Search

There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log10 cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was

The Santa Barbara Basin is an extraordinary archive of environmental and ecological change, where varved sediments preserve microfossils that provide an annual to decadal record of the dynamics of surrounding ecosystems. Of the microfossils preserved in these sediments, benthic foraminifera are the most abundant seafloor-dwelling organisms. While they have been extensively utilized for geochemical and paleoceanographic work, studies of their morphology are lacking. Here we use a high-throughput imaging method (AutoMorph) designed to extract 2D data from photographic images of fossils to produce a large image and 2D shape dataset of recent benthic foraminifera from two core records sampled from the center of the Santa Barbara Basin that span an ~800-year-long interval during the Common Era (1249-2008 CE). Information on more than 36,000 objects is included, of which more than 22,000 are complete or partially-damaged benthic foraminifera. The dataset also includes other biogenic microfossils including ostracods, pteropods, diatoms, radiolarians, fish teeth, and shark dermal denticles. We describe our sample preparation, imaging, and identification techniques, and outline potential data uses.

A complex of sedimentological, geochemical, and micropaleontological methods was used to study and compare five new sediment cores along a submeridional transect from the middle to the north of the Norwegian Sea. A combined analysis of the distribution of ice-rafted debris, polar/subpolar foraminifera, calcium carbonate, organic carbon, and continuous geochemical scanning records revealed an alternation of Middle–Late Quaternary glacial and interglacial intervals over the last 260 000 years. In the Late Middle Pleistocene glaciation (MIS 6, 8), the supply of terrigenous material had a much greater influence on regional sedimentation than in the Late Pleistocene (MIS 2–4). Local (between the central and northern parts of the Norwegian Sea) differences in glacial and interglacial sedimentation are shown. [ABSTRACT FROM AUTHOR]

ABSTRACT This study is based on stable isotope analysis of a rich ammonite assemblage from the Sogukcam Formation, which is widely exposed in Yesilbaglar (Olur‐Erzurum, NE Türkiye). The presence of ammonid, planktic, and benthic foraminifers in the marine sediments suggests that they are from the early Cretaceous period. The late Valanginian‐early Aptian‐rich ammonite assemblage includes the following genera and species: Acrioceras sp., Barremites difficilis, Barremites sp., Crioceratites duvalii, Crioceratites sp., Deshayesites aff. dechyi, Deshayesites sp.1, Deshayesites sp.2, Deshayesites sp.3, Deshayesites sp., Dufrenoyia cf. dufrenoyi, Dufrenoyia cf. furcata, Dufrenoyia sp., Hemihoplites sp., Heteroceras sp., Neocomites sp., Phyllopachyceras infundibulum, Protetragonites cf. quadrisulcatus, Protetragonites sp., Ptychoceras sp., Turkmeniceras cf. geokerense, and Turkmeniceras sp. This assemblage suggests that the Sogukcam Formation's deeper facies formed in the late Valanginian to early Aptian period. Fossils and δ18O data show normal paleosalinity levels. During the late Valanginian‐early Aptian period, δ18O values ranged from −3.67‰ to −2.24‰, with paleotemperatures ranging from 21.3°C to 27.9°C. δ13C positive values range from +0.65‰ to +2.86‰. δ13C isotope data show the oxygen minimum zone (OMZ) and changes in sea level and productivity. The presence of planktonic foraminifera and the ammonite assemblage indicates that the formation was deposited in warm subtropical waters ranging from the outer shelf to the open sea. [ABSTRACT FROM AUTHOR]

Describing living community compositions is essential to monitor ecosystems in a rapidly changing world, but it is challenging to produce fast and accurate depiction of ecosystems due to methodological limitations. Morphological methods provide absolute abundances with limited throughput, whereas metabarcoding provides relative abundances of genes that may not correctly represent living communities from environmental DNA assessed with morphological methods. However, it has the potential to deliver fast descriptions of living communities provided that it is interpreted with validated species‐specific calibrations and reference databases. Here, we developed a quantitative approach to retrieve from metabarcoding data the assemblages of living large benthic foraminifera (LBF), photosymbiotic calcifying protists, from Indonesian coral reefs that are under increasing anthropogenic pressure. To depict the diversity, we calculated taxon‐specific correction factors to reduce biological biases by comparing surface area, biovolume and calcite volume, and the number of mitochondrial gene copies in seven common LBF species. To validate the approach, we compared calibrated datasets of morphological communities from mock samples with bulk reef sediment; both sample types were metabarcoded. The calibration of the data significantly improved the estimations of genus relative abundance, with a difference of ±5% on average, allowing for comparison of past morphological datasets with future molecular ones. Our results also highlight the application of our quantitative approach to support reef monitoring operations by capturing fine‐scale processes, such as seasonal and pollution‐driven dynamics, that require high‐throughput sampling treatment. [ABSTRACT FROM AUTHOR]

The upper part of the Harudi Formation of the Kutch basin in Gujarat, western India, has recently yielded a heretofore undocumented assemblage of elasmobranchs, including extinct sand tiger sharks Brachycarcharias lerichei and Striatolamia macrota, extinct tiger sharks Galeocerdo eaglesomei and G. clarkensis, requiem shark Carcharhinus mancinae, as well as sawfish Pristis sp. A bony fish taxon represented by Trichiurus sp. was also recovered. After a 43-years gap, this study provides a taxonomic update on the middle Eocene sharks of Kutch. Their coexistence with the larger benthic foraminifera Nummulites obtusus and planktonic foraminifera Orbulinoides beckmanni dates this fish fauna to 40–41.03 Ma, which corresponds to the time frame of the Bartonian transgression and extreme warming event Middle Eocene Climatic Optimum (MECO). The MECO elasmobranch assemblage of Kutch comes from shelf settings with bathymetry of 30–60 m, and it differs from those associated with Paleocene–Eocene hyperthermal events and deposited in the bay complex. It seems that G. clarkensis and C. mancinae emerged in Kutch during MECO. The global stratigraphic distribution demonstrates that B. lerichei and S. macrota originated in North America, and their appearance in Kutch expands their geographic range into the eastern Tethys realm, possibly as a result of MECO-linked Bartonian/Kirther transgression. [ABSTRACT FROM AUTHOR]

The minor and trace element compositions of biogenic carbonates such as foraminifera are important tools in paleoceanography research. However, most studies have focused primarily on samples with element to calcium (El/Ca) ratios higher than the El/Ca range often found in benthic foraminifera. Here, we systematically assess the precision and accuracy of foraminifera elemental analysis across a wide range of El/Ca especially at relatively low ratios, using a method on a Thermo Scientific iCAP Qc quadrupole Inductively Coupled Plasma Mass Spectrometer (ICP‐MS). We focus on two benthic foraminifera species, Hoeglundina elegans and Cibicidoides pachyderma, and prepared a suite of solution standards based on their typical El/Ca ranges to correct for signal drift and matrix effects during ICP‐MS analysis and to determine analytical precision. We observe comparable precisions with published studies at high El/Ca, and higher relative standard deviations for each element at lower El/Ca, as expected from counting statistics. The overall long‐term analytical precision (2σ) of the H. elegans‐like consistency standard solutions was 6.5%, 4.6%, 5.0%, for Li/Ca, Mg/Ca, Mg/Li, and 6.4%, 10.0%, 4.2% for B/Ca, Cd/Ca, Sr/Ca. The precision for H. elegans‐like Mg/Li is equivalent to a temperature uncertainty of 0.5–1.1°C. Measurement precisions were also assessed based on three international standards (one solution and two powder standards) and replicate measurements of H. elegans and C. pachyderma samples. We provide file templates and program scripts that can be used to design calibration and consistency standards, prepare run sequences, and convert the raw ICP‐MS data into molar ratios. Key Points: Higher relative standard deviations are reported at lower element/calcium values, as expected from counting statisticsConsistency standards having similar ratios to the unknown samples provide an accurate estimate of errorsFor the Hoeglundina elegans Mg/Li—temperature proxy, analytical precision (2σ) is equivalent to a temperature uncertainty of 0.5–1.1°C [ABSTRACT FROM AUTHOR]

Planktonic Foraminifera have been collected from the water column with different plankton sampling devices equipped with nets of various mesh sizes, which impedes direct comparison of observed quantifications. Here, we use data on the community size structure of planktonic Foraminifera to assess the impact of mesh size on the measured abundance (ind m−3) of planktonic Foraminifera. We use data from the FORCIS database (Chaabane et al., 2023, Scientific Data 10: 354) on the global ocean at different sampling depths over the past century. We find a global cumulative increase in abundance with size, which is best described using a Michaelis–Menten function. This function yields multiplication factors by which one size fraction can be normalized to any other size fraction equal to or larger than 100 μm. The resulting size normalization model is calibrated over a range of different depth intervals, and validated with an independent dataset from various depth ranges. The comparison to Berger's (1969, Deep. Res. Oceanogr. Abstr. 16: 1–24) equivalent catch approach shows a significant increase in the predictive skill of the model. The new size normalization scheme enables comparison of Foraminifera abundance data sampled with plankton nets of different mesh sizes, such as compiled in the FORCIS database. The correction methodology may be effectively employed for various other plankton groups such as diatoms and dinoflagellates. [ABSTRACT FROM AUTHOR]

Metal contamination in the Arctic region has increased over the years despite its remote and isolated location. Thus, to evaluate the bioavailable fractions of various metals and their effects on sediment-associated biota, the surface sediments from the fjords were analyzed for bulk concentration of metals and their speciation in different fractions. Metals concentrations were higher in the inner fjord region and decreased towards the outer fjord, supported by the terrigenous influence (TI%) calculated. Cr and Pb showed higher excess values attributed to their additional source other than the catchment rocks. So, to assess the metal-related ecological risk, the bulk concentration of metals was compared with Arctic sediment quality guidelines (ASQGs). Cr, Cd, and Pb concentrations were high, indicating potential adverse biological effects in the study. To avoid the risk of overestimation, metal speciation was conducted, showing that overall metal concentrations were higher in the residual fraction; however, higher concentrations of Mn in labile phases pose a moderate risk to the sediment-associated biota. Additionally, the population density of foraminifera in the sediments was calculated to assess the influence of bioavailable metal on benthic foraminifera. It was found that the presence of metals in bioavailable fractions affected the abundance of the foraminifera. However, no morphological abnormalities were observed in the species. [ABSTRACT FROM AUTHOR]

According to the prevailing view in literature, two Eocene carbonate platform belts developed on northern and southern margins of the Tethys Ocean. However, Eocene platforms in the Malaguide−Ghomaride Units (Betic-Rifian Arc; Spain and Morocco, respectively) in intermediate position to the classic platform belts have been proposed in recent literature. A number of representative Ypresian to Priabonian stratigraphic sections have been revisited and empowered by new data collected for the scope. Ten lithobiofacies (consisting of limestones rich in Larger Benthic Foraminifera (LBF), algae, and corals) and ten microfacies (based on fossil assemblage and their relative abundance, texture, and fabric) were proposed for this intermediate platform belt in recent literature. The paleoenvironmental reconstruction indicate inner to outer ramps (locally also the upper slope) arranged in two sedimentary sequences rich in LBF and corals. A great development of carbonate seagrass factories in most of the areas in which inner ramps developed has been identified. These factories correspond to a warm-temperate system with warm-water conditions mainly in low latitude settings. Trophic resources proposed in these works suggest oligo- to mesotrophic conditions in inner to mid ramp settings, which only evolve to eutrophic conditions in outer ramp and upper bathyal settings. A comparison of the three belts of carbonate platforms at the western Tethys scale has been performed, providing several important constraints in terms of the recorded time period according to the literature, tectonics, transgressive−regressive trendings, relative abundance of fossils, and paleoenvironmental conditions. The Eocene platforms of the westernmost Tethys show a lacunose geological record registered from upper Ypresian (Cuisian) to Bartonian. It shows an important gap at the upper Ypresian (Cuisian)−Lutetian boundary. LBF remained the primary framework builders elsewhere until the Bartonian age, with zooxanthelle−coral build-ups playing a more significant role in the inner ramps than previously assumed. [ABSTRACT FROM AUTHOR]

Bacteria are mostly everywhere, some of them affect health safety of human beings, plants and animals all the time. Photocatalytic antibacterial technology has entered people's field of vision due to their high-efficiency and sustainability. In this study, LaCoO 3 precursors were prepared by solvothermal synthesis, and then calcined to obtain self-assembled LaCoO 3 microspheres. Subsequently, LaCoO 3 /Ag 3 PO 4 microspheres were synthesized by in-situ precipitation method. Compared with pure LaCoO 3 microspheres, the introduction of Ag 3 PO 4 nanoparticles can effectively enhance the antibacterial performance of LaCoO 3 /Ag 3 PO 4 nanocomposites. LaCoO 3 /Ag 3 PO 4 nanocomposites' Minimum Inhibitory Concentrations (MICs) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were tested to be 0.1 mg mL−1 and 0.15 mg mL−1, respectively. Under visible light irradiation for 20 min, the antibacterial rate of nanocomposites against E. coli and S. aureus was 99.9 % and 98.3 %, correspondingly. This can be attributed to the fact that LaCoO 3 /Ag 3 PO 4 heterojunction significantly improves the responsiveness of visible light, carrier separation and migration efficiency of LaCoO 3 , which promotes the nanocomposite to produce a large number of ROS under visible light. In addition, LaCoO 3 /Ag 3 PO 4 nanocomposites had a strong oxidation effect on glutathione (GSH), resulting in the failure of the antioxidant defense system of bacteria. Also, the release of Ag+ and plasma effect of Ag are also important reasons for the high antibacterial performance of LaCoO 3 /Ag 3 PO 4 nanocomposites. The photoresponse of LaCoO 3 -based nanomaterials under visible light is effectively improved by constructing heterojunctions, the separation efficiency of photogenerated electron-hole pairs is increased, and the carrier transport is accelerated, thus achieving high efficiency and broad spectrum antibacterial effect. This research shows that LaCoO 3 nanocomposites can be used as a prospective photocatalytic antibacterial material, enhances the value of practical applications. [ABSTRACT FROM AUTHOR]

Two sediment sections are investigated at Cape Arkhangelos, island of Rhodes, where Pleistocene marine sediments crop out in horsts and grabens of a Mesozoic basement. There, hemipelagic sediments characterized by upper bathyal communities are atypically mixed with much shallower faunal components because they were deposited close to rugged coastal landforms. Biostratigraphic analyses show that the sections were deposited between 1.8 and 0.9 Ma, and between 1.8 and 1.6 Ma, respectively. By combining the planktonic/benthic foraminiferal ratio with 31 bathymetric indicators chosen among extant species of benthic foraminifera, mollusks, and bryozoans, we show that relative sea-level fluctuations can be reconstructed in these atypical settings despite the proximity of steep slopes that favored transportation of allochthonous fauna. The shallow-water components (including gravels and calcareous algae) were transported downslope by the combined action of gravity, currents, and tectonic disturbance that promoted drowning (with a maximum flooding recorded at ca. 1.7 Ma) and then uplift of fault-bounded paleovalleys that formed during the Early Pleistocene. Abrupt facies changes and age differences between sections have been triggered by the irregular paleotopography of the Mesozoic basement, which fostered differential depositional settings, with outer to middle neritic deposits above the horsts and upper bathyal deposits in paleovalleys. [ABSTRACT FROM AUTHOR]

Stable water isotopes (δ18Ow and δDw) have been successfully implemented for the first time in a high-resolution model of the Mediterranean Sea (NEMO-MED12). In this numerical study, model results are compared with available in situ observations to evaluate the model performance of the present-day distribution of stable water isotopes and their relationship with salinity on a sub-basin scale. There is good agreement between the modelled and observed distributions of δ18Ow in the surface water. The model successfully simulates the observed east–west gradient of δ18Ow characterising surface, intermediate, and deep waters. The results also show good agreement between the simulated δDw and the in situ data. The δDw shows a strong linear relationship with δ18Ow (r2=0.98) and salinity (r2=0.94) for the whole Mediterranean Sea. Moreover, the modelled relationships between δ18Ow and salinity agree well with observations, with a weaker slope in the eastern basin than in the western basin. We investigate the relationship of the isotopic signature of the planktonic foraminifera shells (δ18Oc) with temperature and the influence of seasonality. Our results suggest a more quantitative use of δ18O records, combining reconstruction with modelling approaches. [ABSTRACT FROM AUTHOR]

A deep-marine sedimentary succession of Whaingaroan to Altonian age (Early Oligocene–Early Miocene), cropping out near Weber, southern Hawke's Bay, records abrupt changes in depositional paleoenvironments and sedimentary lithofacies. Highly calcareous early Waitakian (latest Oligocene) Weber Formation (Mangatu Group/Waka Supergroup) is unconformably overlain by terrigenous-dominated late Waitakian–Otaian (Early Miocene) Coast Road or Whakataki formations (Tolaga Group/Māui Supergroup). Most notably, in some localities, lowermost parts of the Coast Road Formation (Mangapuku Mudstone Member) contain prominent matrix-supported extra-formational olistoliths of centimetre to decametre scale derived from the underlying Weber Formation. Deposition of these blocks is attributed to deep-water collapse of parts of rapidly growing, over-steepened, reverse-fault-controlled thrust ridge(s). The onset of Coast Road and Whakataki formation deposition and associated abrupt changes in sedimentary lithofacies correlate to prominent Early Miocene lithological, mineralogical, and paleoenvironmental changes elsewhere along the Hikurangi Margin. We attribute these bio- and lithostratigraphic changes as evidence for significant shortening and upper-plate reverse faulting marking the onset of subduction beneath eastern North Island during the mid-Waitakian (c. 23 Ma). Proposed lithostratigraphic revisions presented herein help clarify depositional events and correlative sedimentary packages within the Miocene Hikurangi margin. [ABSTRACT FROM AUTHOR]

Copyright of Kirkuk Journal of Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seawater transported into the South Atlantic from the Indian Ocean via "Agulhas leakage" modulates global ocean circulation and has been linked to glacial‐interglacial climate cycles. However, constraining past Agulhas leakage has been a challenge. We sampled a transect of the Cape Basin in winter 2017 that intersected a mature Agulhas eddy and found that the 15N/14N ratio (δ15N) of mixed‐layer nitrate, zooplankton, and foraminifera (tissue and shells) was 2‰–3‰ lower in the eddy than in the background Atlantic even though the δ15N of the underlying thermocline nitrate was indistinguishable between the two settings. We suggest that the δ15N of foraminifera and other zooplankton in the eddy reflects the original Agulhas Current thermocline nitrate, which is ∼2‰ lower than that of the South Atlantic due to N2 fixation that occurs in the Indian Ocean. Foraminifera δ15N may have been lowered further during eddy migration by in situ N2 fixation and/or recycling of low‐δ15N ammonium. The absence of low‐δ15N Agulhas nitrate in the eddy thermocline can be explained by partial assimilation of the nitrate as it was mixed into the euphotic zone during and after eddy formation, raising its δ15N. The low δ15N of eddy foraminifera, apparent even after several months of eddy migration across the Cape Basin, suggests that fossil foraminifer‐bound δ15N from the region could record variations in past Agulhas leakage. Plain Language Summary: "Agulhas leakage," the flow of seawater from the Indian to the Atlantic Ocean, is a key component of global ocean circulation and predominantly takes the form of eddies. Identifying past changes in leakage can provide insights into the relationship between Atlantic Ocean circulation and climate changes. Here, we investigated whether the ratio of the nitrogen isotopes, 15N and 14N, in organic matter preserved in the shells of fossil foraminifera could be used to investigate past Agulhas leakage. Thermocline (i.e., sub‐surface) nitrate has a lower 15N‐to‐14N ratio in the Agulhas Current region, the source region for Agulhas leakage, than in the South Atlantic. To determine whether foraminifera inhabiting Agulhas leakage reflect this trend, we collected living specimens from inside and outside of a well‐developed Agulhas eddy in the southeastern Atlantic. We found that the nitrogen in foraminifera biomass and shells is isotopically lower in the eddy than in the "background" southeastern Atlantic. This signal can be explained by the lower 15N‐to‐14N ratio of the original (Agulhas‐sourced) nitrate, potentially augmented by internal nitrogen cycle processes occurring within the eddy. Our results strongly suggest that the nitrogen isotopes of fossil foraminifera could be used as an indicator of past variations in Agulhas leakage. Key Points: Nitrogen isotope ratios of mixed‐layer nitrate, zooplankton, and foraminifera in an Agulhas eddy are lower than in the southeast AtlanticDeeper‐dwelling, symbiont‐barren foraminifera record the nitrogen isotope ratio of thermocline nitrateForaminifer‐bound nitrogen isotopes in the Cape Basin sediment record could be used to reconstruct past variations in Agulhas leakage [ABSTRACT FROM AUTHOR]

Living organisms control the formation of mineral skeletons and other structures through biomineralization. Major phylogenetic groups usually consistently follow a single biomineralization pathway. Foraminifera, which are very efficient marine calcifiers, making a substantial contribution to global carbonate production and global carbon sequestration, are regarded as an exception. This phylum has been commonly thought to follow two contrasting models of either in situ ‘mineralization of extracellular matrix’ attributed to hyaline rotaliid shells, or ‘mineralization within intracellular vesicles’ attributed to porcelaneous miliolid shells. Our previous results on rotaliids along with those on miliolids in this paper question such a wide divergence of biomineralization pathways within the same phylum of Foraminifera. We have found under a high-resolution scanning electron microscopy (SEM) that precipitation of high-Mg calcitic mesocrystals in porcelaneous shells takes place in situ and form a dense, chaotic meshwork of needle-like crystallites. We have not observed calcified needles that already precipitated in the transported vesicles, what challenges the previous model of miliolid mineralization. Hence, Foraminifera probably utilize less divergent calcification pathways, following the recently discovered biomineralization principles. Mesocrystalline chamber walls in both models are therefore most likely created by intravesicular accumulation of pre-formed liquid amorphous mineral phase deposited and crystallized within the extracellular organic matrix enclosed in a biologically controlled privileged space by active pseudopodial structures. Both calcification pathways evolved independently in the Paleozoic and are well conserved in two clades that represent different chamber formation modes. [ABSTRACT FROM AUTHOR]

The isotopic and elemental composition of the fossil shells of foraminifera are often used for reconstructing past environments and climates. These so-called proxy relations are based on the effect of environmental conditions (e.g. seawater temperature, pH) on the isotopic ratio (e.g. δ11 B or δ18 O) or partitioning of elements (commonly expressed as El/Ca or DEl ) during calcification. Whereas many studies focused on proxy-calibrations of divalent cations, incorporation of monovalent cations are less well constrained. Here we calibrate shell potassium content (K/Cacc) as a function of 1) seawater K+ concentration, 2) the ratio of potassium and calcium in seawater (K/Casw) and 3) temperature. Moreover, we analyze Na+ incorporation into the calcite as a function of seawater K+ and Ca2+ concentrations. First, we cultured specimens of the larger benthic foraminifer at four different seawater [Ca2+] and constant [K+], resulting in a range of K/Casw. Secondly, we cultured specimens of the same species at four different [Ca2+]sw and [K+]sw while keeping the ratio between these two ions constant. Finally, we tested the effect of temperature (from 18 to 28°C) on K-incorporation in this species. Measured K/Cacc values are not notably affected by [Ca2+]sw, while seawater [K+] positively influences potassium incorporation, resulting in a positive correlation between seawater K/Ca values and K/Cacc. Although the [Na+] in the culture media was constant throughout both experiments, incorporated Na responded positively to decreasing [Ca2+]sw, resulting in a positive correlation between sea water Na/Ca and Na/Cacc. The difference in the controls on K- and Na-incorporation suggests that the (biological) control on these ions differs. Part of the observed variability in element partitioning may be explained by differences in chemical speciation and crystallographic coordination in the calcite lattice. [ABSTRACT FROM AUTHOR]

The ecological quality status (EcoQS) of Vellar and Uppanar estuaries (Southeast coast of India) has been monitored monthly, using a combination of foraminiferal (Foram Stress Index: FSI and exp(H'bc) indices and abiotic (Pollution Load Index: PLI, Dissolved Oxygen: DO, and Total Organic Carbon: TOC) parameters. The Uppanar Estuary shows relatively higher values of PLI and TOC and lower DO values than Vellar Estuary. The highest value of TOC and PLI are recorded during the monsoon season. These variations are well mirrored by the change in exp(H'bc) and FSI. The lowest values of exp(H'bc) are observed with the monsoon season and could be ascribed by an overall reduction of salinity, and to the highest level of TOC and PLI in response to enhanced river discharge. The FSI also exhibits great variability with significant higher values in the Vellar Estuary than in the Uppanar Estuary. The EcoQS evaluated by a combination of pollution- (i.e., PLI, TOC and DO) and foraminiferal-based [i.e., FSI and exp(H'bc)] indices are highly consistent (73.4%). The most frequent disagreement among indices is mostly associated to Uppanar Estuary and, particularly, in the inner stations. This difference might be related to a time-lag response of benthic foraminifera in terms of diversity and assemblages' compositions as well as of the pollution indicators in response to enhanced riverine input. This study further supports the application of foraminiferal-based indices in EcoQS assessment in transitional environments including tropical Indian estuaries. It also fills the gap of knowledge by providing a seasonal perspective on the variation of EcoQS based on a monthly-scale sampling. [ABSTRACT FROM AUTHOR]

There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log10 cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was <45%, foraminifera displayed no selectivity. As most of these extinctions coincided with oceanic anoxic events, we conducted simulations to assess the effects of ocean deoxygenation on foraminifera. Our results indicate that under suboxic conditions, oxygen fails to diffuse into the cell center of large foraminifera. Consequently, we propose a hypothesis to explain size distribution-related selectivity and Lilliput effect in animals relying on diffusion for oxygen during past and future ocean deoxygenation, i.e., oxygen diffusion distance in body. [ABSTRACT FROM AUTHOR]

A section measured from the upper part of the Pimienta Formation and the lowest part of the Tamaulipas Formation located in the central-eastern part of the state of Hidalgo, NE Mexico was studied. The lower part of the succession consists of an argillaceous and laminated dark gray limestone, black shale, black calcareous shale, siltstone and bentonite; the Pimienta–Lower Tamaulipas transition is marked by the sporadic appearance of light-colored limestone in the upper part of the Pimienta and the shift to a succession dominated by thicker beds of yellowish and bioturbated limestone. The microfossil assemblage consists of calpionellids, radiolarians, and planktonic and benthic foraminifers. The biostratigraphic study of the calpionellids enabled three zones to be identifi ed: Calpionella, Calpionellopsis and Calpionellites as well as fi ve subzones, Elliptica, Oblonga, Murgeanui, Darderi and Major, ranging from early late Berriasian to early Valanginian. This allows a chronostratigraphic correlation to be drawn between the Tethys and the Southeastern Pacifi c provinces. In addition, we report the occurrence of abundant radiolarians and planktonic and benthic foraminifers. The paleoenvironmental inferences in the studied section are documented from the predominant wackestone texture and microfossil association, indicating a pelagic basin environment. The abundant occurrence of radiolarians mostly in the Elliptica and Oblonga subzones could suggest an increase in the input of nutrients. [ABSTRACT FROM AUTHOR]

Microfaunal analysis of Cretaceous and Paleogene sediments collected over several decades from Western Siberia has illuminated the diversity, stratigraphic distribution, and paleoecological signifi cance of the rare low trochospiral benthic foraminiferal genus Bagginoides. Here, we describe two new species B. yamalensis n.sp. and B. tibeisalinella n.sp [ABSTRACT FROM AUTHOR]

In the present-day Indo-Pacific coral-reef settings two genera of alveolinoidean porcelaneous larger benthic foraminifera (LBF) occur, namely Alveolinella and Borelis. Alveolinella is represented by a single species, A. quoyi , whose northernmost record is in Okinawa-jima (central Ryukyu Islands, Japan). Although the Indo-Pacific area, and especially the Coral Triangle, is a biodiversity hotspot since the Early Miocene, in-depth investigation on fossil representatives of present-day LBF is limited to a few taxa. To help bridge this knowledge gap, the palaeobiogeographical dynamics of A. quoyi is assessed. Analysis of data from the palaeontological literature shows that its first appearance datum is from the Tortonian (Late Miocene) of East Kalimantan and Papua New Guinea. In the Pliocene–Pleistocene the Indonesian Throughflow constrained the species within the Central Indo-Pacific. Finally, during the Late Pliocene the northward migrants arrived in the shallow-water carbonate settings of Okinawa-jima where the species is still thriving. [ABSTRACT FROM AUTHOR]

Nannofossils and planktonic foraminifers from the Lower Miocene Alkun Formation of central and western Ciscaucasia were studied in the following sections: the stratotype section on the Alkunka River, the Republic of Ingushetia; stratotype of the Caucasian Regional Stage on the Kuban River, Karachay-Cherkessia; Lower Miocene reference section on the Belaya River, Adygea; and in the sections of the Alkun Formation stratotype area on the Fiagdon and Mairamadag rivers, North Ossetia. Planktonic foraminifers in the Alkun Formation were studied for the first time. The available results made it possible to reveal the composition and structure of nannofossil and planktonic foraminiferal assemblages from the Alkun sediments in Ciscaucasia, to refine their stratigraphic and correlation potential and to recognize bionomic conditions of the Alkun basin in the studied area. As a result of the nannoplankton study the Cyclicargolithus floridanus Beds were recognized in the Alkun Formation and, taking into account the occurrence of the zonal species Triquetrorhabdulus carinatus along with Tr. milowii, they are correlated with the upper (Miocene) part of the Aquitanian Zone NN1. Planktonic foraminiferal data permitted to recognize the Streptochilus pristinum Beds. [ABSTRACT FROM AUTHOR]

The boron isotope palaeo-pH/CO 2 proxy is one of the key quantitative tools available to reconstruct past changes in the concentration of CO 2 in the atmosphere. In particular, marine calcifying organisms have been shown to be useful archives of this proxy, enabling quantitative variations in pH/CO 2 to be reconstructed throughout the Cenozoic. In order to provide an alternative proxy archive to the widely used planktonic foraminifera, we investigated the symbiont-bearing, high-Mg, shallow-dwelling, tropical large benthic foraminifera (LBF) species Operculina ammonoides and present a calibration of the relationship between the shell boron isotopic composition and seawater pH. We investigated specimens collected from both several reefs as well as grown in laboratory culture experiments in which pH and DIC were decoupled from each other, measuring newly-formed chambers using laser-ablation as a sample introduction technique. Based on our laboratory culture samples, the resulting linear relationship between the in situ boron isotopic composition of aqueous borate ion (B(OH) 4 −) and the shells of O. ammonoides is characterised by a gradient of 0.38 - 0.10 + 0.12 . In contrast, the boron isotopic composition of the field collected samples displays a near 1:1 relationship with B(OH) 4 −. We suggest that the shallow slope of the laboratory culture regression is the result of the difference between their micro-environment carbonate chemistry and that of the surrounding seawater driven by a pH dependence of the relative rates of calcification and photosynthesis. Based on a model of the effect of these processes on the diffusive boundary layer, we show that this effect is expected in laboratory culture experiments free from micro-turbulence, but not in the foraminifer's natural environment. As such, we demonstrate the utility of these organisms as proxy archive, while also highlighting how laboratory experimental design has the potential to drive important changes in the micro-environment and resulting shell chemistry of organisms of this size. Given that the genus Operculina originated in the late Palaeocene, this work paves the way towards deep-time palaeo-pH/CO 2 reconstructions using foraminifer species which have a very closely related modern representative. [ABSTRACT FROM AUTHOR]

The nature and extent of diversity in the plankton has fascinated scientists for over a century. Initially, the discovery of many new species in the remarkably uniform and unstructured pelagic environment appeared to challenge the concept of ecological niches. Later, it became obvious that only a fraction of plankton diversity had been formally described, because plankton assemblages are dominated by understudied eukaryotic lineages with small size that lack clearly distinguishable morphological features. The high diversity of the plankton has been confirmed by comprehensive metabarcoding surveys, but interpretation of the underlying molecular taxonomies is hindered by insufficient integration of genetic diversity with morphological taxonomy and ecological observations. Here we use planktonic foraminifera as a study model and reveal the full extent of their genetic diversity and investigate geographical and ecological patterns in their distribution. To this end, we assembled a global data set of ~7600 ribosomal DNA sequences obtained from morphologically characterised individual foraminifera, established a robust molecular taxonomic framework for the observed diversity, and used it to query a global metabarcoding data set covering ~1700 samples with ~2.48 billion reads. This allowed us to extract and assign 1 million reads, enabling characterisation of the structure of the genetic diversity of the group across ~1100 oceanic stations worldwide. Our sampling revealed the existence of, at most, 94 distinct molecular operational taxonomic units (MOTUs) at a level of divergence indicative of biological species. The genetic diversity only doubles the number of formally described species identified by morphological features. Furthermore, we observed that the allocation of genetic diversity to morphospecies is uneven. Only 16 morphospecies disguise evolutionarily significant genetic diversity, and the proportion of morphospecies that show genetic diversity increases poleward. Finally, we observe that MOTUs have a narrower geographic distribution than morphospecies and that in some cases the MOTUs belonging to the same morphospecies (cryptic species) have different environmental preferences. Overall, our analysis reveals that even in the light of global genetic sampling, planktonic foraminifera diversity is modest and finite. However, the extent and structure of the cryptic diversity reveals that genetic diversification is decoupled from morphological diversification, hinting at different mechanisms acting at different levels of divergence. [ABSTRACT FROM AUTHOR]

Reconstructing the spatial patterns in thermocline depth is critical for understanding ocean‐atmosphere interactions. Previous foraminiferal proxies of thermocline depth focus on gradients between planktonic foraminifera living in the surface and subsurface ocean. However, both thermocline depth changes and stratification changes will impact this measure. In this study, we outline a method for reconstructing the tropical upper ocean vertical water column profile, enabling the separate assessment of thermocline depth and stratification changes. This method uses oxygen isotope data from surface and sub‐surface calcifying planktonic foraminifera (Globigerinoides ruber albus, Globorotalia tumida, Neogloboquadrina dutertrei, and Pulleniatina obliquiloculata) as well as data from benthic foraminifera from a core site below the thermocline. Using newly generated and compiled oxygen isotope data from Holocene‐aged marine sediments, we construct vertical profiles at 20 core sites in the Tropical Pacific Ocean. Quantitative estimates of thermocline depth along with error ranges from Monte Carlo simulations are extracted from the reconstructed profiles. There is a strong correlation between reconstructed Holocene and climatological thermocline depth, but the East‐West contrast in the depth of the thermocline is underestimated by 30%. Incorporating benthic information in thermocline estimates results in a dramatic improvement in the reconstruction of spatial gradients in thermocline depth compared to a simpler proxy, the difference in oxygen isotope ratio between a deeper calcifying planktonic species and the surface species, G. ruber. Plain Language Summary: The thermocline is a layer of the ocean where temperature changes rapidly, and the depth of this layer is related to many climatic phenomena. Understanding where and when this layer was deeper and shallower in the past is important to our overall understanding of the climate system. We outline a novel method to reconstruct the thermocline with microscopic shells collected from the sea floor. Our method can reconstruct the changes we see across the Pacific today and also recreate the changes found between the last ice age and today. Key Points: We show a novel method for reconstructing the upper water column using oxygen isotope measurements on multiple species of foraminiferaThis method can be used to quantitatively reconstruct spatial and temporal changes in thermocline depthIf a simple differencing method is preferred, thermocline depth can be most accurately reconstructed using subsurface species only [ABSTRACT FROM AUTHOR]

The species Orbirhynchia mantilliana is newly documented in Algeria, identified within the Upper Campanian marly limestone of the Akhdar Member in the Abiod Formation at Djabel Gueroun, Batna Province, Aurès Basin. It is associated with Upper Campanian faunal markers such as the ammonite species Nostoceras (Bostrychoceras) polyplocum, found within the planktic foraminifera Globotruncana calcarata Zone. The O. mantilliana displays a restricted geographic distribution and biogeographic range, confined to Algeria, the United Kingdom, and Germany. [ABSTRACT FROM AUTHOR]

The increase discharge of titanium dioxide (TiO2) nanoparticles, derived from engineered material waste, exerts a detrimental impact on both the marine ecosystem and public health. The cytotoxicity of TiO2 nanoparticles on marine organisms should be imperatively understood to tackle the urgent concern for the well-being of marine life. Various concentrations of TiO2 nanoparticles have proven to reach fatal levels in aquatic organisms, requiring a deeper exploration of cytotoxicity. Notably, certain benthic foraminifers, such as Ammonia veneta, have been identified as capable of incorporating TiO2 nanoparticles into vesicles. However, these organisms exhibit a detoxification mechanism through exocytosis, as indicated by previous transcriptomic inferences. This presents the advantage of assessing the tolerance of foraminifers to TiO2 nanoparticles as pollutants and investigating the long-term effects of cytotoxicity. In this study, we scrutinized the distribution of TiO2 nanoparticles within cells and the growth rates of individuals in seawater media containing 1, 5, 10, and 50 ppm TiO2 nanoparticles, comparing the results with a control group over a 5-week period, utilizing A. veneta stain. Transmission electron microscopy observations consistently revealed high concentrations of TiO2 nanoparticles in vesicles, and their expulsion from cells was evident even with exposure to 5 ppm TiO2 nanoparticles. Under the control and 1 ppm TiO2 conditions, foraminifers increased their cell volume by adding a calcification chamber to their tests every 1 or 2 days. However, the 5-week culturing experiments demonstrated that foraminifers gradually ceased growing under 5 ppm TiO2 nanoparticle exposure and exhibited no growth at > 10 ppm concentrations, despite an ample food supply. Consequently, these findings with A. veneta suggest that the foraminiferal detoxification system could be disrupted by concentrations exceeding 5 ppm of TiO2 nanoparticles. The toxic effect of TiO2 nanoparticles on meiofauna, such as benthic foraminifers, have been poorly understood, though these organisms play an important role in the marine ecosystem. Environmental accumulation of TiO2 nanoparticles on the coast has already exceeded twenty times more than foraminiferal detoxification level. Future studies focusing on toxic mechanism of TiO2 nanoparticles are crucial to prevent the breakdown of the marine ecosystem through accelerating discharge of TiO2 nanoparticles into the ocean. [ABSTRACT FROM AUTHOR]

High Latitude fjords can serve as sediment trap, bearing different type of proxies, from geochemical to micropaleontological ones, making them exceptional tools for paleoenvironmental reconstruction. However, some unconventional proxies can be present and can be used to depict a comprehensive and exhaustive interpretation of past changes. Here, studying a sediment core in Edisto Inlet (Ross Sea, Antarctica) we used irregular echinoid spines and ophiuroids (Ophionotus victoriae) ossicles to trace environmental changes throughout the last 3.6 kyrs BP. Irregular echinoids can serve as proxy for the organic matter content, while O. victoriae ossicles can be used as proxy for steady sea-ice cycle along with organic deposition events. O. victoriae release a high number of ossicles, making estimation about the population quite challenging; still, presence data, can be easily collected. By applying Generative Additive Models to the stratigraphical distribution of these data, we detected an environmental phase that was previously unnoticed by other traditional proxies: the Ophiuroid Optimum (2–1.5 kyrs BP). In conclusion, here we demonstrate how echinoderm presence can be used as a valuable source of information, while proving the potential of modelling binary data to detect long-term trend in Holocene stratigraphical records. [ABSTRACT FROM AUTHOR]

The published literature concerning Lower to mid-Cretaceous (late Barremian–Albian, early Cenomanian) Tibetan Orbitolinidae suggests an apparent extreme high diversity with almost exclusive reference to taxa displaying a complex embryo (subfamily Orbitolininae). The majority of them, among Orbitolina pileus Fossa Mancini described in the late twenties from the border areas of Ladakh (India) and Tibet (China), however need taxonomic reconsideration. The original images of O. pileus are herein interpreted as a mixture of a high-conical mesorbitolinid (of unclear species identity) and a section of Palorbitolinoides orbiculatus Zhang described in the early 80ies from Tibet. The concluding new nomenclatural act considers P. orbiculatus a junior synonym of O. pileus validated herein as Palorbitolinoides pileus (Fossa-Mancini) comb. nov. with the designation of a lectotype. The present study refers to data from the literature and own material from the Albian Langshan Fm. of the northern Lhasa Block of Tibet. [ABSTRACT FROM AUTHOR]

Bora Bora is a volcanic island in the tropical central South Pacifi c Ocean with a barrier reef and large well developed back-reef lagoons. It forms part of the system of shallow water environments in the archipelagos of French Polynesia that provide stepping stones for the interconnectivity of shallow marine faunas between the tropical Western and Eastern Pacifi c biogeographic regions. The fauna has many similarities to foraminiferal faunas in the south western Indo-Pacifi c but has been demonstrated to be unique. This study provides illustrations and discussions of most of the 184 species of benthic foraminifera identifi ed from sediments in the back-reef lagoon environments at Bora Bora, that span from the shallow immediate back-reef sand banks, to the deep lagoons and to the coastal fringing reefs and embayments around the volcanic island. The illustrated specimens and taxonomic discussions are aimed at providing an identifi cation guide to shallow water tropical benthic foraminifera from the central South Pacifi c region. Six new species have been established, including Textularia boraboraensis, Miliolinella mccullochae, Quinqueloculina guilcheri, Triloculina karimimossadeghae, Coscinospira georgforsteri, and Elphidium venecpeyreae. This study also proposes that the family of cymbaloporetids, Cymbaloporidae, are placed within the Superfamily Discorboidea. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The planktonic dinoflagellate Prorocentrum compressum is widespread in warm and temperate seas. A strain identified as P. cf. compressum BEA 0681B isolated from the island of Gran Canaria, NE Atlantic Ocean, showed a divergence in rDNA/ITS phylogenies with respect to P. compressum. The Canarian strain was oval, with an average length‐to‐width ratio of 1.35, smooth thecal surface with less than 150 thecal pores, including oblique pores, sometimes with a bifurcated opening. In contrast, P. compressum was rounder, with a length‐to‐width ratio < 1.2, with reticulate‐foveate ornamentation and 200–300 pores per valve. We propose Prorocentrum canariense sp. nov. These species clustered as the most early‐branching lineage in the clade Prorocentrum sensu stricto. Although this clade mainly contains planktonic species, the closer relatives were the benthic species P. tsawwassenense and P. elegans. Interestingly, P. compressum and P. canariense sp. nov. are widely distributed in temperate and warm seas without an apparent morphological adaptation to planktonic life. The formation of two concentric hyaline mucilaginous walls could contribute to this success. We discuss the use of Prorocentrum bidens to solve the nomenclature issue of P. compressum that was described citing a diatom as basionym. [ABSTRACT FROM AUTHOR]

The subtropical to subpolar planktic foraminifera Globigerina bulloides is a calcifying marine protist, and one of the dominant foraminiferal species of the Nordic Seas. Previously, the relative abundance and shell geochemistry of fossil G. bulloides have been studied for palaeoceanographic reconstructions. There is however a lack of biological observations on the species and a poor understanding of its ecological tolerances, especially for high latitude genotypes. Here, we present observations from the first extensive culturing of G. bulloides under subpolar conditions, including the first low temperature (6–13°C) and variable salinity (30–38) experiments. Carbonate chemistry (pH and [CO32−]) was also manipulated. Experimental conditions were chosen to reflect a range of plausible past and future scenarios for the Nordic Seas. We found G. bulloides to be tolerant of environmental conditions well outside their optimal range (<10°C, salinity <33, pH <8). Observed life span was up to three months, which was attributed to a microalgal diet. Two alternative life strategies were employed, whereby individuals either experienced rapid growth and death, or a prolonged lifespan with minimal growth and death via slow decay. We posit this could help explain differences in geochemical signals recorded from different size fractions of fossil specimens used for palaeoceanographic reconstructions. [ABSTRACT FROM AUTHOR]

The dynamics shaping the El Niño‐Southern Oscillation's (ENSO) response to present and future climate change remain unclear, partly due to limited paleo‐ENSO records spanning past abrupt climate events. Here, we measure Mg/Ca ratios on individual foraminifera to reconstruct east Pacific subsurface temperature variability, a proxy for ENSO variability, across the last 25,000 years, including the millennial‐scale events of the last deglaciation. Combining these data with proxy system model output reveals divergent ENSO responses to Northern Hemisphere stadials: enhanced variability during Heinrich Stadial 1 (H1) and reduced variability during the Younger Dryas (YD), relative to the Holocene. H1 ENSO likely intensified through meltwater‐induced changes to ocean/atmospheric circulation, a response observed in models, but the lack of a similar response during the YD challenges model simulations. We suggest the tropical Pacific mean state during H1 primed ENSO for larger fluctuations under meltwater forcing, whereas the YD mean state likely buffered against it. Plain Language Summary: The El Niño‐Southern Oscillation (ENSO) is one of the planet's largest and most influential recurring climate patterns. The fluctuation between warm (El Niño) and cold events (La Niña) every several years has a substantial impact on global weather patterns that carry important socioeconomic consequences. How the frequency and severity of ENSO events may change in response to present and future climate change is largely uncertain, although lessons from past abrupt climate events can help inform our projections of future ENSO. To that end, we analyzed the chemical composition of small, individual zooplankton shells buried in marine sediments to reconstruct "snapshots" of subsurface temperature variability in the eastern Pacific, a feature closely linked to ENSO, over the last 25,000 years. During this time, two abrupt climate events induced by melting glacial ice ("Heinrich Stadial 1" and the "Younger Dryas") were characterized by different ENSO responses (stronger and weaker, respectively). We suggest that the average climate conditions in the tropical Pacific (temperature, wind strength, etc.) played an important role by either priming the ENSO system for disruption by meltwater (Heinrich Stadial 1) or buffering against it (Younger Dryas). Key Points: Single‐shell foraminiferal trace element ratios reveal a deglacial history of El Niño‐Southern Oscillation's (ENSO) variability from the eastern equatorial PacificMeltwater‐induced changes to ocean and atmospheric circulation likely amplified ENSO during Heinrich Stadial 1A similar amplification during the Younger Dryas is not observed, suggesting mean state may mediate millennial‐scale ENSO variability [ABSTRACT FROM AUTHOR]

This paper introduces ForametCeTera, a pioneering dataset designed to address the challenges associated with automating the analysis of benthic foraminifera in sediment cores. Foraminifera are sensitive sentinels of environmental change and are a crucial component of carbonate-denominated ecosystems, such as coral reefs. Studying their prevalence and characteristics is imperative in understanding climate change. However, analysis of foraminifera contained in core samples currently requires washing, sieving and manual quantification. These methods are thus time-consuming and require trained experts. To overcome these limitations, we propose an alternative workflow utilizing 3D X-ray computational tomography (CT) for fully automated analysis, saving time and resources. Despite recent advancements in automation, a crucial lack of methods persists for segmenting and classifying individual foraminifera from 3D scans. In response, we present ForametCeTera, a diverse dataset featuring 436 3D CT scans of individual foraminifera and non-foraminiferan material following a high-throughput scanning workflow. ForametCeTera serves as a foundational resource for generating synthetic digital core samples, facilitating the development of segmentation and classification methods of entire core sample CT scans. [ABSTRACT FROM AUTHOR]

The benthic foraminiferal community is an excellent bio-indicator of pollution in coastal and marginal marine settings. Their abundance, diversity and its relationship with environmental parameters, viz. grain size, organic carbon (Corg) and trace metals concentration, from the surface sediment layer of the southwestern shelf of the Bay of Bengal, have been used to understand the marine pollution in this study. A total of 32 surface sediment samples were collected at various water depths.The samples were analysed for grain size distribution, organic matter (OM), foraminiferal and trace metals studies. Statistical analyses such as correlation matrix, PCA (Principal Component Analysis) and cluster analysis show that the foraminiferal species composition is significantly influenced by the organic carbon (Corg), Co, Pb, Zn, Cr, and Ni concentrations. The dominance of stress-tolerant species, viz. Ammonia beccarii, Ammonia tepida, Nonion faba, Bulimina marginata, Bolivina robusta, Elphidium craticulatum and Elphidium advenum, as well as less species diversity, demonstrates the elevated Corg and trace metal pollution in the marine environment. [ABSTRACT FROM AUTHOR]

The mid-Brunhes dissolution interval (MBDI; Marine Isotope Stage (MIS) 13 to 7; ~ 533–191 ka) is characterized by various paleoclimatic/paleoceanographic events in the world. We investigated fossil deep-sea benthic foraminifera and sediment geochemistry at the onset of the MBDI (~ 670–440 ka) using Ocean Drilling Program (ODP) Site 758 and core GPC03 in the northeast tropical Indian Ocean (TIO), primarily focusing on the relationship between the paleoceanographic conditions of the surface and deep oceans. Based on multi-dimensional scaling, MDS axis 1 is related to the specific depth habitats of benthic foraminiferal fauna, possibly at the trophic level. In MDS axis 1, the difference between the two core sites was smaller from ~ 610 to 560 ka, whereas it was larger from ~ 560 to 480 ka. In contrast, MDS axis 2 may be related to the low food supply at episodic food pulses/relatively stable and low food fluxes. MDS axis 2 showed generally similar stratigraphic variations between the two cores during ~ 610–560 ka, but was different during ~ 560–480 ka. The proportion of lithogenic matter to biogenic carbonate was relatively low from ~ 610 to 530 ka under the highstand when sediment transport to the study area was reduced. Thus, both the depth gradient in the distribution of benthic foraminiferal fauna and the lithogenic supply between the two cores changed coincidently across the MIS 15/14 (~ 570–540 ka) transition. Such paleoceanographic conditions across MIS 15/14 transition were attributed to the long-term weakening of the wind-driven mixing of surface waters, which might have been caused by the weakening of the Indian summer monsoon in the northeast TIO, possibly with the northward displacement of the InterTropical Convergence Zone in the Northern Hemisphere. In particular, the depth gradient in the distributions of benthic foraminiferal faunas represents the paleoceanographic linkage between the surface and deep oceans through particulate organic matter ballasting by calcareous plankton skeletons in addition to lithogenic matter, which changed transiently and significantly across MIS 15/14 transition close to the onset of the MBDI. [ABSTRACT FROM AUTHOR]

• Sahune (Oxfordian, Late Jurassic) in south-eastern France Basin is newly described. • Carbonate bodies enclosed within Terres Noires Formation formed at cold seeps. • Associated fauna indicate seepage at bathyal depth ca. 1.500 m. • Several seep ostracod families have evolved at seeps since the Oxfordian. • Colonization of bathyal environments occurred earlier than thought. Hydrocarbon seeps represent some of the most extreme marine habitats but are also home to rich communities developed around chemosynthesis rather than photosynthesis. Here we describe the outcrop of Sahune (Drôme department, south-eastern France), that illustrates a new seeping site during the Late Jurassic (middle Oxfordian), as formally demonstrated by geochemical proxies. We report the associated fauna composed of foraminifers, radiolarians, crinoids, echinoids and ostracods that all point to seepage at bathyal depth. The foraminifer assemblage and the occurrence of the irregular echinoid Tithonia oxfordiana together point to a middle Oxfordian age. We provide an in-depth analysis of the ostracod community, which is the oldest so far reported in such environments. The new species Procytherura praecoquum may be cognate to the seepage site and could illustrate the oldest known example of pore clusters, sometimes proposed as representing ectosymbiosis. The Sahune assemblage demonstrates that cold seep ostracod communities were already a mixture of taxa from platform and deep-sea oligotrophic environments. The post-Jurassic diversification of ostracods at cold seeps was related to colonization events and diversification of families that have been inhabitants of such ecosystems at least since the Oxfordian. The Sahune record changes our current conception of the deep-sea colonization by the ostracods Tethysia and Procytherura that occurred earlier than traditionally considered. [ABSTRACT FROM AUTHOR]

Late Cretaceous-Miocene foraminiferas were recovered from the BG-1 well in the offshore Eastern Dahomey Basin. Four (4) lithostratigraphic units comprising Ogwashi-Asaba, Upper Araromi, Lower Araromi and Afowo Formations have been delineated and assigned based on the textural characteristics of the sediments. Forty-nine (49) foraminiferal species were identified, with a total count of 47 calcareous species (96%) comprising both planktonic and benthic forms and two arenaceous forms (3%). Seven (7) foraminiferal zones were recognised and dated from the Upper Cenomanian to Late Miocene age. The Globotruncana aegyptica zone, marked by the disappearance of the Maastrichtian forms at 3060 ft, coincided with the appearance of the Early Paleocene benthic forms such at the Anomalinoides umboniferus- Anomalinoides midwayensis zone. The Cretaceous-Paleogene (K-Pg) boundary was recognised at 3060 ft. Seven MFSs and SBs dated from the Upper Cenomanian and Upper Miocene ages were identified in the sequence stratigraphic analysis. The stacking patterns of the lowstand and highstand systems tracts reveal the interplay of progradational and aggradational parasequence signatures of siltstones and sandstone lithologies. The paleodepositional sedimentary packages of the BG-1 well are recognised from the Inner-Neritic to Bathyal environment. The sequence stratigraphic integration of lithofacies and foraminifera assemblages in this study has created a model of the distribution of the elements in the hydrocarbon system of the offshore Eastern Dahomey basin. Therefore, this study will underscore the critical role of sequence biostratigraphy in enhancing the accuracy and efficiency of exploration and development efforts in the hydrocarbon industry. [ABSTRACT FROM AUTHOR]

Aim: We are using the fossil record of different marine plankton groups to determine how their biodiversity has changed during past climate warming comparable to projected future warming. Location: North Atlantic Ocean and adjacent seas. Time series cover a latitudinal range from 75° N to 6° S. Time period: Past 24,000 years, from the Last Glacial Maximum (LGM) to the current warm period covering the last deglaciation. Major taxa studied: Planktonic foraminifera, dinoflagellates and coccolithophores. Methods: We analyse time series of fossil plankton communities using principal component analysis and generalized additive models to estimate the overall trend of temporal compositional change in each plankton group and to identify periods of significant change. We further analyse local biodiversity change by analysing species richness, species gains and losses, and the effective number of species in each sample, and compare alpha diversity to the LGM mean. Results: All plankton groups show remarkably similar trends in the rates and spatio‐temporal dynamics of local biodiversity change and a pronounced non‐linearity with climate change in the current warm period. Assemblages of planktonic foraminifera and dinoflagellates started to change significantly with the onset of global warming around 15,500 to 17,000 years ago and continued to change at the same rate during the current warm period until at least 5000 years ago, while coccolithophore assemblages changed at a constant rate throughout the past 24,000 years, seemingly irrespective of the prevailing temperature change. Main conclusions: Climate change during the transition from the LGM to the current warm period led to a long‐lasting reshuffling of zoo‐ and phytoplankton assemblages, likely associated with the emergence of new ecological interactions and possibly a shift in the dominant drivers of plankton assemblage change from more abiotic‐dominated causes during the last deglaciation to more biotic‐dominated causes with the onset of the Holocene. [ABSTRACT FROM AUTHOR]

Copyright of Spanish Journal of Palaeontology is the property of Socieadad Espanola de Paleontologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Because of their excellent preservation record, testate zooplankters provide valuable proxy ocean climate data through the Quaternary–Recent. Commonly, specimen abundances are sought, which are time-consuming to collect manually and require taxonomic expertise. While machine learning models obviate these problems, it is questioned whether the current use of specimens selected by experts to train the models impartially captures the variation within the source populations. To illustrate the potential value of the latter and their relevance to the selection of representative specimens, the 2D outline shape of the planktonic foraminifer Truncorotalia crassaformis from four globally distributed, late-Quaternary–modern collections is examined. Large intra-sample variation is attributed to changes in the size and shape of the last-formed chamber, which often departs radically from its predecessors. Similar outlines occur in each collection, and no single axial shape is dominant when the aggregated data, aligned on their centroids and adjusted for size and position, are projected onto their principal components. Several partitions based on distance from the centroid of the standardized data are considered as sources of representative specimens, with that at ±1.645σ (standard deviations, nominally 90%) suggested as suitable. This procedure obviates the need for expert-based consensus sampling; for greater environmental resolution, it can be applied to individual water mass samples. It assists, but does not fully resolve, the following basic diagnostic question: which characters separate Truncorotalia crassaformis from its relatives? [ABSTRACT FROM AUTHOR]

Microscopic eukaryotes are important components of coastal wetland ecosystems. The goal of this study was to investigate the diversity of microeukaryotes in the tidal pools of a New Jersey salt marsh and to compare the assemblages of natural and artificial pools excavated for controlling mosquito populations. We evaluated microeukaryotic assemblages using the amplicon sequencing of 18S and rbcL DNA markers and the microscopic identification of diatoms in water and sediment samples. 18S unique amplicon sequence variants (ASV) representing ciliates, dinoflagellates, diatoms, and cercozoans were the most diverse, while the reads of dinoflagellates, diatoms, ciliates, and nematodes were the most abundant. The dominant ASVs were attributed to organisms that are characteristic of coastal plankton and sediments or those known for their resistance to salinity, desiccation, hypoxia, and UV stress. The sediment assemblages were more diverse compared to those from the water column and contained a larger portion of ASVs that were not assigned to any low-rank taxa, reflecting the current gaps in understanding the diversity of microeukaryotes. Most taxonomic groups were significantly different in their abundance and composition between natural and artificial pools. Dinoflagellates, haptophytes, chrysophytes, pelagophytes, and raphidophytes—the groups that include a large proportion of mixotrophic taxa and species known for forming harmful algal blooms—were more abundant in the artificial than in the natural pools. Fungi, labyrinthulomycetes, and peronosporomycetes were also more abundant in artificial pools, which may be related to organic matter enrichment. Diatoms and foraminifera showed an opposite trend of higher abundance in natural pools. [ABSTRACT FROM AUTHOR]

Gas hydrates are globally acknowledged as a significant strategic alternative energy source, and there is a consensus on the necessity to enhance their exploration. However, gas hydrates are highly prone to decomposition under variations in external environmental conditions, which can result in subsea methane seepage activities. Consequently, investigating subsea methane seepage activities holds substantial theoretical and practical significance for exploring gas hydrates. This paper evaluates the history of methane seepage activities in the Qiongdongnan Basin (QDNB) by analyzing the carbon and oxygen isotopic characteristics of benthic foraminifera and the geochemical properties of pore water from gravity sediment cores at sites QH-CL4 and QH-CL40. The results indicate that since the Marine isotope stage2 (MIS2), continuous micro-methane seepage activity has been present in the QDNB, characterized by a slight negative deviation in the carbon isotopes of benthic foraminifera. Methane seepage activity intensified during 14.6 ka BP and between 19.64–23.22 ka BP. This increase is thought to be associated with rising seawater temperature during the Bølling–Allerød interstadial and declining sea level during the Last Glacial Maximum, respectively. Moreover, current geochemical characteristics of pore water reveal strong methane seepage activity, with flux as high as 28.968 mmol·m-²·a-¹. This ongoing activity has led to gas hydrate formation within shallow layers while also causing negative deviations in pore water salinity.

Abstract The minor and trace element compositions of biogenic carbonates such as foraminifera are important tools in paleoceanography research. However, most studies have focused primarily on samples with element to calcium (El/Ca) ratios higher than the El/Ca range often found in benthic foraminifera. Here, we systematically assess the precision and accuracy of foraminifera elemental analysis across a wide range of El/Ca especially at relatively low ratios, using a method on a Thermo Scientific iCAP Qc quadrupole Inductively Coupled Plasma Mass Spectrometer (ICP‐MS). We focus on two benthic foraminifera species, Hoeglundina elegans and Cibicidoides pachyderma, and prepared a suite of solution standards based on their typical El/Ca ranges to correct for signal drift and matrix effects during ICP‐MS analysis and to determine analytical precision. We observe comparable precisions with published studies at high El/Ca, and higher relative standard deviations for each element at lower El/Ca, as expected from counting statistics. The overall long‐term analytical precision (2σ) of the H. elegans‐like consistency standard solutions was 6.5%, 4.6%, 5.0%, for Li/Ca, Mg/Ca, Mg/Li, and 6.4%, 10.0%, 4.2% for B/Ca, Cd/Ca, Sr/Ca. The precision for H. elegans‐like Mg/Li is equivalent to a temperature uncertainty of 0.5–1.1°C. Measurement precisions were also assessed based on three international standards (one solution and two powder standards) and replicate measurements of H. elegans and C. pachyderma samples. We provide file templates and program scripts that can be used to design calibration and consistency standards, prepare run sequences, and convert the raw ICP‐MS data into molar ratios.

Abstract Seawater transported into the South Atlantic from the Indian Ocean via “Agulhas leakage” modulates global ocean circulation and has been linked to glacial‐interglacial climate cycles. However, constraining past Agulhas leakage has been a challenge. We sampled a transect of the Cape Basin in winter 2017 that intersected a mature Agulhas eddy and found that the 15N/14N ratio (δ15N) of mixed‐layer nitrate, zooplankton, and foraminifera (tissue and shells) was 2‰–3‰ lower in the eddy than in the background Atlantic even though the δ15N of the underlying thermocline nitrate was indistinguishable between the two settings. We suggest that the δ15N of foraminifera and other zooplankton in the eddy reflects the original Agulhas Current thermocline nitrate, which is ∼2‰ lower than that of the South Atlantic due to N2 fixation that occurs in the Indian Ocean. Foraminifera δ15N may have been lowered further during eddy migration by in situ N2 fixation and/or recycling of low‐δ15N ammonium. The absence of low‐δ15N Agulhas nitrate in the eddy thermocline can be explained by partial assimilation of the nitrate as it was mixed into the euphotic zone during and after eddy formation, raising its δ15N. The low δ15N of eddy foraminifera, apparent even after several months of eddy migration across the Cape Basin, suggests that fossil foraminifer‐bound δ15N from the region could record variations in past Agulhas leakage.

Metal contamination in the Arctic region has increased over the years despite its remote and isolated location. Thus, to evaluate the bioavailable fractions of various metals and their effects on sediment-associated biota, the surface sediments from the fjords were analyzed for bulk concentration of metals and their speciation in different fractions. Metals concentrations were higher in the inner fjord region and decreased towards the outer fjord, supported by the terrigenous influence (TI%) calculated. Cr and Pb showed higher excess values attributed to their additional source other than the catchment rocks. So, to assess the metal-related ecological risk, the bulk concentration of metals was compared with Arctic sediment quality guidelines (ASQGs). Cr, Cd, and Pb concentrations were high, indicating potential adverse biological effects in the study. To avoid the risk of overestimation, metal speciation was conducted, showing that overall metal concentrations were higher in the residual fraction; however, higher concentrations of Mn in labile phases pose a moderate risk to the sediment-associated biota. Additionally, the population density of foraminifera in the sediments was calculated to assess the influence of bioavailable metal on benthic foraminifera. It was found that the presence of metals in bioavailable fractions affected the abundance of the foraminifera. However, no morphological abnormalities were observed in the species.

We present the first version of the Ocean Circulation and Carbon Cycling (OC3) working group database, of oxygen and carbon stable isotope ratios from benthic foraminifera in deep ocean sediment cores from the Last Glacial Maximum (LGM, 23-19 ky) to the Holocene (