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Laminated diatomaceous sediments occur intermittently in the Bering Sea over the past 5 million years. A varve (annually deposited) origin for the laminae has been suggested, but there is currently no consensus. Here, we report results of a study of two laminated intervals dating from ∼528 ka and ∼ 782 ka from IODP Site U1340 on the Bowers Ridge. We combine conventional micropaleontological methods with scanning electron microscope analysis that resolves the seasonal cycle of flux events recorded and demonstrates an annual origin for the laminae. Resting spores of Chaetoceros spp., and more rarely of Thalassiosira antarctica represent early spring blooms with the latter likely due to increased meltwater input. Diatom laminae containing concentrations of Shionodiscus trifultus, Thalassiosira spp., Actinocyclus curvulatus, and Neodenticula seminae, represent flux from the main spring-summer bloom episodes, with the latter indicating influx of seed populations from the North Pacific Alaskan Stream. Concentrations of Coscinodiscus spp. in the uppermost part of the diatom laminae represent “Fall Dump” sedimentation of these stratified-adapted diatoms in response to break down of summer stratification in autumn/early-winter storms. The lithogenic laminae represent mainly winter deposition and rare earth element analysis suggests provenance from the southern Bering Sea shelf and the Aleutian Arc. Productivity was high in the studied intervals with total mass fluxes around 5 times higher than modern values. Variation in lamina thickness and diatom composition contain periodicities of 2–8 years, as well as a bi-decadal variability likely related to influence of the Pacific Decadal Oscillation.

Analysis of benthic foraminifera in surface samples from 23 sites on the Northeast Greenland continental shelf reveal key assemblage differences between sites. Cluster analysis creates two clear geographical faunal assemblage zones: the 1) inner shelf, and 2) mid and outer shelf sites. These assemblages differ significantly, with the inner shelf sites being characterised by a high percentage and concentration of calcareous species, whilst the mid and outer shelf sites are dominated by agglutinated taxa. At almost all sites, the calcareous assemblages are dominated by Cassidulina neoteretis and Cassidulina reniforme, suggesting that they thrive across the shelf. Stetsonia horvathi, Oridorsalis tener, as well as Glomulina oculus and other miliolid species are found to be key calcareous species at many sites in the inner shelf zone, but they are rare-to-absent on the mid and outer shelf. Canonical correspondence analysis shows that September sea-ice cover and bottom water oxygen content are positively correlated with benthic foraminiferal assemblages at inner shelf sites, whereas organic carbon content is correlated with those in the mid and outer shelf. The formation of seasonal sea-ice and the Northeast Water polynya rejects brine into surrounding waters and transports CO2 to the seafloor, creating a highly corrosive environment for calcium carbonate. These environments are also highly productive, as indicated by the high organic carbon content and low bottom water oxygen content. The oxidation of this organic material creates CO2. We propose that these processes are key drivers in the dissolution of calcareous tests. In contrast, extensive sea-ice, high bottom water oxygen content and low primary productivity in the glacier-proximal region facilitates carbonate preservation.

Highlights: • Silicoflagellates more common and diverse in late Eocene, lower in Oligocene. • Record of new species Corbisema tajmahalii from Late Eocene, with interpreted double skeleton (DS). • First known Bachmannocena DS, has corner-aligned configuration. • Observation of early evolution of Stephanocha raupii, transferred to Distephanopsis. Abstract Study of the South Pacific Ocean sediments from IODP Expedition 378, Holes U1553A and U1553B, shows 19 late Eocene to late Oligocene silicoflagellate species. The late Eocene includes Corbisema tajmahalii n. sp., observed over a ∼ 8.4 m interval and proposed as a new subzone within the Corbisema apiculata Zone. The new species is characterized by the presence of basal ring that has three sides and an arrowhead-shaped outline with the two minor-axis corners more closely spaced. This study has found the first known Bachmannocena double skeleton, in corner-aligned configuration that suggests evolutionary relationship with the Corbisema triacantha group of Cenozoic silicoflagellates. Also observed is the apparent early evolution of Stephanocha raupii at ∼29.6 Ma, derived from a skeletal diversity related to Distephanopsis crux, thus the species is here transferred to Distephanopsis (abbreviated as Ds.). Silicoflagellate skeletal abundance declines after the Eocene-Oligocene boundary, with generally low abundance except for two sediment samples immediately below the Ds. raupii n. comb. first appearance.

A new Pentaplacodinium species with six precingular plates is described from Bahía Concepción and Bahía de la Paz, Gulf of California. The non-fossil motile stage is described as Pentaplacodinium lapazense, whilst the fossil stage is described as Operculodinium lapazense. The cyst morphology is compared to topotype material of Operculodinium israelianum, which is larger, has longer processes and has a different wall structure. The motile cells display a plate formula of Po, Pt, X, 2′ + *2′, 6′′, 6c, 7 s, 5′′′, 1p, 1′′′′. A typical gonyaulacalean fission line and plate overlap are observed. SSU-ITS-LSU ribosomal DNA sequences demonstrate that Pentaplacodinium saltonense is its closest relative. The species is homothallic. This species occurs in relatively shallow and restricted coastal areas, and has a preference for higher sea-surface temperatures and salinities. MicroFTIR spectra of the cysts are compared to spectra of cysts of other gonyaulacaleans and suggest very similar compositions. No yessotoxins were detected in any of the analyzed strains, hence, this species is unlikely to be responsible for the elevated yessotoxin concentration observed in shellfish on the southern and central coastal region of the Gulf of California.

The acritarch genus Radiosperma has been reported from plankton and sediments since the late 19th century, with suggested biological affinities ranging from invertebrate eggs to tintinnids. Here, the genus description is improved and its two species, Radiosperma corbiferum and Radiosperma textum, are redescribed. Radiosperma textum is shown to be a ciliate cyst related to Askenasia based on new SSU and LSU rRNA sequences. The spatiotemporal distribution and ecology of both species are discussed. The chemical composition is documented based on micro-Fourier Transform Infrared spectroscopy. Furthermore, new SSU and LSU rRNA sequences for several flask shaped ciliate cysts (Fusopsis, Strombidium) are also included in the analysis and the occurrence of fossilizable cysts in the ciliophoran clade is reviewed.

Safe autonomous navigation is an essential and challenging problem for robots operating in highly unstructured or completely unknown environments. Under these conditions, not only robotic systems must deal with limited localization information but also their maneuverability is constrained by their dynamics and often suffers from uncertainty. In order to cope with these constraints, this article proposes an uncertainty-based framework for mapping and planning feasible motions online with probabilistic safety guarantees. The proposed approach deals with the motion, probabilistic safety, and online computation constraints by: 1) incrementally mapping the surroundings to build an uncertainty-aware representation of the environment and 2) iteratively (re)planning trajectories to goal that is kinodynamically feasible and probabilistically safe through a multilayered sampling-based planner in the belief space. In-depth empirical analyses illustrate some important properties of this approach, namely: 1) the multilayered planning strategy enables rapid exploration of the high-dimensional belief space while preserving asymptotic optimality and completeness guarantees and 2) the proposed routine for probabilistic collision checking results in tighter probability bounds in comparison to other uncertainty-aware planners in the literature. Furthermore, real-world in-water experimental evaluation on a nonholonomic torpedo-shaped autonomous underwater vehicle and simulated trials in an urban environment on an unmanned aerial vehicle demonstrate the efficacy of the method and its suitability for systems with limited onboard computational power. Note to Practitioners—Emergent robotic applications require operating in previously unmapped scenarios. This article presents a unified mapping–planning strategy that enables robots to navigate autonomously and safely in harsh environments This work was supported in part by the School of Engineering and Physical Sciences (EPS), Heriot-Watt University, as part of the Centre for Doctoral Training (CDT) in Robotics and Autonomous Systems (Heriot-Watt University and The University of Edinburgh); in part by the Scottish Informatics and Computer Science Alliance (SICSA), ORCA Hub EPSRC (EP/R026173/1), and consortium partners; and in part by the EXCELLABUST and ARCHROV projects under Grant H2020-TWINN2015, CSA, ID:691980 and Grant DPI2014-57746-C3-3-R, respectively, for conducting the experiments in Section VII-A at the Computer Vision and Robotics Institute (VICOROB), University of Girona

Weathering of organic carbon contained in sedimentary rocks (petrogenic OC, OCpetro) is an important control on the concentrations of carbon dioxide (CO2) and oxygen in the atmosphere. Of particular significance are steep mountainous catchments, where high rates of physical erosion introduce OCpetro to the surface, where oxygen in air and water can help drive oxidative weathering reactions, yet measurements of CO2 emissions from OCpetro oxidation are still scarce. Here, we use in situ gas accumulation chambers and show that CO2 fluxes, and their environmental controls, can be determined during a stand-alone, short-term (8 days) field campaign, applied to a remote setting. In the rapidly eroding Waiapu River catchment, New Zealand, dominated by mudstones, we measured high rates of CO2 release (222–1590 mgC m−2 d−1) in five accumulation chambers in the near-surface of naturally fractured and bedded rock outcrops. The corresponding CO2 concentrations are very high (pCO2 ~ 4700–27,100 ppmv), and such values could influence acid-hydrolysis reactions during chemical weathering of co-occurring silicate minerals. The CO2 is radiocarbon depleted (fraction modern, F14C = 0.0122–0.0547), confirming it is petrogenic in origin. Stable carbon isotopes suggest a source from OCpetro, but δ13C values of the CO2 are lower by ~3.5–3.7 ± 0.1 ‰ from those of OCpetro (−25.9 ± 0.1 ‰), consistent with isotope fractionation associated with microbial respiration of OCpetro. Over 6 days of measurement, we find that CO2 fluxes respond quickly to changes in temperature and humidity, indicating an environmental regulation that is captured by our short-term installation. The approaches applied here mean that future research can now seek to constrain the climatic, lithological and biological controls on OCpetro oxidation across regional to global scales.