Recent publications
We report the first record of fecampiidan platyhelminths parasitic in tanaidacean crustaceans. Two fecampiidans (0.75 mm and 1.10 mm in length) were found in a female of Pseudotanais sp. (Pseudotanaidae; 1.75 mm in length) collected at 794 m depth off the southern coast of Japan, northwestern Pacific. Fresh individuals were yellow or light yellow, but completely faded in ethanol. In a maximum likelihood tree based on 28S rRNA sequences, the parasite was placed in a moderately-supported Fecampiidae clade, suggesting it is a member of Fecampiidae. The 28S sequence from the parasite was 25.0%, 32.6%, and 35.5% divergent in Kimura 2-parameter (K2P) distance from Fecampia cf. abyssicola, Kronborgia cf. amphipodicola, and Kronborgia isopodicola sequences, respectively.
Biological clocks are a ubiquitous feature of all life, enabling the use of natural environmental cycles to track time. Although studies on circadian rhythms have contributed greatly to the knowledge of chronobiology, biological rhythms in dark biospheres such as the deep sea remain poorly understood. Here, based on a free-running experiment in the laboratory, we reveal potentially endogenous rhythms in the gene expression of the deep-sea hydrothermal vent shrimp Rimicaris leurokolos. Oscillations with approximately 12 h periods, probably reflecting tidal influence, greatly prevail over others in the temporal transcriptome, indicating R. leurokolos probably depends on a circatidal clock consisting of at least some components independent from the circadian clocks. The tidal transcripts exhibit an antiphased expression pattern divided into two internally synchronized clusters, correlated with wide-ranging biological processes that occur in the nucleus and cytoplasm, respectively. In addition, the tidal transcripts showed great similarities with genes in fruit flies and mice exhibiting approximately 12 h ultradian rhythms, indicating that the tide probably had a broad impact on the evolution of approximately 12 h oscillations found across the Metazoa. These findings not only provide new insights into the temporal adaptations in deep-sea organisms but also highlight hydrothermal vent organisms as intriguing models for chronobiological studies, particularly those linked to approximately 12 h ultradian rhythms.
Evaluation of long-term detailed cherry flowering phenology is required for a deep understanding of the sensitivity of spring phenology to climate change and its effect on cultural ecosystem services. Neodani Usuzumi-zakura (Cerasus itosakura) is a famous cherry tree in Gifu, Japan. On the basis of detailed decadal flowering phenology information published on the World Wide Web, we estimated the probability distributions of the year-to-year variability of the true dates of first flowering (FFL), first full bloom (FFB), last full bloom (LFB), and last flowering (LFL) from 1924 to 2024 by applying a Bayesian statistical state space model explained by air temperature data. We verified the estimated values against flowering phenology records of the tree from the literature and a private collection. The true dates of FFL and FFB could be explained by means of daily minimum air temperature from 1 December to 28/29 February and that of daily mean air temperature from 1 to 31 March, and those of LFB and LFL by means of daily mean air temperature from 1 to 10 April. Results were similar when we used air temperature data recorded at weather stations both 1 km and 29 km from the tree. These results indicated that our proposed Bayesian statistical state space model can estimate cherry flowering phenology that takes into account centennial-scale air temperature data recorded at a nearby weather station with a coarse temporal resolution.
Plain Language Summary
The Chiba composite section (CbCS) is a sedimentary sequence formed in an ocean basin around the northern limit of the Kuroshio Current in the northwestern Pacific, and it is designated as the Global Boundary Stratotype Section and Point for the Chibanian Age. The CbCS offers a continuous, high‐resolution record of the interglacial period of marine isotope stage (MIS) 19, when the Earth's orbit resembled that of the Holocene (MIS 1). We quantitatively reconstructed summer sea surface temperature fluctuations by analyzing an organic compound called alkenone preserved in the sedimentary rocks. Combined with knowledge of previously published winter temperature proxies in the CbCS, we uncovered seasonal differences within the paleo‐oceanic structure related to the East Asian Summer and Winter monsoon variability. Millennial‐scale variations are evident in summer and winter temperature records, corresponding to meltwater events in the North Atlantic. The amplitude of millennial summer temperature fluctuations during MIS 20–18 is generally lower than in winter, suggesting that the Kuroshio Current dominated during summer. In contrast, the enhanced Oyashio Current controlled by the East Asian Winter monsoon intruded into the sedimentary basin during winter.
Future changes in sea-level pressure (SLP) around Japan are investigated using the Coupled Model Intercomparison Project phase 6 (CMIP6) projections, and their impacts on future regional change of surface air temperature and precipitation, including their extremes, are estimated based on observed statistics. The SLP patterns around Japan are quantified by defining a surface wind index, and are compared with the CMIP5 projections, revealing a similar mean change but a reduction in inter-model uncertainty. The future seasonal cycle represented by the index indicates that the spring SLP pattern will appear earlier, but the autumn pattern will be delayed. The CMIP6 models projecting stronger winds from warm (wet) areas tend to simulate a warmer (wetter) future climate over Japan, which is consistent with the statistical relationships in observations. The impact of future SLP changes on regional climate is assessed using the index based on observed relationships. The results indicate that future westerly anomalies (relative to the present day) in summer will increase mean precipitation on the Sea of Japan side of eastern and western Japan, but decrease extreme precipitation on the Pacific side of eastern Japan. The southerly anomalies in winter and autumn will increase mean and extreme precipitation over western Japan.
This study derives the paleotemperature equation based on the oxygen isotope records of freshwater-bivalve shells. We examined the oxygen isotope ratios (δ18O) of aragonite shells of the cultured freshwater bivalve Corbicula sandai (Cyrenidae), a species endemic to Lake Biwa, Japan, along with the temperature and δ18O values of water at the culture site. The δ18O values of cultured specimen shells showed clear periodicity corresponding to the culture period; they decreased with increasing water temperature and increased with decreasing water temperature. The observed water temperatures were strongly correlated with the δ18O values for shells minus the δ18O values for water; the following equation for the temperature was calculated by the least-squares method. T \left(^\circ \text{C}\right)=18.19 \left(\pm 0.37\right)-3.93 (\pm 0.33)\times ({{\updelta }^{18}\text{O}}_{\text{aragonite}/\text{VPDB}}-{\updelta }^{18}{\text{O}}_{\text{water}/\text{VSMOW}}). Using this equation, water temperatures from May 2, 2019, back to 2009 were reconstructed based on the δ18O values of two specimens collected in the lake, then compared with the observed water temperatures at lake depths of 0.5–20 m. In the northern basin of the lake, the water temperature in the shallow layer below the top 15 m, which is the habitat depth of C. sandai, was 26–28°C during the summer and 6–8°C during the winter; the reconstructed water-temperature range of 12–28°C agreed well with the observed higher values. The growth rates of cultured specimens significantly slowed at temperatures below 12–13°C, and the reconstructed minimum-water temperature of approximately 13°C indicates that the equation exhibits reliable accuracy. The growth records of the cultured specimens suggest that the reconstructed water-temperature fluctuations reflect the water temperatures from early spring (April–May) to late autumn (December).
Organic matter in meteorites reveals clues about early Solar System chemistry and the origin of molecules important to life, but terrestrial exposure complicates interpretation. Samples returned from the B-type asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer mission enabled us to study pristine carbonaceous astromaterial without uncontrolled exposure to Earth’s biosphere. Here we show that Bennu samples are volatile rich, with more carbon, nitrogen and ammonia than samples from asteroid Ryugu and most meteorites. Nitrogen-15 isotopic enrichments indicate that ammonia and other N-containing soluble molecules formed in a cold molecular cloud or the outer protoplanetary disk. We detected amino acids (including 14 of the 20 used in terrestrial biology), amines, formaldehyde, carboxylic acids, polycyclic aromatic hydrocarbons and N-heterocycles (including all five nucleobases found in DNA and RNA), along with ~10,000 N-bearing chemical species. All chiral non-protein amino acids were racemic or nearly so, implying that terrestrial life’s left-handed chirality may not be due to bias in prebiotic molecules delivered by impacts. The relative abundances of amino acids and other soluble organics suggest formation and alteration by low-temperature reactions, possibly in NH3-rich fluids. Bennu’s parent asteroid developed in or accreted ices from a reservoir in the outer Solar System where ammonia ice was stable.
In subsurface methanogenic ecosystems, the ubiquity of methylated-compound-using archaea—methylotrophic methanogens1, 2, 3–4—implies that methylated compounds have an important role in the ecology and carbon cycling of such habitats. However, the origin of these chemicals remains unclear5,6 as there are no known energy metabolisms that generate methylated compounds de novo as a major product. Here we identified an energy metabolism in the subsurface-derived thermophilic anaerobe Zhaonella formicivorans⁷ that catalyses the conversion of formate to methanol, thereby producing methanol without requiring methylated compounds as an input. Cultivation experiments showed that formate-driven methanologenesis is inhibited by the accumulation of methanol. However, this limitation can be overcome through methanol consumption by a methylotrophic partner methanogen, Methermicoccus shengliensis. This symbiosis represents a fourth mode of mutualistic cross-feeding driven by thermodynamic necessity (syntrophy), previously thought to rely on transfer of hydrogen, formate or electrons8, 9–10. The unusual metabolism and syntrophy provide insights into the enigmatic presence of methylated compounds in subsurface methanogenic ecosystems and demonstrate how organisms survive at the thermodynamic limit through metabolic symbiosis.
Tropical Cyclone (TC) RAI (2021) made a devastating landfall in the Siargao-Dinagat Islands of the southeastern Philippines on December 16, 2021, causing about USD 942 M in damage, 405 reported deaths and 52 missing. Yet, observational studies on the environmental conditions during TC RAI remain limited, and a comparison with other landfalling TCs were not done. To shed light on the factors that made this TC reach a maximum sustained wind speed (MSW) of 105 kts (194.5 kph) and 915 hPa mean sea level pressure according to the WMO-IBTrACS, this study investigated the meteorological statistics of this TC relative to other landfalling TCs in the Philippines from 1979 to 2020 and the environmental features with cases having similar landfalling month, location, and track. When compared with Philippine landfalling TCs from 1979 to 2020, this TC, among violent typhoons, ranked second in terms of MSW and translational speed. Moreover, the TC had a westward movement, faster translational speed, larger radius, and greater intensity when compared to seven other TCs that made landfall in the same month and region. The environmental factors along the path of TC RAI that may have contributed to its intensification include, but are not limited to, the above normal SST (+ 0.5 to 1.5 °C) and ocean heat content, high low-level relative humidity (RH), and high specific humidity. These factors resulted in strong low-level convergence and intensification until landfall. Composite analysis of and comparison with the other seven landfalling TCs reveal that the atmospheric conditions during TC RAI had a consistently higher near-surface RH850hPa–500 hPa, which may have helped sustain its movement across the central Philippines. Moisture from the Philippine Sea was also drawn into the central Philippines, which received at least 125–150 mm of rainfall. The extension of the western North Pacific Subtropical High along 20 °N and strong easterly flow may have facilitated the TC’s straight and westward movement. The findings of this study are essential for quantitatively ranking the destructiveness of this event, while identifying key indicators of TC intensification and trajectory for landfalling TCs in central and southern Philippines.
Four decades of seismic reflection, onshore‐offshore and ocean‐bottom seismic data are integrated to constrain a high‐resolution 3‐D P‐wave velocity model of the Hikurangi subduction zone. Our model shows wavespeeds in the offshore forearc to be 0.5–1 km/s higher in south Hikurangi than in the central and northern segments (VP ≤ 4.5 km/s). Correlation with onshore geology and seismic reflection data sets suggest wavespeed variability in the overthrusting plate reflects the spatial distribution of Late Jurassic basement terranes. The crustal backstop is 25–35 km from the deformation front in south Hikurangi, but this distance abruptly increases to ∼105 km near Cape Turnagain. This change in backstop position coincides with the southern extent of shallow slow‐slip, most of which occurs updip of the backstop along the central and northern margin. These relationships suggest the crustal backstop may impact the down‐dip extent of shallow conditional stability on the megathrust and imply a high likelihood of near/trench‐breaching rupture in south Hikurangi. North of Cape Turnagain, the more landward position of the backstop, in conjunction with a possible reduction in the depth of the brittle ductile transition, reduces the down‐dip width of frictional locking between the southern (∼100 km) and central Hikurangi margin by up‐to 50%. Abrupt transitions in overthrusting plate structure are resolved near Cook Strait, Gisborne and across the northern Raukumara Peninsula, and appear related to tectonic inheritance and the evolution of the Hikurangi margin. Extremely low forearc wavespeeds resolved north of Gisborne played a key role in producing long durations of long‐period earthquake ground motions.
In boreal summer, the Asian monsoon circulation carries abundant water vapor from the Indian Ocean to the lower–middle troposphere in the Himalayan region. This creates conditions favorable for some of the heaviest orographically induced precipitation in the world over the steep and topographically complex southern slopes of the Himalayas. Here, we introduce summer precipitation variability, including extreme events over the Himalayas, and its dynamics based on studies using in situ observations, spaceborne precipitation radar, and cloud-resolving numerical models. Specifically, we focus on the diurnal cycle, low pressure systems (LPSs), intraseasonal oscillations (ISOs), and their interplay, which represent an important background environment for extreme precipitation events in the Himalayas. In the diurnal cycle of precipitation, twice-daily precipitation maxima corresponding to daytime and nighttime peaks occur across higher elevations, while a single peak appears at night over lower elevations. The daytime peak is the result of anabatic flow driven by surface heating of the slopes, whereas the nighttime peak is caused by acceleration of low-level monsoon flows (i.e., the nocturnal jet) from the Gangetic Plain toward the Himalayas. Additionally, LPSs such as monsoon lows and monsoon depressions, together with mid-latitude troughs and their interaction can modulate strong inflows of moisture toward the Himalayan slopes, occasionally leading to extreme precipitation events when the flow with abundant water vapor is forced to ascend over the Himalayan slopes. The locations of the LPSs and mid-latitude troughs are strongly controlled by ISOs that act as large-scale environmental conditions for the genesis and development of the LPSs and troughs. Thus, improved understanding of the controlling multiscale processes, including the diurnal cycle, is essential for better prediction of extreme precipitation events and mitigation of related disasters over the Himalayas.
We examine a mechanism of the interannual variability of the realization frequency of the Madden‐Julian oscillation (MJO). The activity of boreal‐winter MJO realization is quantified by the number of MJO active days during the tracking of the real‐time multivariate MJO index. In active years of MJO realization (MJO‐A), multiple MJOs are initiated in the Indian Ocean (IO) and they propagate into the western Pacific (WP), but not so in inactive years (MJO‐IA). This contrast is explained by whether vertical moisture advection over the WP is disrupted or not. It is related to differences in boreal‐winter mean convection and circulations: MJO‐A (MJO‐IA) years are characterized by enhanced and suppressed (suppressed and enhanced) convection over the WP/IO and Maritime Continent (MC), respectively. This modulation results from combined effects of the El Niño‐Southern oscillation (ENSO) and quasi‐biennial oscillation (QBO). During moderate‐to‐strong El Niño, MJO is realized actively irrespective of QBO, if no additional convective suppression over the eastern IO and/or MC due to other forcing such as a positive Indian Ocean Dipole mode. During other ENSO phases, stronger QBO‐easterly phases favor MJO realization irrespective of ENSO. This QBO–MJO connection except for El Niño conditions is due to zonally heterogeneous QBO impacts that the seasonal mean static stability change near the tropopause over the WP alters the mean convective activity there. This zonal heterogeneity and ENSO phase‐dependency of QBO impacts is interpreted with a focus on vertical propagation of Kelvin wave structure over the MC, affected by both QBO winds and background Walker circulations.
The petrologic and mineralogical characteristics and alteration processes of the nakhlites NWA 6148 and NWA 10153 were studied. Both consist of augite, olivine, and mesostasis. Based on the characteristics of each volume fraction of the components and the chemical composition of olivine and pyroxene, NWA 6148 correspond to lava units crystallized at 1346–1391 Ma in the nakhlite body. The position of NWA 10153 in the nakhlite body is unclear. Iron oxides/hydroxides, barite, and calcite fill the fractures of NWA 6148, which are terrestrial weathering products. In NWA 10153, olivine grains are replaced by goethite, magnetite, saponite, amorphous silica, jarosite, and siderite. Although it is uncertain whether all of the alteration minerals were formed on the surface of Mars or on the surface of Earth, NWA 10153 records two different alteration environments: reducing, neutral to alkaline, and oxidizing and acidic. As in NWA 6148 and NWA 10153, the assemblage of alteration mineral species in other nakhlites is also heterogeneous even within the same lava unit. The nakhlite body was altered by the oxidizing acidic fluid after a ‐bearing reducing neutral to alkaline fluid. The drastic change of alteration environments may have been caused by an impact event.
We analyzed the water‐soluble chemical composition of an 81.2‐m‐long ice core collected in 2019 from ∼ 6,000 m elevation on a south‐facing glacier in the Nepal Himalaya. The ice core chronology is based on variability in nitrate and calcium ions, which reveal an apparently seasonal periodicity (with winter maxima) throughout the core's length. Two annual boundaries are consistent with the tritium peak representing nuclear tests conducted in 1963 CE and with the spike in sulfate ions due to the eruption of Krakatau in 1883 CE. The ice core spans 145 years from 1875 to 2019 CE. Dating uncertainties due to the layer counting methodology were estimated as ±1 year for 1963–2019 CE and ±2 years for 1875–1963 CE. Comparison with earlier ice cores drilled on the northern side of the Himalayas revealed that the ion components exhibit inverse correlations with two key climatic indices: the North Atlantic Oscillation and Southern Oscillation Index. Composite analysis of reanalysis climate data suggests that these inverse relationships reflect springtime pressure patterns, which show regional differences between the northern and southern sides of the Himalayan range.
Over the past two decades, numerous studies have emphasised the importance of including organic matter (OM) in land surface models (LSMs) to accurately represent soil thermal and hydrological properties. This is particularly relevant in Arctic regions, where organic-rich soils are widespread. Consequently, most LSMs incorporate parameterisations that account for OM effects, although these implementations are often simplified. Recent advancements in global soil datasets now enable more precise modelling of soil properties by providing detailed inputs for soil composition and physical characteristics. This study enhances the ORCHIDEE LSM by refining the representation of soil organic and mineral content, as well as improving parameterisations of heat capacity, thermal conductivity, and porosity, using data from the SoilGrids 250m v2.0 database. The updated model is evaluated across multiple Arctic sites and compared against two earlier versions: (1) a Bulk version that neglects OM effects and (2) a simplified version with a basic OM prescription. Results show that incorporating OM into thermal process modelling significantly improves soil temperature simulations, particularly at greater depths. For some sites, root mean square errors (RMSE) are reduced by up to 25% compared to the Bulk version, especially during the snow-free summer months. These findings highlight the value of high-resolution soil datasets, such as SoilGrids, for improving simulations of thermal dynamics in carbon-rich Arctic soils.
The Arctic–Boreal Zone is rapidly warming, impacting its large soil carbon stocks. Here we use a new compilation of terrestrial ecosystem CO2 fluxes, geospatial datasets and random forest models to show that although the Arctic–Boreal Zone was overall an increasing terrestrial CO2 sink from 2001 to 2020 (mean ± standard deviation in net ecosystem exchange, −548 ± 140 Tg C yr⁻¹; trend, −14 Tg C yr⁻¹; P < 0.001), more than 30% of the region was a net CO2 source. Tundra regions may have already started to function on average as CO2 sources, demonstrating a shift in carbon dynamics. When fire emissions are factored in, the increasing Arctic–Boreal Zone sink is no longer statistically significant (budget, −319 ± 140 Tg C yr⁻¹; trend, −9 Tg C yr⁻¹), and the permafrost region becomes CO2 neutral (budget, −24 ± 123 Tg C yr⁻¹; trend, −3 Tg C yr⁻¹), underscoring the importance of fire in this region.
Gold (or electrum) in hydrothermal fluid precipitates directly from gold sulfide complex and/or partly via suspended nanoparticles. The hydrothermal fluid contains “invisible gold” that is atomically dispersed in sulfide minerals or as nanoparticles with a size of less than 10 nm. However, the contribution of these gold nanoparticles to the formation of native gold and its alloy with silver (electrum) remains unclear. The Higashi–Aogashima Knoll Caldera hydrothermal field, south of Tokyo, Japan, is an area of significant seafloor hydrothermal activity that is known for high-grade gold-containing minerals in sulfide-rich rocks. In this study, dry-polished thin sections were created to minimize sample damage and scanning and transmission electron microscopy were used to investigated the cross-sectional and three-dimensional morphologies of native gold grains in a sulfide-rich mound rock from the Central Cone site of the caldera. The surfaces of the gold grains comprised nanoparticles with sizes of 5–50 nm that were also attached to their periphery, which suggests that gold nanoparticles in deep-sea hydrothermal fluid were involved in the mineralization of the gold. In addition, the distribution of silver was uneven within the gold grains, which suggests that the gold precipitation comprised multiple stages at different temperatures that resulted in the post-deposition or secondary remobilization of silver.
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