conditions and cold water bottom (Koutsoukos et al., 1989). The high abundance of planktonic foraminifera, especially the genus Ticinella, allows us to infer aerobic warm water conditions. According to P/B ratio, high abundance of planktonic foraminifera indicates pelagic conditions on the middle to outer shelf, in which the circulation was sluggish due to the natural barrier, which existed at the west of the basin (UMV) where the Ancestral Cordillera Central was emerging (ACC). (Vergara, 1994). In conclusion, during the middle ‐ late Albian in the (UMV) basin, there was water column stratification, due to warm temperatures in the upper part of the water mass and cool water in the bottom. These conditions are similar with the modern oceans. (Premoli Siva & W. Sliter, 1999).
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Live (stained) benthic foraminifera from the Rhône prodelta: environmental controls and interannual variability Goineau, A.1, Fontanier, C.1, Ernoult, E.1, Lansard, B.2, Buscail R.3, Mojtahid, M.1, Kerhevé, P.3, Zaragosi, S. 4, Metzger, E. 1, Mouret, A. 4, Artéro, C. 3, Rabouille, C. 2 1 Laboratoire des Bio‐Indicateurs Actuels et Fossiles (BIAF), Université dʹAngers, France. aurelie.goineau@univ‐angers.fr 2 Laboratoire des Sciences du Climat et de lʹEnvironnement (LSCE), Gif‐sur‐Yvette, France. 3 Centre de Formation et de Recherche sur lʹEnvironnement Marin (CEFREM), Université de Perpignan, France. 4 Environnements et Paléoenvironnements Océaniques (EPOC), Université Bordeaux 1, France. Living (rose‐Bengal stained) benthic foraminifera were investigated at 20 stations sampled in September 2006 in the prodelta of the Rhône river (Gulf of Lions, NW Mediterranean, BEHEMOTH cruise). The depth of these stations ranges between 15 and 100 m depth. An important dataset of environmental parameters (temperature, salinity, granulometry, pore water and sediment oxygenation, redox elements, organic mater quantity and quality) was constituted, providing a better understanding of the spatial distribution of the benthic foraminiferal communities (>150 μm size fraction) in this studied area. The lowest species richness value (S = 8 taxa) is recorded at Station 28 (18‐m depth) located in the immediate vicinity of the river mouth. The highest diversity (S = 69 taxa) is observed at the deepest Station 48 (100‐m depth). In term of foraminiferal density, lower values are generally recorded at the vicinity of the Rhône, with a minimum density of 5 foraminifera/50 cm3 recorded once again at Station 28. The highest densities are observed in the western stations of our study area, where organic mater preferentially accumulates. The foraminiferal distribution seems to be influenced by the granulometry, the organic matter in the upper sediment, the related redox conditions within the sediment and a melting pot of undetermined stressing conditions prevailing in front of the mouth of the Rhône river. In order to highlight a putative interannual variability of foraminiferal communities, the overall foraminiferal distribution in September 2006 is compared with foraminiferal observations performed in May 2005 in the same study area (MINERCOT 2 cruise). The 13C positive excursion of the Valanginian/Hauterivian interval. Comparison of bulk carbonate, photic zone and diagenetic records in Vocontian Basin (SW France) GRESSIER Vincent, MINOLETTI Fabrice and EMMANUEL Laurent Université Pierre et Marie Curie – Paris6 JE 2477 Biominéralisations & Paléoenvironnements Case postale 116 ‐ 4, place Jussieu F – 75252 PARIS CEDEX 05 [email protected] Bulk carbonate carbon isotope records of the Early Cretaceous marine deposits are similar in northern Italy, France and Switzerland. A period of relatively stable D13C values in the Lower Valanginian is followed by a rapid positive excursion in the Upper Valanginian and a progressive return to pre‐excursion values in the Lower Hauterivian. This isotopic evolution is also recorded in terrestial plants and belemnite. The purpose of this work is to extract the calcareous nannoflora from Valanginian/Hauterivian samples and compare their geochemistry signature to bulk carbonates ones. Samples were processed following a protocol enabling the separation of the various micrometric components of pelagic deposits: mono‐ and oligospecific assemblages of calcareous nannofossils, planktic and benthic foraminifera, euhedral diagenetic calcite crystals, fine micrite. The separation of the components is achieved via a sequence of filtration steps (from 60μm down to 2μm). Our study focuses on the Valanginian/Hauterivian interval of the Angles section (Vocontian Basin, southeastern France). After treatment, various pure fractions are obtained containing: ‐ W. Barnesae (coccoliths) or nannoconids (Incertae Sedis) wich record goechemistry evolution of the photic zone ‐ Euhedral calcite crystals (diagenetic overprint) This study permits the quantification of carbonate production/sedimentation and the reconstruction of long‐term geochemical evolution of the photic‐zone (coccoliths and nannoconids). Geochemical
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results show that diagenesis does not significantly alter primary isotopic signal for this section. Isotopic curves based on the monospecific fractions (coccoliths and nannoconids) record the same evolution with the positive carbon‐isotope excursion in the Valanginian and a progressive return to pre‐excursion values. The isotopic record of bulk carbonate is controlled by the coccolith/nannoliths ratio in the sample and shows the necessity of a good knowledge of the composition of bulk carbonate before analysis. Salinity influence on planktonic foraminiferal Mg/Ca: A case study from the Red Sea J. Groeneveld 1*, M. Raitzsch 2, M. Siccha 3, G. Trommer 3, Ch. Hemleben 3, M. Kucera 3 1 Marum, University Bremen, Leobener Str., D‐28359 Bremen, Germany 2 Europrox, University Bremen, Leobener Str., D‐28359 Bremen, Germany 3 Institut für Geowissenschaften, University Tübingen, Sigwartstrasse 10, D‐72076 Tübingen, Germany * corresponding author: jgroeneveld@uni‐bremen.de We present new data from the Red Sea, which is characterized by a large salinity gradient and small temperature changes providing an ideal setting to explore the influence of salinity on Mg/Ca. We analysed the planktonic foraminifer Globigerinoides ruber from a series of core tops and from plankton tows. Analyses were performed on bulk samples by ICP‐OES and on single shells by LA‐ICP‐MS to detect inner test variability. The bulk measurements on the core tops show Mg/Ca ratios between 4.64 and 22.36 mmol/mol with no correlation to temperature at the site locations. Correlation with salinity, however, is highly significant (r2 = 0.68). When expected Mg/Ca ratios are subtracted from the analysed values the correlation coefficient between δ(Mg/Ca) and salinity further increases (r2 = 0.74). The bulk measurements on specimens from the plankton tows vary between 4.49 and 4.97 mmol/mol, being lower than the core top samples. When the Mg/Ca ratios are corrected for temperature influence, δ(Mg/Ca) shows a correlation with salinity (r2 = 0.95). Thus, the bulk measurements from the plankton tows support previous cultivating experiments by Nürnberg et al. (1995) and Lea et al. (1999), which showed an influence of salinity on Mg/Ca. In addition, we used Laser Ablation ICP‐MS, SEM analysis, and pteropod preservation index to verify the discrepancy between plankton tow material and the core top samples, i.e. whether diagenetic alteration has caused the anomalous bulk Mg/Ca ratios in the core tops. Results do not indicate the presence of coatings on the core top samples, but rather show homogeneous Mg/Ca ratios throughout the test walls with highest values always present in the oldest chambers. The correlation between core top Mg/Ca and salinity points to an artificial dependency in which differences in salinity provided a varying potential for diagenetic changes. Holocene Climate Variability in the Western Mediterranean Sea Sean Halligan1, Angela Hayes1, Michal Kucera2 1 Department of Geography, Mary Immaculate College, University of Limerick, Ireland 2 Institut für Geowissenschaften, Eberhard Karls Universität Tübingen, Germany. This research focuses on climate variability in the western Mediterranean Sea during the Holocene. Beginning approximately 11, 500 calendar years before present, the Holocene was initially recognized as a period of climatic stability (Mayewski et al., 2004). In recent times, however, high resolution palaeoclimatic records from the western Mediterranean Sea provide strong evidence for Holocene climatic variability in this region (Cacho et al., 2000; Frigola et al., 2007). This evidence is based primarily on sedimentological and geochemical data. Here we present new high resolution data on Holocene climatic variability in the western Mediterranean Sea based on analyses of planktonic foraminifera in two sediment cores: (M40/4 82‐2‐SL from the Gulf of Lion, latitude 42.31˚ N; longitude 3.78˚ E; water depth 1070m; the section to be analysed is 130cm in length) and (M40/4 87‐SL‐6 from the Balearic Basin, latitude 38.99˚ N; longitude 4.03˚ E; water depth 1897m; the section to be analysed is 37cm in length). The objectives of this project are to provide a palaeoenvironmental construction of
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the Holocene within the western Mediterranean, placing particular emphasis on the occurrence/absence of rapid climate change events and to analyse and constrain the timing of any climatic change events within the context of both regional and global scales. Planktonic foraminiferal census counts are used to reconstruct sea surface temperature (SST) profiles, for both cores, through the use of artificial neural networks (ANN). Time series observations of planktonic foraminifera in the NE Atlantic Ocean (Porcupine Seabight) A. Harbers1, J.Schönfeld1, M.Chapman2, O.Pfannkuche1 1 Leibniz Institut of Marine Sciences IfM‐geomar, Wischhofstr. 1‐3, 24148 Kiel, Germany 2 School of Environmental Scienes, University of East Anglia, Norwich, UK Correspond to: aharbers@ifm‐geomar.de Modern planktonic foraminifera collected with a sediment trap and subfossil assemblages from surface sediments in the northeastern Atlantic have been studied to show recent variations of faunal assemblages. Another focus was on CaCO3 flux and dependency of planktonic foraminifera to surface ocean temperature and chlorophyll concentrations. The sediment trap operated from April to August 2004 and covers the spring bloom and early summer conditions with sampling intervals of 8 days. Eight different species were recorded in the sediment trap deployed in the Porcupine Seabight off southern Ireland. Several species, Globorotalia scitula, Globorotalia hirsuta, Turborotalita quinqueloba and Globigerinita glutinata appear predominately in spring. While other species, Neogloboquadrina pachyderma, Globigerina bulloides and Globorotalia inflata are abundant in spring and summer. In 2004, the highest flux of foraminiferal tests occurred in June while in 1994 the highest number of tests accumulated in late July. The faunal composition is similar to subfossil assemblages from surface sediments, but the species proportions are different. A relationship between chlorophyll concentrations and weight of deposited planktonic foraminifera was recognized. A similar relationship between surface ocean temperature and the number of deposited foraminifera and pteropods was also recognized. The weight of deposited foraminifers increased about 30 days after the chlorophyll maxima. This is mainly effected by the subtropical G. hirsuta and G. scitula, which were frequent in 2004 and rare in surface sediment samples. Only 0.86 % of the total carbonate flux is contributed by planktonic foraminifera, which is one order of magnitude lower as in earlier studies. The three‐ranked species, G. hirsuta, N. pachyderma and G. bulloides contribute 76 % to the foraminiferal carbonate flux at this site. Test surface coatings of planktonic foraminifera investigated with single pulse laser ablation (LA) ICP‐MS Ed Hathorne and Stephan Steinke MARUM‐Centre for Marine Environmental Sciences ([email protected]) Test surface coatings enriched in trace elements have been reported for planktonic foraminifera from core top and plankton tow samples (Hathorne et al., 2003; Eggins et al., 2003). Such coatings could bias geochemical proxy data making it important to understand the composition and formation of the coatings. The observation of such surface coatings in plankton tow samples suggests these coatings can form in the upper water column, perhaps under biological control. Here we use a novel single pulse LA‐ICP‐MS technique and SEM imaging to investigate the surface coatings of various planktonic foraminifera from sediment trap and core top samples from the N. Atlantic. Comparison with a calcite standard analysed with the same technique suggests test surface coatings are as rich in Ca as calcite and are not simply authigenic oxides or clays. Some tests have much higher element/Ca ratios, such as Mg/Ca and Mn/Ca, in the very near surface while Ca counts indicate the presence of a Ca rich phase. A large variability is observed in the surface chemistry of the different tests analysed with some tests displaying little surface trace element enrichments. The possible reasons for such different surface chemistries will be discussed along with implications for cleaning techniques used for bulk analyses.
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Nannofloral Assemblage Change During the Early Toarcian Anoxic Event in the Paris Basin and Biogeochemical Insights Michael Hermoso 1, Fabrice Minoletti 2 1University of Oxford, Department of Earth Sciences Parks Road, Oxford, OX1 3PR, UK ([email protected]) 2Université Pierre et Marie Curie ‐ Paris6, Equipe Biominéralisations et Paléoenvironnements Case postale 116, 75005 PARIS ([email protected]) The Jurassic was marked by a large diversification of calcareous nannoplankton, subsequently to the Triassic‐Jurassic extinction event. Within this trend, extreme and hostile environments for nannoflora emplaced as for example at the Plienbaschian‐Toarcian boundary, which records nannoplankton radiations. After that, significant environmental perturbations have been recorded within the Early Toarcian leading to widespread black shale deposition. Despite alleged unfavourable conditions for coccolithophores (enhanced salinity, global warming, seawater acidification...), no extinction event of the calcareous nannoplankton were recorded; on the contrary, a number of appearances has been described. The purpose of this study is to examine the nannofloral change during the T‐OAE relating to environmental changes of the seawater composition inferred by an integrated geochemical approach (C and O isotopes, trace metals, TOC and biomarkers) in the Paris Basin examined by the Sancerre core (Centre France) and the Bascharage section (Luxembourg). In particular, we detail how each environmental perturbation is connecting with calcareous nannofossil assemblage evolution. Neither the onset of the anoxia, nor the well‐known C‐isotope negative excursion are linked with nannofloral assemblage shifts, except the over‐expression of the Incertae sedis Orthogonoides hamiltoniae during strongest anoxic stages. However, after the C‐isotope excursion (falciferum subzone), the Crepidolithus genus dominates over other nannofossils at the expense of Schizosphaerella calcareous dinoflagellates and Lotharingius and Biscutum coccolithophore genera. A coeval chemical change of the seawater in terms of a salt concentration is observed at this level and calls into question the palaeocology of Crepidolithus coccolithophore and its tolerance in respect to salinity. Furthermore, a Sr/Ca anomaly (up to 130 mmol/mol) has been measured on Crepidolithus‐rich assemblages. This novel observation on huge coccolithes challenges the biogeochemistry of murolith‐producing coccolithophores at times of extraordinary high productivity. North Atlantic Climate change during the Mid‐Pleistocene (MIS 19 to MIS 31) based on foraminifer and isotopes studies in IODP Site 1314 Hernández‐Almeida I.1, Sierro, F. J.1, Cacho, I. 2, Flores, J. A. 1 1Department of Geology, Faculty of Sciences, University of Salamanca, 37008 Salamanca, Spain. [email protected] 2G.R.C. Marine Geosciences, Department of Stratigraphy and Paleontology, University of Barcelona, Barcelona, Spain. The foraminifer assemblages, oxygen isotopes and Ice Rafted Debris (IRD) content in IODP Site 1314 from Gardar Drift were studied to reconstruct ice‐sheet dynamics and climate variability in the North Atlantic during the Middle Pleistocene (MIS 19 to MIS 31). Based on preliminary bio‐ and magnetostratigraphic models, we estimated a relatively high and constant sedimentation rate during the Pleistocene of around 7.0–7.5 cm/ky. 624 samples were analysed in this interval with an average temporal resolution of around 0.45 ky. The coarse biogenic fraction (> 150 μm) consisted mainly of planktonic and benthic foraminifers, but radiolarians, diatoms, ostracods and echinoderms were also present. Many of the samples analyzed at this site contained abundant lithic grains, consisting mainly of quartz, volcanic glass and basalt, these were considered a IRD. Stable isotope measurements were carried out on the planktonic foraminifer N. pachyderma left coiling. The analytical reproducibility of laboratory standards was better than ± 0.02 ‰ for δ13C and ± 0.06 ‰ for δ18O. The foraminifer assemblage was dominated by Neogloboquadrina pachyderma left coiling during glacial periods and Globigerina bulloides accompanied by N. pachyderma right coiling and Globorotalia inflata during interglacial times. High percentages of N. pachyderma left appear during glacial periods and are well
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correlated with high contents of IRD and high natural gamma radiation. Magnetic susceptibility, which follows an opposite trend, displays a more complicated signal that is strongly influenced by the nature of the clastic input, probably reflecting changes in lithology of the IRD. The δ18O record and the abundance of N. pachyderma left follow similar patterns. This relationship allows us to correlate site 1314 with other sites from the North Atlantic, providing a better understanding of regional climate variability during this period. Coccolithophorid and calcareous dinoflagellate species fluxes in the vicinity of the Azores Front (33°N 22°W) during 2003/2004: a sediment trap investigation Hoffmann, R.1, Schulz, H.1, Waniek, J.2 and Kucera, M.1 1 Department of Micropaleontology, Institut für Geowissenschaften, Sigwartstr. 10, 72076 Tübingen, Germany; email: [email protected]. 2 Leibniz Institute for Baltic Sea Research, Seestr. 15, 18119 Rostock‐ Warnemünde, Germany. Fluxes and species composition of coccospheres, coccoliths, calcareous dinoflagellates, radiolaria, silicoflagellates, diatoms, and amorphous organic and lithogenic particles were determined in an annual sediment trap time series from the long‐term mooring station L1/K276‐23. These new data by SEM complement investigations on the planktonic foraminifera and pteropods from the same samples in order to estimate the biogeochemical role of the calcareous particle flux in the north east Atlantic. The flux of the individual phytoplankton groups closely matches the bulk particle flux which is largely composed of fecal pellets. Although the fecal pellets complicate the quantification of individual particles, our estimates agree well with those of earlier trap studies in the region. The average specimen flux during the year was 1,1*108 ind./m2/d of coccoliths, 2,6*105 ind./m2/d of calcareous dinoflagellates, and 8,4*105 ind./m2/d of diatoms, with increased values for these groups during spring (May) and winter (January‐February). The oligotrophic summer season was characterized by fluxes lower by several orders of magnitude. Emiliania huxleyi (37% relative abundance) is the most important coccolithophorid species and shows minor fluctuations like Calcidiscus leptoporus (5%). In contrast, Florisphaera profunda (12%) displays a distinct bloom during the winter period. By far the most frequent calcareous dinoflagellate species is Thoracosphaera heimii (91%) throughout the year, followed by the summer species Calcidinellum levantinum (1,5%). The flux of siliceous organic particles does not show strong seasonal fluctuations except for a peak in late June, when the lithogenic flux is exceptional, too. The latter particles are not composed in fecal pellets. Statistical methods including canonical correspondence analysis allow to attribute individual species to specific environmental parameters. The analysis shows that chlorophyll‐a and sea surface temperature are clearly opposed to each other, suggesting that the species are either adapted to a highly nutritious regime during winter, or to summer stratification causing oligotrophy in the region. Can Island biogeography work also in paleobiogeography? Katarína Holcová Department of Geology and Paleontology, Charles University Prague, [email protected] The two main predictions of Island Biogeography are: (1) Islands close to a source area should have a higher number of species than islands further from the source area for islands of equivalent areas. (2) Larger islands should have more species than smaller islands for islands located at similar distances from the source area. In the island‐biogeographical concept, the Central Paratethys basins represent islands, source areas were the Mediterranean and/or the Indo‐Pacific or the Atlantic Oceans. The validity of both island‐biogeographical predictions for ancient marine basins was tested for numbers of foraminiferal species. The 1st prediction: Numbers of benthic foraminiferal species in the similar paleoenvironment from different partial Central Paratethys basins were compared for the following intervals: (1) Kiscellian; (2) Egerian; (3) Eggenburgian, (4) Karpatian. The first presumption of island biogeography was confirmed for all studied intervals: the maximum numbers of species in
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assemblages decrease with increase of distance from the source area. The 2nd prediction: Total numbers of foraminiferal species for the eleven stratigraphical intervals (Cicha et al. 1998) were compared with the estimated areas of the Central Paratethys basins from the paleogeographical maps of Rögl 1998 and Popov et al. 2004 (using ArcGis software). From the Late Eocene to the Egerian, estimations of relative changes of area of the basin differ and these unconform data cannot be compared with increase of numbers of foraminiferal species. Marked decrease of number of foraminiferal species at the Egerian/Eggenburgian boundary may be correlated with marked decrease of area of the Central Paratethys basins. Small area of the basins from the Eggenburgian to the Karpatian can be compared with low numbers of foraminiferal species. Marked increase of number of foraminiferal species in the Early Badenian may be influenced by opening of new sea ways as well as by increase of area of the Central Paratethys Basins. Disagreement between area of the basins and numbers of foraminiferal species in the Late Badenian and Sarmatian may be caused by deterioration of paleoenvironment in these intervals. Succession of the Bryozoa‐rich communities in the Middle Miocene of the Central Paratethys Katarína Holcová 1, Kamil Zágoršek 2 1 Department of Geology and Paleontology, Charles University Prague, [email protected] 2 Department of Paleontology, National museum Prague A rapid increase in bryozoan abundances and species diversity informally termed “bryozoan events“ was observed in many localities of the Central Paratethys. The event was related to the establishment of a specific palaeoenvironment which has been interpreted using foraminifera, calcareous nannoplankton, sedimentology and oxygen and carbon isotopic data. Study was focused on the Middle Miocene bryozoan event which was initiated by the large Middle Miocene transgression. Colonization of the bottom by Bryozoa‐rich communities was studied on 13 sections and the following idealized succession was reconstructed: 1. interval without fauna 2. interval with only foraminifera, high nutrient markers commonly occur (Melonis, Uvigerina) 3. The FO of Bryozoa was correlated with the FO of Orbulina. Foraminiferal assemblages were
dominated by passive suspension feeders (Cibicidoides or Cibicidoides‐Lobatula assemblages), high nutrient markers disappeared. Interval is characterized by negative correlation between abundances of Bryozoa and foraminifera (r = ‐ 0.65). It may indicate that benthic foraminifers and Bryozoa was food competitors.
4. The LO of Globigerinoides bisphericus corresponds with change in foraminiferal assemblages: herbivore foraminifera started prevail (Asterigerinata and Amphistegina‐Elphidium assemblages). Suspension‐feeding foraminifera cannot probably more compete with the Bryozoa and composition of foraminiferal assemblages shifted to herbivore species. No correlation between abundances of foraminiferal and Bryozoan assemblages was observed in this interval (r = 0.16). 4a. In the interval 4, horizons with decrease of Bryozoa abundance (up to its disappearance) were recorded. Abundance of detrivore foraminifera gradually increases (Asterigerinata‐Bolivina and Bolivina‐Cassidulina assemblages). Lower negative correlation (r = ‐0.45) between abundance of foraminiferal and bryozoan assemblages were observed for samples with more than 30% of detrivore benthic foraminifera. Decrease of δ13C value can be correlated with these horizons. Decrease of oxygen content in sediment is expected and interpreted as a cause of decrease of bryozoan abundance. Organic material in suspension which was eaten by Bryozoa may be after decrease of bryozoan abundance partly deposited at the bottom and made food for detrivore foraminifers.
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Carbonate microfossil assemblages of the Eastern Equatorial Pacific: evidence of bioproductivity and circulation changes over the last 250 kyr Ivanova, E.V. 1, Beaufort, L. 2, Ovsepyan, E.A. 1, Vidal, L. 2 1 Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia. [email protected] 2 Universite Paul Cezanne ‐ CEREGE, Aix en Provence, France. A quantitative study of coccolithophore, planktic and benthic foraminiferal assemblages and abundance (in grain size fraction > 0.150 mm) in the IMAGES Core MD02‐2529 (08°12.5ʹ N, 84° 07.5ʹ W, w.d. 1619 m) off Costa Rica monitors variations in primary and export production, and climate dynamics at glacial‐interglacial and millennial time scales through the last 250 kyr. Cross‐spectral analysis ascertains a pronounced glacial‐interglacial and precession ‐ driven variability in the distribution of eutrophic and oligotrophic coccolithophore and planktic foraminiferal species. On the millennial time‐scale, a few ka decoupling is found between the maximum of benthic and planktic foraminiferal abundance at the LGM and the beginning of Termination I respectively. The highest total abundance of benthic foraminifer coincides with the maximum percentage and abundance of several productivity‐related species at about the LGM. However, the total planktic foraminiferal abundance and maximum percentage of thermocline‐dwelling N. dutertrei is established at ~ 16 cal ka (H‐1). This decoupling most probably results from the difference in planktic and benthic foraminifer diet. In turn, primary production estimated by coccolithophore data shows a gradual increase over the Termination I that culminated at ~ 13 cal ka. This pattern is supported by the summary record of the most productivity‐related planktic foraminiferal species: G. bulloides, G. glutinata and N. dutertrei. High productivity values seem to indicate a thermocline shoaling and stronger influence of nearby coastal upwellings in Papagayo and Panama Bights on the site location via the filaments and eddies. This calls upon a more frequent La‐Nina over the Termination I. However, benthic assemblages suggest a decrease in export production during the Termination I due to a strong grazing in the surface waters. High amount of epibenthic species points to an intensification of intermediate circulation and better ventilation which could affect the organic matter flux to the bottom. A test of Kaiho’s Benthic Foraminiferal Oxygen Index in the Marmara Sea Kaminski, M.A. 1 Phipps, M. 2 Yasar, D. 3 1 Department of Earth Sciences, UCL, Gower Street, London, WC1E 6BT, U.K.. Email: [email protected] 2 Laboratoire des Bio‐Indicateurs Actuels et Fossiles, University of Angers, 2 bd Lavoisier, 49045 ANGERS Cedex 01, France. Email: [email protected] 3 Institute of Marine Science & Technology, Dokuz Eylül University, Haydar Aliyev Caddesi 10, Inciralti, Izmir, Turkey. In the summer of 2002, we collected 30 grab samples at 10 to 50m depth intervals along a depth transect on the southern shelf of the Marmara Sea, from a depth of 18 m to 350 m. At each station, temperature, salinity and oxygen contents were measured in vertical profile, and bottom sediments were sampled for benthic foraminifera and stained with Rose Bengal. The calcareous benthic foraminifera (dead assemblages) were picked from the >125 μm fraction and the 211 identified species were grouped into morphogroups using the scheme of Kaiho (1991, 1994). The Benthic Foraminiferal Oxygen Index (BFOI) was calculated at each station and compared with the bottom‐water oxygen values measured on board ship. Calculated BFOI values were converted to analogue oxygen values using Kaiho’s (1994) empirical relationship between BFOI and Bottom Water Dissolved Oxygen values. Stations collected from depths of 15–30m represent the pycnocline and summer chlorophyll maxima. Here, the observed and calculated oxygen values are strikingly similar. The zone from 30m to 75m represents the inflow of the summer Mediterranean countercurrent, which has higher dissolved oxygen content that the ambient Marmara Sea water. Here we observed a significant deviation between the observed and calculated oxygen values, with oxygen calculated from the BFOI being much lower than the measured oxygen values in this zone. This could be due to seasonal
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variation in the local hydrography, with a stronger summer current of Mediterranean origin causing elevated oxygen values in the summer compared with the winter conditions. The depth zone from 75m to 140m represents stable hydrographic conditions found below the summer mixed layer. Here, observed and calculated oxygen values correlate remarkably well. Below 150m, the observed and calculated dissolved oxygen values again diverge, suggesting the existence of a second bottom water undercurrent. In winter the inflowing Mediterranean water is denser and switches its position, descending to deeper depths in the Marmara Sea. Our results indicate that Kaiho’s BFOI can faithfully represent the dissolved oxygen values in areas that are not significantly influenced by seasonal changes in dissolved oxygen content. On the other hand, the complex hydrography of the well‐oxygenated inflowing Mediterranean current is reflected by regional variations in the BFOI. To more fully understand the relationship between observed and calculated oxygen values it would be necessary to repeat the shipboard oxygen measurements along the depth transect in winter. Calcium isotope fractionation in foraminifera B. Kısakürek1, A. Eisenhauer1, F. Böhm1, J. Erez2 1 IFM‐GEOMAR, Germany (bkisakurek@ifm‐geomar.de) 2 The Hebrew University, Israel δ44/40Ca was determined on two species of cultured planktonic foraminifera (Globigerinoides ruber (white) and Globigerinella siphonifera) and the culturing solutions. The culturing experiments were performed under controlled laboratory conditions wherein a single environmental parameter (i.e., temperature, salinity, pH and solution chemistry) can be simulated while others are kept constant. The results of temperature experiments carried out between 18 and 27°C follow the temperature dependent Ca isotope fractionation with a shallow slope of ~0.02‰/°C established for inorganic calcite as well as some species of planktonic foraminifera (Marriott et al., 2004; Gussone et al., 2003). However, calcium isotope signatures of foraminifera cultured at temperatures >27°C deviate from this trend with a higher degree of fractionation at higher temperatures. This finding is consistent with the results of Griffith et al. (in press), who observed that high temperatures (>27°C) are associated with particularly low δ44/40Ca values in Globigerinoides ruber (white) and Globigerinoides sacculifer from a sediment trap. This phenomenon appears to be biologically controlled and will be discussed in relation to our understanding of the biomineralization processes in foraminifera (Erez, 2003). In this regard, the results of pH experiments conducted between 7.9 and 8.4 constitute an important link because symbiotic activity strongly manipulates the pH in the chemical microenvironment of foraminifera. In addition, δ44/40Ca was determined on one species of benthic foraminiferan (Amphistigina lobifera) cultured at various temperatures and pH levels. Our data set allows us to compare the calcium isotope fractionation behavior in planktonic versus benthic foraminifera. Roles of agglutinated foraminifera in benthic ecosystem; evidences and speculations Hiroshi Kitazato Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokosuka, Japan Agglutinated foraminifera are important members of benthic foraminiferal community. They sometimes occupy majority of the community under extreme environments such as deep‐sea below the CCD or low saline brackish waters. Agglutinated foraminifera should play important roles in any of benthic ecosystems. However, we tend to ignore agglutinated foraminifera, as they are not so important for paleoceanography, for instance, no calcareous tests for isotopic study, difficult to fossilize and other reasons. Sediment‐water interface at sea floor is an important reaction center for global carbon cycle. Benthic organisms consume sinking organic materials and mineralize them into carbon dioxide. Rest of organic carbon finally buries into deep in the sediment. At Redox boundary at sediment‐water interface, series of biogeochemical reactions mainly by microbial activities are taking place. The reactions starts from oxic mineralization, denitrification, manganese oxide reduction, iron oxide reduction, sulphate reduction and methanogenesis deep into sediment. Many of benthic
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foraminifera take part in oxic mineralization. Some benthic foraminifera, such as Globobulimina spp. and Nonionella sp. are crucial to denitrification process. Recent study reveals that either iron or manganese oxide reduction are, sometimes, much more important process than oxic or denitrification processes. Certain species of agglutinated foraminifera may show some relations to iron or manganese processes. 1) Some species of agglutinated foraminifera, Textularia kategattensis, show similar distributional
pattern with iron oxide reduction zone at sediment‐water interface. 2) Deep‐sea agglutinated foraminifera, Torypammina, Rhabdammina and others, prefer to gather on the
surface of ferro‐manganese nodules. They sometimes may collect iron or manganese ions on test surface.
3) Cementing materials of agglutinated foraminifera sometimes contain distinct amount of iron or some heavy metals.
These phenomena indicate that agglutinated foraminifera may have some relation to iron/manganese oxide process. How do some agglutinated foraminiferal species adapt to iron/manganese oxide reduction processes? We should investigate relationship between iron or manganese reduction and agglutinated foraminifera. This kind of approach may solve missing link in carbon budget at deep‐sea floor where agglutinated foraminifera occupy majority of benthic community. Sedimentary labile organic carbon and redox control on species distribution of benthic foraminifera: A case study from Lisbon‐Setúbal Canyon. K.A. Koho 1*, R. García 2, H.C. de Stigter 3, E. Epping 3, E. Koning 3, T.J. Kouwenhoven 1, G.J. van der Zwaan 1, 4 1Faculty of Geosciences, Utrecht University, 3584 CD Utrecht, The Netherlands 2Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany 3Royal Netherlands Institute for Sea Research (NIOZ), 1790 AB Den Burg (Texel), The Netherlands 4Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands *corresponding author: Tel. +31 (0)30 253 5170, E‐mail: [email protected] Living (rose Bengal stained) benthic foraminifera from 11 stations in the Lisbon‐Setúbal Canyon and the adjacent continental slope were counted, and their species distributions was related to the following environmental parameters: Pore water nitrate (as a redox indicator) and CPE (chloroplastic pigment equivalents) contents as a measure of labile organic matter, and total organic carbon as a measure of bulk organic matter availability. The results indicate that the canyon sediments are enriched in organic carbon and phytopigments at all water depths in comparison with the open slope. Water depth apparently controls sedimentary phytopigment content but not total organic carbon. Further, no significant correlation was observed between pigment and total organic carbon content. Therefore, it appears that sedimentary organic matter alone is not a good measure for benthic food availability but should be used with care and preferentially replaced by other indices such as phytopigment concentrations. The abundance of calcareous foraminifera correlates with phytodetritus content, whereas a weaker correlation is observed for the agglutinated taxa. Therefore, calcareous foraminifera appear to require a more labile food source than agglutinated taxa. The foraminiferal species composition also varies with pigment content and nitrate penetration depth in the sediment, in agreement with the TROX concept. Phytopigment‐rich (surficial CPE content > 20g/cm3) sediments with a shallow nitrate penetration depth (~ 1cm depth) are inhabited by infaunal species such as Chilostomella oolina and Melonis barleeanum. With declining CPE content and increasing nitrate penetration depth, the foraminiferal assemblages change from the mesotrophic Cibicides kullenbergi assemblage to the oligotrophic Nutallides umbonifera assemblage.
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A case story of a multi‐disciplinary approach from deep‐water clastic deposits Offshore Nigeria; Methodology and Applications G.V. Laursen1, D. Hulks1, L.K. Møller1, L. Gemmer1, T.C. Elde1, W. Oxborough1, P. Brockbank1, Ø, Clausen1, A.M. Robinson1, A. Hibbitt1, H. Heggebø1, L. Martinsen2 1 StatoilHydro, 4035 Stavanger, Norway 2 Chevron, 1500 Louisiana, Houston, Tx. 77002 An integrated multidisciplinary approach based on the principles of sequence stratigraphy is used to characterise the Nigerian deepwater systems. Sequence stratigraphic building blocks (3rd order) are mapped out regionally in an interactive process between seismic interpreters and biostratigraphers (using standard biostratigraphic methods based on nannofossils, foraminifera and palynology). A special study of the microfacies was used to fine tune the pick of the sequence stratigraphic surfaces: A biostratigraphic procedure was used to quantify the foraminiferal fauna, where few pioneering species indicate high allocthonous (sand) depositional conditions, whereas diverse assemblage indicates stable, quiescent conditions. This improves the stratigraphic framework in periods with absence of calcareous taxa (e.g. few global markers) and is used to improve the understanding of the temporal and spatial variability of deep water reservoirs. In order to identify the depositional system, amplitude extraction at proportional slices was used in between the framework horizons to reveal the geometry of the individual channel complexes. The formation pressures follow the tightly constrained sequences and are used to further confirm the picked sequences. Structural reconstruction uses the refined framework horizons to constrain timing of topography development and trap formation relative to fairway development, reservoir deposition and hydrocarbon migration. The detailed understanding of the nature, distribution and connectivity of the reservoir units can then be used in exploration, e.g. presence of channel sands imply that sand has been transported further out in the basin, or maybe an interval with low microfacies index (based on foraminifera) suggests that sedimentation rates were high and therefore the possibility of finding sand will increase. Benthic Foraminifera of the Benguela Upwelling System as potential denitrifyers Leiter Carola, Altenbach Alexander V. Department for Earth and Environment, Richard‐Wagner‐Str. 10, 80333 München, Germany. [email protected] , [email protected]‐muenchen.de During the TMS meeting 2007 in Anger, the anoxic microhabitats of Virgulinella fragilis were discussed. From our ongoing foraminiferal counts, we can describe a number of species found as commensales of V. fragilis. These species, for which the ability to thrive in oxygen depleted environments is assumed, are typifying the oxygen depleted diatomaceous oozes on the inner shelf off Namibia. All these commensales of V. fragilis may also be found outside of the mud, under oxic conditions. But within the anoxic environments, this consortia is consistent, and guided by V. fragilis. For a number of species, Risgaard‐Petersen et al. (2006) made evident facultative complete denitrification by benthic foraminifera. The species discussed by Risgaard‐Petersen et al. (2006) and our consortium shows a convincing overlap. Therefore the existence of a benthic foraminiferal denitrifying consortia might be presumed. This assumption seems sound and well justified also because of the observations on intracellular bacteria and kleptoplasts in a number of these species. Benthic foraminifera as bio indicators of marine pollution Linshy V.N.*, Sujata, R. Kurtarkar & Nigam, R. Micropaleontology Laboratory, National Institute of Oceanography, Dona Paula‐403004, Goa, India *Corresponding author: [email protected] Foraminifera are considered to be one of the best indicators for marine pollution studies along the marginal marine environments. They are highly sensitive to the changes in the physico‐chemical parameters in their ambient environment (natural as well as anthropogenic). The response to such
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changes may vary from variations in abundance, diversity, growth, morphology and chemistry of the hard parts. Foraminifers incorporate signatures of these changes and preserve them in their hard part called test. The foraminiferal test has a very good fossilization potential which makes the studies possible even long after their death. This renders foraminifers a positive edge over other micro‐organisms and makes them the ideal bio‐indicators for short‐ long term changes of the marine environments, from global to local scales. In most of the field studies, the foraminiferal characteristics are attributed to the site specific (the type and extend of stresses vary in different sites) filed evidences; but such studies are yet to give a complete account of the specific responses of foraminifera to specific stresses, be it natural or anthropogenic. Laboratory culture studies emerged as a supporting tool, providing experimental support to the field based findings, there by refining and revaluating them. In the laboratory, field conditions are regenerated and only desired parameters (like type and amount of pollutants) are varied in such a way that the foraminiferal responses to specific pollutants/changes can be documented separately; which help solving the above controversies and extend credibility to the numerous field based claims/findings. This poster exhibits the basic principles and methodology engaged in the laboratory experiments of benthic foraminifera in the above discussed context. Some of the results are presented, which will help establishing experimental studies as an advanced tool for effective monitoring of marine pollution. Special emphasis is given to the effect of heavy metals Mercury and Cadmium on some of the benthic foraminiferal species collected from the coastal areas off Goa. Seasonal record of foraminiferal export fluxes in the Bay of Biscay Lončarić N. † 1, 2, Howa H. 1, Schmidt S. 3 1 BIAF ‐ Bio‐Indicateurs Actuels et Fossiles, Université Angers, France. 2 LEBIM ‐ Laboratoire de Bio‐Indicateurs Marins, Ile d’Yeu, France. 3 EPOC‐ Environnements et Paléoenvironnements Océaniques, Université Bordeaux, France This study provides the first seasonally resolved record of foraminiferal export fluxes settling from the productive zone of the pelagic Bay of Biscay. Sediment export fluxes have been sampled from June 2006 until April 2007 as a part of the on‐going ANR‐FORCLIM program. Two sediment traps have been deployed approximately 100 km off the Arcachon lagoon, at the water depth of 2000 m. The most prominent maximum in foraminiferal export flux occurred in June and July (with 88% of the semi‐annual foraminiferal flux of the fraction >250 μm exported from the productive zone), at the time of high SST and very low chlorophyll‐a concentration in the surface water. During the rest of the year the fluxes of all major species remained low. The magnitude of these fluxes appeared lower than what is typically found in the oligotrophic open ocean. The total foraminiferal flux was dominated by species Globigerina bulloides, Globorotalia inflata, Orbulina universa and Neogloboquadrina pachyderma (dex). Some secondary species like Hastigerina pelagica and Globigerinoides trilobus showed periodic maxima that differed from the general trend of the summer bloom. Next to the summer maximum, the total mass flux showed additional maxima during December and February/March that appeared correlated to the enhanced concentrations of the chlorophyll‐a from the surface water, although delayed by a few weeks. The gross of the mass flux was composed of the fine material of the <100 μm fraction, in particularly at the lower trap which revealed significantly higher fluxes comparing to the upper trap, with an order of magnitude higher contribution of the fine material. Large differences between the mass fluxes recorded at 800 m and 1700 m water depth and great contribution of fine material in the lower trap suggest other source of the sediment, rather than only vertical pelagic settling from the productive zone. Pleistocene climate events in the SW Pacific Ocean: biotic and geochemical evidences Lupi C.* and Cobianchi M. Dipartimento di Scienze della Terra, Università degli Studi di Pavia, Via Ferrata 1, 27100 Pavia (Italy) * corresponding author: [email protected]
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An integrated study, based on micropalaeontological and geochemical data (calcareous nannofossils and C, O isotopes) of the IMAGES site MD97‐2114 (East New Zealand), has been performed to detect climate and oceanographic events during Pleistocene in the SW Pacific Ocean. The investigated site is located at 1935 m on the northern slope of the Chatham Rise, a plateau placed east of New Zealand. It records the last 1.07 Ma spanning from the Marine Isotope Stage (MIS) 29 to the MIS 1, on the basis of magneto‐biostratigraphic and isotopic analyses. The analysed calcareous nannofossil assemblages result abundant, well diversified and well preserved. The comparison among the abundances of nannofossil proxies and the δ18O and δ13C curves documents as several paleoecologic, paleoceanographic and paleoclimate events occur in the studied area during Pleistocene; some of these are described below. The assemblage composition and species richness show subtropical features throughout the whole core suggesting that the Subtropical Front was always located on the Chatham Rise during glacial/interglacial periods, at least since the Early Pleistocene. Up to MIS 18, calcareous nannofossil assemblages indicate meso‐oligotrophic stratified water column; from MIS 14 to MIS 8 nannofossils suggest enhanced nutrient levels probably linked to the intensification of the Deep Western Boundary Current. Finally, from MIS 8 to the core top, nannofossil assemblages are indicative of relative meso‐oligotrophic conditions. The recorded δ13C curve experiences two major negative shifts (in the MIS 28‐25 and in the MIS 12‐11 intervals, respectively) following intervals characterised by δ13Cmax episodes, which precede the two major climate change and ice‐sheet expansion events in the Pleistocene, i.e. the Middle Pleistocene Revolution and the mid‐Brunhes event. In these intervals, many nannofossil bioevents are also recorded documenting a clear relationship among carbon cycle, ice‐sheet volume and primary productivity. Paleobathymetry of the Southalpine foreland basin (Cenozoic, NE Italy) inferred from Micropaleontological and geometrical data N. Mancin 1 & R. Fantoni 2 1 Dipartimento di Scienze della Terra, Università di Pavia, via Ferrata 1, 27100 Pavia, Italy [email protected] 2 ENI Exploration & Production Division, via Emilia 1, 20097 San Donato Milanese (MI), Italy The studied Venetian‐Friulian Basin (VFB) represents the north‐eastern portion of the major and complex Southalpine foreland basin and is the result of the superposition of three overlapping chain migration during Cenozoic, different both in age and direction of tectonic transport. They are: the Dinarides to the East, the Southern Alps to the North and the Northern Apennines to the South‐West. Its peculiar location in a so important tectonic knot combined with a very good subsurface bulk of data make the VFB a very interesting geological topic from a scientific point of view. This research aims to provide a paleobathymetric reconstruction of the Cenozoic subsurface succession of the VFB mostly based on the analysis of fossil foraminiferal assemblages. In order to fulfil this goal, over 500 cuttings and 20 wall‐core samples from thirteen ENI wells, distributed along two seismic‐based cross sections and covering over 20 000 m of studied successions collectively, were used. The proposed bathymetric ranges obtained through micropalaeontological data were also compared with the initial water‐depth calculated through the geometrical measuring, on seismic profiles, of the sedimentary thicknesses that fill the inherited space of the studied basin. Paleobathimetric results clearly record the progressive infilling (e.g from about 1300 m, estimated as water‐depth for the upper Paleocene sediments of the Scaglia Rossa Fm. to about 50 m proposed for the upper Eocene deposits of the Possagno Marl) of both the inherited and new created accommodation space, providing also evidence for the sedimentary response to tectonics through belt erosion and sediment accumulation in the foreland basin. Moreover, results integrate and complete the stratigraphic frame already available from the literature (Mancin et al., 2007; Mancin et al., 2008) providing a synthetic data base useful to unravel the depositional and paleogeographical history experienced by the VFB during Cenozoic.
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Benthic Foraminifera as bioindicators for active cold‐water coral mounds: Results from the Porcupine and Rockall Banks in the North Atlantic Stephan Margreth1, Silvia Spezzaferrinn2, Federica Tamburini3, Henk de Haas 4 and the Pelagia Cruise Scientific Party 1 University of Fribourg, Department of Geosciences, [email protected] 2 University of Fribourg, Department of Geosciences, [email protected] 3 ETH Zurich, Institute of Plant Nutrition, [email protected] 4 Royal Netherlands Institute for Sea Research, Departement of marine Chemistry and Geology [email protected] Along the European continental margin cold‐water corals build up mound shaped reefs, the so‐called “cold‐water coral mounds”. These mounds differ in their growth stage, which is defined by the amount of living cold‐water corals Lopelia pertusa and Madrepora oculata. On the Rockall Bank growing mounds were observed. On the Porcupine Bank and in the Porcupine Seabight the cold‐water carbonate mounds are in a declining or even buried stage. A pre‐drilling cruise (64PE276) was organized in October 2007 by the CARBONATE Group. In addition to seismic– and videolines, box cores were taken from the different cold‐water coral mounds. High abundance of Globigerina bulloides and Globigerinita glutinata are observed on the Rockall Bank, suggesting upwelling and/or high productivity in the mixed layer. Significant lower occurrences of these species occur on the Rockall Bank, lowest values are on the Porcupine Seabight. The distribution of benthic foraminifera shows an on‐off‐mound pattern. Growing mounds ecosystems with abundant living cold‐water coral, are dominated by Discoanomalina coronata (contribution of 27%), Globocassidulina subglobosa (contribution of 25%) and Stromatorbina concentrica. This latter species is observed only in these active ecosystems. Discoanomalina coronata is rare in on‐mound sediments from the Porcupine Bank (declining mounds). The benthic foraminiferal assemblages in off‐mound sediments display high abundances of Uvigerina spp., the Cibicides/Cibicidoides group, Hyalina balthica and the Bulimina group. We suggest that Discoanomalina coronata and Stromatorbina concentrica are potential bioindicators for on‐mound ecological conditions. This research is funded by Swiss National Found Grant N. 200021‐117 928. The laminated sapropel S5 from ODP core 971C ‐ deciphering the seasonal productivity signal during sapropel formation K.J. Sebastian Meier1, Jürgen Möbius2, Luc Beaufort3, Kay‐ChristianEmeis2 and Patrizia Ziveri4 1Christian‐Albrechts‐Universität zu Kiel, Germany, [email protected]‐kiel.de 2Universität Hamburg, Germany 3CEREGE, Aix en Provence, France 4Universitat Autònoma Barcelona, Spain The dark‐coloured sapropel units enriched in organic carbon that are found in the sedimentary record of the Mediterranean Sea have formed due to a combination of increased productivity and preservation. Although stagnant bottom water prevailed during the formation, most sapropels show no indication of lamination. An exception is the S5 sapropel from ODP core 971C located south of Crete on the moat of the Napoli mud volcano, which is unusually thick and consists mainly of a laminated to intermittently laminated diatom ooze. The laminated sections consist of couplets of alternating dark‐ and light‐coloured layers that have been interpreted as a seasonal ‘varve’ type sedimentation, which gives the unique opportunity to study the seasonal variability in productivity during sapropel formation. For this, smear slides from individual layers were investigated with the automated coccolithophore recognition system SYRACO. In general, coccolithophore assemblages are heavily dominated by Florisphaera profunda throughout the sapropel. Within the laminated sections, F. profunda dominance is higher in the dark‐coloured laminae, whereas the relative abundance of F. profunda in the light‐coloured laminae drops down to levels similar to pre‐ and post‐sapropel deposition. The same signal can be observed in the thickness of the liths of Emiliania huxleyi, which
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become thicker in the light‐coloured laminae. This may indicate that productivity levels during sapropel formation were not elevated generally but increased seasonally and only to a very limited extent. Relationship between coccolithophore assemblage and dust supply during Heinrich Events in the Eastern tropical Atlantic Alejandra Mejía‐Molina1, José‐Abel Flores1, Maria A. Bárcena1, Francisco J. Sierron1, Francis Grousset2 and Jullien, E2 1 Universidad de Salamanca. Departamento de Geología. Salamanca, Spain. Email: [email protected]; [email protected]; [email protected] 2 EPOC, UMR 5805, Université Bordeaux I, Talence, France. Email: [email protected]‐bordeaux1.fr; [email protected]‐bordeaux1.fr Information obtained from the study of a CALYPSO giant piston core (MD03 2705), located in 18°10ʹN and 21°W during the DUST expedition (Marion Dufresne II Cruise) off Mauritania/Senegal, allows us to recognize alternations in the coccolithophore assemblage during the last 70 kyr. The coccolithophore assemblage shows an alternation in the cold‐warm species, related to interglacial‐glacial stages. Furthermore, we observe, relationship of coccolithophore response with rapid climate oscillations between cold and warm conditions during the last glaciation (ʺHeinrich‐likeʺ events), linked with a wind intensification. In this study, we examine the coccolithophore assemblage, in combination with other proxies, including wind‐transported microfossils (phytoliths and fresh‐water diatoms) and the dust record. Variations in the sea surface water productivity of coccolithophores (variations in the nutricline/thermocline position) were monitored. During the last glacial interval (MIS 2‐4), we observe an inverse decreases in the numbers of upper photic zone species (mainly Noelaerhabdaceae species) during the glacial period, caused by a deepening of the thermocline and stratification of the surface waters. In addition to the previous argued and as a consequence of the dust supply, the low availability of light in the Photic Zone (by the increase of turbidity of the surface water masses), could be stimulate the lower photic zone nannoflora taxa. The terrigenous record exhibits a good correlation between Florisphaera profunda during the ʺHeinrich‐likeʺ events responding to an increase of turbidity of superficial water masses. Additionally, high abundances of Gephyrocapsa muellerae and Emiliania huxleyi (>4μm) have been observed in the ʺHeinrich‐likeʺ events (with the exception of Heinrich 3) coinciding with positive pulses of dust and an increasing of wind‐transported microfossils, indicating low temperatures of the surface water masses. Distribution of Recent and subrecent shallow‐water benthic foraminifera in the Western Mediterranean Sea: Development of a transfer function for quantitative sea level reconstructions Yvonne Milker, Gerhard Schmiedl, Christian Betzler, David Jaramillo & Miriam Römer Geologisch‐Paläontologisches Institut, Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, e‐mail: yvonne.milker@uni‐hamburg.de We present results on relative sea level changes during the Holocene in shallow water carbonate environments of the Western Mediterranean Sea based on benthic foraminiferal transfer functions and planktic/benthic ratios. In order to assess the ecology and bathymetric significance of various shallow‐water benthic foraminifera, we investigated the distribution of recent taxa in 47 surface samples from 20 to 235 m of three areas in the Western Mediterranean Sea (Alboran Platform, Oran Bight and Mallorca Shelf). This knowledge was then applied to the paleoenvironmental evaluation of the 4.7 m long sediment core 401‐1 from 74 m water depth of the Mallorca Shelf. The dead faunas in the surface samples and fossil faunas in core 401‐1 are highly diverse, with high benthic foraminiferal numbers, whereas living benthic foraminifera occur only in low numbers in the surface‐samples. The Recent faunas exhibit a distinct bathymetric zonation that is similar in all study areas. A major faunal change occurs at around 70 m water depth. Above this water depth, the faunas are dominated by Cibicides spp., Elphidium complanatum and E. crispum, Asterigerinata mamilla, Gavelinopsis praegeri and
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Neocornobina terquemi. Below this water depth, the fauna is dominated by Cassidulinidae (Cassidulina laevigata and C. carinata, Paracassidulina minuta and Globocassidulina subglobosa) and Buliminidae (Bulimina elongata and B. aculeata). The assemblages in core 401‐1 are dominated by Neoconorbina terquemi, Cassidulina laevigata and C. carinata in the upper and by various Rosalinidae in the lower part. The significance of the observed bathymetric trends and the potential influence of other environmental parameters, such as substrate and food fluxes, has been analysed by application of a variety of multivariate statistical methods including Principal Component Analysis, Cluster Analysis and Canonical Correspondence Analysis. For quantitative sea level reconstructions, different transfer functions have been developed by adaptation and modification of existing methods. These methods are based on (1) the plankton‐benthos ratio, (2) the middle depth range of distinct benthic foraminifera, and (3) the weighted averages of various benthic foraminifera. All applied transfer functions reflect a sea level low stand (48.0 m (+/‐ 7.2 m) – 50.5 m (+/‐4.0 m) water depth) in the lower core section, a rapid rise to approximately 83.4 m (+/‐8.9 m) water depth in the core section from 282 cm to 152 cm core depth, followed by a shallowing trend to 66.7 m (+/‐4.2 m) in the upper core section (152 cm to 61 cm core depth) and a slightly sea level rise from 66.7 m (+/‐4.2 m) to 73.4 m (+/‐ 7.1 m) in the upper core. The documented sea level rise during deposition of the lower sediment unit can be attributed to the postglacial eustatic sea level evolution while the reasons for the shallowing trend in the upper part of the core remain ambiguous. Benthic foraminifera as bio‐indicators of drill cutting disposals M. Mojtahid 1, E. Bicchi 1, G. Duchemin 1, F. Jorrisen 1, J. Durrieu 2; F. Galgani 3, R. Camps 2, L. Cazes 2 1 Laboratoire des Bio‐Indicateurs Actuels et Fossiles (BIAF) UPRES EA 2644, Université d’Angers. 2, Boulevard Lavoisier, 49045 Angers Cedex, France, and Laboratoire d’Etude des Bio‐Indicateurs Marins (LEBIM). Ker Chalon, 85350 Ile D’Yeu, FRANCE 2 TOTAL, département Environnement Opérations. Avenue Larribau, 64018 Pau, FRANCE. 3 IFREMER, avenue J.‐Monnet, 34203 Sète, FRANCE. e‐mail adresses: [email protected]‐angers.fr; erica.bicchi@univ‐angers.fr; gerald.duchemin@univ‐angers.fr; frans.jorissen@univ‐angers.fr; [email protected]; [email protected]; [email protected]; [email protected] We present a study of benthic foraminiferal faunas from the outer continental shelf off Congo, Gabon and Angola (West Africa), with the aim to determine the impact of the discharge of oily drill cuttings on the sea floor environment, to judge the regenerating capacity of the benthic ecosystem, and to investigate the possibility to develop an environmental monitoring method for open marine continental shelf environments, based on benthic foraminifera. We studied the spatial distribution and microhabitats of living and dead foraminiferal faunas. Our results describe a zonation of foraminiferal faunas around the former disposal sites. At the immediate vicinity of the discharge points, faunas are characterized by low foraminiferal densities followed by very high foraminiferal densities, with high percentages (about 80%) of opportunistic taxa. Far away from the disposal site, foraminiferal densities decrease, and the percentages of opportunistic species are lower (40–60% of indicator species). We used these data to develop a quantitative pollution index, values of which are strongly correlated to distance to the disposal site. This foraminiferal index offers the possibility to quantify the impact of anthropogenic eutrophication in continental shelf environments, but its validity must be tested in other continental shelf environments.
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Biometric Analysis of phenotypic variation in recent Neogloboquadrina pachyderma in the northern Atlantic Ocean, its usability as a proxy for SST and its application to glacial Atlantic Ocean Tobias Moller1, Michal Kucera1, Hartmut Schulz1 and Robert Spielhagen2 1Geowissenschaftliches Institut Universität Tübingen, Sigwartstraße 10, 72076 Tübingen 2 IFM‐Geomar, Wischhofstraße 1‐3, 24148 Kiel In the context of this work, the morphological variability of the planktic foraminifera Neogloboquadrina pachyderma was investigated in a number of recent samples from the North Atlantic. Apart from the linear correlation of shell size and the sea surface temperature, none of the others morphological parameters (Radius Ratio, Lobateness, Elongation Ratio, Box Ratio, Compactness Coefficient) showed a relationship to any of the investigated parameters. This linear correlation of the mean shell size and the sea surface temperature has been used to develop a formula, allowing the reconstruction of past sea surface temperatures. Subsequently, this model has been applied to nine samples from a sediment core, located in the Fram Strait, representing the last 20 000 years. The reconstructed temperatures during the Last Glacial Maximum in the North Atlantic are cooler than nowadays but still warm enough to suggest ice‐free conditions during the summer. It is speculated that the relatively mild glacial conditions in the summer in the Nordic seas reflect similar summer insulation (at 60°N) in the LGM as today. Morphometric and stable isotope (δ13C, δ18O) analyses of planktonic foraminiferal cryptic species: new perspectives for paleoceanographic reconstructions Raphaël Morard a*, Frédéric Quillévéré a, Gilles Escarguel a, Yurika Ujiie b, Thibault de Garidel Thoron c, Christophe Lécuyer a, Colomban de Vargas b aUMR CNRS 5125 Paléoenvironnements et Paléobiosphère, Université Claude Bernard Lyon 1, 27‐43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France bUMR CNRS 7144 Evolution du Plancton >et PaleOceans, Station Biologique, BP 74, 29682 Roscoff, France cAix‐Marseille Université, CNRS/INSU, CdF, IRD, CEREGE, Europôle Méditerranéen de lʹArbois, BP 80, 13545 Aix‐en‐Provence Cedex 4, France *speaker [email protected]‐lyon1.fr Calcareous shells of planktonic foraminifera (Globigerininae) extracted from marine sediments are one of the most important fossil remains which constitute a fundamental archive of past climate and paleoceanographic changes. Many environmental parameters of the past oceans, including temperature and primary productivity, can be predicted from the abundance, form and stable isotope composition (δ13C, δ18O) of shells of individual planktonic foraminiferal morphospecies. These predictions are based on the assumption that each morphospecies represents a biologic species with a unique habitat. DNA sequence analyses have challenged morphospecies concepts in planktonic foraminifera and consequent ecological interpretations. These studies have revealed an extensive cryptic (genetic) diversity in all cosmopolitan morphospecies analyzed so far (de Vargas et al., 1999; 2001; 2002; Darling et al., 1999; 2006). Furthermore, they have suggested that the subtle morphological differences known within morphospecies and classically treated as ecophenotypic variants may likely differentiate cryptic species adapted to different environments (Huber et al., 1997; Darling et al., 1999; 2006; de Vargas et al., 1999; 2001; 2002; Kucera and Darling, 2002). In this broad context, it is crucial to distinguish the morphological variability resulting from genetic isolation from that due to ecological plasticity in order to further interpret the paleoceanographic meaning of the planktonic foraminiferal fossil record. Here, we analyzed shell morphology and chemistry among cryptic species of the symbiont‐bearing Orbulina universa and the non symbiont‐bearing Globorotalia truncatulinoides, two morphospecies that have been extensively used as paleoceanographic indices for the late Neogene. In order to further deciphering the environmental significance of morphometric and stable isotope variations among cryptic species, our analyses are based on a new method that allows DNA extractions from single living specimens without destruction of the calcareous shells (de Vargas et al.,
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in prep.). Morphometric analyses of specimens from the Atlantic, Indian and Pacific Oceans demonstrate that the cryptic species are indeed distinguishable based on their porosity (O. universa) or shell outline (G. truncatulinoides). The wide geographic coverage of our study points to the non‐random biogeographic distribution of the cryptic species. This distribution is primarily correlated with the degree of stratification, and thus productivity, of the water column. Finally, isotopic compositions of single‐shell representatives of two cryptic species of O. universa reveal some unexpected δ13C fractionation differences. This suggests that metabolic processes differently affect the δ13C signal among cryptic species of O. universa. We interpret these data as the result of differences in trophic strategy and photosymbiotic‐related ecology linked to specializations at peculiar environments of the world ocean. The Middle Miocene Climate Transition in the central Mediterranean: changing paleoenvironments as revealed by benthic foraminifera Mourik, A.A. 1, Sprong, J. 2, Kouwenhoven, T.J. 1, Abels, H.A.1, Hilgen, F.J. 1, Van der Zwaan, G.J. 1, 3 1Utrecht University, Department of Earth Sciences, Budapestlaan 4, 3584 CD, Utrecht, The Netherlands ([email protected]) 2 Laboratory of Stratigraphy, Department of Geography and Geology, K.U. Leuven, Belgium 3 Faculty of Biology, University of Nijmegen, The Netherlands The Middle Miocene Climate Transition is one of the major steps in Cenozoic climate evolution. After the Mid Miocene Climatic Optimum (~17‐15 Ma), a rapid expansion of the East Antarctic Ice Sheet (EAIS) at 13.82 Ma changed global climate considerably. The associated sea level fall may have affected the already narrowed Tethyan seaway connecting the Atlantic, via the Mediterranean, to the Indian Ocean. Narrowing and closure of the eastern part of this seaway will have caused major changes in ocean circulation both on a regional and a global scale. To gain more insight into the combined effects of climate change and seaway closure on paleo‐environments and circulation patterns, we have analysed benthic foraminiferal assemblages from the Maltese Islands (Malta, Gozo: central Mediterranean). In our studied sequence (~14.9‐13.1 Ma), there is a remarkable transition from limestone (Globigerina Limestone Formation) to clay (Blue Clay Formation), exactly coinciding with the phase of major EAIS expansion. Benthic foraminiferal assemblages of the Globigerina Limestone Formation suggest well‐ventilated bottom waters in the interval preceding the major climate step. After a transitional phase, coinciding with the major climate shift, the assemblages in the Blue Clay Formation indicate changing environments. Possibly this can be related to an increase in organic matter supply and/or decreased ventilation of the basin due to changing bottom‐water circulation. Variations in bottom water trace metal concentrations during the deposition of sapropel S1, as derived from benthic foraminifera S. Ní Fhlaithearta1, F. J. Jorissen2, C. Fontanier2, P. R. D. Mason1, G. J. de Lange1, E. J. Rohling3, J. S. L. Casford4, G.‐J. Reichart 1 & 5 1 Utrecht University, (2) University of Angers 3 Southampton Oceanographic Centre 4 Durham University 5 AWI Bremerhaven The Mediterranean Seaʹs sedimentary record is characterised by the regular recurrence of organic rich layers, known as sapropels. These layers are deposited during precession minima. Hypotheses on the conditions leading to sapropel deposition invoke enhanced fresh water and nutrient input, enhanced primary productivity as well as decreased deep water ventilation. In this study we focus on the youngest sapropel, S1, and use the trace metal composition of benthic foraminifera and their stable isotopic composition to reconstruct bottom water conditions before, during and directly after sapropel deposition. The benthic foraminifer, Hoeglundina elegans, being less susceptible to early diagenetic overgrowth, is analysed by LAICP‐MS (laser ablation‐inductively coupled plasma‐mass spectrometry)
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producing S1 spanning profiles of Ba, Mg, Sr and Mn. In conjunction with carbon and oxygen isotope measurements of Uvigerina sp. and Globobulumina sp. these records constrain bottom water oxygenation history. Particulate versus dissolved organic matter uptake by deep‐sea benthic foraminifera revealed by in situ 13C‐labeling experiments Hidetaka Nomaki*, Nanako O. Ogawa, Hisami Suga, Naohiko Ohkouchi, Hiroshi Kitazato Japan Agency for Marine‐Earth Science and Technology *[email protected] Benthic foraminifera have a variety of feeding ecologies and utilize different food sources on the seafloor. In deep‐sea settings, particulate organic matter such as phytodetritus, surface sediments, and bacteria often constitute the major food sources for benthic foraminifera. Foraminifera gather this particulate organic matter with their reticulopodia and incorporate it to food vacuoles. In addition, direct incorporation of dissolved organic matters like glucose or amino acids by carrier‐mediated transport system via cell membrane has been reported for some agglutinated foraminifera. For some deep‐sea benthic foraminiferal species, dissolved organic matters may be good food sources since a concentration of dissolved organic carbon is possibly more stable thorough the season. In this study, the importance of dissolved and particulate organic carbon to deep‐sea benthic foraminifera was evaluated by conducting in situ 13C‐labeling experiments in the central part of Sagami Bay, Japan (water depth 1453 m). Both 13C‐labeled glucose and Chlorella (Chlorophyta) were injected into a series of in situ‐culture cores and incubated for 1, 2, 9 days, and 1 year. Glucose was chosen as a representative of dissolved organic carbon in the interstitial water, and Chlorella as a representative of phytodetritus. Chlorella was incorporated by foraminiferal species that are known to ingest phytodetritus with various extents ranging from 0.0 to 40% of their cell between species. On the other hand, glucose was incorporated into every examined species with similar extents ranging from 0.1 to 0.3% of their cell. Many foraminiferal species incorporated glucose faster than Chlorella. Results indicate that dissolved organic carbon in the sediments may provide an accessible and abundant food source for many benthic foraminifera while rate and extent of phytodetritus utilizations substantially differ between species. Habitats of Globigerinoides ruber (d’Orbigny) in the eastern Mediterranean Sea since the Marine Isotopic Stage 12 L. Numberger1, CH. Hemleben1, R. Hoffmann1, A. Mackensen2, H. Schulz1, M. Kucera1 1Eberhard‐Karls‐University, Sigwartstr. 10, 72076 Tübingen, Germany 2Alfred Wegener Institute, Columbusstrasse, 27568 Bremerhaven, Germany The chemical composition of shells of planktonic foraminifera, e.g. Globigerinoides ruber (d’Orbigny, white), is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. These results imply either that the morphotypes represent cryptic species which possess different ecological preferences or that the species produces predictable morphological aberrations under different ecological conditions. At any rate, the link between shell chemistry and morphology in G. ruber implies an as yet poorly understood but potentially powerful factor that could be used to better interpret paleoenvironmental data obtained from this species. Here we investigate the presence and distribution through time of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the eastern Mediterranean. In 115 samples from MIS 12‐9 and MIS 2‐1 at ODP Site 964 and the piston core GeoTü‐SL96, we have defined four arbitrary morphological types within the species, determined their relative abundance and stable isotopic composition. We show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the isotopic composition of the types differs. A multivariate analysis of the abundances of the different morphotypes of G. ruber indicates a systematic variation at both sites between warm stages, which are
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characterised by high abundances of the “normal” morphotype and cold stages, which show higher proportions of the type “platys”. An exception to this is observed in MIS 12, which is distinguished by the higher abundance of the “elongate” type. The three abundant morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within individual glacial and interglacial stages and show predictable reversal patterns between glacials and intergalcials, except for MIS10 which is thus characterised not only by a unique composition of G. ruber morphotypes, but also by a unique pattern of isotopic offset among them. Interestingly, the sign of the offset in the stable isotopic composition of individual morphotypes is systematically reversed between the two Sites, except of MIS10, indicating a more uniform upper water column structure and/or seasonal production pattern within the central Mediterranean at that time. This interpretation is consistent with other proxy evidence for anomalously warm surface waters in the eastern Mediterranean during the MIS 10 glacial. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1 per mill, their understanding is essential for the interpretation of all G. ruber – based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary. Assemblages of foraminifera at the continental slope off Western Ireland – influence of variations in bottom current strength and positioning N.L. Owen1, L.T. Toms2, P.D.W. Haughton2, R.J. Edwards3, and P.M. Shannon2 1 Department of Geology, Museum Building, Trinity College Dublin, Dublin 2 2 UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4 3 Department of Geography, Museum Building, Trinity College Dublin, Dublin 2 [email protected] Slopes west of Porcupine Bank on the Irish Atlantic margin have been extensively sampled by gravity cores. This section was selected because it is relatively stable, is known to be / have been swept by northward flowing bottom‐currents, and high resolution seismic profiling reveals that the section is plastered by thin contourite sheets. Four gravity cores have been examined in order to construct a down slope stratigraphy and assess variations in bottom current activity. Sedimentological evidence implies that enhanced bottom currents moved down slope during MIS 2 and peaked in velocity during MIS 3. Stable isotope measurements (delta18O and delta13C) have been obtained from planktonic and benthic foraminifera preserved in gravity core 9/97/10 (1260m water depth) on the western flank of the Porcupine Bank. Alternation between colder and warmer climate episodes can clearly be identified and coincide with changes in texture and sediment composition. Variations in assemblages of benthic foraminifera appear to be primarily controlled by variations in organic matter flux, but a response to bottom currents (particularly by epifaunal taxa) is also apparent, particularly during MIS 3 interstadials. Study of core 9/97/27/II (2756m water depth) has revealed an episode of enhanced productivity preceding Heinrich Event 4. During this interval, the abundance of benthic foraminifera is four times the maximum of any other in the core. The sedimentology of this core does not vary in‐line with stadial‐interstadial climate variations, as can clearly be observed at intermediate depths. Palaeoenvironmental Inferences from Campanian Foraminiferal and Ostracod Assemblages from the Miechów Trough, Southern Poland Peryt, D.1, Witek, A.2, Jaskula, I.2 1 Institute of Paleobiology, Polish Academy of Sciences, 00‐818 Warszawa; Poland. [email protected] 2 Department of Ecosystem Stratigraphy, University of Silesia, 41‐200 Sosnowiec; Poland. The studied section at Jezówka comprises a 8‐m‐thick sequence of carbonate strata divided by a hardground into two complexes. The studied interval represents the upper part of the planktonic foraminifer Globotruncana ventricosa Zone (Globotruncana arca and Globotruncana ventricosa Subzones). Foraminiferal assemblages in the studied interval are moderately to highly diverse. More than 80 taxa were identified at the generic or specific level. The identified taxa represent 4 suborders:
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Globigerinina, Textulariina, Lagenina, Rotaliina. Representatives of Globigerinina and Rotaliina dominate foraminiferal assemblages. P/B ratio values vary from 40 to 70%; keeled forms make 40 to 70% of planktonic foraminiferal assemblages; H(S), the Shannon‐Weaver heterogeneity index is generally high: 2,6‐3,2; number of benthic species in the assemblages exceeds 20 and the proportion of agglutinated tests vary from 3 to 25%. Benthic foraminiferal assemblages are dominated by epifaunal morphogroups. Ostracod assemblages are represented by 2 suborders: Platycopida and Podocopida. More than 50 species were identified. High incidence of platycopids indicate low oxygen environments. They form 30 to 55% of the studied assemblages. High proportion of planktonic foraminifera within assemblages, high values of the H(S) diversity index of benthic foraminiferal assemblages and predominance within ostracod assemblages of intermediate ‐ deep water species indicate an outer shelf environment with a shallowing episode during formation of the hardground on the boundary between Globotruncana arca and Globotruncana ventricosa Subzones. It is correlated with the Mid‐Campanian Event. High contribution of keeled forms to planktonic foraminiferal assemblages, high proportions of epifaunal morphogroups within benthic foraminiferal assemblages and low to moderate contribution of platycopids to the ostracod assemblages indicate mesotrophic to oligotrophic surface waters and generally aerobic bottom‐water conditions with a few short episodes of less oxygenated bottom‐waters. Experimental dissolution studies on lower Eocene foraminiferal assemblages from Egypt T.M.Phuong Nguyen and Robert P. Speijer Department of Earth and Environmental Sciences, K.U Leuven, Celestijnenlaan 200E, 3001 Leuven, Belgium. [email protected] We carried out dissolution experiments on a foraminiferal assemblage from a marl sample (lower Eocene GSSP, Dababiya, Egypt), in order to unravel the impact of dissolution on planktic/benthic ratios and the composition of benthic and planktic foraminiferal assemblages. The well‐preserved assemblage consists of 95% planktics, and represents open marine deposition in a deep epicontinental basin. Our results corroborate results from previous studies, which show that P/B ratios (%P) reduce withincreasing dissolution and that the absolute numbers of planktics and benthics both decrease withexposure time. However, planktic foraminifera decrease much faster than benthics, pointing to a higher susceptibility of most planktics. Comparison between size fractions confirms the expectation that the smaller specimens dissolve significantly faster than larger ones. Consequently, increasing dissolution causes a shift towards higher relative abundance of larger specimens. Our results also provide information on the relative susceptibility of different taxa to dissolution. During the experiment, the planktic assemblage first looses the smooth, finely perforate Globanomalina, then the non spinose, microperforate Zeauvigerina and Chiloguembellina, followed by the cancellate Subbotina. Consequently, planktic assemblages gradually become enriched in the muricate Morrozovella and Acarinina. Among the benthics, the small Tappanina disappeared first, followed by the miliolid Spiroloculina and serial taxa, and eventually rotaliines. Consequently, the benthic assemblage becomes increasingly dominated by Lenticulina spp. and textulariines (Gaudryina spp.). Taken together, dissolution leads to assemblages with reduced absolute numbers and P/B ratioʹs and enhanced relative numbers of muricate planktics, Lenticulina and textulariines. Assemblages similar to the latter have been widely observed in lower Paleogene sequences in the region. The experimental results confirm our suspicions on the quality of these assemblages and they allow us to differentiate between primary environmental signals and taphonomical overprint. In general, assemblages characterized by a low P/B ratio, low foraminiferal numbers, and high relative numbers of arenaceous and robust calcareous taxa within (hemi) pelagic sediments are not suitable for paleoenvironmental reconstructions.
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Foraminiferal test abnormalities as proxies of environmental change in SW Baltic Sea Irina Polovodova, Joachim Schönfeld and Wolf‐Christian Dullo Leibniz Institute for Marine Sciences IFM‐GEOMAR, Wischhofstr. 1‐3, 24148, Kiel, Germany, ipolovodova@ifm‐geomar.de The living benthic foraminiferal assemblages in Flensburg and Kiel fjords (SW Baltic Sea) were investigated in the years 2005‐2007. The faunal studies were accomplished by geochemical analyses of surface sediments. Abnormal tests were commonly found in recent benthic foraminiferal assemblages in Kiel Bight, western Baltic Sea. We assessed 18 different modes of malformations, which were classified into 5 groups: chamber‐, aperture‐, umbilicum‐, coiling‐ and test‐ abnormalities. In both fjords different types of test abnormalities are over‐represented in Ammonia beccarii and under‐represented in Elphidium excavatum subspecies compared to their average proportions in the living assemblages. We found two species‐specific abnormality types (bulla‐like chamber covering the umbilicum and spiroconvex tests), which occurred only in Ammonia beccarii. In outer Kiel and Flensburg fjords the highest frequencies of abnormal tests were associated with occasional salt‐rich bottom waters inflows from the Belt Sea. It is suggested that coincidence of salinity changes with a reproduction period might be harmful, especially for young individuals, leading to development of abnormal tests. On the other hand, pollution by heavy metals led to higher percentages of abnormal tests in the inner parts of both fjords. Our data indicate a non‐linear response of abnormal tests to heavy metals content of surface sediments and enhanced sensitivity of certain abnormality modes only. Tests of Ammonia beccarii found in Gelting Bay, Flensburg Fjord showed traces of dissolution and development of double tests. Such specific abnormal tests mirror the peculiar environmental setting characterized by changes in salinity and enhanced sediment redeposition. This study shows that within a certain area the naturally induced development of abnormal foraminiferal tests might be higher than human induced one. Thus, the abnormal foraminiferal tests as an indicator of environmental pollution must be used with care, especially in areas exhibiting the high natural variability. Living planktic foraminifera in hemi‐pelagic environments Retailleau, S.1, Howa, H. 1, 2, Schiebel, R.3, S. Terrien1, Jorissen, F.1, Labeyrie, L.4 1 Laboratory of Recent and Fossil Bio‐Indicators, UPRES EA 2644, Université d’Angers, France sophie.retailleau@univ‐angers.fr 2 Laboratory of Marine Bio‐Indicators Study, Ile d’Yeu, France 3 NOCS, University of Southampton, UK 4 LSCE‐CNRS Gif‐sur‐Yvette, France Planktic foraminiferal population dynamics in hemi‐pelagic habitats are assumed indicative of regional hydrography and ecology (cf. Parker, 1973; Brinton, 1986; Ortiz et al., 1995). We have analyzed planktic foraminiferal population dynamics from the inner southern Bay of Biscay, as part of the French national research project FORCLIM (Howa et al., 2007). Three cruises on R/V Côte de la Manche were performed in June 2006, April 2007, and November 2007. Planktic foraminifers were sampled by means of plankton tows (mesh size 100 μm) at water depth intervals of 0‐20‐40‐60‐80‐100 m, 12 km offshore, at 145 m water depth. Simultaneously, temperature, salinity, oxygen, and fluorescence, were recorded by CTD profiles. Samples were stained with Rose‐Bengal solution to discriminate living from dead specimens. Highest standing stocks of planktic foraminifers of 90 specimen/m3 occurred in November. In June, and April, maximum standing stocks of 14 sp./m3 and 31 sp./m3 were present, respectively. The species assemblage resembles that of the outer Bay of Biscay (Pujol, 1980) and the open North Atlantic (Schiebel and Hemleben, 2000). Despite the water depth of only 145 m, subsurface dwelling Globrotalia scitula and Globorotalia inflata were observed during all three sampling periods. Differences in species assemblages and standing stocks are compared to environmental parameters. Standing stocks were small when surface water salinity during April was low (~29‰), and possibly inhibited production of shallow dwelling species. A strong thermocline recorded in June caused nutrient limitation in surface waters and limited biological productivity,
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causing low standing stocks of planktic foraminifers. In contrast, highest standing stocks occurred during November when the water column was well mixed, and nutrient entrainment supported biological production. The presence of subsurface dwelling species at shallow waters is interpreted as a reaction to the availability of refractory organic matter from surface sediments. Seasonal evolution of the foraminifer fluxes in the Northwest Mediterranean based on the study of a 12‐year‐long sediment trap record Rigual‐Hernández, A.S.1,*, Bárcena, M.A.1, Sierro, F.J.1, Flores, J.A.1 and Heussner, S.2 1Área de Paleontología, Departamento de Geología, Universidad de Salamanca. CP 37008 Salamanca. 2CEFREM, UMR 5110 CNRS‐ University of Perpignan Via Domitia 52 avenue Paul Alduv, 66860 Perpignan Cedex, France * Corresponding author. Tlf. 0034 637223439. E‐mail: [email protected] We studied the annual evolution of the planktonic foraminifer assemblages through the analysis of two sediment trap records from the Gulf of Lions (Northwest Mediterranean). Sea surface circulation in this region is the result of the interaction between the Northern Current and wind‐driven currents along the continental shelf. Particle fluxes to the sea floor were controlled by changes in sea surface circulation and primary productivity, which underwent strong annual cycles. To investigate seasonal and annual changes in particle fluxes over the last decade two sediment traps were deployed in the middle part of the Planier and Lacaze‐Duthiers canyons and samples were taken monthly or fortnightly from 1993 to 2006. Although eleven planktonic foraminifer species were recognized in our study, the assemblage was generally dominated by Globigerina bulloides, Neogloboquadrina pachyderma, Globorotalia inflata and Globorotalia truncatulinoides. The foraminifer assemblages in both sediment traps show a clear relationship with the seasonal changes of stratification of the water column and the spring phytoplankton bloom. Globigerina bulloides is the dominant species in both records and its distribution is closely related with the primary productivity cycles. The seasonal distribution of Neogloboquadrina pachyderma and Globorotalia inflata seems to be mainly controlled by water temperature, and secondarily by the primary productivity. Globorotalia truncatulinoides is an abundant species at times of strong vertical water mixing, which usually occurred in winter in this region. Temperature and primary productivity seem to play a secondary role on the distribution of this species. Coccolithophorid assemblage variations in ODP site 1233 (South Pacific) covering the last 70 kyr, focusing on Termination I. M. Saavedra‐Pellitero, J.A. Flores and F.J.Sierro Departamento de Geología, Universidad de Salamanca, Plaza de la Merced s/n 37008, Salamanca, España. [email protected] ODP site 1233 is located 40 km offshore Southern Chile (41°0,01’8217’’ S, 74° 26,99’ W at 838 m water depth) in a small fore‐arc basin on the upper continental slope isolated from turbidity currents. At this location, the mean sedimentation rates were extremely high (ca. 100cm/kyr) during the Holocene and the records show a pronounced variability (in compositional changes, and in marine and oceanic paleoenvironments; Lamy et al., 2004) on multi‐centennial to millennial timescales (Mix et al., 2003). Given these characteristics, ODP site is very sensitive to even small past oceanographic changes. The lack of high resolution paleoceanographic records from the South Pacific during the last glacial period and the succeeding deglaciation, led us to study the biological responses to climatic events in this region over the last 70ky using coccolithophores. The coccolith record has been shown to be responsive to millenial‐scale oscilations and variations in the position of current systems. Smear slides were prepared to assess the relative abundance of coccolithophore taxa and coccoliths fluxes using the Flores and Sierro technique (1997), using a petrographic microscope (1000X). Additional studies were performed under Scanning Electron Microscope, using a combined technique of filtration and dilution (Andruleit, 1996). One focus of this study was the last deglaciation, Termination I. Given this focus,
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the resolution was increased during the time interval from ~24kyr to ~10kyr. A high productivity was interpreted during glacial period and a marked decrease during deglaciation, based on the absolute abundance of coccoliths obtained. Variations of coccolithophore assemblages point out cold and warm consecutive episodes. Combining morphological with genetic characters: Single cell analysis on coccolithophores from plankton filter samples Scherrer, S., Brupbacher, U. and Thierstein, H. R. Geological Institute, ETH Zürich, Universitätsstr. 6, CH‐8092 Zürich, Switzerland. [email protected] DNA sequence information of coccolithophores is currently largely restricted to cultured species representing only a minor fraction of all extant coccolithophore taxa. For a better understanding of the complete coccolithophore phylogeny, as well as the inter‐ and intraspecific genetic variation, it is essential to investigate environmental samples and to analyze natural populations. We have shown before that genomic DNA is present on plankton filter samples and can be amplified by PCR with specific primers (Scherrer et al., oral contribution at TMS spring meeting 2007). However, the sequence spectrum obtained was not entirely representative of the species diversity present on the filter, impeding the connection of genetic to morphological data. Sequence abundances were presumably biased by the PCR reaction. We have now developed a method to characterize both morphological and genetic characters within single cells: Single cells were cut out from filters by laser capture microdissection (LCM) resulting in small filter sections, each containing only one cell. These pieces were then investigated morphologically in the SEM. For genetic analysis, microsections were transferred after SEM examination to tubes for PCR amplification and subsequent sequencing. Being able to genetically characterize single cells after morphological examination by SEM allows us to address the open question to what extent coccolith morphology is influenced by environmental (phenotypic plasticity) and by genetic factors. Stored plankton filter material can therefore be used to assess morphological and genetic variation of individuals in natural environments within one species. Moreover, samples of uncultured species can be genetically analyzed to get a more complete and accurate picture of coccolithophore phylogeny. Benthic foraminifera from Coral Mounds in the Porcupine Seabight (NE Atlantic) Schönfeld, J., Dullo, W.‐Chr., Pfannkuche, O., Rüggeberg, A. and Flögel, S. Leibniz‐Institute of Marine Sciences IFM‐GEOMAR, Wischhofstrasse 1‐3, 24148 Kiel; Germany. jschoenfeld@ifm‐geomar.de Cold‐water coral ecosystems are characterised by a high diversity and population density in a strong hydrodynamic environment. In this study, we focus on the distribution and ecology of foraminifera from Galway and Propeller Mounds in the Porcupine Seabight. Epibenthic species are major constituents of the living and dead foraminiferal assemblages. In the living fauna, attached species showed higher population densities at elevated positions and features of active habitat selection. Clustering, the occupation of exposed edges, and the recruitment on other epizoans infer a response to the prevailing hydrodynamic regime. Correspondence and factor analyses revealed, however, that among the elevated species only Discanomalina coronata shows a covariance with near‐bottom current velocities. The distribution of endobenthic foraminifera around Galway Mound follows the biofacies patterns as defined by the macrobenthos. But one small patch has been observed at the southern flank of the mound where in particular Melonis barleeanum and Uvigerina mediterranea, are unusually frequent. The local hydrodynamics, oxygenation of near‐bottom waters and the mound geometry depicts this place as a zone of enhanced sediment baffling and accumulation of particulate organic mater. The benthic foraminiferal assemblages from coral mounds well fit into basinwide‐scale distribution patterns of species along the western European continental margin. The diversity of the foraminiferal faunas, as displayed by Fisherʹs alpha index, is not higher on the carbonate mounds as in
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their vicinity. Nonetheless, the living benthic foraminiferal assemblages show a broad ʺmid‐slope diversity maximumʺ between 700 and 1000 m water depth, which is the depth interval of coral mound formation at the Irish and Armorican Margin. The foraminiferal diversity maximum is about 1000 m shallower than comparable maxima of other organisms, for instance nematodes and gastropods. Coccolithophorid calcification in a high CO2 ocean: from organism to ecosystem K. G. Schulz, U. Riebesell Leibniz Institute for Marine Sciences (IFM‐GEOMAR), Kiel, Germany kschulz@ifm‐geomar.de Anthropogenic carbon dioxide (CO2) released mainly by the combustion of fossil fuels currently changes the oceansʹchemistry. Increasing surface water CO2 concentrations decrease ocean pH and carbonate saturation state. Coccolithophores, at the base of the marine food web, are unique primary producers as they utilize dissolved inorganic carbon such as CO2 not only in photosynthetic carbon fixation but also by calcium carbonate precipitation. Both processes, particulate organic and particulate inorganic carbon production in coccolithophores have been shown to be sensitive to changing carbonate chemistry in the ocean. While highly controlled laboratory experiments can provide process based understanding at the organism level, mesocosm setups such as the Pelagic Ecosystem CO2 Enrichment studies (PeECE) are ideal for perturbation experiments at the ecosystem level. Integrating both approaches is necessary for predicting the future of marine coccolithophores in a high CO2 ocean. Molecular identification of an Ammonia species (Foraminifera, Rotaliida) from the Kiel Fjord (Germany) Magali Schweizer1, Anna Nikulina2, Irina Polovodova2, Joachim Schönfeld2 1 Geologisches Institut, ETHZ, Universitätstrasse 6, 8092 Zürich; Switzerland. [email protected] 2 Leibniz Institute for Marine Sciences IFM‐GEOMAR, Wischhofstr. 1‐3, 24148, Kiel, Germany The foraminiferal genus Ammonia is well known for the complexity of its taxonomy. Despite detailed molecular studies, there are still many discussions regarding the recognition of Ammonia species based on morphological criteria. Here we obtained DNA from several specimens belonging to an Ammonia population in the inner Kiel Fjord. Specimens were collected alive, picked, dried and imaged with an SEM prior to DNA extraction. DNA was extracted and amplified with foraminiferal specific primers for regions of the small subunit (SSU) and the large subunit (LSU) of ribosomal DNA (rDNA). The SSU region studied here is widely used in foraminiferal molecular phylogenies and gives a first idea of the taxonomic position for the sampled Ammonia. However, former molecular studies of Ammonia were performed on a region at the beginning of the LSU. This gene has been preferred because it is more variable than the SSU. Therefore we performed phylogenetic analyses with our LSU sequences and the ones deposited in GenBank by Maria Holzmann. The molecular phylogeny obtained from the LSU partial gene indicates that the Ammonia specimens collected in the Kiel Fjord belong to clade T6, which has been identified as Ammonia aomoriensis (Asano, 1951). This genotype has also been recognized in shallow seas around Japan and China, as well as the Dutch and German Wadden Sea (Mok Bay (NL) and Wilhelmshaven (D)). The occurrence of the same genotype in two remote shallow‐water populations isolated from each other could be facilitated and sustained by migratory birds or water used as shipsʹ ballast.
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How similar are morphological and genetic diversities recognizable on a typical plankton filter? Magali Schweizer1, Hans R. Thierstein1, Hartmut Schulz2 1 Geologisches Institut, ETHZ, Universitätstrasse 6, 8092 Zürich; Switzerland [email protected] 2 Institut für Geowissenschaften, Eberhard‐Karls‐Universität Tübingen, Sigwartstrasse 10, 72076 Tübingen; Germany Coccolithophore sequences currently available from GenBank concern almost exclusively cultured strains. Recently, it has been shown that it is possible to retrieve DNA from dried filters (Scherrer et al., oral contribution, TMS meeting 2007). This opens new perspectives for research on environmental coccolithophore samples collected by filtration. Here we evaluate how easy it is to link SEM observations of coccolithophores and other organisms with DNA sequences obtained from a single filter piece. For that purpose, we cut small filter fragments containing low numbers of planktic organisms collected in September 2007 at different depths in the Arabian Sea. The filter fragments were coated and scanned in a SEM to document all the recognizable organisms on them; DNA was then extracted from each filter piece. The DNA extractions were amplified with universal and specific primers for SSU rDNA and the positive amplifications were cloned. A total of about 70 different clones were obtained from different primer sets (universal eukaryotic primers and primers specific for Prymnesiophyceae). All clones were sequenced and the results were compared with the SEM inventory previously obtained. None of the coccolith bearing taxa recognizable with the SEM was identified in the DNA sequences. The majority of the sequences belong to Prymnesiophyceae that bear no hard parts (Isochrysidaceae and Pleurochrysidaceae) and were therefore not identified in the SEM. New primers are currently being developed to specifically amplify coccolith bearing taxa that may have been out‐competed by naked ones during amplification. Stable Isotope record in Pleistocene Coccoliths Recovered in Western Mediterranean and North‐Western Africa D. Simón‐Baile1, 2, P. Ziveri2, J.A. Flores1, F.J. Sierro1 1 Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain 2 ICTA, Universitat Autónoma de Barcelona (UAB), Edifici Cn ‐ Campus UAB, 08193Bellaterra, Spain Restricted coccoliths fractions were analyzed for oxygen and carbon isotopes to reconstruct variations in oceanographic conditions and marine productivity during the last 20Ky, and to assess the interactions and latitudinal gradient between the Western Mediterranean Sea (WM) and the North‐Western African margin (NWA). We selected here the two high giant CALIPSO piston cores, MD95‐2043 and MD03‐2705 recovered during Marion Dufresne cruises at 36°N‐2°W from the Alboran Sea (WM) and at 18°N‐21°W off Mauritania‐Senegal (NWA), respectively. Repeated decanting and microfiltering techniques allow separation and concentration of sediment fractions dominated to high degrees by the coccolith carbonate from a single species. The cosmopolitan Emiliania huxleyi and the surface dwellers Helicosphaera carteri and Calcidiscus leptoporus were isolated from every sample even when its abundance in the original sample was low. Different fractions from the same site show offsets in the isotopic ratios that coincide with the range of non‐equilibrium effects obtained from previous culture experiments, suggesting that this disequilibrium or ʺvital effectsʺ could be used as a proxy for different coccolithophore responses to ecology changes. As a marginal sea dominated by evaporation, the Mediterranean is a particularly sensitive system to climate changes. It registers and amplifies the smallest climatic changes occurring at the mid‐latitude regions. In general, the major source of nutrients is the Atlantic Ocean. The satellite derived current primary productivity shows higher values in the Atlantic margin consistent with the general trend of our core results for the chosen time interval. The coccolith results will be compared with foraminifera and other possible non‐temperature related influence on isotope fractionation will be considered. Keywords: Coccoliths, stable isotopes, Mediterranean, North Atlantic.
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3D‐imaging and quantification of foraminifera with high‐resolution X‐ray CT Robert P. Speijer1, Denis Van Loo2, 3, Bert Masschaele2, Veerle Cnudde2, 4 and Patric Jacobs2, 4 1 Department of Earth and Environmental Sciences, K.U.Leuven, B‐3001, Leuven, Belgium 2 UGCT, Centre for X‐ray Tomography, Ghent University, B‐9000, Ghent, Belgium 3 IBiTech, Institute Biomedical Technology, Ghent University, B‐9000, Ghent, Belgium 4 Department of Geology, Ghent University, B‐9000, Ghent, Belgium [email protected] High‐resolution X‐ray CT (HRXCT) enables 3D‐imaging and biometric quantification of foraminifera. In this paper we exemplify the basic possibilities and opportunities of this new technique by means of analyses on various planktic and benthic taxa. The X‐ray scan consists of 1200 individual radiographs which, after reconstruction with Octopus software, provides virtual cross sections each <1 micrometer apart perpendicular to the coiling axis or in any other preferred direction. These cross sections can be used for the 3D depiction with VGStudioMax, showing an exterior view and interior structures. Due to the high density contrast between the hollow chambers and the testʹs calcite and by using Morpho+ and Mimics software the chambers can be accurately segmented. The segmentation also provides the numeric key information on ontogenetic growth, as the volume of each chamber can be accurately measured in cubic micrometers. Several 3D parameters can be determined with this technique, such as volume, surface area of the aperture, and equivalent radius. The equivalent radius (i.e. the radius of a sphere corresponding to the measured volume), which we used in this study, is independent of shape and is a particularly useful parameter for visualizing the exponential growth patterns in foraminifera. The use of HRXCT could open up a new era in fundamental biometric‐evolutionary research on foraminifera. In particular, intraspecific variation and phylogenetic relationships between species can be assessed on the basis of measured shapes and sizes. Such data also provide a new means of morphologic evaluation of molecular phylogenies and cryptic species that are widely used in paleoceanographic and paleoclimatic research, and provide testing ground for theoretical growth models of foraminifera. Upper Danian lower Selandian stratigraphy and paleoenvironment along a paleobathymetric transect in the Nile Valley Basin (Eastern Desert, Egypt) J. Sprong1, R.P. Speijer1, A. Bornemann2, E. Steurbaut1, 3, P. Schulte4, M. Youssef5 1 Department of Earth‐ and Environmental Sciences, K.U.Leuven, Leuven, Belgium 2 Institut für Geophysik und Geologie, Universität Leipzig, Leipzig, Germany 3 Royal Belgian Institute of Natural Sciences, Brussels, Belgium 4 Institut für Geologie und Mineralogie Universität Erlangen‐Nürnberg, Erlangen, Germany 5 Geology Department, South Valley University, Qena, Egypt [email protected] We performed a benthic foraminiferal study on five sections in the Egyptian Nile Valley basin in order to quantify a prominent sea‐level fluctuation within the Danian‐Selandian transition. A sea‐level fluctuation of ~75 m is recorded at a level with conspicuous marker beds (the upper Danian event beds) in the homogeneous marl sequences of the Dakhla Fm. Assemblages in the most northerly sections, Qreiya and Araas, are very similar, with an outer neriticbathyal benthic foraminiferal assemblage (zones P2‐P3a). The shallower Aweina and Duwi sections contained fewer bathyal taxa. A shift towards a middle‐outer neritic assemblage is observed several meters below the upper Danian event beds in the shallower settings, and immediately below those beds in the deeper sections of Qreiya and Araas. The upper Danian event beds, indicating transgressive conditions, interrupt this shallowing (P3a/P3b boundary). This transgressive phase is associated with severe anoxia and eutrophication leading to absence of benthic life. A low diversity middle‐neritic benthic assemblage, characterized by Neoeponides duwi, returned when oxygenation had improved somewhat. As sea level continued to rise and oceanographic conditions normalized, river discharge (in the Nile Valley) and upwelling (in the Duwi area) probably retreated further south and sea‐floor oxygenation improved. Consequently, the normal bathymetrically arranged benthic assemblages reappeared in the
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studied region. The upper Danian event beds in Egypt correlate with glauconitic beds related to a sea‐level fluctuation in the Tunisian Through. Considering the differences in depositional settings between those areas, the local sea‐level fluctuations were part of a regionally significant sea‐level cycle. Foraminiferal response to abrupt warming during the PETM, a reconstruction of a coastal paleoenvironment in Tunisia STASSEN Peter1, DUPUIS Christian2, STEURBAUT Etienne1, 3 and SPEIJER Robert P.1 1Department of Earth and Environmental Sciences, K.U.Leuven, Belgium ([email protected]) 2Faculté Polytechnique de Mons, Belgium 3Department of Paleontology, Royal Belgian Institute of Natural Sciences, Brussels, Belgium The climate record of the late Paleocene‐early Eocene consist of a long‐term trend of global warming that culminated in the highest ocean temperatures of the Cenozoic. During this long‐term trend, one of the most abrupt Cenozoic global warming events took place, the Paleocene‐Eocene Thermal Maximum (PETM). Despite the large number of studies on the PETM in marine environments, our knowledge of the faunal responses in shallow marine environments remains quite poor. The Sidi Nasseur and Wadi Mezez sections in Tunisia give extra insights in the complex interactions between temperature, oxygen levels and productivity. The sections expose upper Paleocene to lower Eocene shales and marls of the El Haria Formation up to the phosphatic layers underlying the Metlaoui Limestones. The TOC δ13Corg record reveals a 4‰ negative excursion very similar to the δ13Corg record of Dababiya in Egypt (GSSP) which marks the base of the Eocene. The Paleocene foraminiferal assemblages consist of numerous calcareous benthic foraminifera (e.g. Anomalinoides midwayensis, Frondicularia phosphatica). These, together with arenaceous foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. A sharp faunal turnover marks the disappearance or diminution of many common Paleocene taxa. In the following PETM interval, benthic foraminifera are less frequent and consist of opportunistic arenaceous taxa together with lagenids, bi‐ and triserial calcareous forms. Planktic foraminifera become abundant, suggesting an increase in water depth, comparable with the planktic excursion assemblage observed within the PETM worldwide. More mysterious is the increasing abundance of spines and shell fragments of burrowing echinoids. All these faunal parameters suggest more stressed probably food‐rich and/or oxygen‐poor sea‐floor conditions during the PETM. The following Eocene recovery fauna is mainly composed of lenticulinids and typical bi‐, triserial forms indicating more restricted coastal or lagoonal eutrophic conditions. Mg/Ca ratios and stable isotopes in three Globigerinoides ruber (white) morphotypes of the tropical and subtropical South Atlantic: a first step towards morphotype‐specific Mg/Ca‐temperature calibrations Stephan Steinke1, Anne Seidenglanz2, Jeroen Groeneveld1, Ed Hathorne1, Rebecca Rendle‐Bühring1 1 MARUM ‐ Zentrum für Marine Umweltwissenschaften, Universität Bremen, Bremen, Germany (ssteinke@uni‐bremen.de) 2 School of Ocean Sciences, Bangor University, Wales, UK Traditionally, planktonic foraminifera species and their elemental and isotopic signatures are used under the assumption that the species being used to provide proxy palaeoenvironmental information is genetically continuous with a unique habitat and a single environmental preference. Recently discovered genetic diversity in planktonic foraminifera now poses significant problems for these assumptions. It is suggested that morphological variability within recent populations of planktonic foraminifera is related to genetic variability and environmental adaptation causing geochemical (e.g. Mg/Ca, d18O, d13C) variability. Here we present a comparison of Mg/Ca ratios and stable isotopes on sample pairs of three G. ruber (white) morphotypes ‐G. ruber sensu stricto (s.s.) and G. ruber sensu lato (s.l.; ʹcompactʹ and ʹelongateʹ)‐ from surface samples of the tropical and subtropical South Atlantic. The
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purpose of this study is to understand environmental adaptations and to examine the relationship between morphological variability and isotopic and trace metal composition within planktonic foraminifera G. ruber (white). G. ruber s.s. refers to specimens with spherical chambers sitting symmetrically over previous sutures with a wide, high arched aperture. G. ruber s.l. ʹcompactʹ refers to a more compact test with a diminutive final chamber and small aperture whereas G. ruber s.l. ʹelongateʹ is characterized by an elongated shape. The G. ruber s.s. specimens generally show significantly higher Mg/Ca ratios compared to ʹcompactʹ and ʹelongatedʹ forms. First calibration results for the three morphotypes indicate temperature dependencies of 4.1%, 4.8% and 7.1% increase in Mg/Ca per °C for G. ruber s.s., G. ruber s.l. ‚compactʹ and ‚elongateʹ, respectively. This study represents a first step towards the establishment of morphotype‐specific Mg/Ca‐temperature relationships to quantify possible effects of change in the proportion of distinct morphotypes in a population through time. Coccolith assemblages and coccolith isotope signals as a proxy for the reconstruction of the Last Glacial in the North Atlantic Katharina Stolz 1, Karl‐Heinz Baumann 1, Patrizia Ziveri 2, and Rüdiger Henrich 1 1 FB 5 Geosciences, University of Bremen, Postfach 330 440, 28334 Bremen; Germany (kstolz@uni‐bremen.de) 2 Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra (Barcelona); Spain. The analysis of coccolith assemblages and coccolith isotope signals was done to document the changes in surface‐ocean circulation, and therewith the changes in primary productivity in the subpolar North Atlantic during the last Glacial. Our records were generated using sediments from ODP Site 980, located on the eastern flank of the Rockall Plateau. This site has a high potential to strongly react to climatic and oceanographic changes within the last Interglacial/Glacial cycle. Analyses of δ18O from foraminifera and the abundance of the polar species Neogloboquadrina pachyderma (s.) as well as the input of IRD show large‐amplitude, millennial‐scale fluctuations (McManus et al., 1999). The studied coccolith assemblage shows drastic changes in numbers throughout the glacial record, with total numbers of coccoliths much lower than in the previous Interglacial. Within the major cooling trend of this period, several cooling phases can be pointed out. The assemblage is dominated by Emiliania huxleyi. The interstadials are indicated by fluctuations in the occurrence of Calcidiscus leptoporus and the subtropical form Syracosphaera pulchra. Their high abundances denote an enhanced influence of the warm North Atlantic Current (NAC). A decrease of numbers in the coccolith assemblage in the stadials (sometimes connected with Heinrich Events) points to a weakened influence of the NAC, an enhanced inflow of cold polar waters from the North, and therewith a climatic and ecologic deterioration. Furthermore the analysis of different E. huxleyi morphotypes gives hints to the alternating inflow of colder and warmer surface water masses. In addition to using the coccolith assemblages for palaeoenvironmental reconstructions, we will also present data on the stable isotope analyses of the fine fraction (<20μm), as well as of some selected and separated coccolith species. A new model of foraminiferal calcification pathways in shallow benthic foraminifera: miliolids vs hyaline species Toyofuku, T., de Nooijer Jan Lennart, Nomaki, H., Oguri, K. and Kitazato, H. Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Natsushima‐cho 2‐15, Yokosuka 237‐0061, JAPAN [email protected] The magnesium‐calcium (Mg/Ca) ratio of foraminiferal calcite is positively correlated with ambient sea water temperature and therefore, Mg/Ca ratios of fossil foraminifera have become a popular tool to reconstruct paleo‐sea water temperatures. Foraminiferal magnesium contents, however, varies not only with temperature but also with seawater pH and salinity. In addition, there is considerable variability between species and within specimens. Despite its abundance in seawater (approximately 5
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times higher than calcium), calcitic test of most hyaline species display very low Mg/Ca ratios. This indicates that foraminifera themselves control the chemical composition of the fluids from with calcite is precipitated, for example by actively discriminating Ca ions and Mg ions after vacuolization of sea water. Differences in the Mg/Ca ratios between hyaline and miliolid species may indicate that such mechanisms may be related to their different calcification pathway. In this study, we measure foraminiferal Mg/Ca ratios in miliolids (precipitating high‐Mg calcite) and hyaline (both low‐Mg and high‐Mg) species through culturing studies. The Mg/Ca indicates a strong positive correlation with ambient temperature for all species. However, the absolute amount of incorporated Mg differs from species to species. Internal Ca ions concentrations and pH can now be visualized in living and calcifying foraminiferal cells by recently applied fluorescent probes to analyze physiological management of the calcification pathway. Stored Ca ions are transported to the calcification site during chamber formation and are consumed during calcite precipitation. Foraminiferal pH shows lower than ambient values (<~6) after sea water vacuolization, with values in between (~7.5) towards the aperture. In contrast, a mosaic‐like high pH (~8.5) distribution or high pH zone (>~8.5) was observed during calcification. The low pH (<~6) conditions were kept at large parts of the cell except for around the site of precipitation. These results are integrated to construct a new model of chemical control on calcification fluids and on calcite precipitation in hyaline and miliolid species. The evolutive turnover of benthic foraminifera in the images Site 97‐2114 (SW Pacific Ocean) During the middle Pliestocene Transition Trattenero I. & Mancin N. Dipartimento di Scienze della Terra, Università degli Studi di Pavia, Via Ferrata 1, 27100 Pavia (Italy) Corresponding author: [email protected] This work aims to improve the knowledge of the evolutive turnover of benthic foraminifera, known as “Stilostomella Extincion”, occurred during the Middle Pleistocene Transition (MPT). This time interval (1.25 ‐ 0.7 My) records a gradual transition from high‐frequency (41 kyr) to low‐frequency, high‐amplitude climate cycles (100 kyr), therefore, it represents an interval of re‐arrangement of the oceanographic circulation and climate system at a global scale. During the MPT, benthic foraminifera assemblages record a global evolutive turnover, which begins approximately at the MIS 25/24 transition and ends at the MIS 15/14 transition and is characterized by the extinction of most of the uniserial and elongated taxa, with an average rating of 23% extinct species per My instead of 5‐11% species per My recorded during the whole Cenozoic. The oceanic core studied, come from the IMAGES site MD 97‐2114 (SW Pacific Ocean) located on the northeastern slope of the Chatham Rise (New Zealand) at middle bathyal water depth. The core studied is approximately 30 m length and covers a substantially continuous time interval of 1,07 Myr as inferred from bio‐magnetostratigraphic and isotope data. Preliminary results can be summarized as follows: in the studied MD 97‐2114 site the dynamics of the “Stilostomella Extinction” are quite well recorded in agreement with the literature data. In particular, the relative abundances of the infaunal elongate‐uniserial taxa, belonging mostly to the orders Stilostomellidae and Pleurostomellidae and to the superfamily Plectofrondiculariina, show a strong and positive correlation with the major climate cycles: they decrease during cold climate intervals and are recovered during warm climate intervals. Since MIS 25/24 boundary, the recovery doesn’t compensate the loss occurring in the cold intervals, leading to a first decreasing trend. A second decreasing phase in recorded around the MIS21/20 boundary and culminate with the total disappearance of the elongate‐uniserial taxa at the MIS 14/13 boundary.
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Multi‐proxy reconstruction of Holocene paleoceanography in the Red Sea Gabriele Trommer1, Michael Siccha1, Hartmut Schulz1, Christoph Hemleben1, Katharine Grant2, Eelco Rohling2, Michal Kucera1 1Institute of Geosciences, Eberhard‐Karls University of Tuebingen, Germany 2National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK gabriele.trommer@uni‐tuebingen.de The Red Sea is characterised by strong environmental gradients co‐varying along the N‐S axis of the basin. Although the circulation system is at present mainly controlled by the Indian Monsoon, the Red Sea is also influenced by Mediterranean climate. In order to evaluate the different contributions of these two climate systems on the Red Sea basin through time, we investigated the Holocene record of two cores (KL17 in the northern and KL9 in the central Red Sea) by XRF and colour core scanning and micropaleontological methods. The northern Red Sea core features two sapropel layers at app. 9400 and 11000 yrs BP, which are not present in the core from the central Red Sea, indicating probably an enhanced contribution of the Mediterranean climate system. Despite of these differences, the general trend in the composition of the planktonic foraminiferal community of both cores is very similar. G. sacculifer abundances decrease from the early to mid Holocene in both cores, while recently G. sacculifer dominates in the northern and G. ruber in the central Red Sea. Faunal counts further indicate a distinct transient event at around 3 000 yrs BP, when for a short time period G. ruber became the dominant species across the entire Red Sea. Since early Holocene conditions favoured G. sacculifer as the dominant species at both core sites, this change implies a dramatic alteration of the RS environment. Based on this argument, we speculate that this event can be linked to a change in nutrient availability and Red Sea circulation. Changes in SE Atlantic watermass distribution during the MidLatePleistocene Ufkes, E.1, Schneider, R.R.2, Jansen, J.H.F.3 and Kroon, D. 1, 4 1 Dep. of Paleoclimatology & Geomorphology, Vrije Universiteit, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands [email protected] 2 Institute for Geosciences, Christian Albrechts University, Kiel, Germany 3 Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands 4 School of Geosciences, Grant Institute, Edinburgh, Scotland, UK We infer variations in SE Atlantic watermass responses from planktonic foraminiferal fauna composition in core T89‐40 retrieved from Walvis Ridge. The core contains a sediment record of about 1.1 My (isotopic stage 31) and lies at the crossroads of three distinct oceanographic realms; the Benguela Upwelling System, subtropical gyre, Angolan tropical waters. We interpret our results to reflect major changes in biogeography and/or adaptation to different environments during the mid‐Pleistocene. To evaluate the influence of Milankovitch rhythms as potential forcing mechanisms for watermass variations in the SE Atlantic, we filtered principal components at orbital frequencies. The filtered records of principal components based on the foraminiferal data set show especially a strong change in the influence of the 100ky frequency band: a change in phase relationship between the upwelling and subtropical gyre related principal component from anti‐phase (1081 800 ky) to in phase since 600 ky. This supports our assumption that in addition to orbital insolation variations, watermass changes related to shifts in ABF have a strong impact on the regional planktonic foraminiferal distribution. During the mid‐Brunhes the S. Atlantic circulation system reaches its ʺlate Pleistocene stateʺ: warm water input from the North strongly diminished and only sporadically occurred during periods of strong southward frontal shifts. Prior to the mid‐Brunhes, the ABF was located several degrees further South hindering eastward extent of the subtropical gyre during mid‐Pleistocene interglacials. The distribution of left‐coiled G. truncatulinoides, marked by a regional period of near‐absence from 960 ky to 610 ky, is influenced by changes in stratification of the watercolumn induced by deep‐water cooling at around 960 ky and surface‐water cooling around 610 ky, and development of new habitats.
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Causes of Cenozoic evolution of deep‐sea benthic foraminifera Van Kerckhoven, L.1, 2, Hayward, B.W.1 1 Geomarine Research, Auckland, New Zealand 2 University of Auckland, Auckland, New Zealand Corresponding author: [email protected] This PhD research project is part of a wider collaborative study with the overall goal to increase understanding of the causes of global evolution and extinction in the deep sea. This is being addressed by focusing on a distinctive group of benthic foraminifera, which became extinct during the late Pliocene‐Middle Pleistocene (3‐0.12 Ma). Nineteen genera and 95 species belonging to three families of cosmopolitan deep‐sea benthic foraminifera, were wiped out during this Last Global Extinction (LGE). All these extinct species, referred to as the “Extinction Group”, shared elongate, cylindrical morphologies (often uniserial) with small, specialized apertures. The LGE was coeval with the pulsed expansion of the northern hemisphere ice cap, rendering deep‐sea conditions colder and more oxygenated during increasingly severe glacials. This leads to the proposition that the LGE wiped out remnants of the Greenhouse biota, when they or their food supply were unable to cope with the large and rapid changes in the deep‐sea environment. To test this hypothesis this particular research project extends our group’s Pliocene‐Pleistocene studies back in time. “Extinction Group” species in ODP Sites 689 (Southern Ocean) and 1211 (North Pacific Ocean) are analyzed to obtain a record of their occurrence and abundance through the whole of the Cenozoic, allowing the investigation of palaeoenvironmental drivers of abundance, extinctions and originations of species. Preliminary results of this research on ODP Site 689 reveal high population dynamics throughout the Cenozoic without extreme periods of high turn‐over. In a second phase, the research will be focused on a detailed study of the “Extinction Group” species through the Palaeocene‐Eocene warm event. Mg/Ca ratios of Globigerina bulloides and Globorotalia inflata from Core Top and Plankton Tow Samples in the Western Mediterranean Sea Ulrike van Raden1, Jeroen Groeneveld2, Markus Raitzsch2, Christoph Hemleben3, Michal Kucera3 1Dept. of Earth Sciences, ETH Zürich, Switzerland, [email protected] 2RCOM Bremen, Universität Bremen, Germany 3IFG Tübingen, Eberhard‐Karls Universität Tübingen, Germany Mg/Ca ratios in foraminiferal calcite are a widely applied proxy for reconstructing past ocean temperatures. Previous works considered temperature to be the dominant environmental factor controlling foraminiferal Mg/Ca. In this work we analyzed Mg/Ca in planktonic foraminifera in samples from the Western Mediterranean to examine the usability of Mg/Ca‐paleothermometry in regions with increased salinity. For this study five core top and two plankton tow locations were sampled covering a sea surface salinity gradient of 1.5 psu. Trace element concentrations in foraminiferal calcite with focus on Mg/Ca in shells of G. bulloides and G. inflata were measured with ICP‐OES and LA‐ICP‐MS. In all samples Mg/Ca ratios are higher than the values predicted by published calibrations for temperature reconstruction. The corresponding reconstructed temperatures in our samples are up to 13 °C higher than the analysed calcification temperatures. The Mg/Ca ratios in both species of neither the core top nor the plankton tow samples show a convincing correlation with calcification temperature or salinity. Additional SEM and LA‐ICP‐MS analyses exclude contamination and diagenetic overgrowths. But it cannot be excluded that partial recrystallization of shell calcite or diffusion of diagenetic material into the tests has occurred. LA‐ICP‐MS analyses of G. inflata show that the outer gametogenetic calcite has lower Mg/Ca than the inner part of the chamber wall, which results in higher bulk Mg/Ca in younger specimens compared to specimens after reproduction. This explains a declining Mg/Ca ratio in G. inflata with sampling depth in the plankton samples. Our results suggest that calcification temperature is not the main determinant of Mg/Ca in shells of G. inflata and G. bulloides. Although the exact reason for this anomaly is unknown, it seems that Mg/Ca in planktonic foraminifera is not a reliable method for reconstructing past water temperatures in the Western Mediterranean Sea.
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Seasonality in the Mediterranean Sea: A calibration study using paired single specimen D18O and Mg/Ca measurements of G. ruber alba J.C. Wit1, 2, G.‐J. Reichart1, S.J.A Jung2,3, D. Kroon2,3
1 Department of Geochemistry, Faculty of Geosciences, Utrecht University, Budapestlaan 4 3584 CD Utrecht, The Netherlands, e‐mail: [email protected] 2 Department of Paleo‐climatology and Geomorphology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, The Netherlands 3 School of GeoSciences, Institute of Earth Sciences, University of Edinburgh, United Kingdom Seasonality is increasingly recognised as an important parameter of the climate system. We investigated a novel approach for reconstructing seasonality using paired D18O and Mg/Ca measurements on single planktic foraminifera G. ruber alba. The Mediterranean Sea was selected for calibrating and testing this approach, because seasonality will be a dominant factor in this basin due to its semi‐enclosed properties. A central North Atlantic site was used in order to assess the applicability of the method in an open ocean setting. D18O temperature variations in single specimen G. ruber alba reflect measured sea surface (0‐50 m) temperatures at both sites. This suggests that single specimen measurements of 18O/16O isotopes from G. ruber alba allows the reconstruction of seasonality. The variations observed in single specimen analyses of Mg/Ca show a similar variability in reconstructed temperatures. However, when comparing Mg/Ca and D18O based temperature no correlation is observed, indicating an offset in one or both temperature proxies. Mg/Ca measurements show large intra‐test variability, which cannot be linked to changes in ambient seawater chemistry, but might be connected to fluctuations in symbiont activity during test formation. An assessment of the mechanisms behind this offset and the intra‐test Mg/Ca variation together with its possible influence on the oxygen isotopes is therefore needed to improve the reconstruction of seasonality. Productivity and ventilation variability off NW Africa during the last 30,000 years Michelle Zarrieß1, Andreas Mackensen1, Stefan Mulitza2 1Alfred‐Wegener Institute for Polar and Marine Research, Columbusstr., D‐27568 Bremerhaven, [email protected] 2MARUM‐Center for Marine Environmental Sciences, Bremen University, Loebener Str., D‐28334 Bremen, Germany Two AMS‐dated deep‐sea sediment cores from the continental slope off NW‐Africa (12° N, 3231m and 3671m water depth) were analyzed for their stable isotopic, foraminiferal and geochemical composition to reconstruct millennial‐scale variability in paleoproductivity and paleoventilation. In particular, we determined (i) the stable isotopic composition of the planktic foraminifera Globigerinoides ruber (pink) and several epifaunal to infaunal living benthic foraminifera species, (ii) the foraminiferal distribution pattern and (iii) the elemental composition of sediments by X‐ray Fluorescence Spectroscopy (XRF) to document varying primary productivity and deep‐water ventilation rates during the last 30,000 years. Small differences in (13C values between epifaunal and shallow infaunal foraminifera as well as low organic carbon accumulation rates (CorgAR) demonstrate reduced organic matter flux to the seafloor during Heinrich events H1 and H2. In addition, small differences in (13C values of epifaunal and deep infaunal foraminifera together with high abundance of the latter ones (e.g. Globobulimina affinis, Chilostomella oolina, Bolivina pacifica) indicate ventilation weakening by reduced NADW formation in the Northern Hemisphere during H1 and H2. High K/Al ratios and sedimentation rates reflect enhanced terrigenous input during H1 and H2. In contrast, during the African Humid Period (AHP) between 14.8 and 5.5 cal. kyr BP increasing differences in (13C values and high abundance of shallow infaunal foraminifera (Uvigerina peregrina) provide evidence for an increase in both organic‐matter flux and bottom‐water oxygen content. In the late AHP, CorgAR decreases and epifaunal species (Epistominella exigua, Hoeglundia elegans) dominate the foraminiferal distribution, suggesting productivity changing towards a more seasonal pulsed
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organic matter flux. After the AHP the CorgAR rises again and induces strong oxygen consumption in the water column. This, in conjunction with an increasing influence of South Atlantic Central Water (SACW), which has a high nutrient and low dissolved oxygen content, induces carbonate dissolution. This is confirmed by low benthic foraminiferal accumulation rates and low carbonate accumulation rates as well as a high planktic foraminifera fragmentation index. After the AHP benthic foraminiferal fauna comprises mainly Melonis barleeanum and G. affinis.