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Loriciferans are known to survive in extreme environments, most notably in the case of a recently described Spinoloricus species from a hypersaline anoxic Mediterranean basin. Our new discovery of members of the genus Rugiloricus inside spherical agglutinated structures from sediment samples collected in the manganese nodules fields of the eastern Clarion-Clipperton Zone (CCZ, abyssal equatorial Pacific) demonstrates that these tiny animals are able to spring fresh surprises. Nearly all developmental stages of an undescribed Rugiloricus species were found inside the spheres, from the first instar larva and large free larva to the two stages of the postlarva inside the larval exuvium. Only the adults were missing. The spheres themselves were almost certainly not created by the loriciferans. Their origin is unclear, although similar agglutinated structures from the same study area contain cells that resemble monothalamous foraminifera, suggesting that they are possibly made by foraminifera. One of our CCZ samples also yielded a single free specimen of the loriciferan genus Pliciloricus that was not hidden inside an agglutinated structure. This specimen is particularly interesting because, like nested Russian dolls, it has all stages inside the larval exuvium: first the larval exuvium itself with the two toes, then a very thin postlarval exuvium and finally the adult male with two testes filled with mature spermatozoa.

Xenophyophores are important megafaunal organisms in the abyssal Clarion-Clipperton Zone (CCZ; equatorial Pacific), a region hosting commercially significant deposits of polymetallic nodules. Previous studies assigned those with attached, fan-like tests to Psammina limbata, a species described from the central CCZ based on morphology. Here, we redescribe the holotype of P. limbata and then show that limbata-like morphotypes collected in the eastern CCZ include three genetically distinct species. Psammina aff. limbata is closest morphologically to P. limbata. The others are described as P. microgranulata sp. nov. and P. rotunda sp. nov. These fan-shaped species form a well-supported clade with P. tortilis sp. nov., a morphologically variable species exhibiting features typical of both Psammina and Semipsammina. A second clade containing Psammina sp. 3, and two species questionably assigned to Galatheammina branches at the base of this group. The genus Psammina includes another 9 described species for which there are no genetic data, leaving open the question of whether Psammina as a whole is monophyletic. Our study increases the number of xenophyophore species described from the eastern CCZ from 8 to 11, with a further 25 morphotypes currently undescribed. Many additional species of these giant foraminifera undoubtedly await discovery in abyssal settings.

Based on a combination of morphological and molecular data, we describe five new species and two new genera of xenophyophores from the Clarion–Clipperton Zone (abyssal eastern Pacific), an area with commercially valuable seafloor deposits of polymetallic nodules. Bizarria bryiformis gen. et sp. nov. displays unusual features, notably an organic-walled test, largely devoid of agglutinated particles, comprising interconnected branches growing upwards from the nodule substrate; the bases of the branches contain dark masses of waste material (stercomare) and pale strands of cytoplasm (granellare), the whitish, tuft-like extremities contain sediment particles. Tendalia reteformis gen. et sp. nov. forms a delicate network of agglutinated tubes. Shinkaiya contorta sp. nov. is characterized by a contorted, partly reticulated plate-like test while the simpler plate-like test of Galatheammina interstincta sp. nov. combines characters typical of Galatheammina and Psammina. In Semipsammina mattaeformis sp. nov., a thin, delicate test with one or more tubular extensions forms a flat canopy over the mat-like stercomare encrusting the nodule substrate. Tendalia reteformis and S. contorta are free-living; the other species are sessile on nodules. Together, they illustrate the considerable morphological diversity of xenophyophores in a region where they dominate the megafauna, and highlight some major taxonomic challenges posed by these giant monothalamous foraminifera.

We describe Aschemonella monile Gooday and Holzmann sp. nov. from the Clarion-Clipperton Zone (CCZ, abyssal eastern equatorial Pacific), a region characterized by commercially significant concentrations of polymetallic nodules. The new species is the most abundant xenophyophore (giant agglutinated foraminifera) in our main sampling area (12-14 degrees N; 116 degrees 30'-117 degrees 26'W). Additional specimens originate from the central CCZ, and from a third area, similar to 900 km NW of the main area, where A. monile numerically dominates the megabenthos in photographic surveys of the seafloor (average densities 1.54 individuals/m(2); peak densities > 3 individuals/m(2)). Aschemonella monile is much larger (>= 7 cm in length) than previously described species of the genus, with a test comprising an irregular sequence of self-contained, partly overlapping 'segments', creating a multichambered structure. A similar, much rarer species from the main study area, described here as Aschemonella aspera Gooday and Holzmann sp. nov., has an unsegmented test with a very rough, coarsely agglutinated wall. Genetic data suggest that A. monile is distinct from A. aspera and most closely related to a group comprising Rhizammina algaeformis and Aschemonella ramuliformis. Both new species have delicate tests that are often attached to nodule surfaces, making them particularly vulnerable to seafloor disturbances.

We investigated benthic foraminifera inhabiting the empty tests of radiolarians in surface sediment samples from the abyssal Clarion–Clipperton Fracture Zone (13°50’N, 116°35’W; ~4080 m water depth), eastern equatorial Pacific, an area licensed for the future mining of polymetallic nodules. Based on two megacore samples (>150 µm, 0–1 cm sediment layer; 78.6 cm2 surface area), we examined 288 radiolarian tests that were occupied by ‘live’ (stained) inhabitants presumed to be foraminifera based on test morphology and wall structure; these quantitative data were supplemented by qualitative records from three additional cores. The radiolarian inhabitants comprised organic-walled and agglutinated monothalamous (single-chambered) and less common polythalamous (multichambered) forms. Among the 27 distinctive morphotypes, a few can be assigned to a described superfamily (Komokiacea) or to genera such as Lagenammina, Thurammina and Hormosinella, while two brown, organic-walled multichambered forms resemble the genera Hospitella and Placopsilinella. The remainder were assigned to informal morphotypes. The radiolarian inhabitants are generally small (9% of the total ‘live’ (stained) foraminiferal assemblage, thereby making non-negligible contribution to local species diversity and foraminiferal abundance in our study area. Our new observations, and previous studies of benthic foraminifera inhabiting the empty shells of other foraminifera, suggest that high biodiversity among meiofaunal-sized deep-sea organisms (particularly foraminifera) is enhanced by the colonisation of small cryptic microhabitats. Based on their complex test morphology, we suggest that at least some of the diverse monothalamous foraminifera that typically dominate abyssal foraminiferal assemblages have little or no mobility, making them well suited to this mode of life.

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.

The benthic biota of the Clarion–Clipperton Zone (CCZ, abyssal eastern equatorial Pacific) is the focus of a major research effort linked to possible future mining of polymetallic nodules. Within the framework of ABYSSLINE, a biological baseline study conducted on behalf of Seabed Resources Development Ltd. in the UK-1 exploration contract area (eastern CCZ, ~4,080 m water depth), we analysed foraminifera (testate protists), including ‘live’ (Rose Bengal stained) and dead tests, in 5 cores (0–1 cm layer, >150-μm fraction) recovered during separate megacorer deployments inside a 30 by 30 km seafloor area. In both categories (live and dead) we distinguished between complete and fragmented specimens. The outstanding feature of these assemblages is the overwhelming predominance of monothalamids, a group often ignored in foraminiferal studies. These single-chambered foraminifera, which include agglutinated tubes, spheres and komokiaceans, represented 79% of 3,607 complete tests, 98% of 1,798 fragments and 76% of the 416 morphospecies (live and dead combined) in our samples. Only 3.1% of monothalamid species and 9.8% of all species in the UK-1 assemblages are scientifically described and many are rare (29% singletons). Our results emphasise how little is known about foraminifera in abyssal areas that may experience major impacts from future mining activities.

Xenophyophores, giant, fragile, agglutinated foraminifera (protists), are major constituents of the abyssal megafauna in the equatorial Pacific Clarion-Clipperton Zone (CCZ), a region where seabed mining of polymetallic nodules may occur in the future. As part of a baseline study of benthic communities we made extensive collections of xenophyophores in two areas (UK-1 and OMS) licensed for exploration by the International Seabed Authority. Based on test morphology, we distinguished 36 morphospecies (34 new to science) among 130 specimens. Twenty of these morphospecies yielded 184 DNA sequences, a 14-fold increase in genetic data for xenophyophores that confirms their high diversity in the eastern CCZ. A further 15 morphospecies (8 new to science) were recognised in samples from two other areas (APEI-6 and Russian exploration license area) within or adjacent to the CCZ. This large number of species confirms that the CCZ is a focal area for xenophyophore diversity. More broadly, it represents an unprecedented increase in the known global diversity of xenophyophores and suggests that many species remain undiscovered in the World's oceans. Xenophyophores are often sessile on nodules in the CCZ, making these delicate organisms particularly vulnerable to mining impacts. They can also play a crucial role in deep-sea ecosystems, providing habitat structures for meiofaunal and macrofaunal organisms and enhancing the organic content of sediments surrounding their tests. The loss of xenophyophores due to seabed mining may therefore have wider implications for the recovery of benthic communities following major human disturbances on the abyssal seafloor.

Foraminifera are a major component of the abyssal meiofauna in parts of the eastern Pacific Clarion-Clipperton Zone (CCZ) designated by the International Seabed Authority for polymetallic nodule exploration. We analysed the diversity and distribution of stained (‘live’) and unstained (dead) assemblages (0–1 cm layer, >150-μm sieve fraction) in megacorer samples from 11 sites (water depths 4051–4235 m) within three 30 × 30 km ‘strata’ in the United Kingdom 1 (UK1 Strata A and B; 5 and 3 samples, respectively) and Ocean Minerals Singapore (3 samples) exploration contract areas and separated by distances of up to 28 km within a stratum and 224 km between strata. Foraminiferal assemblage density, diversity and composition at the higher taxon/morphogroup level were largely consistent between samples. Stained assemblages were dominated (>86%) by single-chambered monothalamids, mainly spheres, tubes, komokiaceans and forms that are difficult to categorise morphologically. Hormosinaceans were the most common multichambered group (∼10%), while calcareous taxa (mainly rotaliids) represented only ∼3.5% of stained tests. Dead foraminifera were more evenly distributed between monothalamids (56%) and multichambered taxa (44%). Almost all test fragments were monothalamids, mainly tubes. Morphospecies were added regularly with each new sample and totalled 580 (stained + dead, complete + fragments), of which 159 occurred in all three strata, 222 were shared between UK1 Strata A and B, 209 between UK1A and the OMS Stratum, and 193 between UK1B and the OMS Stratum. Individual strata yielded 310–411 and individual samples 132–228 putative morphospecies. The majority (550) of the 580 species were represented by intact tests of which 462 included at least some that were stained. Most of the stained (∼80%) and stained + dead (∼75%) species were monothalamids, almost all of them undescribed. Many species were rare; 146 of the 550 species with complete tests (stained + dead) were singletons and 53 doubletons. Values of Morisita's index indicated that most individual species represented by ≥ 10 complete tests had aggregated distributions. In MDS plots, all 11 samples fell within the 95% confidence limit, consistent with a general uniformity in assemblage composition. However, there was also a weak grouping of UK1A samples, while a plot of Bray-Curtis similarity against distance between samples suggests that there may be some gradual change in assemblage composition related to distance. We conclude that the foraminiferal assemblages at our eastern CCZ sites are highly diverse, dominated by undescribed monothalamids, include many rare species, and are fairly similar across the study area, but with a patchy distribution at the level of individual morphospecies.

There is growing interest in mining polymetallic nodules in the abyssal Clarion-Clipperton Zone (CCZ) in the Pacific. Nonetheless, benthic communities in this region remain poorly known. The ABYSSLINE Project is conducting benthic biological baseline surveys for the UK Seabed Resources Ltd. exploration contract area (UK-1) in the CCZ. Using a Remotely Operated Vehicle, we surveyed megafauna at four sites within a 900 km2 stratum in the UK-1 contract area, and at a site ~250 km east of the UK-1 area, allowing us to make the first estimates of abundance and diversity. We distinguished 170 morphotypes within the UK-1 contract area but species-richness estimators suggest this could be as high as 229. Megafaunal abundance averaged 1.48 ind. m−2. Seven of 12 collected metazoan species were new to science, and four belonged to new genera. Approximately half of the morphotypes occurred only on polymetallic nodules. There were weak, but statistically significant, positive correlations between megafaunal and nodule abundance. Eastern-CCZ megafaunal diversity is high relative to two abyssal datasets from other regions, however comparisons with CCZ and DISCOL datasets are problematic given the lack of standardised methods and taxonomy. We postulate that CCZ megafaunal diversity is driven in part by habitat heterogeneity.

International audience; Dead benthic foraminiferal faunas (> 150 μm) from the Rhône prodelta (Gulf of Lions, NW Mediterranean) were analysed at 41 stations (15–100 m water depth) sampled in June 2005 and September 2006, and compared to the living faunas investigated during previous studies at the same stations. The comparison between dead and living assemblages enhances the understanding of taphonomic processes that may modify the composition of the dead faunas in this area. We observed a loss of individuals from living to dead assemblages of species characterised by a fairly fragile test and therefore more prone to fragmentation or dissolution (e.g., Bolivina alata, Quinqueloculina tenuicollis). Allochthonous dead and/or live specimens may be transported to some parts of the prodelta, particularly the shallowest sites where hydrodynamic processes (i.e., river flood, storm swells, longshore currents) are more intense. These specimens may originate from relict deltaic structures (e.g., Elphidium spp. from the lobe of Bras de Fer) or from surrounding areas (e.g., Ammonia beccarii forma beccarii from the river). Opportunistic species (e.g., Bulimina marginata, Cassidulina carinata) characterised by high reproductive rates have much higher relative abundances in the dead than in the living fauna. Cluster analyses based on dead foraminiferal assemblages divide our study area into four main thanatofacies directly related to distinct local environmental conditions prevailing in the prodelta. Close to the river mouth, Ammonia beccarii forma beccarii and Ammonia tepida are found in sediments subject to a high riverine influence (i.e., bottom currents, high organic and inorganic material input of continental origin). Elphidium species are abundant in the silty-sandy relict deltaic lobe west of the river mouth which is characterised by strong longshore currents that disturb the benthic environment. Nonion fabum, Rectuvigerina phlegeri and Valvulineria bradyana are found along the coast west of the Rhône River mouth, in the area defined as the “river plume” thanatofacies. In the more stable and deeper prodeltaic area, species known to feed on fresh phytodetritus (e.g., Bulimina aculeata/marginata, C. carinata, Hyalinea balthica) dominate the faunas. Since only minor variations in species relative abundances and spatial distributional patterns are observed between the living and the dead faunas, we consider that our thanatofacies have not been influenced by substantial transport of dead tests. This suggests that fossil benthic foraminifera can provide a reliable tool for investigating the development of the palaeo-Rhône prodelta.

International audience; The Rhone River is the most important source of freshwater and sediment to the western Mediterranean Sea. Deltaic lobes and littoral prisms compose the sedimentary units that make up the whole "Rhone subaqueous delta", which reaches up to 50m in thickness. Individual lobes, that accompanied the retreat of the Rhone during sea-level rise, and the subsequent westward then eastward shift of the main outlet, display averaged sedimentation rates in excess of 1cmyr-1, containing both continental and marine material. During the industrial period, most of the river flow was delivered through the Pégoulier and Roustan distributary channels, which evolved under human influence. Within the prodeltas associated to these distributaries, very expanded sedimentation rates (andgt;10cmyr-1), allow the documentation of historical extreme climate events.A 7.71. m long piston core (RHS-KS57) was retrieved from the distal prodelta (79. m water depth). A multi-proxy study was carried out, using microfossil assemblages (ostracods, benthic foraminifera and coccoliths) in combination with sedimentological and geochemical proxies. Our results show that (1) Four different intervals (I-IV, spanning a time-range comprised between ~. 1600. AD and Present-day) have been differentiated from this multi-proxy analysis. They correspond to a different position of distributary channels. Each interval correlates with the different phases of channel avulsion, induced by climate events or by human activity. (2) The signature of extreme floods, that can be identified by the punctuated occurrence of freshwater (continental) ostracods (e.g. Candona spp., Ilyocypris sp.) correlating with increases in grain-size and/or organic carbon content. They correspond to decadal-scale increased runoffs reported in historical archives. Our study demonstrates the relevance of benthic microfossil studies for reconstructing paleoenvironmental changes in transitional (marine/continental) settings. © 2012 Elsevier B.V.

Recent years have seen a rapid increase in survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ) abyssal plain, a vast area of the central Pacific that is currently being actively explored for deep-sea minerals (ISA, 2016). Critical to the development of evidence-based environmental policy in the CCZ are data on the biogeography and connectivity of species at a CCZ-regional level. The London Workshop on the Biogeography and Connectivity of the CCZ was convened to support the integration and synthesis of data from European Union (EU) CCZ projects, supported by the EU Managing Impacts of Deep-Sea Resource Exploitation (MIDAS) and EU Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans) projects. The London Workshop had three clear goals: (1) To explore, review and synthesise the latest molecular biogeography and connectivity data from across recent CCZ cruises from both contractor and academia-funded projects; (2) To develop complementary and collaborative institutional and program-based academic publication plans to avoid duplication of effort and ensure maximum collaborative impact; (3) To plan a joint synthetic data publication highlighting key results from a range of planned molecular biogeography/connectivity publications. 32 participants attended the workshop at the Natural History Museum in London from 10-12 May 2016. Presentations and discussions are summarised in this report covering (1) overviews of current CCZ environmental projects, (2) policy and industry perspectives, (3) synthesis of DNA taxonomy and biogeography studies, (4) summaries of the latest population genetic studies, (5) summaries of the latest broader morphological context, (6) an overview of publication and proposal plans to maximise collaborative opportunities and finally a series of workshop recommendations.