Species Of Benthic Foraminifera Research Articles

Paleocene and Eocene deep-water benthic foraminifera at IODP Site U1511, Tasman Sea: Part 2

Deep-water benthic foraminifera are investigated from Paleocene to Eocene sediments recovered from IODP Hole U1511B in the northeastern Tasman Sea. The recovered foraminifera display exceptional three-dimensional preservation: they are relatively unaltered by sediment diagenesis and compaction. We examined 33 samples from Cores U1511B-33R to -42R, and recovered 79 species of deep-water agglutinated foraminifera (DWAF) and 13 species of calcareous benthic foraminifera. The assemblage consists entirely of “cosmopolitan” forms originally described from the Carpathians, Caucasus, Trinidad, and the western Tethys, and other DSDP/ODP sites, implying that there is little or no endemism among deep-water benthic faunas in the semi-isolated Tasman Sea. The Paleocene–Eocene interval is characterized by successive acmes of Spiroplectammina, Trochammina, ammodiscids, and Karrerulina, and therefore bears striking similarity to previously studied sections in the western Tethys and Boreal North Atlantic. The taxonomic turnover among the DWAF is minor across the P/E contact, with only three apparent extinctions and three originations from the uppermost cores of the Paleocene and the lowermost cores of the Eocene. Calcareous benthic foraminifera were not observed in the Eocene samples, possibly a result of the shoaling of the CCD.

Assessing the Calibration of Benthic Foraminifera Elemental Ratios from the Northeastern Atlantic

On six different species of benthic foraminifera covering various microhabitats and recovered from the Northern Atlantic Ocean, we tested the potential of the Mg/Ca and Sr/Ca ratios as proxies for paleoceanography. We performed analysis using two instruments (ICP-OES and ICP-MS) and compared results obtained from living and dead specimens. Our results are in good agreement with previous published calibrations for Hoeglundina elegans, Uvigerina mediterranea, U. peregrina, Melonis barleeanum, and Globobulimina spp. However, we observed a strong variability between living and dead specimens, and between both instrumental approaches. We discuss the impact of the cleaning procedure, as well as the natural variability between samples recovered at different depths inside the sediment. No specific trend can be deciphered from our dataset, but we observed that species from the Uvigerina genus presented the lowest external reproducibility and the best agreement between living and dead specimens. We highlight that both species should not be mixed for analysis, since U. mediterranea presents lower values and a reduced range of variability compared to U. peregrina. We explored the temperature and the Δ[CO32−] as potential controls on the variability of both ratios from U. peregrina and showed that neither of these two parameters can be discarded.

Unexpected increase in structural integrity caused by thermally induced dwarfism in large benthic foraminifera.

Climate change is predicted to negatively impact calcification and change the structural integrity of biogenic carbonates, influencing their protective function. We assess the impacts of warming on the morphology and crystallography of Amphistegina lobifera, an abundant benthic foraminifera species in shallow environments. Specimens from a thermally disturbed field area, mimicking future warming, are about 50% smaller compared with a control location. Differences in the position of the ν1 Raman mode of shells between the sites, which serves as a proxy for Mg content and calcification temperature, indicate that calcification is negatively impacted when temperatures are below the thermal range facilitating calcification. To test the impact of thermal stress on the Young's modulus of calcite which contributes to structural integrity, we quantify elasticity changes in large benthic foraminifera by applying atomic force microscopy to a different genus, Operculina ammonoides, cultured under optimal and high temperatures. Building on these observations of size and the sensitivity analysis for temperature-induced change in elasticity, we used finite element analysis to show that structural integrity is increased with reduced size and is largely insensitive to calcite elasticity. Our results indicate that warming-induced dwarfism creates shells that are more resistant to fracture because they are smaller.

The Badenian/Sarmatian (Middle Miocene) boundary in the Central Paratethys (Kreminna, western Ukraine): Foraminiferal and palynological evidence

The Badenian/Sarmatian boundary in the Paratethys basin, that marks the transition from normal marine to restricted semi-marine conditions due to isolation of the basin from the world ocean at the onset of Sarmatian time, is still far from being fully understood. The Kreminna section is located at the northeastern margin of the Carpathian Foreland Basin (Central Paratethys) in the Medobory Hills region. The Miocene deposits that overlie here the Upper Cretaceous substratum comprise the >1 m thick upper Badenian marls and clays passing upwards into ~4 m thick Sarmatian marly limestones with intercalations of marls, clays and limestones, and >2 m thick limestones in the uppermost part of the exposure. Fifty-three species of benthic foraminifera and four species of planktonic foraminifera have been recorded. Six benthic foraminiferal assemblages are composed almost exclusively of calcareous forms; agglutinated taxa are practically lacking. Elphidium spp., miliolids, Lobatula lobatula and Ammonia spp. are the most common calcareous benthic foraminifera in the material studied. Planktonic foraminifera are represented only by species of Globigerina and occur rarely in the lowermost part of the section. A characteristic feature of palynofacies is the very low proportion of land-derived elements – sporomorphs and cuticles, which suggests a sedimentary setting without terrestrial influx, and taxonomical impoverishment of dinoflagellate cyst assemblages, which are either monospecific or consist mainly of two to three species: in a majority of samples, assemblages with Polysphaeridium zoharyi and P. subtile occur. Most δ18O values range from –1.5 to ~+0.5‰ VPDB and most δ13C values are between 0 and +2‰ VPDB. In general, the δ13C curve mirrors the δ18O changes in the section. The Badenian/Sarmatian boundary is placed at the level where the Cibicidoides ungerianus Assemblage is replaced by the Elphidium fichtelianum Assemblage. At the boundary, planktonic foraminifers and most abundant stenohaline benthic foraminifera disappeared. Bottom waters were well-oxygenated both in the latest Badenian and earliest Sarmatian in the Kreminna location.

Multi‐proxy palaeoenvironmental reconstruction of the Skagerrak from the Lateglacial to Middle Holocene

This study uses a multiproxy approach including the first use of 187Os/188Os, %C37:4 biomarkers, carbonate content, sedimentological grain size, geochemical X‐ray fluorescence and microfossil benthic foraminifera species combined with radiocarbon dating, measured on six cores from across the Skagerrak, in order to study the Lateglacial to Middle Holocene history of the area. A new chronostratigraphic framework is developed based on the appearance of specific benthic foraminifera species along with changes in carbonate/X‐ray fluorescence and grain size data. This allowed the correlation of cores based on a series of radiocarbon dated tie points. Analysing the cores together reveals several events recorded in the Skagerrak including: (i) an increased freshwater input (bracketed between 13.3 and 11.3 cal. ka BP) signified by radiogenic 187Os/188Os values, high %C37:4 values and an increase in sand content; (ii) the Glomma drainage event, signified by a sudden appearance of Valvulineria as well as higher %C37:4; and (iii) the opening of the Danish Straits and English Channel leading to the development of modern‐day conditions and circulation patterns in the Skagerrak, signified by the appearance of Hyalinea balthica and a fall in %C37:4.

Foraminiferal biofacies distribution in the outer channel of Chilika Lagoon, Odisha, India

Benthic foraminiferal assemblages are widely used as a proxy to monitor the coastal environment’s health. The current work involves the seasonal distribution of foraminifera in the outer channel sector of the Chilika Lagoon, Odisha during 2017–2018. The outer channel is marine as the sea mouth is nearby. Altogether 28 species of benthic foraminifera are identified, among which dominant are Ammonia spp. The other calcareous taxa are Elphidium spp, Quinqueloculina sp., Haynesina spp., Pararotalia sp., Hanzawaia sp., Nonionellina sp. and agglutinated forms such as Miliammina sp., Trochammina sp. and Textularina sp. are found in moderate abundance. Based on the pre-monsoon abundance, the cluster analyses show two distinct biofacies zones in the studied area. Total foraminiferal number (TFN) increases during pre-monsoon compared to post-monsoon months. A trend of decreasing abundance was observed in TFN, mainly calcareous taxa towards the inner part of the lagoon, that is, away from the sea mouth.

Biostratigraphy and Paleoecology of the Sinjar Formation (Late Paleocene-Early Eocene) in the Dokan and Sinjar Areas, Iraq

Biostratigraphy of the Sinjar Formation is investigated in two sections (Dokan and Sinjar) from northeastern and northwestern Iraq, respectively. Two hundred samples from all the limestones and marl that form the main lithological components of the studied sections were collected. The studied limestones and marl are rich in microfossils. Through thin sections, we were able to identify thirty species of benthic foraminifera and fifteen species of other microfossils (coral, algae, mollusca, bryozoa, and echinoids) at Dokan section, and fifty-one species of benthic foraminifera and thirty species of other microfossils at Sinjar section. 3 biozones were distinguished from both sections 1-Biozone A: Kathina sp.- Lockhartia hunti Assemblage zone (SBZ 5) (Dokan section); (Kathina pemavuti - Lockhartia hunti Assemblage zone (Sinjar section), 2- Biozone B: Idalina sinjarica Total Range zone (SBZ 6-7) and 3-Biozone C: Alveolina globosa- Alveolina pasitisilata Concurrent Range Zone (SBZ8-10). These zones indicate the Late Paleocene –Early Eocene age of the Sinjar formation. The biostratigraphic correlations in the studied sections are based on benthic foraminiferal zonations. Showed the correlation comparison between the biostratigraphic zones of the commonly used benthic zonal scheme around the Late Paleocene -Early Eocene in and outside of Iraq. paleoecological studies suggest that the carbonate sedimentation of the Sinjar Formation thrived in 18-25oC, with mesophotic to oligophobic light, under an oligotrophic to mesotrophic middle ramp environment with normal marine to slightly saline and at water depths from 40 - 80 m. Stable isotopic carbon (δ13C) and oxygen (δ18O) data revealed generally hot conditions with high productivity during the deposition of the Sinjar Formation accompanied by an abrupt change in paleoenvironmental conditions across the Paleocene-Eocene contact.

A new Oligocene–lowermost Miocene succession from the Gawran Gorge, NE Sagirma Anticline, Qaradagh, Sulaimaniyah, Kurdistan Region, NE Iraq

The rock units in the Gawran Gorge, Sagirma Mountains (from the High Folded Zone), near the Sulaimaniyah city, in the Kurdistan Region, NE Iraq, were investigated in order to describe and biostratigraphically date the sedimentary succession. Twenty-seven species of larger benthic foraminifera were identified belonging to 16 genera. Several other fossil groups were also recognized, including echinoid, bryozoan, bivalve, gastropods and coral remains. Two biozones were recognized––the Praerhapydionina delicata–Austrotrillina asmariensis/Peneroplis evolutus Assemblage Zone and the P. delicata/ Austrotrillina howchini Interval Zone,which indicate a late Oligocene–lowermost Miocene age for the succession. This section was correlated to the surrounding successions having a similar age in the High Folded Zone of Iraq, and to sediments in other countries, so as to indicate the wider distribution of the lithostratigraphic unit.

Benthic Foraminifera from the Lower Miocene Sediments of Murachbann, Western Kachchh, Gujarat, India: Implications for Inferring Palaeoenvironment

A thorough taxonomic study was carried out for the first time using high-resolution microscopy from Neogene sections of western Kachchh, India. In the present study, 25 species of benthic foraminifera belonging to 3 classes viz. Globothalamea, Tubothalamea, Nodosariata and 4 orders Rotaliida, Textulariida, Miliolida and Polytmorphinida have been identified from limestone and silty-claystone of Murachbann section belonging to lower Miocene. This taxonomic study provides the distribution of benthic foraminifera species from Murachbann section. The attempt is made to interpret depositional palaeoenvironment based on this distribution of the studied foraminifera. Keywords: Morphology, Taxonomy, Benthic Foraminifera, Limestone, Palaeoenvironment, Chhasra Formation

Macrofossil Characteristics and Bathymetric Environment of Sumber Makmur Village, Muara Sahung, Kaur, Bengkulu

The research location is administratively located in Sumber Makmur Village, Muara Sahung District, Kaur Regency, Bengkulu Province. In the study area, outcrops that had fossils were found, which were shown by the presence of carbonate rock lithology. The study was conducted to determine the deposition environment in the research area. The method used is a previous literature study that aims to determine the physical geological conditions and regional stratigraphy of the research area. Furthermore, field observations and laboratory analysis were conducted in the form of paleontological analysis to determine the characteristics and types of fossils found in the study area. Paleontological research was conducted on two formations, namely the Lemau Formation and the Simpangaur Formation. In the Lemau Formation, several species of benthic foraminifera were found, namely Cibicides praecinestus, Elphidium macelium, Marginopora vertebralis, Elphidium articulatum, and Planorbulina mediterranensis. Then, in the Simpangaur Formation, several species of benthic foraminifera were found, namely Streblus beccari, Bolivina schwageriana, Anomalinella rostrate, Cibides praecinestus, Cibides margaritiferus, Lagena sulcata, Quinqueloculina bradyana, and Lenticulina calcar. In addition, macrofossils were found in marine life with phylum mollusks such as Lunatia elevatum, Murex vanuxemi, Turritella terebra, Conus sauridens, and Plocostoma neumayeri. Based on these data, it can be interpreted that the depositional environment in the study area is in the Transition-Edge Neritic marine environment.

Recent benthic foraminiferal assemblages and sedimentary facies from two atolls of Maldivian Archipelago (Indian Ocean): Reef and seagrass indicators

The Maldives Archipelago is an isolated tropical carbonate platform in the Indian Ocean that includes diverse reef and perireef modern environments. We provide a study of benthic foraminiferal assemblages from seagrass and macroalgae dominated habitat and from unvegetated environments.A total of 252 species of benthic foraminifera were identified from 35 samples and biotic indexes were calculated. The assemblages are dominated by genus Amphistegina, and its spatial distribution appears related to depth and seagrass cover, but it is also influenced by hydrodynamic energy.Multivariate analysis distinguished six principal assemblages, being A. lobifera-A. radiata assemblage associated with unvegetated seabed from 15 to 76 m water depth (mwd).The study of recent tropical vegetated and unvegetated benthic associations is also useful for paleoecological and paleoenvironmental interpretations. The foraminiferal indexes (FI and ILS) are calculated to assess the health of reefal communities and compared with those given by previous works in the investigated areas.

The Benthic Foraminiferal Assemblages in the Seagrass Bed of Tanjung Berakit Waters, Bintan Island

Seagrass is the most common ecosystem in Tanjung Berakit waters. Therefore, Tanjung Berakit waters have a very important role as a benthic foraminiferal habitat. This study was conducted to describe the distribution of benthic foraminifera relating to the environmental condition of the waters. The samples were collected from eight stations by handling garb in November 2017. This study collected 18 species of shallow water benthic foraminifera dominated by Amphistegina and Heterostegina. This study recorded a correlation between the sediment texture and foraminiferal assemblages. The most common foraminifera were inhabiting fine-textured sediments, especially very fine sand and silt. Only a few foraminifers are collected from extremely fine sediments such as clay sediments, or extremely coarse including pebbles.

“LARGER” BENTHIC FORAMINIFERA OF THE CENOMANIAN. A REVIEW OF THE IDENTITY AND THE STRATIGRAPHIC AND PALAEOGEOGRAPHIC DISTRIBUTION OF NON-FUSIFORM PLANISPIRAL (OR NEAR-PLANISPIRAL) FORMS

A key but challenging task for biostratigraphers is to provide a biozonal/bioevent framework for geological correlation. Species of Larger Benthic Foraminifera (LBF) are important biostratigraphic markers in depositional environments where classical biostratigraphic fossils such as planktonic micro- and macrofossils are rare or absent – e.g., tropical-subtropical shallow water platforms. However, a lack of taxonomic rigour in identifying some LBF species, together with a lack of good age-calibration of their occurrences, has given rise to artificially extended biostratigraphic and paleogeographic ranges for many taxa, diluting their usefulness. In this study, the occurrences of Cenomanian LBF belonging to a “planispiral morphogroup”, both agglutinated and calcareous, have been critically evaluated to determine (i) identity; (ii) stratigraphic range; and (iii) palaeogeographic distribution. Since the last major review of the group in 1985, a voluminous literature has appeared reporting occurrences and adding new taxa. An extensive review of some 600+ published items on Cenomanian planispiral LBF – mostly published after 1985 – and a critical review of the confidence in species identification and age-calibrations therein, has led us to identify 39 taxa (three in “open” status) which appear to have distinct identity. The vast majority of these records are from Neotethys although some also occur in (or are endemic to) the Caribbean/West Atlantic and the Eastern Pacific. The quality of the published taxonomic data is variable and many published records based on identity can be discounted or termed “unconfirmed”. Likewise, many records (confirmed or otherwise) are poorly age-calibrated due to lack of corroborating biostratigraphy or chemostratigraphy, or by using circular reasoning. We summarise and illustrate the main defining characteristics of each taxon and their possible confusion species, including new taxa described since the mid-1980s. We publish new, more confident, age-ranges for these taxa – confirmed by identity and/or age-calibration – and identify where published range data may be unreliable. Paleogeographic distribution maps for each taxon are also provided. Particular stratigraphic issues around the Cenomanian- Turonian boundary are observed due to the difficulty of identifying that boundary, or its preservation, in shallow marine carbonate settings. Although most Cenomanian planispiral LBF are somewhat long-ranging, an increase in diversity throughout the middle – late Cenomanian has shown potential for biostratigraphic resolution to at least substage level using this group. Integration of the planispiral taxa with other LBF morphogroups, after similar treatment, will yield even higher biostratigraphic resolution of Cenomanian LBF and provide a sound basis for biozonation (both local and global), correlation, and age calibration.

Variations in benthic foraminifera biofacies since Mid-Pleistocene (MIS 7) in the Campos Basin slope, Eastern Brazil: Assessing present-day and past controlling factors

Benthic and planktonic foraminifera faunal and stable isotopic (δ18O and δ13C) analyses on foraminiferal tests were carried out on a piston core, collected from the Campos Basin slope at a water depth of 1475 m. The core location is in front of Cape São Tomé and exhibits landslide scars features. Benthic foraminifera biofacies with ecological indexes and statistics, lithological facies, biostratigraphy and stable isotopic analysis were used to understand the paleoenvironmental evolution of the region by comparison with modern foraminiferal assemblage. Six biofacies were identified between Marine Isotope Stage (MIS) 7 to MIS 1. The main ecological factors controlling the modern assemblages are: bottom currents, slope stability, oxygen concentration, and nutrient input. However, the last two factors are linked to oceanic processes associated with the Paraíba do Sul river, the influence of which has changed in the past. In particular, Biofacies 3, contains infaunal species, points to dysoxic or anoxic periods in the environment, which are interpreted as periods of increased river influence. Changing environmental conditions were observed as the dominant benthic foraminifera species varied down the core, from Epistominella exigua that thrives in stressful conditions, such as sea level oscillations to Globocassidulina crassa, that prefers mild environments during periods of sea level stability.

New larger benthic foraminifera from Brač Island, Croatia: Further evidence for early–middle Campanian foraminiferan high diversity in the inner platform facies of the Adriatic Carbonate Platform

Four new species of larger benthic foraminifera are described from lower–middle Campanian inner-platform carbonates of the island of Brač, Croatia: Bakhtiarella minima sp. nov. (family Bakhtiarellidae), Biconcava brattiana sp. nov. (family Mayncinidae), Paravanneauina campaniana gen. et sp. nov. and Calveziconus pygmaeus sp. nov. (family Orbitolinidae). The latter two taxa are also reported from time-equivalent strata of the Gavrovo–Tripolitza Platform, southwestern Greece. The new taxa provide further evidence for the pronounced Campanian diversification within the Late Cretaceous Global Maturation Cycle of larger benthic foraminifera in the inner platform facies of the Mediterranean Adriatic Carbonate Platform.

Evaluation of radioactive properties and microfaunal evidence in the Bosphorus and the Dardanelles straits and Golden Horn sediments

The aim of this study is to investigate radioactive pollutants from pollution loads transported from the Black Sea to the Aegean Sea by the Turkish Straits System and their effects on microfauna (benthic foraminifer and ostracod) assemblages. In the study, the effects of gross alpha and beta activity on the species number, species diversity, dominant species and species richness of benthic foraminiferal and ostracod assemblages were investigated in 16 bottom sediments taken from different depths in the Golden Horn, Bosphorus and Dardanelles straits. In the studied sediment samples examined 61 genera and 64 species of benthic foraminifera, 23 genera and 26 species of ostracoda were identified. In addition two migratory foraminifera species were observed as Spiroloculina antillarum of Atlantic-Pacific origin and Peneroplis pertusus of Indo-Pacific origin. A relationship between the abundance of microfauna and high gross alpha and beta values was found in the Dardanelles samples, but not in the Bosphorus and Golden Horn samples. In this study, the highest radioactivity value was observed in the deepest bottom sediment samples. Consequently, the gross alpha and beta values were seen to be close to each other in the Dardanelles Strait and Golden Horn samples, and they had a broad-spectrum in the Bosphorus samples.

Gelasian to Calabrian (Early Pleistocene) marine ostracods and foraminifera from Mida Section (Cap Bon, Tunisia) Les ostracodes et les foraminifères marins du Gélasien au Calabrien (Pléistocène inférieur) de la coupe de Mida (Cap Bon, Tunisie)

We report for the first time a rich and well-preserved marine ostracod and foraminifera association from lower Pleistocene fossiliferous sandstones of the Mida Section (Cap Bon, NE Tunisia).Micropalaeontological analysis of nine samples taken along an eight-meter exposure revealed 46 ostracod species belonging to 34 genera, 15 species of benthic foraminifera belonging to 14 genera and 8 species of planktonic foraminifera belonging to 4 genera. The ostracod association enabled us to draw a palaeoenvironmental reconstruction of this area during the Gelasian to Calabrian time, highlighting a regressive cycle from circalittoral to shallow infralittoral palaeoenvironments. Planktonic foraminifera were used to constrain the age of the section to the end of Gelasian-beginning of Calabrian. Moreover, the discovery of Bythocythere turgida in the lower part of the section allowed to infer that these sandstones were deposited during the early Pleistocene cold periods.

Deep-sea paleoenvironmental evolution in the mid-Cretaceous of the Basque Pyrenees based on microfaunal analysis (Armintza section)

The mid-Cretaceous Black Flysch Group and Plentzia Formation constitute two key lithostratigraphic units in the evolution of the Pyrenean rift system but many of their paleoenvironmental characteristics are poorly known. In this work, a microfaunal analysis (planktonic and benthic foraminifera and ostracods) of these two units at the Armintza section has been carried out in order to interpret the paleoenvironmental conditions (paleodepth, oxygen level and water masses) in which they deposited, and to relate them to the contemporary tectono-sedimentary settings. Based on the high proportion of planktonic foraminifera with respect to total foraminifera and the assemblages of benthic foraminifera species, a paleodepth of ∼600 m is estimated for studied units. During syn-rift deposition of the organic-rich Black Flysch Gp. in middle Albian-early Cenomanian times, the relative abundance of planktonic foraminifera and the proportions of different shell morphotypes suggest the presence of a shallow water mass and the stagnation of deeper waters. Moreover, the presence of abundant hypoxia-tolerant benthic foraminifera species and the occurrence of only rare hypoxia-tolerant platycopid ostracods indicate severe hypoxia conditions (<1.5 ml/l) or even anoxia at the seafloor. A noticeable change is recorded at the contact between the Black Flysch Gp. and the Plentzia Fm. (lower-middle Cenomanian transition). During post-rift deposition of the Plentzia Fm. in earliest middle Cenomanian times, developed microfaunal assemblage shows an important increase in benthic foraminifera species, many of which indicate intermediate waters, and dominance of keeled planktonic foraminifera suggesting the end of water stagnation and the inflow of an intermediate water mass. In addition, the presence of hypoxia-tolerant species of ostracods and benthic foraminifera indicates the development of mild hypoxia conditions at the seafloor during this interval.

Foraminifera associated with cold seeps in marine sediments

Cold seep foraminifera have attracted considerable attention as they provide valuable insights into the study of cold seeps. This study provides a comprehensive overview of the manifestations of foraminifera in cold seep environments and methane seepage activities. Certain taxa of benthic foraminifera, such as Uvigerina, Bolivina, Bulimina, Chilostomella, Globobulimina, Nonionella, Melonis, Epistominella, Cibicidoides, and Globocassidulina, are known to inhabit geochemical conditions induced by methane-rich environments and may feed on associated methanotrophic microbial communities. Secondary mineralization on foraminifera shells is a widespread manifestation in seep sediments, and alters the microstructure, elementary composition, and isotopic signatures of foraminifera. On one hand, the precipitation of secondary authigenic Mg-rich, Mn-rich, Sr-rich, and Ba-rich calcite coatings have been observed on microfossils. On the other hand, micron-sized crystal pyrite and gypsum aggregates can also grow on the foraminifera walls. The negative δ13C and positive δ18O anomalies in both planktonic and benthic foraminifera from seep-associated sediments can serve as proxies for tracing past seepage activities, either in their live form or being adulterated by methane-derived authigenic carbonate after deposition. Seeping activities are recognized with a significant impact on benthic foraminifera, and the presence of cold seep-related species and significant isotopic anomalies in shells can be used to reconstruct past methane seepage events. Intensive methane seepage tends to suppress benthic foraminifera populations, while moderate intensity seepage may lead to a thriving benthic foraminiferal community, with hypoxia-enduring taxa such as Uvigerina, Melonis, and Bulimina being predominant. In contrast, oxygen-loving epibenthic taxa such as Cibicidoides often occur in areas of low methane flux. Compared to planktonic foraminifera, the single species of benthic foraminifera can provide a more comprehensive record of seepage evolution. Live benthic specimens are preferred for in-situ seep studies, while the superimposition of secondary minerals on the original shells should not be ignored when observing dead individuals. The significance of the evolution of methane seepage, changes in environmental parameters of the living habitat, and species sensitivity in cold seeps are emphasized in explaining the variation in foraminiferal assemblages and fluctuations in stable isotopes.

The response of benthic foraminifera to environmental changes in Epie creek, Yenagoa, Bayelsa State

Epie creek, located at the Southern part of Nigeria has been known for its use as sink for the disposal of untreated sewage and industrial effluents. Benthic foraminifera are increasingly been used as environmental bio-indicators of pollution. Their munity structure provides information on the general characteristics of the environment and some species are sensitive to specific environmental parameters. This study investigates recent foraminifera from sediment samples collected from ten (10) stations (ranging in depths from 1m to 4.2m) in the Epie creek from Igbogene to Tombia- Etegwe. The environmental factors that necessitate their existence such as temperature, pH, salinity and dissolved oxygen were measured during the sampling time. Metals were determined using atomic absorption spectrophotometer. Recognized benthic foraminifera species belonging to four (4) genera of three (3) families and four(4) suborder were identified. Five (5) benthic foraminifera taxa were identified from sediment samples which include Lenticulina stellata, Saccammina sp, Marginulina costata, Marginulina cf. planata and Trochammina sp. The stress tolerant specie, Trochammina ,sp. was common in the study area confirming a stressed environment.