Recent Foraminifera Research Articles

Recent Foraminifera from the Pennar Estuary, Andhra Pradesh

Abstract 45 foraminiferal species belonging to the suborders Textulariina, Miliolina and Rotaliina, identified from 180 bottom sediment samples from the Pennar estuary in the east coast of India are reported and illustrated.

Oxygen isotopic-hydrographic relationships among recent planktonic Foraminifera from the Indian Ocean

The stable isotopic composition of fossil Foraminifera has become an increasingly important tool in palaeoecological and stratigraphic studies of marine sediments1–3, prompting several studies of the factors governing the isotopic composition of living and recent Foraminifera. Many studies have documented the good agreement between the inferred depth of growth from oxygen isotopic data4–8 and the depth stratification found in plankton tows9–11. Although results have suggested disequilibrium in some species12–14, especially among the benthic species15–16, recent data from Sargasso Sea plankton tows17–19 and Indian Ocean core top sediments20,21 suggest that oxygen isotopic equilibrium is nearly achieved in many ecologically important species. In the present study, oxygen isotopic data on as many as eight species and subspecies of planktonic Foraminifera from 52 Indian Ocean core top samples permit a comprehensive comparison of the isotopic–temperature trends across the major oceanographie regions of the Indian Ocean (Table 1). Several shallow-dwelling species (Globigerinoides ruber, G. sacculifer and Orbulina universa) were used as a measure of the upper 50–100 m of the water column (the mixed surface layer). Several deep-dwelling species (G. truncatulinoides (left and right coiling varieties), G. inflata, G. scitula and G. hirsuta) were used for comparison with hydrographie data from 200 to 300m depths. The results show that the isotopic difference between the shallow and deep-dwelling species is directly related to the temperature difference between the surface waters and the depth of the permanent thermocline. This isotopic–temperature relationship suggests that isotopic analyses of species which inhabit different water depths may be used to determine the thermal gradient in the upper water column during the Cenozoic.

Oxygen and carbon isotope studies in recent foraminifera from the southwest Indian ocean

Eighteen species of planktonic foraminifera have been analyzed for their oxygen and carbon isotopic composition in five Recent samples of deep-sea sediment from the southwest Indian Ocean; one sample of glacial age and one mid-Holocene sample were also studied. On the basis of oxygen isotopic composition three groups are recognized. Species in the first group ( Globigerinoides ruber, G. sacculifer and G. conglobatus; G. Globigerina rubescens and Globigerinita glutinata) calcity in the near-surface Tropical Water, so that the oxygen isotopic composition of their test carbonate may be used to indicate surface temperature. Species in the second group ( Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Orbulina universa, Globigerinella siphonifera and Sphaeroidinella dehiscens) are associated with the sub-surface high-salinity Subtropical Water, so that their oxygen isotope composition indicates trends in the temperature of this water mass. The third group (the species of Globorotalia) calcity in the deeper Central Water. The average oxygen isotopic composition of each Globorotalia species is more or less constant over the range studied and does not reflect the surface temperature trend. The carbon isotopic composition of three species ( Globigerina rubescens, Globigerinoides ruber and Globigerinita glutinata indicate departure from isotopic equilibrium by at least 3% 0. Among the remaining species the variation of carbon isotopic composition with depth (where depth is inferred from the temperature estimated from oxygen isotopic composition) implies that N. dutertrei, P. obliquiloculata and G. siphonifera occupy the shallow subsurface oxygen minimum, while the deeper-dwelling globorotaliids approach the deeper oxygen minimum. Hence it is possible, despite scatter among the data, to discern the pattern of oxygen content with depth in the overlying water masses from an examination of oxygen and carbon isotopic composition among foraminiferal species in the sediment. This promises to be an exciting new tool for palaeo-oceanographic investigations.

Distribution of Recent Foraminifera in Gulf of Alaska: ABSTRACT

Distribution of Recent Foraminifera in Gulf of Alaska: ABSTRACT

Recent Foraminifera of an Estuarine Environment in Broken Bay, New South Wales

The foraminiferal fauna of Broken Bay, a complex estuary along the east coast of Australia, has been analysed. All the species found (181) have been identified and the individuals counted. From these data biotopes have been determined and their geographical extent briefly analysed in relation to the sediment distribution and the hydrological parameters. A large and varied benthonic population exists predominantly in the section of the estuary not subject to large salinity changes. Taxonomic notes on 56 species, out of 168 forming the benthonic population, are also included; two species, Haplophragmoides australensis and Cribrononion sydneyensis, are described as new taxa. An additional five species and one subspecies are recorded for the first time from Australian waters.

Wall structure and classification of fossil and recent Elphidiid and Nonionid Foraminifera

Wall structure and classification of fossil and recent Elphidiid and Nonionid Foraminifera

Recent Foraminifera from the Honiara Bay area, Solomon Islands

Recent Foraminifera from the Honiara Bay area, Solomon Islands

Recent foraminifera of Chipurupalle stream, east coast of India

The Chipurupalle stream is a marginal marine environment near Visakhapatnam, east coast of India. The foraminifera, as well as seasonal variations in their abundance and distribution in the stream, have been investigated in relation to different ecological factors like salinity, temperature, pH and dissolved oxygen of waters in contact with the sediment, and texture and organic matter content of the sediments. In all, 39 species of foraminifera have been identified from the stream. Of them 17 species are never found in living condition in the stream and are not only scarce in occurrence but are confined to the confluence area. The remaining 22 species represented by living specimens comprise four agglutinated, four calcareous imperforate, and 14 calcareous hyaline forms. Ammonia beccarii (Linné), A. tepida (Cushman), Quinqueloculina seminulum (Linné), Elphidium simplex Cushman, Globigerina sp., and Miliammina fusca (Brady) are the only foraminifera which are common to abundant in occurrence in the stream. Ammonia beccarii and Quinqueloculina seminulum seem to reproduce in the Chipurupalle stream in December while Elphidium simplex does so in May, The former may also have a secondary bloom in May.

The ecology and distribution of Recent foraminifera from the reefs and shoals around Barbuda, West Indies

The ecology and distribution of Recent foraminifera from the reefs and shoals around Barbuda, West Indies

The relationship of Recent foraminifera to the sedimentary facies in the turbulent zone, Cardigan Bay

The relationship of Recent foraminifera to the sedimentary facies in the turbulent zone, Cardigan Bay

Application of association–analysis to distribution studies of Recent Foraminifera

Counts of species of foraminifera from 75 samples of sediment from East Bay, MacKeazie King Island, in the Canadian Arctic were converted to a matrix of presence–absence data (56 species × 75 stations). These were submitted to both normal and inverse association–analysis as a preliminary test of the application of that multivariate method to problems in marine ecology. The results are compared with observations made at the time the survey was carried out. Although the pattern of sampling was not the most suitable for association–analysis, the results indicate that the method may prove quite informative.

Oxygen-18 Studies of Recent Planktonic Foraminifera: Comparisons of Phenotypes and of Test Parts

Oxygen isotopic comparisons of phenotypes of Recent Planktonic Foraminifera with both normal and diminutive final chambers are compatible with a model in which the latter develop as a response to environmental stress. Isotopic evidence shows that Spheroidinella dehiscens is probably not a late-stage, aberrant form of Globogerinoides sacculifer.

Recent Foraminifera from off Pentakota, East Coast of India

A study of the foraminiferal content of samples of the shelf sediments off Pentakota on the east coast of India reveals that the outer shelf sediments at depths greater than 90 meters contain an abundant shallow-water warm-water benthonic fauna. A 70-cm. core taken from a depth of about 1 50 meters in the same area consists of oolitic sediments in the lower 45 cm. and silty clays in the upper 25 cm. The oolitic sediments of the core abound in shallow-water warmwater benthonic fossils. A comparison of the faunas in the core and in the surface sediments of the sea floor is made, and the extent of the relict fauna of the outer shelf sediments is evaluated. After the elimination of the relict elements from population counts, the living population of the sediments of the modern time surface is divided into three depth zones, ranging from 0 to 1 5 meters, from 15 to 40-45 meters, and greater than 40-45 meters. Sediments and fresh water discharged into the Bay of Bengal by the Godavari River to the south of Pentakota and carried northward along the coast and northeastward into deeper waters off Pentakota are found to inhibit the development of populations within the area of their influence. Recent foraminifera from off Pentakota, east coast of India

Recent Foraminifera in the Canadian Arctic

Recent Foraminifera in the Canadian Arctic

An Application of Canonical Analysis as a Method for Comparing Faunal Areas

In a Recent environment two foraminiferal populations can be observed, living and dead. If a Recent environment were preserved at a given instant, the fauna available for observation would be the total population. The dead population is often one or two orders of magnitude larger than the living population, and therefore the dead population is essentially equivalent to the total population. Because most species have certain environmental preferences which often include a characteristic depth range, paleoecological interpretations can be made providing the preserved (fossil) population is equivalent to the total population. Ecological studies of Recent Foraminifera have therefore shown not only the relationship of environmental variables to the distribution and abundance of the living population, but also the relationship of the living population to the total population. The basic data for such studies consist of counts of the numbers of individuals of each species in each sample (a sample usually consists of 10 ml wet sediment). Field and laboratory methods have been described by Phleger (1960). In an area of ecologic interest there are usually many species. While similarities and differences in the distribution of abundances of a single species are often easily recognizable, the assimilation of a large amount of data consisting of the abundance of many species distributed among many samples is very difficult. Greig-Smith (1964) summarized many of the quantitative procedures that have been used to deal with such problems in plant ecology. Most of the procedures calculate from a data matrix a measure for ascertaining the degree of association or correlation between species or between samples. Some measures use presence or absence data while others use abundances. The resulting association or correlation matrix is then subjected to analysis to discover grouping or an underlying structure. Some of the procedures utilize various ramifications of 'factor analysis' for this purpose. Seal (1964, pp. 170-9) reviews the statistical applicability of these procedures. Streeter (1964) has used vector analysis (see Imbrie 1963), a somewhat similar technique, on foraminiferal distributions. Recently, Kaesler (1966) has applied the methods of 'numerical taxonomy' (Sokal & Sneath 1963) in defining Ostracoda and Foraminifera assemblages. All of the above procedures define groupings by consideration of the entire study area as a single unit or statistical universe. The purpose of this study is to investigate the utility of a type of multi-variate analysis called canonical variate analysis which is a method for comparing or discriminating between two or more statistical universes. Rather than trying to define groups or an underlying structure, the method statistically compares groups which the investigator has already defined by some criteria of interest such as bathymetry, sediments, hypothesized faunal boundaries, etc. Our main concern here is not how the researcher constructs his hypothesis of subareas or biofacies but how he can compare them. The data for the analyses of the present study are taken from Phleger's (1956) classic study 'Significance of living foraminiferal populations along the Central Texas Coast'. The data from his

Recent Foraminifera from the Beach Sands of Jaffna, Ceylon

Recent Foraminifera from the Beach Sands of Jaffna, Ceylon

Patterns of Foraminiferal Distribution, Northwest Gulf of Mexico: ABSTRACT

Within the past 30 years, several investigators have collected material and reported on Recent Foraminifera in the northwest Gulf of Mexico. The investigations include lagoon, delta, shelf, slope, and abyssal environments. Each report, however, includes only a limited area of investigation. This report is an attempt to evaluate and integrate the existing data in the form of geographic-distribution patterns. The species reported in approximately 1,200 samples form the basis of this study; environmental data come from sedimentologic and oceanographic investigations. Marginal marine environments: Faunas reported primarily from Texas bays and lagoons change geographically in composition. On the southwest, the Laguna Madre and lower Corpus Christi and lower Aransas bays are dominated primarily by miliolids and secondarily by species of Elphidium and Streblus. The miliolids are replaced by the Elphidium-Streblus fauna in Aransas, lower San Antonio, Matagorda, and Galveston Bays and in the pass area of Sabine Lake. These areas contain the so-called Lower Bay fauna. The landward parts of these same water bodies contain an Upper Bay fauna, usually dominated by the arenaceous Ammotium salsum; where streams enter the bays, Eponidella usually is characteristic. Sparse data from Louisiana bays indicate that the Upper Bay fauna predominates throughout the coastal area. The southwest-t -northeast changes occur in response to changing climatic zones, increasing stream discharge, and sediment type. Marine environments: The continental shelf extending from the Gulf beach to about 70 fm. contains a variety of geographically bounded faunas. Despite the emphasis on depth facies, many shelf genera show a pronounced change along strike. For example, the inner shelf from the beach to about 20 fm. generally is dominated by species of Elphidium and Streblus. Offshore from south Texas, a band of Elphidium is dominant nearshore and is succeeded by a band of Streblus in somewhat deeper water; the bands are reversed offshore from southeast Texas and Louisiana. The middle shelf, 20-50 fm. deep, is characterized by a laterally diverse system of dominant taxa. Hanzawaia, Virgulina, and Proteonina occur in elongate and commonly interfingering bands. These dominant forms, however, are replaced in the vicinity of the Mississippi delta by Nonionella, Buliminella, and Epistominella. The outer shelf contains dominant abundances of Cibicides, Uvigerina, and Bigenerina; species of Bolivina occur mainly on the outer shelf off southeastern Louisiana. The continental slope, in contrast to the shelf, is characterized by more uniform lateral distributions of genera. The upper slope from 70 to approximately 500 fm. is strongly dominated by species of Bolivina. This genus is replaced by Bulimina from 500 to 900 fm. and can be considered as indicative of the middle-slope environment. The lower-slope and abyssal environments deeper than 900 fm. are characterized by Pseudoparrella, Eponides, and Glomospira. The number of species per sample increases from a low average of about 10-12 in the bays and nearshore zone to a maximum of more than 55 at or near the shelf-slope break. The faunal diversity decreases again on the slope reaching a minimum of 10-15 species in abyssal samples. Planktonics increase uniformly in abundance from the beach into the Sigsbee Deep. Their increase is related directly to decreasing rates of dilution by sediments and other organisms. End_of_Article - Last_Page 2322------------

Interpretation of Depositional Environment in Gulf Coast Petroleum Exploration from Paleoecology and Related Stratigraphy: ABSTRACT

ABSTRACT The application of paleoecology and related stratigraphic studies in environmental interpretation is playing an increasingly important role in Gulf Coast petroleum exploration. Studies of the ecology of Recent Foraminifera of the Gulf of Mexico, both planktonic and benthonic, in the last 20 to 25 years have provided the basis for more accurate paleoecologic interpretations. Accurate paleoecologic interpretation also depends upon sufficient knowledge and consideration of the associated lithology, sedimentation, and tectonics, which are related components of stratigraphy. In the interest of uniformity and a certain degree of standardization, the following eight depositional environments as proposed by the New Orleans paleoeological study group (1966) of the Gulf Coast Section of the Society of Economic Paleontologists and Mineralogists have been adopted herein: (1) Non-marine, (2) Transitional, (3) Inner Shelf (Inner Neritic), (4) Middle Shelf (Middle Neritic), (5) Outer Shelf (Outer Neritic), (6) Upper Slope (Upper Bathyal), (7) Lower Slope (Lower Bathyal), and (8) Abyssal. Recent and fossil Foraminifera characteristic of the various depositional environments are listed. Methods of paleoecological investigation are also presented, with a review of some of their limitations. Oil and gas reservoirs were deposited in specific environments with a definite relation ship between petroleum occurrence and depositional history. The accurate reconstruction of depositional environments and the application of this knowledge in petroleum exploration will result in more successful exploration programs.

Study of Ecology and Distribution of Recent Foraminifera in Northwestern Gulf of Mexico: ABSTRACT

ABSTRACT Eight different stations in the Gulf of Mexico from 3 to 3300 feet in depth are studied in detail in an attempt to group the Foraminiferal assemblages found at each station into useful ecologic indicators. It was found that four ecological provinces exist out to the bottom edge of the continental slope: 1) beach and nearshore environment; 2) continental shelf; 3) continental slope; and 4) a shallow, clear, warm-water, calcareous environment (found on Stetson Bank). These environments are controlled by a combination of chemical and physical factors, including depth of water, temperature, salinity, food supply, chemical effects, turbidity, biologic competition, currents, and circulation. The benthonic Foraminifera are the most reliable ecological indicators but a more detailed ecological framework can be ascertained by the use of both benthonic and planktonic Foraminifera.

Distribution of Recent Foraminifera in Upper Florida Bay and associated sounds. : Lynts, G. W. 1962. Contr. Cushman Found. Foram. Res. 13(4): 127–144.

Distribution of Recent Foraminifera in Upper Florida Bay and associated sounds. : Lynts, G. W. 1962. Contr. Cushman Found. Foram. Res. 13(4): 127–144.