Agglutinated Forms Research Articles

Influence of methane and other hydrocarbon gases on foraminifera and nematodes in the Northwestern part of the Black Sea

This study investigates the response of foraminifera and nematodes to different types of methane and other hydrocarbon gases (alkanes, alkins) in bottom sediments of the northwestern shelf and continental slope of the Black Sea. Foraminifera are represented by 39 species from six orders, 13 families, 24 genera. Nematoda are represented by 48 species from six orders, 17 families, 27 genera. Both groups of meiobenthos are characterized by impoverished simple diversity and abundance/density as well as by much smaller sizes of foraminiferal tests compared to those from areas not affected by hydrocarbon gases, indicating stressful conditions for their life in the study areas. Among foraminifera, calcareous hyaline taxa dominate, but agglutinated forms are present as well and occasionally play a dominant role. A significant number of the identified nematode species belong to the tyobiotic type from the families Comesomatidae and Linhomoidae. They are characterized by a long, thin body and a small or completely undeveloped oral cavity, indicating their feeding on small particles of sediment or bacteria. Nine groups of foraminifera and nematodes were identified according to their tolerance and sensitivity to methane (15 species), ethane (five species), propane (eight species), butane (10 species), pentane (11 species), ethylene (20 species), propylene (two species), acetylene (three species), and isobutylene (one species). This study provides evidence for the first time that different types of methane, its homologues, and other hydrocarbon gases affect the reproduction, diversity, abundance, and growth of foraminifera, as well as density and simple diversity of nematodes.

Microfossils from the Bangkok Clay Formation (Upper Holocene) of central Thailand: Paleoenvironmental insight

Palynomorphs and benthic foraminifers are reported from the Upper Holocene Bangkok Clay Formation at a whale-fall excavation site in Samut Sakhon Province, located 15 kilometers from the shoreline of the Gulf of Thailand. The aim of this research is to interpret the paleoenvironment of the whale-trapped layer using bioindicator assemblages. Twenty-two palynomorphs are identified. The palynomorphs are composed of tropical plants and categorized based on their ecological communities into five groups: mangrove, back mangrove, floodplain, terrestrial, and ferns. Of these, mangrove and floodplain pollen assemblages are dominant. The pollen was transported via aeolian and fluvial systems to deposit in the delta system, then wave and tide processes dispersed them to the deeper part of the sea floor. The foraminiferal assemblage is dominated by marine ammonioids and miliolids without agglutinated forms, representing a shallow marine setting with low freshwater influence. The assemblages of foraminifers together with ostracods, gastropods and diatoms suggest sedimentary deposition in shallow subtidal marine environments, where salinity varied from slightly brackish to normal. The terrigenous sediment influx was high; the depositional environment is likely to be the distal part of a prodelta.

Five million years of life history record in an uppermost Cretaceous northern Tethyan marine succession, Eastern Carpathians (Romania): Microfossil content and palaeoenvironmental assessment

New biostratigraphic investigations based on palynomorphs (mainly dinoflagellate cysts), foraminifera and calcareous nannoplankton recovered from eight geological sections indicate that the Hangu Formation near the Pluton-Pipirig area (Tarcău Nappe, Eastern Carpathians, Romania), previously assigned to the Senonian–Paleocene interval, includes only uppermost Cretaceous deposits. The palynological assemblages are moderately rich, with a total of 167 well-preserved taxa. The marine palynomorphs – essentially consisting of dinoflagellate cysts (dinocysts) – are dominated by peridinioid taxa, mainly recorded in upper Upper Campanian–lower Maastrichtian deposits, and by a high-diversity assemblage of gonyaulacoid taxa during the late Maastrichtian. Marine algae and dinogymnioid dinocysts were less common. The terrestrial palynoflora is dominated by fern spores and angiosperm pollen, with subordinate gymnosperm pollen. The foraminiferal assemblages include an assortment of well-preserved agglutinated forms, present mainly in the upper Maastrichtian deposits, whereas calcareous benthics and planktonic foraminifera are rare and poorly preserved. Calcareous nannoplankton assemblages are also rare, often represented by two taxa (Micula staurophora and Watznaueria barnesiae); certain important biostratigraphic markers were found to be reworked in the analyzed deposits. Age assignments for the studied sections were mainly provided by dinocysts, through the identification of significant marker taxa and comparisons with well-calibrated Campanian–Maastrichtian dinocyst assemblages from well-dated sections and stratotypes, located mostly in the Northern Hemisphere.Indices such as particulate organic matter (POM) composition, the relative abundance of dinocyst eco-groups, as well as agglutinated foraminiferal morphogroups, were used to reconstruct the depositional environments of the Hangu Formation from the studied area. The upper Upper Campanian–lower Maastrichtian deposits from the Pluton-Pipirig sections were mainly deposited in neritic marine conditions, although occasional redeposition of the sediments transported by turbidity currents towards deeper water settings is not excluded, either. The depositional environments evolve towards outer neritic to distal (bathyal) during the late Maastrichtian, as indicated by palynofacies constituents and by high frequencies of gonyaulacoid dinocysts and deep-water benthic foraminifera.

Melt stripping and agglutination of pyroclasts during the explosive eruption of low viscosity magmas

Volcanism on Earth and on other planets and satellites is dominated by the eruption of low viscosity magmas. During explosive eruption, high melt temperatures and the inherent low viscosity of the fluidal pyroclasts allow for substantial post-fragmentation modification during transport obscuring the record of primary, magmatic fragmentation processes. Here, we show these syn-eruption modifications, in the form of melt stripping and agglutination, to be advantageous for providing fundamental insights into lava fountain and jet dynamics, including eruption velocities, grain size distributions and melt physical properties. We show how enigmatic, complex pyroclasts termed pelletal lapilli form by a two-stage process operating above the magmatic fragmentation surface. Melt stripping from pyroclast surfaces creates a spray of fine melt droplets whilst sustained transport in the fountain allows for agglutination and droplet scavenging, thereby coarsening the grain size distribution. We conclude with a set of universal regime diagrams, applicable for all fluidal fountain products, that link fundamental physical processes to eruption conditions and melt physical properties.

Foraminiferal stratigraphy and palaeoenvironment of a storm-influenced marine shelf: Upper Aptian – lower Albian, Svalbard, Arctic Norway

This study presents the first record of foraminifera from the Lower Cretaceous Carolinefjellet Formation on the Svalbard archipelago, Arctic Norway. The Svalbard foraminiferal assemblages are dominated by agglutinated forms with a subordinate calcareous component. Several stratigraphically important species are recognised, and four assemblage zones are established: 1) Serovaina loetterlei Zone of middle Aptian or lower, 2) Ammobaculites wenonahae Zone of the middle Aptian, 3) Gaudryina tailleuri Zone of the upper Aptian, 4) Verneuilinoides borealis Zone of the lower Albian. The assemblages exhibit characteristic Boreal features, previously reported from the North Slope of Alaska, Arctic Canada, Western Siberia, and older Mesozoic strata in Svalbard. The study therefore allows for Circum-Arctic correlations and the extensions of stratigraphic ranges of several Boreal species.The investigated succession exhibits a large-scale fining-upwards trend. The lower part (the Dalkjegla Member) is characterised by abundant hummocky cross-stratified and wave-ripple cross-laminated sandstone beds, indicating deposition on a storm-dominated shelf. The upper part (the Innkjegla Member) is dominated by mudstones containing strata-bound siderite concretions and carbonate-cemented sandstone beds, suggesting deposition under more quiescent, middle to outer shelf conditions. An upwards increase in trace fossil diversity and degree of bioturbation, in concert with expanding foraminiferal diversity and morphogroup variability, reflects a long-term deepening of the shelf with fluctuating oxygen conditions. In combination with XRF data, diversity statistics, and morphogroup application, the present study thus sheds a new light on higher frequency palaeoenvironmental changes in upper part of the Carolinefjellet Formation.

Reservoir quality of the Surmeh (Arab-D) reservoir in the context of sequence stratigraphy in Salman Field, Persian Gulf

The Upper Jurassic Surmeh reservoir in the northern Persian Gulf is a stratigraphic equivalent of Arab-D reservoir that is one of the best Jurassic reservoir rocks of the Arabian Peninsula. In this study, in the first step the palaeontology, sedimentary environment, sequence stratigraphy and reservoir quality of the Surmeh reservoir was investigated in a core-bearing well in Salman oil field. The palaeontological studies reveal a moderately diverse assemblage of benthic foraminifera. Dominated foraminifera include the agglutinated forms and miliolids and there are also fragments of alga, stromatoporoids, corals, bivalves, gastropods and echinoderms. These recorded fauna and flora resulted in distinction of three zones that characterize the age of undifferentiated Kimmeridgian-Tithonian. Based on petrographic observations, along with palaeontological materials, eight microfacies were identified that represent four sub-environments of a carbonate inner ramp including supratidal, intertidal, lagoon and shoal. These studies combined with well log responses resulted in identification of a 3rd order sequence and parts of an incomplete one that is composed of an incomplete HST. These 3rd order sequences comprise four 4th order subordinate sequences.In addition by integration of petrographic analyses, sub-environments energy regimes and petrophysical data, five reservoir zones were identified. Also, based on core porosity and permeability 6 Hydraulic Flow Unit (HFU) with poor to excellent reservoir quality in ascending trend were identified. The reservoir zone I, which belongs to the sabkha and littoral facies, represents the worst reservoir quality (includes HFU1 to HFU3), while the reservoir zone III with best reservoir quality (includes HFU4 and HFU5) comprises the back shoal grain-supported facies. The introduced sequences and reservoir zones in the studied well were propagated to three other wells throughout the Salman Field via using log responses. Also they were correlated with those introduced for Arab-D reservoir in the southern parts of the Persian Gulf providing a correlation framework. This pattern can be used in the next exploration wells which are going to be drilled especially in the northern parts of the Persian Gulf.

BENTHIC FORAMINIFERA AS POLLUTION INDICES IN THE MARINE ENVIRONMENT OF WEST COAST OF INDIA

Two ecosystems affected by acidic pollutants (Thana Creek, Bombay and inshore area of Trivandrum, Kerala) and two other ecosystems affected by alkaline pollutants (Cola Bay, Goa and inshore area of Karwar, Karnataka) were studied for pollution effects monitoring through Foraminifera. In the Thana Creek area, Bombay, the magnitude of corrosive effect, lower—than—normal ornamentation, deepening of grooves and sutural thickenings, enlargement of pores, widening of apertures in Foraminifera were taken as indices of pollution effect. In the, Cola bay area, Goa, the environment becomes hypertrophic resulting in large—sized, robust, mostly megalospheric forms of Ammonia. Elphidium and Florilus scaphum are recorded at the proximal zone near the discharge point; miliolids in the transitional zone and dominantly smaller—sized Nonionella, Fursenkoina pontoni, Bulimina marginata at the distal zone quite far from thc discharge point where pollutants are diluted and dissipated. In the Karwär area, Karnataka, pollutant causes reduced diversity with a decrease in foraminiferal population. Moreover, there is a reduction in size followed by test wall thinning in Nonion and Ammonia, increase of agglutinated forms near shore, and dispersal and dilution of the pollutants resulting in foraminiferal abundance. In the Trivandrum area, Kerala, the effluent effect presents morphological anomalies (Operculina, Cibicides), erosion along peripheries, induced growth in last few chambers, inferred dissolution and consequent destruction of small, thin—walled forms suggested by their absence, thus leaving only the larger ones in the entire area. Living/dead ratio is negatively oriented at all sites.

Neocomian Fahliyan formation carbonates in the oil well X2 (Dorood oil field, Persian Gulf): Biostratigraphic data from benthic foraminifera and algae

The Fahliyan Formation of the Khami Group is the most important oil and gas reservoir in southwestern Iran. The formation attains a thickness of 435.5 m in the oil well X2 in Dorood oil field, Persian Gulf. It is represented mainly by thin-bedded limestones. This formation unconformably overlies the evaporate late Jurassic Hith Formation and conformably underlies the Gadvan Formation. Integrated palaeontological and sedimentological studies supported by an analysis of 150 thin-sections led to the identification of 21 benthic foraminiferal genera dominated by agglutinated forms with an additional 8 algal genera. Two foraminiferal biozones of Berriasian through Hauterivian age include the Pseudochrysalidina (Dokhania) arabica acme zone and Pseudocyclammina lituus- Coscinoconus assemblage zone, and an algal zone includes the Salpingoporella annulata range zone have been recognized. The correlation of the lower Cretaceous petroleum source rock in the Persian Gulf with regions from Tethyan Realm is limited by the lack of the analog formation that can be used for comparison. In this way, the foraminiferal zones are correlated with coeval zones in south and southwest of Iran.

Pleistocene epilithic foraminifera from the Arctic Ocean

Attached epilithic foraminifera constitute an important but overlooked component of the benthic foraminiferal assemblage in the Pleistocene sediment of the central Arctic Ocean. We report 12 types of epilithic foraminifera that have colonised lithic and biogenic grains found in glacial sediments, including representatives of the genera Rhizammina, Hemisphaerammina, Ammopemphix, Diffusilina, Subreophax, Placopsilina, Placopsilinella, Hormosinelloides and Tholosina, accompanied by mat-like and ribbon-like forms of uncertain taxonomic affinity. The attached agglutinated forms appear to be colonisers, adapted to extremely oligotrophic conditions.

Study of marsh foraminifera from the coastal plain of Buenos Aires (Argentina) and its ecological implications.

The objective of this work was determinate the diversity and abundance of benthic foraminifers from recent sediments of Channel 15, Samborombón Bay (35º57´-35º58´S and 57º25´-57º22´W). From this analysis, we identified 31 species grouped within 17 genera. The assemblages were composed mainly of hyaline and agglutinated forms characterized by Elphidium aff. poeyanum, Elphidium gunteri, Ammonia parkinsoniana, Arenoparella mexicana and Trochammina inflata, reflecting an environment of marsh or floodplain. The foraminifer's tests were generally well preserved, with morphologies that indicate predominantly epifauna and epifauna-infauna. The present work shows that despite having a general fauna characteristic of these environments, there are small microenvironments that are characterized by the state of preservation, diversity and abundance of the found specimens. In that context, three associations were recognized; A, dominated by Astrononion sp.1 that was registered in the central part of the channel; association B, characterized mainly by E. aff. poeyanum that was founded in the internal and external areas of the channel and association C, characterized by a considerable increase of mentioned agglutinated species (close to 50%) registered in the center of the channel. This study represents one of the first contributions on the distribution of foraminifera and their ecological characteristics from recent sediments in Samborombón Bay.

Anachronistic facies and carbon isotopes during the end-Permian biocrisis: Evidence from the mid-Tethys (Kisejin, Iran)

Late Permian mass extinction (LPME) research has focused primarily on Tethyan sections because it is believed that these successions are more complete than those from other localities, and provide a more comprehensive record of the largest, most devastating extinction event in Earth history. The Kisejin section, a previously undocumented mid-Tethyan, Upper Permian-Lower Triassic succession located in the Central-Iran Plate. The Kisejin section contains a continuous Permian-Triassic sequence with only small breaks in sedimentation and was examined in order to determine sedimentologic, biostratigraphic, and carbon isotopic trends across the Permian-Triassic transition. Abnormal (anachronistic) carbonates developed in the study area following the LPME, and include microbialites, edgewise conglomerates, sparitic microspheres, and microbially-coated grains; microbialites occur as thrombolites, stromatolites, and as agglutinated forms. Renalcis-type calcimicrobes are documented for the first time from Permian-Triassic boundary microbialites (PTBMs) of Iran. Coated grains fall into two groups, and include pre-PTBM ooids, which are dense and cloudy, and possibly microbial in origin, and post-PTBM cortoids with destructive and constructive micrite envelopes. Latest Permian conodonts (H. praeparvus, M. ultima), coupled with carbon isotopic values, place the Permian-Triassic boundary within the lowermost thrombolite unit, about 2.1 m above the boundary between the Nessen Formation and the Elika Formation, and indicate that microbialite growth began during the latest Permian. Our study of this previously unknown section shows that, unlike other well-known PTB sections from Iran, the microbialite pattern is complicated, and is more similar to PTBM successions from Turkey. In addition, we note a similarity between the unusual facies of the Kisejin section and those of eastern Tethyan sections from China (i.e. sparry microspheres and Renalcis-type calcimicrobes); these unusual facies have not been previously reported from other well-known Iranian sections, including Julfa and Abadeh, which are thick and have been extensively studied.

Assessing the composition of fragmented agglutinated foraminiferal assemblages in ancient sediments: comparison of counting and area-based methods in Famennian samples (Late Devonian)

Abstract. Benthic foraminifera have been used as proxies for various paleoenvironmental variables such as food availability, carbon flux from surface waters, microhabitats, and indirectly water depth. Estimating assemblage composition based on morphotypes, as opposed to genus- or species-level identification, potentially loses important ecological information but opens the way to the study of ancient time periods. However, the ability to accurately constrain benthic foraminiferal assemblages has been questioned when the most abundant foraminifera are fragile agglutinated forms, particularly prone to fragmentation. Here we test an alternate method for accurately estimating the composition of fragmented assemblages. The cumulated area per morphotype method is assessed, i.e., the sum of the area of all tests or fragments of a given morphotype in a sample. The percentage of each morphotype is calculated as a portion of the total cumulated area. Percentages of different morphotypes based on counting and cumulated area methods are compared one by one and analyzed using principal component analyses, a co-inertia analysis, and Shannon diversity indices. Morphotype percentages are further compared to an estimate of water depth based on microfacies description. Percentages of the morphotypes are not related to water depth. In all cases, counting and cumulated area methods deliver highly similar results, suggesting that the less time-consuming traditional counting method may provide robust estimates of assemblages. The size of each morphotype may deliver paleobiological information, for instance regarding biomass, but should be considered carefully due to the pervasive issue of fragmentation.

Paleoenvironmental perturbation across the Cenomanian/Turonian boundary of the Kopet-Dagh Basin (NE Iran), inferred from geochemical anomalies and benthic foraminiferal assemblages

A Cenomanian/Turonian boundary succession in the northeastern Tethyan realm, Kopet-Dagh Basin in NE Iran, was studied to examine the effects of biological productivity, atmospheric CO2 concentration, and sea water temperature on the benthic foraminiferal assemblages. Our δ13Ccarb and δ13Corg chemostratigraphy of the Gharesu section reveals three positive peaks that can be correlated with carbon isotope peaks in the CTB reference sections (Eastbourne, England; Pont d'Issole, France; Rock Canyon, USA). Two intervals of suspected high sea surface temperature were distinguished according to pCO2 maxima (Δ13C; difference between δ13Ccarb and δ13Corg), low δ18O values, and high TOC bearing deposits. These intervals are followed by falling pCO2 and cooling caused by enhanced burial of organic matter into the sediments. Patterns of changes in the benthic foraminiferal assemblages are correlated with these climatic changes. Warm intervals are characterized by low diversity of benthic foraminifera, dominance of agglutinated forms, and high abundance of infaunal morphogroups or opportunistic epifauna due to intensified weathering, high primary productivity, and oxygen deficiency in the bottom water. The cold intervals coincide with higher diversity of benthic foraminifera and dominance of calcareous benthic taxa.

Early Eocene evolution of carbonate depositional environments recorded in the Čikola Canyon (North Dalmatian Foreland Basin, Croatia)

The stratigraphic succession in the Cikola Canyon (part of the North Dalmatian Foreland Basin) was studied in detail to describe both the sedimentological characteristics and fossil assemblages of the Lower Eocene deposits during the initial stage of the foreland basin formation. The North Dalmatian Basin now represents a part of the Outer Dinarides, and was developed in front of the evolving Dinaric structures by tectonic deformation and marine transgression of an emerged and denuded Mesozoic Adriatic Carbonate Platform (AdCP). During the initial phase, a distal ramp of a foreland basin was formed, characterised by carbonate sedimentation, lasting until the Middle Eocene. In a studied section more than 300 m thick, porcelaneous foraminifera, Alveolina, Orbitolitesand complex miliolids (Idalina, Periloculina) prevail, associated with conical agglutinated forms, nummulitids and red algae. These samples belong to the SBZ 11–12 (Ypresian), according to occurrences of Alveolina decastroi, Alveolina cremae, Alveolina multicanalifera and Coskinolina liburnica. Two main lithological units have been described: 1) mudstones to wackestones with sporadic occurrences of ostracods and charophyceae, deposited in restricted lagoonalsettings with several episodes of freshwater influences, and 2) foraminiferal packstones to grainstones with complex miliolids, alveolinids, corallinacean algae and nummulitids, deposited within inner and middle ramp settings. Palaeogene deposition of ramp carbonates in the Outer Dinarides area was mainly controlled by the continuous compressional tectonics, and the deposits today appear in more or less discontinuous outcrops. Palaeogene transgression occurred at different times over various parts of the former carbonate platform area, and subsequent carbonate sedimentation was characterised by deposition in similar environments during different time intervals over spatially restricted carbonate ramps controlled by synsedimentary tectonics.

Relationship between ‘live’ and dead benthic foraminiferal assemblages in the abyssal NE Atlantic

Dead foraminiferal assemblages within the sediment mixed layer provide an integrated, time-averaged view of the foraminiferal fauna, while the relationship between dead and live assemblages reflects the population dynamics of different species together with taphonomic processes operating over the last few hundred years. Here, we analysed four samples for ‘live’ (Rose-Bengal-stained) and dead benthic foraminifera (0–1cm sediment layer, >150µm) from four sites in the area of the Porcupine Abyssal Plain Sustained Observatory (PAP-SO; NE Atlantic, 4850m water depth). Two sites were located on abyssal hills and two on the adjacent abyssal plain. Our results indicate that the transition from live to dead benthic foraminiferal assemblages involved a dramatic loss of delicate agglutinated and organic-walled tests (e.g. Lagenammina, Nodellum, Reophax) with poor preservation potential, and to a lesser extent that of some relatively fragile calcareous tests (mostly miliolids), possibly a result of dissolution. Other processes, such as the transport of tests by bottom currents and predation, are unlikely to have substantially altered the composition of dead faunas. Positive live to dead ratios suggest that some species (notably Epistominella exigua and Bolivina spathulata) may have responded to recent phytodetritus input. Although the composition of live assemblages seemed to be influenced by seafloor topography (abyssal hills vs. plain), no such relation was found for dead assemblages. We suggest that PAP-SO fossil assemblages are likely to be comparable across topographically contrasting sites, and dominated by calcareous and some robust agglutinated forms with calcitic cement (e.g. Eggerella).

Foraminiferal biofacies and depositional environments of the Burdigalian mixed carbonate and siliciclastic Dam Formation, Al-Lidam area, Eastern Province of Saudi Arabia

Four outcrops along a west to east transect in the Al Lidam escarpment of Saudi Arabia were investigated to understand the vertical and lateral distribution of foraminiferal assemblages for paleoenvironmental reconstruction. The samples were processed using the standard acetic acid method, which extracts foraminifera from lithified carbonate rocks without destroying the fossil content. The foraminiferal assemblages from the Dam Formation are dominated by calcareous porcelaneous Miliolina (Quinqueloculina, Peneroplis, Triloculina, Cornuspira, Sigmoilinita, Coscinospira, Spirolina, Pyrgo, Borelis), followed by hyaline genera (Elphidium sp., Ammonia, Cibicides, Discorbinella) and a minor percentage of agglutinated forms, e.g., Textularina.The high percentage of calcareous porcelaneous taxa and the absence of planktonic foraminifera indicate that the Dam Formation was deposited in a restricted carbonate platform environment, very shallow hypersaline shallow marine, gently sloping ramp (inner ramp to mid ramp) which ranges from supratidal to subtidal with local reef patches towards the basin. The formation was deposited in an arid subtropical climatic environment with water temperatures ranging from 20 to 35°C. Based on the observed assemblage composition, the present day Arabian Gulf can be considered as a modern analogue for the Dam Formation during Miocene times.

Benthic foraminiferal assemblages and bottom water evolution off the Portuguese margin since the Middle Pleistocene

The upper 250 meter-long sediment core of Site U1391 (1085m water depth) retrieved from the Portuguese margin in the Northeast Atlantic Ocean was adopted for the benthic foraminiferal analyses to disclose the variations in Mediterranean Outflow Water (MOW) intensity over the last ~0.9Ma. Benthic foraminifera are abundant at this site and mainly composed of the hyaline forms (80%, such as Cibicidoides/Cibicides spp., Globobulimina spp., Bulimina spp., Uvigerina spp., Melonis spp., Sphaeroidina bulloides, Hoeglundina elegans, Gyroidinoides spp., Lenticulina spp. and Planulina ariminensis), while the agglutinated and porcelaneous forms have only 5% and 14.1% on average, respectively.Down-core variations of the benthic foraminifera show glacial-interglacial contrasts, especially those of Lenticulina spp. and Planulina ariminensis, which is also supported by the benthic foraminiferal cluster analysis. During the interglacial periods, the fauna are dominated by Sphaeroidina bulloides, Lenticulina spp., Planulina ariminensis, Dentalina spp., Cibicidoides robertsonianus and the agglutinated forms, while by Cibicidoides pachyderma, Praeglobobulimina ovata, Praeglobobulimina pupoides, Bulimina mexicana, Uvigerina mediterranea, Bolivinita quadrilatera and mililoids during the glacial periods.Benthic foraminiferal faunal data at Site U1391 was detailed analyzed to disclose the bottom water property over the last ~0.9Ma. Variations of the character species or assemblages, such as Planulina ariminensis, and the “elevated epibenthos” group suggest that the MOW intensity has typical glacial-interglacial cycles, strengthening during the interglacial periods and weakening during the glacial periods, and reaches its peak at MIS 11. The strongest MOW intensity during MIS 11 confirms the climatic influence of waving sea level on the MOW current by its +20m high-stand above the present sea level.The agglutinated benthic foraminifera have a significantly positive correlation with the MOW index of “elevated epibenthos”, which suggests that their abundance can be used to monitor the hydrodynamic conditions of bottom water off the Portuguese margin. Consistent with the MOW intensity, the lower miliolids content implies a lower salinity which supported the stronger vertical density gradient during the interglacial periods in this region; while the glacial ocean has a higher salinity with a weak vertical density gradient/MOW intensity.

Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient.

Ocean acidification causes biodiversity loss, alters ecosystems, and may impact food security, as shells of small organisms dissolve easily in corrosive waters. There is a suggestion that photosynthetic organisms could mitigate ocean acidification on a local scale, through seagrass protection or seaweed cultivation, as net ecosystem organic production raises the saturation state of calcium carbonate making seawater less corrosive. Here, we used a natural gradient in calcium carbonate saturation, caused by shallow-water CO2 seeps in the Mediterranean Sea, to assess whether seaweed that is resistant to acidification (Padina pavonica) could prevent adverse effects of acidification on epiphytic foraminifera. We found a reduction in the number of species of foraminifera as calcium carbonate saturation state fell and that the assemblage shifted from one dominated by calcareous species at reference sites (pH ∼8.19) to one dominated by agglutinated foraminifera at elevated levels of CO2 (pH ∼7.71). It is expected that ocean acidification will result in changes in foraminiferal assemblage composition and agglutinated forms may become more prevalent. Although Padina did not prevent adverse effects of ocean acidification, high biomass stands of seagrass or seaweed farms might be more successful in protecting epiphytic foraminifera.

Abyssal foraminifera attached to polymetallic nodules from the eastern Clarion Clipperton Fracture Zone: a preliminary description and comparison with North Atlantic dropstone assemblages

We examined encrusting organisms on seven polymetallic nodules from the eastern Clarion Clipperton Fracture Zone (CCFZ, ∼4070 m water depth, eastern equatorial Pacific). Apart from occasional sponges and a single bryozoan, all the organisms were foraminifera or foraminifera-like protists. A total of 75 morphotypes (presumed to be morphospecies) was recognised, with between 9 and 19 being present on individual nodules. Additional species were observed during shipboard examination of the nodules, bringing the total number of species to 86. The assemblage was dominated by a variety of mat-like formations, clusters of patches, isolated domes, broad trails, anastomosing networks and branched or unbranched tubular structures that either lay flat against the nodule surface or projected away from the surface. These forms were interpreted as monothalamous foraminifera (monothalamids). Most have mainly agglutinated walls but a few are predominately organic. Some can be assigned to the Komokiacea (notably the genus Chondrodapis) or families such as the Hemisphaeramminidae ('domes'), while others (e.g. many of the mats and patch-like forms) are difficult to place into existing monothalamid groupings. Some of the branching and anastomosing tubes resemble the genus Rhizammina. The most easily recognisable morphotypes include Telammina, in which tiny chambers are linked by extremely thin tubes to form a network, and sinuous orange tubes that incorporate sponge spicules and can be assigned to the genus Saccorhiza based on the occasional presence of a proloculus. Polythalamous foraminifera are also fairly common. They include various calcareous species (mainly Cibicides spp.), as well as agglutinated forms such as Hormosina, ?Placopsilina and trochamminaceans. Similar assemblages, including some morphospecies that are clearly identical to ours, have been described previously from somewhat deeper sites (4500–5000 m) in the CCFZ. In order to explore distributions at a global scale, we compared our Pacific nodule assemblages to foraminifera attached to ice-rafted dropstones from several deep seamounts in the abyssal northeast Atlantic Ocean, mainly on the Porcupine Abyssal Plain (4630–4680 m depth) with additional material from the BIOTRANS area (3796–4351 m). These hosted superficially similar assemblages of mats, tubular forms, komokiaceans and polythalamous calcareous and agglutinated foraminifera. However, apart from the sometimes extensive development of Telammina networks, there were no morphospecies in common between the Pacific and Atlantic assemblages. These preliminary observations, based on limited material, suggest that most of the foraminiferal morphospecies encrusting hard substrates are widely distributed at regional scales in the abyssal Pacific but not necessarily at global scales. The study of abyssal encrusting assemblages poses considerable challenges. Priorities for the future include the development of reliable methods for distinguishing living and dead individuals, and molecular approaches to clarifying the taxonomic affinities of novel morphotypes.

Upper Cretaceous agglutinated foraminifera from a red sediment interval in the southern Norwegian Sea

Foraminiferal assemblages from a red sediment interval of the uppermost Santonian–middle Campanian Nise Formation, offshore Norway were examined for taxonomy and their paleoenvironmental implications using morphogroup analysis. The relatively highly diversified assemblages are composed only of deep-water agglutinated forms, and in total 61 taxa were identified. The taxonomic and morphogroup composition of the assemblages resemble both the slope flysch-type biofacies in containing robust tubular forms and rzehakinids, and assemblages described from Cretaceous Oceanic Red Beds (CORBs) in the North Atlantic and the Carpathians in the high abundance of infaunal forms in supposedly environments with low flux of organic matter. The intermediate nature of the assemblages in the red sediment interval is probably related to the shallower bathyal depositional settings and higher flux of organic matter due to the proximity to land in a narrow seaway inferred frommorphogroup analysis than abyssal settings of other CORBs. The foraminifera from the red sediment may be regarded as the background deep-water assemblage which reflectswell-oxygenated and low-nutrient environments only with small terrigenous input in the Norwegian Sea which was tectonically active during the Cretaceous.