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

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.

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. 

Late Pliocene to Early Pleistocene Planktonic Foraminifera from Northern Indian Ocean (Andaman and Nicobar Islands): Interpretation on Cooling Event and Ocean Upwelling

2021 ◽  
Vol 51 (3) ◽  
pp. 115-138
Author(s):  
Rikee Dey ◽  
Amit K. Ghosh ◽  
Ajoy Kumar Bhaumik ◽  
Arindam Chakraborty ◽  
Stuti Saxena ◽  
...  
Keyword(s):  
Indian Ocean ◽  
West Coast ◽  
Planktonic Foraminifera ◽  
Early Pleistocene ◽  
Northern Indian Ocean ◽  
Late Pliocene ◽  
Globigerina Bulloides ◽  
Neogloboquadrina Pachyderma ◽  
Nicobar Islands ◽  
Identification Analysis

ABSTRACT Thirty-two planktonic foraminiferal taxa have been identified based on Bright Field microscopic study as well as Scanning Electron Microscopy on the samples collected from the outcrop adjacent to the type section of Neill West Coast Formation at Neil Island of Ritchie's Archipelago, northern Indian Ocean. The planktonic foraminiferal taxa belong to ten genera viz., Dentoglobigerina, Globigerina, Globigerinoides, Globoconella, Globorotalia, Globorotaloides, Globoturborotalita, Neogloboquadrina, Orbulina, and Trilobatus. A number of statistical analyses have been done in addition to taxonomic study to interpret the palaeocenographic scenario. We performed PCA analysis on the foraminiferal content of the samples to test the relatedness. Two biozones have been established by Stratigraphically Constrained Cluster Analysis (CONISS). We used SHEBI (SHE analysis for biozone identification) analysis to precisely demarcate seven biozones. Attempts have been made to decipher the Plio–Pleistocene boundary in the Neill West Coast Formation based on specific zonal markers. The presence of some taxa (e.g., Globoconella inflata, Globigerina bulloides, and Neogloboquadrina pachyderma) indicates the initiation of a cooling event from late Pliocene onwards. An event of ocean upwelling also has been identified based on the presence of Globigerina bulloides, Neogloboquadrina pachyderma, and N. dutertrei from the late Pliocene to early Pleistocene of the northern Indian Ocean that also correlates with palaeoceanographic records known from other upwelling regions.

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.

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