Ecosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses

Abstract. The systematic bioturbation of single particles (such as foraminifera) within deep-sea sediment archives leads to the apparent smoothing of any temporal signal as record by the downcore, discrete-depth mean signal. This smoothing is the result of the systematic mixing of particles from a wide range of depositional ages into the same discrete depth interval. Previous sediment models that simulate bioturbation have specifically produced an output in the form of a downcore, discrete-depth mean signal. Palaeoceanographers analysing the distribution of single foraminifera specimens from sediment core intervals would be assisted by a model that specifically evaluates the effect of bioturbation upon single specimen populations. Taking advantage of recent increases in computer memory, the single-specimen SEdiment AccuMUlation Simulator (SEAMUS) was created in Matlab, whereby large arrays of single specimens are simulated. This simulation allows researchers to analyse the post-bioturbation age heterogeneity of single specimens contained within discrete-depth sediment core intervals, and how this heterogeneity is influenced by changes in sediment accumulation rate (SAR), bioturbation depth (BD) and species abundance. The simulation also assigns a realistic 14C activity to each specimen, by considering the dynamic Δ14C history of the Earth and temporal changes in reservoir age. This approach allows for the quantification of possible significant artefacts arising when 14C dating multi-specimen samples with heterogeneous 14C activity. Users may also assign additional desired carrier signals to specimens (e.g., stable isotopes, trace elements, temperature, etc.) and consider a second species with an independent abundance. Finally, the model can simulate a virtual palaeoceanographer by randomly picking whole specimens (whereby the user can set the percentage of older, broken specimens) of a prescribed sample size from discrete depths, after which virtual laboratory 14C dating and 14C calibration is carried out within the model.

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Sediment core fossils in ancient Lake Ohrid: testing for faunal change in molluscs since the Last Interglacial period

Biogeosciences Discussions ◽

10.5194/bgd-7-3969-2010 ◽

2010 ◽

Vol 7 (3) ◽

pp. 3969-3999 ◽

Cited By ~ 3

Author(s):

C. Albrecht ◽

H. Vogel ◽

T. Hauffe ◽

T. Wilke

Keyword(s):

Sediment Core ◽

Fossil Record ◽

Interglacial Period ◽

Ancient Lake ◽

Last Interglacial ◽

Lake Ohrid ◽

Last Interglacial Period ◽

History Of ◽

Extinction Events ◽

Mollusc Shells

Abstract. Ancient Lake Ohrid is probably of early Pleistocene or Pliocene origin and amongst the few lakes in the world harboring an outstanding degree of endemic biodiversity. Although there is a long history of evolutionary research in Lake Ohrid, particularly on molluscs, a mollusc fossil record has been missing up to date. For the first time, gastropod and bivalve fossils are reported from the basal, calcareous part of a 2.6 m long sediment succession (core Co1200) from the north-eastern part of Lake Ohrid. Electron spin resonance (ESR) dating of mollusc shells from the same stratigraphic level yielded an age of 130±28 ka. Lithofacies III sediments, i.e. a subdivision of the stratigraphic unit comprising the basal succession of core Co1200 between 181.5–263 cm appeared solid, grayish-white, and consisted almost entirely of silt-sized endogenic calcite (CaCO3>70%) and intact and broken mollusc shells. Here we compare the faunal composition of the thanatocoenosis with recent mollusc associations in Lake Ohrid. A total of 13 mollusc species (9 gastropod and 4 bivalve species) could be identified within Lithofacies III sediments. The value of sediment core fossils for reconstructing palaeoenvironmental settings was evaluated. The agreement between sediment and palaeontological proxies was tested. The combined findings of the ecological study and the sediment characteristics suggest deposition in a shallow water environment during the Last Interglacial period. We tested for major faunal changes since the Last Interglacial period and searched for signs of extinction events. The fossil fauna exclusively included species also found in the present fauna, i.e. no extinction events are evident for this site since the Last Interglacial. The thanatocoenosis showed the highest similarity with recent Intermediate Layer (5–25 m) mollusc assemblages. The demonstrated existence of a mollusc fossil record in Lake Ohrid sediment cores also has great significance for future deep drilling projects. It can be hoped that a more far reaching mollusc fossil record will then be obtained, enabling insight into the early evolutionary history of Lake Ohrid.

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Penguin occupation in the Vestfold Hills

Antarctic Science ◽

10.1017/s095410200800165x ◽

2008 ◽

Vol 21 (2) ◽

pp. 131-134 ◽

Cited By ~ 11

Author(s):

Tao Huang ◽

Liguang Sun ◽

Yuhong Wang ◽

Renbin Zhu

Keyword(s):

Sediment Core ◽

Environmental Changes ◽

Sediment Cores ◽

East Antarctica ◽

Before Present ◽

The Holocene ◽

History Of ◽

Vestfold Hills ◽

Free Area ◽

Ornithogenic Sediment

AbstractDuring CHINARE-22 (December 2005–March 2006), we investigated six penguin colonies in the Vestfold Hills, East Antarctica, and collected several penguin ornithogenic sediment cores, samples of fresh guano and modern penguin bone and feather. We selected seven penguin bones and feathers and six sediments from the longest sediment core and performed AMS14C dating. The results indicate that penguins occupied the Vestfold Hills as early as 8500 calibrated years before present (cal. yrbp), following local deglaciation and the formation of the ice free area. This is the first report on the Holocene history of penguins in the Vestfold Hills. As in other areas of Antarctica, penguins occupied this area as soon as local ice retreated and the ice free area formed, and they are very sensitive to climatic and environmental changes. This work provides the foundation for understanding the history of penguins occupation in Vestfold Hills, East Antarctica.

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Reconstructing the accumulation history of a saltmarsh sediment core: Which age-depth model is best?

Quaternary Geochronology ◽

10.1016/j.quageo.2017.02.004 ◽

2017 ◽

Vol 39 ◽

pp. 35-67 ◽

Cited By ~ 14

Author(s):

Alexander J. Wright ◽

Robin J. Edwards ◽

Orson van de Plassche ◽

Maarten Blaauw ◽

Andrew C. Parnell ◽

...

Keyword(s):

Sediment Core ◽

History Of ◽

Accumulation History

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The Holocene history of the southwestern Baltic Sea as reflected in a sediment core from the Bornholm Basin

Boreas ◽

10.1111/j.1502-3885.2000.tb00981.x ◽

2000 ◽

Vol 29 (3) ◽

pp. 233-250 ◽

Cited By ~ 89

Author(s):

ELINOR ANDRÉN ◽

THOMAS ANDRÉN ◽

GUSTAV SOHLENIUS

Keyword(s):

Baltic Sea ◽

Sediment Core ◽

Bornholm Basin ◽

The Holocene ◽

History Of

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No significant ice-sheet expansion beyond present ice margins during the past 4500 yr at Rauer Group, East Antarctica

Quaternary Research ◽

10.1016/j.yqres.2010.04.004 ◽

2010 ◽

Vol 74 (1) ◽

pp. 23-25 ◽

Cited By ~ 4

Author(s):

Sonja Berg ◽

Bernd Wagner ◽

Duanne A. White ◽

Martin Melles

Keyword(s):

Sediment Core ◽

Radiocarbon Dating ◽

Ice Sheet ◽

East Antarctica ◽

Antarctic Ice Sheet ◽

The Holocene ◽

The Core ◽

The Past ◽

Field Evidence ◽

History Of

AbstractThe history of glacial advances and retreats of the East Antarctic ice sheet during the Holocene is not well-known, due to limited field evidence in both the marine and terrestrial realm. A 257-cm-long sediment core was recovered from a marine inlet in the Rauer Group, East Antarctica, 1.8 km in front of the present ice-sheet margin. Radiocarbon dating and lithological characteristics reveal that the core comprises a complete marine record since 4500 yr. A significant ice-sheet expansion beyond present ice margins therefore did not occur during this period.

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Excavations at South Cadbury Castle, 1967: A Summary Report

The Antiquaries Journal ◽

10.1017/s0003581500034351 ◽

1968 ◽

Vol 48 (1) ◽

pp. 6-17 ◽

Cited By ~ 3

Author(s):

Leslie Alcock

Keyword(s):

Bronze Age ◽

Iron Age ◽

Great Depth ◽

Late Bronze Age ◽

Summary Report ◽

Early Neolithic ◽

The Third ◽

Stone Wall ◽

History Of ◽

The Hill

The situation, character, and antiquarian history of South Cadbury Castle, Somerset, have already been described (Alcock (1967a); (1967b)). A reconnaissance excavation in 1966 hinted that occupation of the hilltop had begun in the Early Neolithic, and after a hiatus had been resumed sometime in the Late Bronze Age. It demonstrated that from early in the pre-Roman Iron Age there was a rich and intensive occupation, during which the defences were probably built. This appeared to have been ended by a sack at the hands of the Roman invaders c. A.D. 45. Late Roman pottery, metalwork, and coins showed that activity was renewed in the third-fourth centuries A.D. Imported pottery of well-known forms proved that the site was reused in the fifth—sixth centuries. Finally, it was refortified with a mortared stone wall as a Late Saxon burh. The reconnaissance also showed that on top of the hill (fig. 1, c) rock-cut pits and post-holes were readily discernible under the turf; that on the slopes within the defences (fig. 1, B) traces of buildings of various dates had survived many centuries of ploughing; and that in the rear of the inner rampart (fig. 1, A), a great depth of hill-wash and plough-soil overlay stratified levels of the Iron Age.

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