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1

Characterictics of turbulent horizontal heat exchange in subsurface layers of the Southern Ocean. Part II. Indian Ocean and Pacific

100%
Druet C., Siwecki R.
Oceanologia
|
1986
|
tom 24
2
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Content available

Planktonic foraminiferal response to Middle Miocene cooling in the Southern Ocean [ODP Site 747, Kerguelen Plateau]

84%
Majewski W.
Acta Palaeontologica Polonica
|
2010
|
tom 55
|
nr 3
541-560
The response of planktonic foraminifera to changing oceanographic conditions during Middle Miocene Climate Transition (MMCT) ~14 million years ago (Ma) at ODP Site 747 (Kergeulen Plateau) is investigated. Faunal changes are presented in the background of sea surface temperature (SST) estimates and multi−taxon δ18O and δ13C data presented in other studies. Four faunal transitions are distinguished between 15.0 and 12.2 Ma. The first two affected only a limited number of taxa, and do not lead to large−scale assemblage reorganizations. They are only minor assemblage changes within the pre−MMCT fauna. The first (14.5–14.4 Ma) is marked by a reduction in the Globorotalia zealandica plexus in favor of the Globorotalia praescitula plexus, coupled with the first signs of increased seasonality. The second (14.3–14.2 Ma) is characterized by recovery and diversification of the G. zealandica plexus and an increase in Turborotalita quinqueloba in response to further enhanced seasonality. The third faunal transition across the Middle Miocene Shift (MMS) in 18O (13.9–13.8 Ma) affects almost all planktonic foraminifera, leading to dismembering of the pre−MMCT assemblage. These changes were triggered by the SST drop by ~7C, followed by reduced sea−surface salinity following the MMS, which favored the opportunistic Neogloboquadrina continuosa. Its dominance spans the transitional period (13.8–13.2 Ma), during which several planktonic foraminiferal events gradually shaped the post−MMCT assemblage. The fourth faunal threshold took place during the hiatus in the ODP Hole 747A record spanning 13.2–12.5 Ma. It is expressed by the establishment of an assemblage dominated by Globorotalia praescitula and Globigerina bulloides in association with diminishing of the low−salinity surface layer. The two dominant taxa exhibit well−defined morphologies, much different from their earlier relatives. The microperforate foraminifera show relatively few morphological changes, probably due to their morphological conservatism. Their changes are thought to herald the large foraminiferal transformations, especially in case of the third and fourth faunal transition thresholds.
3
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Tracing the signature of various frontal systems in stable isotopes (oxygen and carbon) of the planktonic foraminiferal species Globigerina bulloides in the Southern Ocean (Indian Sector)

84%
Khare N., Chaturvedi S. K.
Oceanologia
|
2012
|
tom 54
|
nr 2
Twenty-five surficial sediment samples, collected on board ORV Sagar Kanya during her 199th and 200th cruises along a north-south transect between latitudes 9.69◦N and 55.01◦S, and longitudes 80◦E and 40◦ E were studied for isotopic variations (values of δ18O and δ13C) of the indicator planktonic species Globigerina bulloides. The results indicate that from latitudes 9.69◦N to 15◦ S both these isotopes (δ18O and δ13C) fluctuated significantly. Between latitudes from around 15◦S to 30–35◦S δ18O values steadily increased, whereas δ13C showed a decreasing trend. However, to the south of latitudes 30–35◦S, both isotope values showed a similar response with a gradual increase up to latitude 50◦S, beyond which δ18O continued to increase while δ13C declined. The characteristic patterns of the values of both isotopes indicates that the signatures of different water masses are associated with various frontal systems and/or water masses across the transect. The signature of the Polar Front at around latitude 50◦S shows the specific response of the isotopic values (δ18O and δ13C) of G. bulloides. Such a response beyond 50◦S latitude is ascribable to the general decrease in the ambient temperature, resulting in a continuous increase in δ18O values, while δ13C values decrease as a result of reduced photosynthesis in regions approaching higher latitudes owing to low light penetration. To further corroborate our results, those of many such transects from geographically distinct regions need to be studied for isotopic variations in the calcareous shells of planktonic foraminiferal species. The results have the potential to be used as a proxy to assess the movement of frontal systems in southern high latitude regions.
4

Larval ascaridoid nematodes [Anisakidae] in fish from the South Shetland Islands [Southern Ocean]

84%
Rokicki J., Rodjuk G., Zdzitowiecki K., Laskowski Z.
Polish Polar Research
|
2009
|
tom 30
|
nr 1
49-58
5

On the biology of Lepidonotothen macrophthalma [Norman, 1937] from the Scotia Ridge, Southern Ocean

84%
Sosinski J., Kompowski A.
Bulletin of the Sea Fisheries Institute
|
2002
|
nr 2
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