scholarly journals CHANGES IN WATER MASSES IN THE LATE QUATERNARY RECORDED AT URUGUAYAN CONTINENTAL SLOPE (SOUTH ATLANTIC OCEAN) / MUDANÇAS NAS MASSAS DE ÁGUA DURANTE O QUATERNÁRIO TARDIO REGISTADAS NO TALUDE CONTINENTAL URUGUAIO (OCEANO ATLÂNTICO SUL)

2018 ◽  
Vol 3 (4) ◽  
pp. 280-289
Author(s):  
Sandro Monticelli Petró ◽  
Leticia Burone
Keyword(s):  
Continental Slope ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Sensu Stricto ◽  
Water Masses ◽  
Globigerinoides Ruber ◽  
Climate Zones ◽  
Globigerina Bulloides ◽  
The Core ◽  
Neogloboquadrina Pachyderma

Planktonic foraminifera inhabit in the ocean waters and their spatial distribution is driven mainly by surface temperature. Thus, the tests remain deposited in the ocean sediment show different assemblages according to global climate zones. The main goal of this study was to assess the planktonic foraminifera found in the lowest continental slope of Uruguayan Continental Margin (UCM), and to identify the best criteria for future late Quaternary biostratigraphic and paleoceanographic models and based on carbonate preservation to identify water masses changes. For this purpose, this work examines foraminifera within a sediment core (T-90, 372 cm recovery, 3273 m water depth) collected in the lowest slope of UCM using a gravity corer. Forty height samples were selected along the core for foraminifera presence/absence analysis, and 13 samples, in the core section between 20 and 100 cm for foraminiferal faunal census. The age model was based on three AMS 14C dating. Foraminifera were absent in the core bottom, but were very abundant in its upper part. This variation of foraminifera was associated with fluctuations of lysocline in the glacial/interglacial transition, related to changes in geometry of bottom water masses. The most abundant species were Globorotalia inflata, Neogloboquadrina incompta, Globigerina bulloides, Globorotalia crassaformis, Globigerinoides ruber (white, sensu stricto) and Neogloboquadrina pachyderma. Principal component analysis (PCA) allowed to distinguished 3 groups of species in terms of climate zones: G. inflata (transicional), N. incompta (subpolar) and N. pachyderma (polar). Cluster analysis also identified three patterns of relative abundance among these three species, which can be related to oscillations in the latitude of Brazil-Malvinas Confluence zone during the last 15 ka. For future studies, it will be possible to check the relationship between these species as indicators of others paleoceanographic events in the study area. ResumoOs foraminíferos planctônicos habitam os oceanos sendo a sua distribuição espacial influenciada principalmente pela temperatura das águas de superfície. As suas carapaças depositadas no sedimento oceânico registam diferentes associações de acordo com as zonas climáticas globais. O principal objetivo deste trabalho é identificar mudanças de massas de água, no talude inferior da Margem Continental Uruguaia (UCM), com base na preservação de carbonatos e nas associações de foraminíferos planctônicos. Este trabalho baseia-se no estudo de foraminíferos planctônicos num testemunho de sedimentos (T-90, 372 cm de recuperação) recolhido a 3273 m de profundidade de lâmina de água, no talude continental inferior de UCM. Foram selecionadas 40 amostras ao longo do testemunho para análise presença / ausência de foraminíferos, e 13 amostras, na seção central entre 20 e 100 cm para o estudo das associações de foraminíferos. O modelo de idade foi baseado em três datações de radiocarbono por AMS. Os foraminíferos estão ausentes na extremidade inferior do testemunho, mas são muito abundantes na secção superior. Esta variação da abundância de foraminíferos poderá estar associada a flutuações da lisoclina na transição glacial/interglacial, relacionadas com mudanças na geometria das massas de água do fundo. As espécies mais abundantes ao longo do testemunho são Globorotalia inflata, Neogloboquadrina incompta, Globigerina bulloides, Globorotalia crassaformis, Globigerinoides ruber (branco, sensu stricto) e Neogloboquadrina pachyderma. A análise de componentes principais (PCA) permitiu distinguir 3 grupos de espécies em termos de zonas climáticas: G. inflata (transicional), N. incompta (subpolar) e N. pachyderma (polar). A análise de agrupamento permitiu identificar três padrões de abundância relativa entre essas três espécies, que podem estar relacionadas a oscilações na latitude da zona de confluência Brasil-Malvinas durante os últimos 15 ka. Estudos futuros, poderão basear-se na relação entre estas espécies para traçar eventos paleoceanográficos na região estudada. 

Ultrastructure of Some Planktonic Formainifera

1974 ◽  
Vol 32 ◽  
pp. 190-191
Author(s):  
William H. Zucker
Keyword(s):  
Cell Biology ◽  
Water Mass ◽  
Planktonic Foraminifera ◽  
Uranyl Acetate ◽  
Ethanol Dehydration ◽  
Globigerinoides Ruber ◽  
Light Microscope Level ◽  
Globigerina Bulloides ◽  
Glutaraldehyde Solution ◽  
Diamond Knife

Planktonic foraminifera are widely-distributed and abundant zooplankters. They are significant as water mass indicators and provide evidence of paleotemperatures and events which occurred during Pleistocene glaciation. In spite of their ecological and paleological significance, little is known of their cell biology. There are few cytological studies of these organisms at the light microscope level and some recent reports of their ultrastructure.Specimens of Globigerinoides ruber, Globigerina bulloides, Globigerinoides conglobatus and Globigerinita glutinata were collected in Bermuda waters and fixed in a cold cacodylate-buffered 6% glutaraldehyde solution for two hours. They were then rinsed, post-fixed in Palade's fluid, rinsed again and stained with uranyl acetate. This was followed by graded ethanol dehydration, during which they were identified and picked clean of debris. The specimens were finally embedded in Epon 812 by placing each organism in a separate BEEM capsule. After sectioning with a diamond knife, stained sections were viewed in a Philips 200 electron microscope.

CARBONATE DISSOLUTION AND ULTRASTRUCTURAL BREAKDOWN IN PLANKTONIC FORAMINIFERA IN THE SEA OF OKHOTSK

2017 ◽  
Author(s):  
Alexandra Romanova ◽  
Alexandra Romanova ◽  
Vladimir Anin ◽  
Vladimir Anin ◽  
Sergey Pletnev ◽  
...  
Keyword(s):  
Sea Of Okhotsk ◽  
Planktonic Foraminifera ◽  
Carbonate Dissolution ◽  
Calcite Dissolution ◽  
The Sea Of Okhotsk ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
Thin Walled ◽  
Shell Fragments ◽  
Degree Of Fragmentation

80 sediment stations collected along the meridian transect across the Sea of Okhotsk were studied in order to reveal patterns of dissolution based on planktonic foraminifera. The degree of calcite dissolution intensity from planktonic foraminifera determined by different indices (degree of fragmentation, presence of susceptible to dissolution species, benthos/ plankton ratio). The highest degree of dissolution evidenced by a large number of shell fragments and corroding walls were found in sediments from the area of the Kuril Islands. The most revealing measure of probable dissolution of foraminiferal shells in the central part of the sea is a low number and lack of thin-walled species. The effects of dissolution on foraminiferal shells were studied for dominated species Neogloboquadrina pachyderma sin and Globigerina bulloides using a scanning electron microscope. The results are important for understanding processes of sedimentation, the paleo-oceanologial reconstructions and for obtaining reliable results in isotope analyzes.

CARBONATE DISSOLUTION AND ULTRASTRUCTURAL BREAKDOWN IN PLANKTONIC FORAMINIFERA IN THE SEA OF OKHOTSK

2017 ◽  
Author(s):  
Alexandra Romanova ◽  
Alexandra Romanova ◽  
Vladimir Anin ◽  
Vladimir Anin ◽  
Sergey Pletnev ◽  
...  
Keyword(s):  
Sea Of Okhotsk ◽  
Planktonic Foraminifera ◽  
Carbonate Dissolution ◽  
Calcite Dissolution ◽  
The Sea Of Okhotsk ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
Thin Walled ◽  
Shell Fragments ◽  
Degree Of Fragmentation

80 sediment stations collected along the meridian transect across the Sea of Okhotsk were studied in order to reveal patterns of dissolution based on planktonic foraminifera. The degree of calcite dissolution intensity from planktonic foraminifera determined by different indices (degree of fragmentation, presence of susceptible to dissolution species, benthos/ plankton ratio). The highest degree of dissolution evidenced by a large number of shell fragments and corroding walls were found in sediments from the area of the Kuril Islands. The most revealing measure of probable dissolution of foraminiferal shells in the central part of the sea is a low number and lack of thin-walled species. The effects of dissolution on foraminiferal shells were studied for dominated species Neogloboquadrina pachyderma sin and Globigerina bulloides using a scanning electron microscope. The results are important for understanding processes of sedimentation, the paleo-oceanologial reconstructions and for obtaining reliable results in isotope analyzes

Planktonic Foraminifera from southwestern Atlantic epipelagic waters: abundance, distribution and year-to-year variations

2000 ◽  
Vol 80 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Esteban Boltovskoy ◽  
Demetrio Boltovskoy ◽  
Frederico Brandini
Keyword(s):  
Planktonic Foraminifera ◽  
Distribution Patterns ◽  
Similar Data ◽  
Southwestern Atlantic ◽  
Data Set ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
Brazil Current ◽  
Southwestern Atlantic Ocean ◽  
Subsurface Waters

The abundance and latitudinal and vertical (0-100 m) distribution of planktonic Foraminifera was investigated on the basis of 38 samples collected in November 1994 in the southwestern Atlantic Ocean (34-60°S, along 51-56°W). Mean foraminiferal densities were 1.5 ind. l−1 (range: 0.15.9 ind. l−1), with highest concentrations in subsurface waters (20-50 m). Couplings between the distribution of chlorophyll a and foraminiferal abundances were very loose. Distribution patterns of the 15 species recorded allowed 6 distinct areas to be defined along the transect surveyed. From north to south these are: Subtropical (dominated by Globigerinoides ruber and G. trilobus), Cold intrusion (Globigerinita uvula), Transitional-Subtropical and Transitional (Globigerina bulloides, Globigerina quinqueloba), Subantarctic (G. quinqueloba), and Antarctic (Neogloboquadrina pachyderma, left coiling). Close comparisons with the yields of a similar data set collected in November 1993 show very good agreement. Foraminiferal thermic régimes were also similar in 1993 and in 1994, but for some species significant differences with previous data were detected. While the southwards extensions of the ranges of warm water species are fairly well circumscribed by the Brazil current-influenced waters, several foraminifers widely used as indicators and palaeoindicators of cool waters (in particular Globigerina bulloides, Globigerina quinqueloba and Globigerinita uvula) were recorded in very significant numbers at temperatures as high as 20-24°C. The implication of these findings for hydrological, ecological, and palaeoecological interpretations is discussed.

scholarly journals A comparison between smaller (>63 μm) and larger (>150 μm) planktonic foraminiferal faunas from the Pleistocene of ODP Site 1073 (Leg 174A), New Jersey margin, NW Atlantic Ocean

2002 ◽  
Vol 21 (2) ◽  
pp. 137-147 ◽  
Author(s):  
Christopher W. Smart
Keyword(s):  
New Jersey ◽  
Atlantic Ocean ◽  
Planktonic Foraminifera ◽  
Size Fraction ◽  
Sea Surface ◽  
General Level ◽  
Size Fractions ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
The Mean

Abstract. Planktonic foraminiferal faunas have been studied from the Pleistocene of ODP Site 1073 (Leg 174A), New Jersey margin, NW Atlantic Ocean and their abundances have been compared in the >63 μm and >150 μm size-fractions from the same samples. Trends in the relative abundance of many species are similar in the two size-fractions, although the general level varies considerably. The mean abundance and ranges of Neogloboquadrina pachyderma (sinistral), N. pachyderma (dextral), Globorotalia inflata and Globigerina bulloides are greater in the >150 μm size-fraction compared with the >63 μm size-fraction. Turborotalita quinqueloba, Globigerinita uvula, G. glutinata, G. clarkei, and juvenile species are more abundant in the >63 μm size-fraction than the >150 μm size-fraction. Peaks (c. 60%) in abundance of G. uvula occur in the >63 μm size-fraction only, although the causes of these patterns are unclear. The data suggest that, in general, consistent palaeoclimatic/palaeoceanographic information is achieved by studying planktonic foraminiferal faunas from either size-fraction. However, because particular smaller species are either under-represented or even absent from the larger (>150 μm) size-fraction, the smaller (>63 μm) size-fraction must be included in studies of planktonic foraminifera. Furthermore, studies that involve planktonic foraminifera in the >63 μm size-fraction could provide different transfer function estimates for sea surface temperatures in areas where workers have only used larger (>125 μm and >150 μm) size-fractions.

Plankton Ecology and the Paleoceanographic–Climatic Record

1982 ◽  
Vol 17 (3) ◽  
pp. 314-324 ◽  
Author(s):  
Paul Loubere
Keyword(s):  
Deep Sea ◽  
Planktonic Foraminifera ◽  
Environmental Data ◽  
Biological Production ◽  
Globigerinoides Ruber ◽  
Neogloboquadrina Pachyderma ◽  
Fossil Material ◽  
Deep Sea Sediments ◽  
Climatic Record ◽  
Relative Abundances

AbstractThe paleoceanographic–climatic record represented by deep-sea microfossils reflects conditions for only certain times of the year. Also, the relative abundances of microfossil species in deep-sea sediments do not usually reflect only one paleoceanographic variable, such as temperature. Rather, species distributions represent the integration of many factors that control biological production in the oceans. This influences the information on past climates that can be extracted from fossil material. The seasonal limitation is due to the cyclic nature of biological production in the open ocean. Case studies of the sediment record in the Atlantic for two species of planktonic Foraminifera, left-coiling Neogloboquadrina pachyderma (Ehrenberg) and Globigerinoides ruber (d'Orbigny), illustrate seasonal bias in environmental data reported by the relative abundances of species in deep-sea sediments. In addition, the study of G. ruber illustrates the operation of two oceanographic parameters in controlling a species distribution. These examples demonstrate that the environmental signal in the sediments is the result of the interplay of the ecological tolerance of the plankton species with seasonally variable biological and physical properties of the upper ocean.

Late Quaternary Paleoceanography of the Gulf of Aqaba (Elat), Red Sea

1980 ◽  
Vol 14 (3) ◽  
pp. 294-308 ◽  
Author(s):  
Z. Reiss ◽  
B. Luz ◽  
A. Almogi-Labin ◽  
E. Halicz ◽  
A. Winter ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Red Sea ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Glacial Maximum ◽  
Gulf Of Aqaba ◽  
Stratigraphic Correlation ◽  
The Core ◽  
Stratigraphic Subdivision ◽  
Calcareous Plankton

AbstractThe quantitative distribution of planktonic foraminifera, pteropods, and coccolithophorids, as well as oxygen-isotope variations were analyzed in four deep-sea cores from the Gulf of Aqaba (Elat) and the northernmost Red Sea. The core record covers about 150,000 yr. Detailed stratigraphic subdivision is facilitated by combining all calcareous plankton groups. Time-stratigraphic correlation and dating beyond the radiocarbon range are possible by comparison of the oxygen-isotope curves. During the glacial maximum salinity rose to more than 50‰, while winter temperature of the upper waters fell by at least 4°C compared to the present. The rise in salinity can be accounted for by sea-strait dynamics and lowering of sea level. The Gulf of Aqaba and the Red Sea were continuously connected through the Straits of Tiran, and there is no indication of desiccation during the glacial maximum.

CARBONATE DISSOLUTION AND ULTRASTRUCTURAL BREAKDOWN IN PLANKTONIC FORAMINIFERA IN THE SEA OF OKHOTSK

2017 ◽  
Author(s):  
Alexandra Romanova ◽  
Alexandra Romanova ◽  
Vladimir Anin ◽  
Vladimir Anin ◽  
Sergey Pletnev ◽  
...  
Keyword(s):  
Sea Of Okhotsk ◽  
Planktonic Foraminifera ◽  
Carbonate Dissolution ◽  
Calcite Dissolution ◽  
The Sea Of Okhotsk ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
Thin Walled ◽  
Shell Fragments ◽  
Degree Of Fragmentation

80 sediment stations collected along the meridian transect across the Sea of Okhotsk were studied in order to reveal patterns of dissolution based on planktonic foraminifera. The degree of calcite dissolution intensity from planktonic foraminifera determined by different indices (degree of fragmentation, presence of susceptible to dissolution species, benthos/ plankton ratio). The highest degree of dissolution evidenced by a large number of shell fragments and corroding walls were found in sediments from the area of the Kuril Islands. The most revealing measure of probable dissolution of foraminiferal shells in the central part of the sea is a low number and lack of thin-walled species. The effects of dissolution on foraminiferal shells were studied for dominated species Neogloboquadrina pachyderma sin and Globigerina bulloides using a scanning electron microscope. The results are important for understanding processes of sedimentation, the paleo-oceanologial reconstructions and for obtaining reliable results in isotope analyzes.

scholarly journals Análise Sedimentar e Micropaleontológica (Foraminíferos) de Seções Quaternárias do Talude Continental Superior do Norte da Bahia, Brasil

2008 ◽  
Vol 35 (2) ◽  
pp. 97
Author(s):  
TÂNIA MARIA FONSECA ARAÚJO ◽  
ALTAIR DE JESUS MACHADO
Keyword(s):  
Coralline Algae ◽  
Globigerinoides Ruber ◽  
Globigerina Bulloides ◽  
The Core ◽  
The North ◽  
North Part ◽  
Brownish Black ◽  
Orbulina Universa ◽  
Quartz Grains ◽  
Upper Slope

Sediment from four cores of the north part of the continental upper slope, Bahia State, consist predominantly of siliciclastic mud in its bottom and carbonatic mud in the top of the majority of the studied cores. The sediment color varies from light olive gray to brownish black. The sediments are mainly composed of foraminifera, mollusk fragments, coralline algae debris, plant fragments and quartz grains. The following major foraminifera benthonic species were recorded in the studied cores: Cibicides pseudoungerianus, Bulimina marginata, Amphistegina lessonii, Cassidulina laevigata, Bolivina subaenariensis, Uvigerina peregrina. The following major foraminifera planctonic species are frequent in the cores: Globigerinoides ruber, Globigerina bulloides, Orbulina universa, Globigerinoides trilobus, G. elongatus, Globigerina quinqueloba, Globigerinoides ruber f. pyramidalis. The siliciclastic sediment (higher quartz percentage) in the core bottom, suggests that sedimentation occurred with strong continental influence, indicating proximity to the coast line. The benthonic foraminifera predominance in the bottom cores and the higher planctonic frequency toward the top cores is an indicative of the sea-level oscilation events during Quaternary time.

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