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Canal systems are advanced architectural features enabling the connection of various body regions via a network of passages. In Foraminifera, they enhance protoplasmic flow. Although they are principally observed in benthic representatives of the multilocular calcitic Order Rotaliida, canal systems presumably first appeared in a tubular, morphologically less complex foraminifer: the Bathonian-Cenomanian trochospiral genus Coscinoconus of the Order Involutinida. Based on the high-resolution analysis of a unique set of aragonitic Coscinoconus specimens, we here demonstrate that the porous system observed in the umbilical mass of these trochospiral Involutinida is a temporary feature. During ontogeny, it is at least partially plugged by aragonite directly secreted by the foraminifer, a process which limits its functional importance. A similar but open (unsealed) porous system is observed in another Involutinida genus, the planispiral Albian marker Hensonina, a controversial form that is here formally reinstated with Hensonina canalicula n. sp. as its type-species. The origin and development of these two porous systems are examined and compared with that of other foraminiferal groups, leading us to propose a clearer definition for wall pores and canal systems. Jurassic-Cretaceous Involutinida offer a fascinating example of a change in the role and function of wall pores through evolution. [ABSTRACT FROM AUTHOR]

The wide range of wall microstructures observed in the test of calcitic Foraminifera is probably unequalled in nature, and contrasts strikingly with the rather homogeneously radial walls of hitherto examined aragonitic foraminifers, be they tubular or multichambered. But do we truly know the actual wall microstructural variability in aragonitic foraminifers? Aragonite is indeed extremely rarely preserved in the fossil record and seldom tested on modern forms. The present study introduces four new genera and species of planispiral to high trochospiral aragonitic multichambered Foraminifera (Incompositus involutus gen. et sp. nov., Krivajella krivaja gen. et sp. nov., Tenuiscolumna evoluta gen. et sp. nov. and Falsotrochosiphonia teres gen. et sp. nov.) discovered in a Berriasian level of the Krivaja Valley, Bosnia and Herzegovina. Their original, aragonitic wall is exceptionally well preserved and dominantly displays a singular microstructure, made of diversely oriented, inequigranular bundles of original aragonite crystals. Such a structure, reminiscent to some extent of that observed in various calcitic foraminifers (Miliolida, Fusulinida, granulate Rotaliida), had never been recognized as such or described in detail before. The existence of an unfamiliar wall type in morphologically distinct multichambered aragonitic foraminifers not only questions the monophyly of the order Robertinida but also evolutionary paths in the entire Phylum. We here demonstrate that the newly described forms are part of a lineage that experienced a long but concealed evolutionary history. It is time to look at the foraminiferal record with new eyes as several aragonitic groups may have eluded our scrutiny. [ABSTRACT FROM AUTHOR]

Upper Triassic calcareous algae, abundant and well-diversified in Tethyan deposits, have rarely been described in rocks of Panthalassan origin. Over the past ten years, several studies were performed on Upper Triassic carbonate deposits of Panthalassan affinity in North America, Japan and Far East Russia, revealing unexpectedly rich and diversified assemblages. The samples were collected from nine localities situated on both sides of the Pacific Ocean. The identified algal assemblage consists of green and red algae, including fourteen dasycladaleans, rare bryopsidaleans, and several rhodophyceans. This paper describes the main algal taxa, including six new species: Holosporella? rossanae Bucur & Del Piero n. sp., Holosporella magna Bucur & Fucelli n. sp., Griphoporella minuta Bucur & Peybernes n. sp., Patruliuspora pacifica Bucur, Del Piero & Peyrotty n. sp., Patruliuspora oregonica Bucur & Rigaud n. sp. and Collarecodium? nezpercae Bucur & Rigaud n. sp. Rivulariacean-like cyanobacteria and thaumatoporellacean algae are also present. The whole Panthalassan algal assemblage comprises both unknown (?endemic) and common taxa of the Tethyan domain. To explain the cosmopolitan distribution of various Upper Triassic benthic organisms (scleractinian corals, calcified sponges, foraminifera), a close connection with the Tethys Ocean was hypothesized by different authors. During the Late Triassic, the Tethys was open to the east on the Western Panthalassa but not to the west, suggesting that Triassic calcareous algae were able to efficiently colonize environments that are estimated to be more than 10'000 km apart. An adventitious transport of calcareous algae and/or their spores is proposed to explain this long-range algal dispersal. [ABSTRACT FROM AUTHOR]

New benthic multichambered foraminifers have been discovered in the Hettangian--Sinemurian of the Northern Calcareous Alps (Adnet, Salzburg, Austria). Originally aragonitic, these forms are completely recrystallized but the early impregnation of their tests by Fe-Mn solutions has, to some extent, allowed an indirect preservation of their primary structure. The most remarkably preserved specimens are found in close vicinity to the marmorea crust, a heavily mineralized multiphased hardground. We describe two new genera, Velleditsiella gen. nov., a microgastropod look-alike foraminifer, which includes the species V. felicitaszae gen. et sp. nov. and V. spinaferra gen. et sp. nov., and Rossanella gen. nov., the first known representative of the superfamily Conorboidoidea, which includes the species R. martinii gen. et sp. nov. Considering their structural and morphological characteristics, Velleditsiella and Rossanella phylogenetically derive from two distinct Triassic lineages, respectively the families Trochosiphoniidae and Variostomatidae. The discovery of diverse aragonitic assemblages in earliest Jurassic strata dismisses the long believed hypothesis that all Jurassic aragonitic multichambered foraminifers originated from a single Oberhauserellidae ancestor. It also supports a lower impact of the Triassic/Jurassic biotic crisis on the evolution of aragonitic foraminifers. Hypotheses for the short term and long term evolution of aragonitic multichambered foraminifers are discussed and new phyletic trees are proposed. [ABSTRACT FROM AUTHOR]

New benthic multichambered foraminifers have been discovered in the Hettangian-Sinemurian of the Northern Calcareous Alps (Adnet, Salzburg, Austria). Originally aragonitic, these forms are completely recrystallized but the early impregnation of their tests by Fe-Mn solutions has, to some extent, allowed an indirect preservation of their primary structure. The most remarkably preserved specimens are found in close vicinity to the marmorea crust, a heavily mineralized multiphased hardground. We describe two new genera, Velleditsiella gen. nov., a microgastropod look-alike foraminifer, which includes the species V. felicitaszae gen. et sp. nov. and V. spinaferra gen. et sp. nov., and Rossanella gen. nov., the first known representative of the superfamily Conorboidoidea, which includes the species R. martinii gen. et sp. nov. Considering their structural and morphological characteristics, Velleditsiella and Rossanella phylogenetically derive from two distinct Triassic lineages, respectively the families Trochosiphoniidae and Variostomatidae. The discovery of diverse aragonitic assemblages in earliest Jurassic strata dismisses the long believed hypothesis that all Jurassic aragonitic multichambered foraminifers originated from a single Oberhauserellidae ancestor. It also supports a lower impact of the Triassic/Jurassic biotic crisis on the evolution of aragonitic foraminifers. Hypotheses for the short term and long term evolution of aragonitic multichambered foraminifers are discussed and new phyletic trees are proposed. [ABSTRACT FROM AUTHOR]

The new, atypical aragonitic foraminiferTubulastella comansgen. et sp. nov. is described from the Late Triassic of Panthalassa (Wallowa terrane, north-east Oregon, USA). This rectilinear, undivided tubular form is closely related to ‘Coptocampylodon?rhaeticus’, a Rhaetianincertae sediscommonly found in the western Tethys. Morphologically and structurally distinct from other aragonitic foraminifers,Tubulastella comansgen. et sp. nov. andT. rhaeticagen. et comb. nov. are part of an independent aragonitic lineage, here embodied by the family Tubulastellidae fam. nov. To understand the origination and taxonomic affinity of this unique taxon, a comparative study betweenTubulastellaand the calcitic syzraniid foraminiferRectostipulinais carried out. Although these forms differ in wall composition, they present identical constructional patterns, providing evidence of their close phylogenetic relationship. The existence of an aragonitic branch in Nodosariata evolution deeply challenges current foraminiferal classifications and evolutionary hypotheses. We here propose to limit the class Nodosariata to a monophyletic group of bi- to plurilocular foraminifers originating from a Silurian earlandiid ancestor, and the order Nodosariida to a monophyletic lineage of primarily single-layered built foraminifers, which takes root in the Middle Pennsylvanian. This new classification reflects an evolutionary transition from calcitic to aragonitic walls, as documented in other shelled organisms, and definitively excludes calcitic unilocular foraminifers (i.e. Ellipsolagenidae and Lagenidae) from the class Nodosariata. http://zoobank.org/urn:lsid:zoobank.org:pub:D8281D59-38FD-4D88-BEC6-14D5C7B8FD2B [ABSTRACT FROM PUBLISHER]

Large benthic agglutinated foraminifers possess subepidermal wall textures similar to the keriothecal textures observed in some Fusulinana. Considering the gap exceeding 50 million years in the record of the first alveolar large agglutinated Mesozoic forms (Textulariana) and their last known Palaeozoic microgranular homologues (Fusulinana), the two groups have been regarded as distinct lineages. The discovery ofWernlina reidaegen. et sp. nov. in Late Triassic carbonate rocks of a Panthalassan terrane questions this assumption. This new form, the earliest unequivocal Mesozoic ‘agglutinated’ alveolar foraminifer, originated from an Endotebidae (Fusulinana). The identification of a Triassic missing link between microgranular and agglutinated foraminifers not only fills the 50 million year gap but also challenges current foraminiferal classification. http://zoobank.org/urn:lsid:zoobank.org:pub:8F01DB56-390C-4D95-A692-9A815338ACFC [ABSTRACT FROM AUTHOR]

Early Jurassic aragonitic foraminifers are outstandingly well-preserved in the Marmorea crust, a multiphased ferromanganese layer limiting the Schnöll and Adnet formations (Adnet, Northern Calcareous Alps, Austria). This remarkable preservation, related to the pervasive impregnation of aragonitic tests prior to their recrystallization, allowed observing unknown diagnostic features of the genus Involutina, which typifies the Suborder Involutinina. Thanks to a detailed examination of the Adnet specimens, this paper clarifies the taxonomy, systematic position, and phylogeny of Involutina. A new diagnosis, structural model, and lineage are introduced for the group. Involutina is the direct descendant of Aulotortus and the two taxa probably showed a parallel evolution. As Aulotortus, Involutina presents a high intraspecific variability and its diversity must be revised downward. Current phylogenetic and taxonomic frames of the Suborder Involutinina are firmly questioned as, contrary to previous schemes, the type-genus possesses more than one lamellar deposit per whorl. In Involutina, the height and distribution of papillae on the test surface is not random and probably related to a biological function. We here propose that the papillose lamellae and tube infoldings that characterize representatives of the genus were rudimentary features for light catching and symbiont positioning, respectively. [ABSTRACT FROM AUTHOR]

The Late Triassic was a time of pronounced radiation in several groups of foraminifers. The rapid evolutionary processes in the Suborder Involutinina caused particularly high diversification of these aragonitic foraminifers, which became a key group for Upper Triassic biostratigraphy. Among them, Triasina hantkeni and Triasina oberhauseri are regarded as the most precise guide fossils. However, while these species are widely used, a poor documentation of the detailed test structure of T. oberhauseri has resulted in misidentifications. The exceptional preservation and abundance of Triasina oberhauseri in the Upper Triassic deposits of the Black Marble Quarry (Wallowa terrane, Oregon, USA) has allowed us to make the first detailed observations of its coiling, innermost structure and lamellae arrangement and to recognize morphological features that were either wrongly interpreted or not described in the original systematic definition of the species. In this paper, we demonstrate that the species possesses characteristics that hamper its assignment to Triasina and we propose a new genus, Aulosina, to accommodate this taxon. Placing emphasis on the accuracy of the morphological description, the diagnosis and the systematic definition of the species are here improved. The identification of innovative features in Aulosina oberhauseri (strengthenings, shortened lamellae) highlights new evolutionary trends for the lineage of Involutinina that have proved useful for the establishment of phylogenetic links between involutinid genera and for understanding the evolutive steps leading to the formation of inner-pillars in tubular foraminifers. The increasing complexity of Involutinina representatives at the end of the Triassic, notably marked by the appearance of internal structures in Triasininae, leads us to regard them as probable symbiont-bearing foraminifers. [ABSTRACT FROM AUTHOR]

Abstract: The early diagenesis of the major carrier phases (Fe and Mn minerals), trace elements (As, Co, Cr, Hg, MeHg, Ni) and nutrients (ΣNO3, , ΣPO4) and their exchange at the sediment water/interface were studied in the Berre Lagoon, a Mediterranean lagoon in France, at one site under two contrasting oxygenation conditions (strictly anoxic and slightly oxic) and at an adjacent site with perennially well-oxygenated water. From the concentration profiles of the primary biogeochemical constituents and trace elements of the pore and bottom waters, as well as the total and reactive particulate phases, it was possible to locate and identify the diagenetic reactions controlling the mobility of trace elements in the sediments and quantify their rates by coupling one-dimensional steady-state transport-reaction modelling and thermodynamic speciation calculations. Under oxic conditions and in the absence of benthic organisms, the main redox reactions were well identified vertically in the surface sediments and followed the theoretical sequence of oxidant consumption: . However, under anoxic conditions, only MnO2, Fe(OH)3 and reduction were present, and they all occurred at the interface. The main biogeochemical controls on the mobility of As, Cr, Hg, MeHg and Ni in the surface sediments were identified as the adsorption/desorption on and/or coprecipitation/codissolution with Fe oxy-hydroxides. In contrast, Co mobility was primarily controlled by its reactivity towards Mn oxy-hydroxides. In sulphidic sediments, As, Hg and MeHg were sequestered along with Fe sulphides, whereas Co and Ni precipitated directly as metallic sulphides and Cr mobility was enhanced by complexation with dissolved organic ligands. The fluxes of trace elements at the sediment–water interface are essentially dependent on the localisation of their remobilisation and immobilisation reactions under the interface, which in turn is governed by the benthic water oxygenation conditions and kinetic competition among those reaction and diffusion processes. Under oxic conditions, the precipitation of Fe or Mn oxy-hydroxides in the surface sediments constitutes the most efficient mechanism to sequester most of the trace elements studied, thus preventing their diffusion to the water column. Under anoxic conditions the export of trace elements to the water column is dependent on the kinetic competition during the reductive dissolution of Fe and/or Mn oxy-hydroxides, diffusion and immobilisation with sulphides. It is also shown that benthic organisms in the perennially oxygenated site have a clear impact on this general pattern. Based on the extensive dataset and geochemical modelling, it is predicted that the planned re-oxygenation of the entire lagoon basin, if complete, will most likely limit or reduce the export of the trace elements from the sediments to the water column and therefore, limit the impact of the contaminated sediment. [Copyright &y& Elsevier]

Abstract: To evaluate the genotoxic risk that contaminated sediment could constitute for benthic organisms, three contaminated (VA, VC and VN) and one uncontaminated (RN) sediment samples were collected in the Berre lagoon (France). Potentially bioavailable contaminants in sediments were obtained using sediment extraction with synthetic seawater adjusted to pH 4 or pH 6, simulating the range of pH prevailing in the digestive tract of benthic organisms. The genotoxic activities of these extracts were evaluated by three short-term bioassays: the Salmonella mutagenicity test using the Salmonella typhimurium strain TA102, the alkaline comet assay and the micronucleus assay on the Chinese Hamster Ovary cells CHO-K1. Results of the Salmonella mutagenicity assay detected a mutagenic response for RN extract at pH 6, and for VA extract at pH 4. Results of the comet and micronucleus assays detected low genotoxic/clastogenic activities for VA and VC extracts at pH 6 and higher activities for RN, VA and VC extracts at pH 4. To identify if metals (Al, Fe, Mn, As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were involved in these genotoxic activities, their concentrations were determined in the extracts, and their speciation was assessed by thermodynamic calculations. Results showed that extracts from sites VA, VC and VN generally presented the highest trace metal contents for both extractants, while the site RN presented lower trace metal contents but the highest Fe and Mn contents. Thermodynamic calculations indicated that Fe, Mn, As and in a lower extend Co, Ni and Zn were mainly present under free forms in extracts, and were consequently, more likely able to induce a genotoxic effect. Results globally showed no correspondence between free metal contents and genotoxic activities. They suggested that these positive results could be due to uncharacterized compounds, acting as direct genotoxic agents or enhancing the genotoxic properties of analyzed metals. [Copyright &y& Elsevier]

Chronic hypoxia and anoxia have strong impacts on coastal ecosystems worldwide. In shallow coastal ecosystems, such situations are essentially driven by high benthic oxygen (O 2) demand resulting from organic matter mineralization in surface sediment and amplified by a low mixing of the water column. However, the benthic O 2 demand may greatly vary according to the O 2 availability, sediment biogeochemical properties, and bioturbation by macrobenthic fauna. Here we examined how the sediment O 2 demand varies in response to seasonal and long-lasting (pluri-decadal) hypoxia in the Berre lagoon, a coastal ecosystem impacted by chronic hypoxia events since 60 years. Oxygen penetration depth, diffusive and total O 2 fluxes were measured in situ using a microelectrode autonomous profiler and benthic chamber deployments at three sites impacted by quite-permanent (PA), seasonal (PI) and occasional (PO) hypoxia in August 2016. They were seasonally repeated at site PI between August 2015 and August 2016. Additional physical and chemical characteristics were also measured in surface sediment. Sediment profile images and characteristics of benthic macrofauna communities enabled to estimate the quality of the benthic ecosystem. The highest benthic O 2 demand was observed after seasonal anoxia in relation to the important accumulation of reduced chemical species in surface sediment. Interestingly, both pluri-decadal hypoxia and normoxia produced relatively high benthic O 2 demand related to a higher accumulation of organic matter and to the presence of reduced chemical species at site dominated by hypoxia, and to the presence of fresher organic matter and active bioturbating macrofaunal communities in normoxic site. The low benthic O 2 demand at site seasonally impacted by hypoxia likely resulted from the degraded state of the macrofaunal community and from the lower accumulation of reduced chemical species. The occurrence of hypoxia and anoxia situations in the Berre lagoon was predicted from the competition between kinetics of benthic O 2 demand and water column reoxygenation events induced by strong wind. The good agreement between the measured and predicted hypoxia/anoxia occurrence clearly indicates that the chronic deoxygenation events in the Berre lagoon, and the resulting degraded ecological state of the benthic ecosystem are driven both by the benthic O 2 demand and by the intensity and duration of the water column stratification. • The benthic oxygen demand (BOD) varies with seasonal and long-lasting deoxygenation events. • BOD is firstly driven by oxygen availability in the water column. • Hypoxia generates highest BOD for the oxidation of accumulated reduced chemical species. • Long-lasting normoxia generates high BOD because of high bioturbation and fresher organic matter. • BOD and water column stratification are responsible of the chronic deoxygenation in the Berre lagoon. [ABSTRACT FROM AUTHOR]

• This is the oldest unit within allochthonous Overthrust Terrane Association (OTA). • Bahamian-type facies are represented with few macrofossils but distinct Foraminifera. • Age is from foraminiferal species known from Europe and North Africa. • Five localities are within Sinemurian–Pliensbachian are described. • Coeval Bahamian-type limestones are not known elsewhere in region. Lower Jurassic carbonate-platform deposits in Timor-Leste have been subject to much controversy. The Perdido Group contains the Bahamian-type facies shallow-water limestone of the Lower Jurassic that had been mixed with an upper Oligocene–lowest Miocene carbonate unit in Audley-Charles's Cablac Limestone. Foraminiferal assemblages from five sites in the Perdido Group are used to confirm a Sinemurian–Pliensbachian age. Species recorded for the first time from Timor and from the broader region, are Biokovina sp., Bosniella oenensis Gušić, Endotriadella ifranensis Bassoullet, Boutakiout, Vachard , Lituosepta recoarensis Cati, Palaeocyclammina complanata Bassoullet, Boutakiout and Echarfaoui, Planisepta compressa (Hottinger), and Radoicicina ciarapicae Gale, Barattolo and Rettori. Previously Siphovalvulina spp. and Meandrovoluta asiagoensis Fugagnoli and Rettori were described from the group. These species allow distinction between the Perdido Group (part of the Overthrust Terrane Association in Timor-Leste) and the carbonate-platform Upper Triassic Bandeira Group (part of the East Gondwana Interior Rift Association). No equivalent facies coeval with the Perdido Group and with similar foraminiferal assemblages have been recognized in the Indonesian, Malayasian, Timor-Leste, or north-west Australian regions. The closest known Sinemurian–Pliensbachian occurrence containing some of the species found in the Perdido Group, is in Western Thailand, with a fauna including Lituosepta cf. recoarensis. [ABSTRACT FROM AUTHOR]

Timor is part of the non-volcanic Outer Banda Arc with chaotic geology in the late Neogene collision zone between Sundaland (Southeast Eurasia) and the Australian continent. Confusion in the distinction between Triassic, Jurassic and Cenozoic shallow-marine carbonate units has led to a lack of appreciation of the widespread extent of Triassic carbonate-platform facies, at least in Timor-Leste. It also resulted in misunderstanding the different tectonostratigraphic/palaeogeographic affinities of the shallow-water limestones. Foraminiferal assemblages are critical in stratigraphic discrimination of these units. This study records for the first time the foraminiferal microfauna of Upper Triassic shallow-water carbonate deposits in Timor. Many of the foraminiferal species are known from North Africa and Europe and date these units to the Carnian–Rhaetian. The Upper Triassic Bandeira Group represents extensive sheet-like carbonate-platform deposits (possibly on horst plateaus as well as shelf areas adjacent land in the intracratonic sea). Contacts between the hard limestone, forming fatus (limestone peaks) and ridges, and friable mud-dominated surrounding units are often obscured under deep tropical soil cover. At all localities the Bandeira Group is closely associated in outcrop with coeval basinal mud-dominated deposits (Babulu and Aitutu groups). With these it forms part of the East Gondwana Interior Rift Association (EGIRA), similar to the classical Dachstein Platform–Hallstatt Basin facies associations found in the European Alps. The basinal units contain turbiditic and debris-slide deposits that include clasts derived from the carbonate platform. Shallow-water carbonate facies attributed to EGIRA, are present throughout the East Gondwana Interior Rift from the Papuan Basin in the north to Exmouth Plateau, part of the Northern Carnarvon Basin, in the south. These were deposited before Gondwanan breakup along this rift system. The Triassic carbonate-platform deposits have a different dominant biogenic mineralogy (aragonite rather than calcite) and a different architecture to the bryozoan-crinoidal carbonate mounds present in the Permian of EGIRA in Timor-Leste. No Lower and Middle Triassic shallow-water carbonate-platform deposits have been recognized in Timor-Leste. The Bandeira Group, confined to the Upper Triassic, belongs to a stratigraphic association (EGIRA; autochthonous) different both in constituent units and outcrop coverage from that of the allochthonous Overthrust Terrane Association to which the Lower Jurassic carbonate-platform deposits (viz. Perdido Group) belong. The Bandeira Group has been confused not only with the Perdido Group but also with other shallow-water limestone units of the Permian and Miocene in some former studies of Timor. The distinction between these units solves a major tectonostratigraphic problem in Timor, and may apply elsewhere along the Outer Banda Arc. • Triassic shallow carbonate-platform facies (Bandeira Group) widespread in Timor-Leste. • Age range Carnian (? late Carnian) to Norian to?early Rhaetian based on Foraminifera. • Part of East Gondwana Interior Rift Association. • Slab-like platform architecture differs from mound-like underlying Permian Limestone. • Distinct from Lower Jurassic equivalent facies of Overthrust Terrane Association. [ABSTRACT FROM AUTHOR]

The present work investigates the significance of Late Triassic ostracods from the Yukon Territory, Canada, and adds to the scientific knowledge of the taxonomy of these organisms during the Norian, which remain poorly documented and understood. Fifteen limestone samples representing distinct marine palaeoenvironments cropping out at Lime Peak, Stikinia terrane, provided 90 species, including 9 newly described: Alatobairdia? sohni n. sp., Bairdia aksala n. sp., B. taan n. sp., B. yukonensis n. sp., Cornutobairdia yukonella n. sp., Lobobairdia whitella n. sp., Mirabairdia canadia n. sp., Hungarella limella n. sp., Leviella riedeli n. sp. Most assemblages point to neritic conditions in the photic zone. A similarity analysis demonstrates the distinct composition of reef-related and algae-related ostracod assemblages. The ostracod-algae associations in Lime Peak reveal that the affinity of Bairdiidae for algae (Dasycladaleans in the case of Lime Peak) was already established in the Norian. A faunal link is identified during the Norian between eastern and western Panthalassa and Japan, in line with studies on other taxa. The flux of species between eastern Panthalassa and Tethyan areas appears very unbalanced in the Late Triassic with most migrations originating from the Tethys. Further data from other Middle and Upper Triassic Panthalassan localities and stages (i.e. Ladinian and Carnian) are needed to confirm whether this apparent trend is due to sampling bias or reflects real dispersal fluxes. [ABSTRACT FROM AUTHOR]

Flat clams are ubiquitous in marine Triassic and Jurassic deep-water environments, where they are often recovered as mono- or pauci-specific assemblages. Their abundance in deep-water facies deposited under oxygen-depleted conditions suggests a potentially unique, but nevertheless debated, paleoecology. The distribution of Halobia cordillerana in an Upper Triassic hemipelagic succession outcropping at Tsiko Lake, Vancouver Island, Canada, serves as a revealing case study. There, deep-water deposits were investigated using a multi-disciplinary approach including facies description (mineralogical, fossil and organic content), taphonomy, morphometry, microscopy (cathodoluminescence, scanning-electron microscope) and independent paleo-redox proxy constraints (framboidal pyrite distributions, Fe speciation). Overall, halobiids' taphonomy at Tsiko Lake is indicative of in situ accumulations with little or no reworking. Among the hemipelagic deposits, three major litho-biofacies (BFC 1, 2, 3) were identified; paleo-redox proxies indicate that these litho-biofacies were deposited under different oxygen conditions ranging from extreme dysoxic (BFC 1) to dominantly euxinic (BFC 3). The distribution of H. cordillerana is shown to be directly influenced by bottom water oxygenation with this organism peaking both in abundance and dimensions under extreme dysoxic to anoxic conditions (i.e. BFC 1 & 2). Conversely, under prevailing euxinic conditions (i.e. BFC 3), the population of H. cordillerana is dominated by forms at larval or post-larval stage which were presumably killed by water-column euxinia. Thus, although the species is here shown to have lived most likely as an epibenthic recliner, an early (larval) planktonic/nektonic stage is needed to explain its mode of occurrence during dominantly euxinic conditions (i.e. BFC 3), and its wide distribution and rapid expansion. Finally, this study highlights the colonizing capacity of halobiids in case of restored oxygen conditions, stressing the potential significance of flat clams for paleoenvironmental reconstruction. • A multi-proxy approach has been undertaken to study the stratigraphic distribution of flat clams. • The development of Halobia cordillerana is influenced by sea-bottom conditions. • Halobia cordillerana was opportunistic and peaked in abundance under dysoxic conditions. • Flat clams could become an extremely useful tool in paleoenvironmental reconstructions. [ABSTRACT FROM AUTHOR]

A more than 300 m thick succession of thick-bedded pink to grey limestone of the Norian – Rhaetian Khodz Group in the NW Caucasus serves to document the development of a temperate carbonate ramp during the final stages of the Cimmerian orogeny. Limestone samples were collected on the west side of Mt. Kolokolnia. The lower part of the Khodz Group contains bioclastic packstone microfacies composed largely of heterotrophic organisms: bryozoans, brachiopods, echinoderms, bivalves, small benthic foraminifers, juvenile ammonoids, agglutinated worm tubes, gastropods, ostracods and sponges. The upper part is comprised of layers of wackestone with frequent evidences of short episodes of emersion. Sponge spicules locally predominate; very few coral fragments also occur. Foraminiferal assemblages of the Khodz Group contain a high proportion of involutinids, including Licispirella violae (Blau), L. iranica (Senowbari-Daryan, Rashidi & Torabi), Coronaserra deminuta (Blau), Coronipora sp., ? Kristantollmanna bicarinata (Blau), Frentzenella perforata Rigaud, Blau, Martini & Rettori, ? Involutina turgida Kristan, ? Trocholina turris Frentzen, and T. ex gr. intermedia / umbo Frentzen, together with porcelaneous foraminifers such as Galeanella tollmanni (Kristan), and Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret), which are typical reef dwellers in tropical platforms. Such faunal and foraminiferal association points to a shallow (photic zone) marine depositional environment. Trocholinids are among the most successful survivors of the end-Triassic crisis. The rich occurrence of diversified trocholinids in temperate Triassic seas at high latitudes within the western Eastern Laurasia palaeobiogeographic province suggests that: 1) temperate areas may have played an important role as refugia for marine life during this major biotic event, and 2) the importance of ocean acidification in the selective extinction of marine organisms is overestimated. • Upper Triassic Khodz Group (Great Caucasus) contains diverse Trocholinidae • Depositional setting is shallow part of temperate carbonate ramp • Foraminiferal assemblage belongs to western Eastern Laurasia bioprovince • Trocholinidae retained their diversity during the end-Triassic biotic crisis • Refugia for survivors might be sought at high palaeolatitudes or in deeper sea [ABSTRACT FROM AUTHOR]

The study of manganese (Mn) and iron (Fe) cycling in early diagenetic processes in estuaries is crucial for understanding the functioning of these vital ecosystems and predicting their responses to environmental change. The present study investigates the dynamic interplay of Mn and Fe in early diagenetic processes at highly contrasted hydrosedimentary conditions in the Loire estuary, which is very rare and allows a comprehensive framework to understand diagenetic processes in a very dynamic environment. One campaign took place in the Brillantes intertidal mudflat in March 2015 (PV1), while 3 others took place in a muddy riverbed along the navigation channel off the city of Paimboeuf during a decennial flood in February (RR1–4), under moderate discharge in June (RRK-4) and low in August 2021 (RR2–4). The monitored riverbed station was upstream, under and downstream the maximum turbidity zone, respectively. By combining sequential extraction techniques for Mn and Fe in solid phases and pore-water analysis, the study provides insights into the behaviour of these elements in sedimentary environments and reveals their speciation and association with specific mineral phases and forms during different diagenesis stages. The remobilization of Mn and Fe in the surface sediments of the Brillantes mudflat (PV1) allows iron sulphide formation within the upper 50 cm of the sediment column (above the sulphate penetration depth). The deeper layers show other authigenic phases formation, such as the probable precipitation of vivianite below the sulphate depletion depth and progressive precipitation of carbonate at depth, leading to definitive burial and accumulation. At the muddy riverbed, following the exceptional flood in February 2021 (RR1–4), significant sediment erosion occurred unveiling to the water column old and reduced sediments. Sharp pore-water gradients for dissolved Mn, Fe and sulphate indicated the sudden exposure of the old 7Be-free and anoxic sediment to low-salinity, well‑oxygenated water. Despite its dark colour, this sediment showed no authigenic FeS/FeS 2 phases. Four months later, changes in the estuarine environment (low river discharge) and the presence of a maximum turbidity zone (TMZ) led to a new deposition of a sediment layer (RRK-4) triggering transient diagenetic reactions. The freshly deposited sediment layer developed important recycling of dissolved Mn, Fe and sulphate above the precedent sediment water interface (SWI) generating a double peak, accompanied by consistently low concentrations of solid Mn and Fe phases specially FeS/FeS 2 and Mn bound to FeS/FeS 2 compared to PV1. Six months after the flood event, in August (RR2–4), the discernible attenuation of dissolved Mn and Fe peaks and sulphate concentration, indicated a gradual recovery of characteristic sediment profiles with the well-known redox layer succession. Overall, despite important sulphate reduction within sediments from both the river and its adjacent mudflats, pyritization is not a major process for Mn and Fe burial. The intense hydrodynamics of the mid estuary prevents thermodynamical equilibrium between pore-water chemistry and solid phases not allowing pyrite formation while in the calmer conditions of intertidal mudflats, pyrite accumulates in intermediate depths but carbonates and phosphates seem to be the preferential phases of burial probably related to methane production and phosphate availability. • A sequence of authigenic Fe and Mn mineral formation was observed in the intertidal mudflat. • Hydrodynamic events in the muddy riverbed do not favour major mineral transformations. • Erosion/sedimentation events and ensuing relaxation were evidenced by pore-water data. [ABSTRACT FROM AUTHOR]

The disequilibrium between 210 Po and 210 Pb has been used as a proxy for the particle flux from the upper ocean. The particle concentration and composition effect on the partitioning behavior of 210 Po and 210 Pb is, however, still unclear. Here, we investigate this association by comparing dissolved (< 0.45 µm) and particulate (small: 1–51 µm; large: > 51 µm) 210 Po and 210 Pb activity with size-fractionated major particle concentration and composition data from the US GEOTRACES GA03 zonal transect cruises. We observed inverse relationships between partition coefficients (K d ) for the radionucli d es and the concentration of suspended particulate matter (SPM) in the water column, known as the “particle concentration effect.” We examined the relationships between 210 Po, 210 Pb, and particle composition in the top 500 m by using Pearson pairwise correlations for individual phases and principal components analysis (PCA) for variations among multiple phases. In addition to these analyses, an end-member mixing model was developed to estimate K d for 210 Po and 210 Pb in the small particulate size fraction from the compositional phases. The model predicted the range of observed K d (Pb) well, but was unable to predict the observed K d (Po) as consistently, possibly because of the bio-reactive nature of 210 Po. Despite this, we found a strong relationship between 210 Po and both CaCO 3 and POM, as well as between 210 Pb and both opal and lithogenic phases. All of our analyses demonstrated that the fractionation of 210 Po and 210 Pb differed between the margins and open ocean along the GA03 transect. [ABSTRACT FROM AUTHOR]

The Thau lagoon is a Mediterranean coastal lagoon used for shellfish farming. It is periodically affected by anoxia events that trigger oyster mortality. To investigate the effects of an anoxia event focussed on nutrient dynamics and the responses of the microbial planktonic communities a 13-day in situ experiment was performed in September 2020. Transparent mesocosms (270 L) were placed at a depth of 4 m, inserted in the sediment, and kept closed throughout the experiment. The experiment comprised three treatments: i) Natural environment (N), i.e. in the natural water outside the mesocosms containing a rope of 30 oysters (Crassostrea gigas), ii) Control mesocosm (C) filled with natural water with no oysters, and iii) Oyster mesocosm (O) filled with natural water containing a rope of 30 oysters. Oyster respiration in the oyster mesocosm depleted oxygen after 54 h. All the oysters from O mesocosm were dead after nine days and decomposition of their flesh combined with releases from the water-sediment interface increased dissolved inorganic nitrogen (dominated by ammonium), phosphates, and ∑H 2 S up to 390, 17 and 295 μmol·L−1, respectively. Phytoplankton biomass consequently increased by 20 (11.8 μg chl al −1) and abundance by 4.5 (186 × 106 cells·L1) dominated largely by green algae <5 μm. During the oyster mortality period (day 6 to day 9) high abundances of heterotrophic flagellates and large ciliate specimens were observed. This shift in the community towards small phytoplankton favours the microbial loop and is detrimental to shellfish farming. In a context of global warming in which the risk of anoxia is higher, the results of the present investigation demonstrate that anoxia triggers shellfish mortality and that the change in the plankton community disrupts the normal functioning of the ecosystem, causing serious financial losses. In this context, it is crucial to predict possible hypoxia and anoxia events using high frequency measurements of dissolved oxygen, by avoiding using shallow zones for oyster production and by reducing shellfish stocks, or by mechanically lifting the oysters out of the water during the night to reduce oxygen respiration in the ecosystem. • In presence of oysters, anoxia was reached after 54 h in the mesocosm. • A picophytoplankton bloom was observed during anoxia and oyster decomposition. • Anoxia and oyster mortalities induced a community shift towards small plankton. [ABSTRACT FROM AUTHOR]

Mercury (Hg) speciation in natural waters is controlled by redox conditions and microbiological activity. Water columns of meromictic lakes have large and stable redox chemical and biological gradients that allow the investigation of many Hg chemical transformations. In this study, Hg speciation (elemental Hg = Hg0, methylated Hg = MeHg) and partitioning between truly dissolved (<3 kDa), colloidal (<0.45 μm and >3 kDa), and particulate (>0.45 μm) fractions, were determined throughout a high-resolution water column profile in the ferruginous meromictic Lake Pavin (Massif Central, France) in July 2018. Total Hg concentrations (THg) in water ranged between 0.4 and 8.8 pmol L−1. The particulate phase represented 10–70% of the THg, with a peak found in the mesolimnion associated with the particulate organic carbon maximum. In the mesolimnion, the colloidal fraction represented 12–68% of THg, and the highest value was found at the top of the sulfidic zone, whereas the truly dissolved Hg species (70 ± 9%) dominated in all the rest of the sulfidic zone. MeHg ranged from less than 10% of THg in the oxic mixolimnion to more than 90% in the anoxic monimolimnion. The Hg methylation was most active within the suboxic zone where iron and sulfate reduction are occurring. These results, associated with those of the partition of organic matter (OM), sulfur, and iron, in conjunction with thermodynamic calculations, allow us to present a conceptual scheme for the Hg cycle in the lake. Atmospheric Hg deposited onto surface waters of the lake is partially photo-reduced and returned to the air, another part is scavenged by biogenic particulate matter and conveyed at depth by settling organic material. Water stratification and redox changes create a sequence of reactions from oxic to ferruginous waters where Hg is successively (i) desorbed from particulate OM where mineralization occurs, (ii) adsorbed onto iron-oxy(hydr)oxides, (iii) desorbed where they dissolved, (iv) precipitate as HgS, (v) methylated, and (vi) reduced as Hg0 in the deepest part of the lake. In brief, the (micro)biological uptake, OM, iron and sulfur recycling, through associated microbial consortia, control the Hg cycling in the Pavin waters. [Display omitted] • Lake Pavin is a permanently stratified ferruginous meromictic lake. • Mercury (Hg) speciation and partition were examined along the water column. • Hg exchange between solution, particles and colloids evolve with redox changes. • Successive Hg methylation, precipitation (HgS), and reduction (Hg0) with depth. • Biological pump, and bacterial iron and sulfur recycling control the Hg cycle. [ABSTRACT FROM AUTHOR]

The benthic compartment of River-dominated Ocean Margins (RiOMar) is largely affected by sedimentary processes, as well as by natural and anthropogenic disturbances. Recent studies have confirmed the major importance of riverine inputs and local hydrodynamics in the spatial structuration of low- and high-energy temperate RiOMar, respectively. Differences in the nature of these structuring factors could also affect the temporal dynamics of these two types of systems. The present study is aiming at: (1) quantifying spatiotemporal changes in surface sediment and benthic macrofauna within the West Gironde Mud Patch (WGMP; high-energy system) over both short (2016–2018) and longer (2010/2016–2018) time scales, (2) identifying the main environmental factors explaining those changes, and (3) achieving a comparison with the Rhône River Prodelta (RRP; low-energy system) in view of further characterizing the functioning of the benthic components of these two temperate RiOMar. Surface sediment characteristics (grain size, quantitative and qualitative descriptors of particulate organic matter) and benthic macrofauna compositions were assessed based on 4 seasonal sampling of 5 stations located along a depth gradient within the WGMP. Results highlighted the existence of spatial patterns for both surface sediment and benthic macrofauna, which are both better explained by local hydrodynamics. Most variables presented seasonal changes. Benthic macrofauna compositions also showed pluri-annual changes, which were attributed to a cicatrization process following a major disturbance caused by the 2013–2014 series of severe winter storms, and suggests the major role of local hydrodynamics in explaining 2010/2016–2018 temporal changes in WGMP benthic macrofauna compositions. The comparison with the RRP further highlighted major discrepancies between the two systems in the main processes (i.e., hydrodynamics versus river hydrological regime) explaining surface sediment characteristics and benthic macrofauna compositions, which supports current RiOMar typologies. • Hydrodynamics leads benthic macrofauna composition in the West Gironde Mud Patch • Strong storms could also affect benthic macrofauna temporal dynamics in this area • The West Gironde Mud Patch can be characterized as a temperate high-energy system • River-dominated Ocean Margins typologies are validated based on macrofauna analysis [ABSTRACT FROM AUTHOR]

Methylation of mercury (Hg) is the crucial process that controls Hg biomagnification along the aquatic food chains. Aquatic sediments are of particular interest because they constitute an essential reservoir where inorganic divalent Hg (Hg) is methylated. Methylmercury (MeHg) concentrations in sediments mainly result from the balance between methylation and demethylation reactions, two opposite natural processes primarily mediated by aquatic microorganisms. Thus, Hg availability and the activity of methylating microbial communities control the MeHg abundance in sediments. Consistently, some studies have reported a significant positive correlation between MeHg and Hg or total Hg (Hg), taken as a proxy for Hg, in aquatic sediments using enzyme-catalyzed methylation/demethylation mechanisms. By compiling 1,442 published and unpublished Hg-MeHg couples from lacustrine, riverine, estuarine and marine sediments covering various environmental conditions, from deep pristine abyssal to heavily contaminated riverine sediments, we show that a Michaelis-Menten type relationship is an appropriate model to relate the two parameters: MeHg = aHg/( K + Hg), with a = 0.277 ± 0.011 and K = 188 ± 15 ( R = 0.70, p < 0.001). From K variations, which depend on the various encountered environmental conditions, it appears that MeHg formation and accumulation are favoured in marine sediments compared to freshwater ones, and under oxic/suboxic conditions compared to anoxic ones, with redox potential and organic matter lability being the governing factors. [ABSTRACT FROM AUTHOR]

The assessment of the potentially harmful effects of metals on biota depends on the speciation and bioavailability of the metals. In the present study, the authors investigated Cu accumulation and toxicity in the aquatic plant Myriophyllum aquaticum after exposure to artificial sediments varying in peat or ferric hydroxide content and spiked with Cu (5-200 mg kg−1). Modeling of the kinetic diffusive gradient in thin film (DGT) measurements revealed fast and slow Cu resupply from the solid phase for sediment formulated with and without peat, respectively. Myriophyllum aquaticum proved to be sensitive to Cu, as the Cu accumulation and growth differed depending on the sediment composition and Cu concentration. Comparing the Cu accumulation in M. aquaticum with total dissolved concentration, free concentration, and concentration in solution derived from DGT measurements (CDGT), Cu concentrations revealed that CDGT concentrations were a better predictor of accumulation than the others. However, the relatively weak correlation observed ( r2 = 0.6) and the fact that plant uptake does not increase proportionally to DGT fluxes suggest that Cu uptake in plants was not diffusion limited. Thus, the free Cu concentrations near the root surface were sufficient to meet the plant's demand during the experiment. Furthermore, labile complexes that continuously resupply the Cu2+ pool may also contribute to the concentrations available for plant uptake. In the range of Cu concentrations investigated in the present study, saturation of uptake processes as well as toxicity are considered responsible for the poor DGT prediction of plant uptake. Environ Toxicol Chem 2014;33:278-285. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Recent multidisciplinary investigations of sediment cores from the ancient marine bay of Alexandria (Egypt) have documented local human activities during the Iron Age (circa 900–1000 B.C.) prior to Alexander the Great's arrival in 331 B.C. (Goiran, 2001; Véron et al., 2006; Stanley et al., 2007, 2010), corroborating the existence of the so-called “Rakhotis” as evoked in previous archaeological literature (Jondet, 1916; Weill, 1919; Chauveau, 1999; Baines, 2003). Lead (Pb) Isotopic Analyses (LIA) from Alexandria Bay indicate a possible anthropogenic imprint as early as circa 2300–2650 (±200) B.C. and, to a lesser extent, 3500–3800 (±170) B.C. (Véron et al., 2006). Here we demonstrate that LIA in sediments from the nearby Maryut Lagoon display isotopic anomalies resulting from the release of contaminant Pb into the Lagoon during the Egyptian Early dynastic (at 2897 ± 187 B.C) and Predynastic (at 3520 ± 145 B.C.) periods that corroborate geochemical data from Alexandria Bay. Pb concentrations in Maryut sediments show enrichments that mirror isotopic findings. The absence of contaminant Pb imprints within the sediments from the nearby Nile Canopic branch confirms that isotopic anomalies found in Alexandria Bay and Maryut Lagoon sediments are local and do not originate from long-distance transport of contaminant Pb associated with Nile suspended material and/or wind-derived aerosols. LIA in Alexandria sediment cores correspond to commonly mined Pb and Cu (copper) ores from Turkey (Black Sea region), Cyprus, Crete and the Oman Gulf. LIA substantiate the use of copper-based relics in the Alexandria region during the Pre and Early dynastic periods, and provide insights into metal trading within the Eastern Mediterranean during the Chalcolithic–Early Bronze Age transition, 6000 years ago. [ABSTRACT FROM AUTHOR]

Abstract: Four sediment samples (Vaïne Airport VA, Vaïne Center VC, Vaïne North VN and Reference North RN) were collected in the Berre lagoon (France). Sediments were analyzed for polycyclic aromatic hydrocarbons (PAHs) by use of pressurized fluid extraction with a mixture of hexane/dichloromethane followed by HPLC with fluorescence detection analysis. Organic pollutants were also extracted with two solvents for subsequent evaluation of their genotoxicity: a hexane/dichloromethane mixture intended to select non-polar compounds such as PAHs, and 2-propanol intended to select polar contaminants. Sediment extracts were assessed by the Salmonella/microsome mutagenicity test with Salmonella typhimurium TA98+S9 mix and YG1041±S9 mix. Extracts were also assessed for their DNA-damaging activity and their clastogenic/aneugenic properties by the comet assay and the micronucleus test with Chinese Hamster ovary (CHO) cells. The PAH concentrations were 611ngg−1dw, 1341ngg−1 dw, 613ngg−1dw and 482ngg−1dw for VA, VC, VN and RN, respectively. Two genotoxic profiles were observed, depending on the extraction procedure. All the non-polar extracts were mutagenic for TA98+S9 mix, and VA, VC, VN sediment samples exerted a significant DNA-damaging and clastogenic activity in the presence of S9 mix. All the polar extracts appeared mutagenic for TA98+S9 mix and YG104±S9 mix, and VA, VC, VN were genotoxic and clastogenic both with and without S9 mix. These results indicate that the genotoxic and mutagenic activities mainly originated from PAHs in the non-polar extracts, while these activities came from other genotoxic contaminants, such as aromatic amines and nitroarenes, in the polar extracts. This study focused on the important role of uncharacterized polar contaminants such as nitro-PAHs or aromatic amines in the global mutagenicity of sediments. The necessity to use appropriate extraction solvents to accurately evaluate the genotoxic hazard of aquatic sediments is also highlighted. [Copyright &y& Elsevier]