Different thermal preferences for brooding and larval dispersal of two neighboring shrimps in deep‐sea hydrothermal vent fields

Temperature is an important factor affecting the distributions and life‐history traits of marine animals. Deep‐sea hydrothermal vents are suitable environments to examine ecologic differences related to temperature, due to the steep temperature gradients around the vents. Rearing experiments under various temperature conditions (5–30 °C) at atmospheric pressure demonstrated a difference in thermal effects on egg hatching and larva in two co‐occurring, vent‐associated alvinocaridid shrimps – the peripherally distributed Alvinocaris longirostris and the centrally distributed Shinkaicaris leurokolos. The duration before hatching became shorter as temperature increased, while the maximum hatching rate occurred at higher temperatures in S. leurokolos (10–20 °C) than in A. longirostris (10 °C). Hatched larvae of both species were negatively buoyant, and larva with normal abdominal length could actively swim and stay suspended in the mid‐ or surface water layers of the culture plates under our experimental conditions. However, no larvae settled or metamorphosed into juveniles under the rearing conditions used in this study. Larvae with shortened abdomens occurred under most of the experimental conditions, although they were less frequent at 10 °C in A. longirostris and 20 °C in S. leurokolos. The maximum survival periods at these temperatures were 88 days in A. longirostris and 30 days in S. leurokolos. These characteristics may cause differences in the distributional ranges of the two species. The present results indicate that temperature is an important factor controlling life‐history traits of vent shrimps.     

Fog and rain water chemistry at Mt. Fuji: A case study during the September 2002 campaign

Measurements of fog and rain water chemistry at the summit of Mt. Fuji, the highest peak in Japan, as well as at Tarobo, the ESE slope of Mt. Fuji in September 2002. The pH of fog and rain water sampled at Mt. Fuji varied over a range of 4.0–6.8. Acidic fogs (pH < 5.0) were observed at the summit when the air mass came from the industrial regions on the Asian continent. The ratio of [SO₄²⁻]/[NO₃⁻] in the fog water was lower at Tarobo than at the summit. High concentrations of Na⁺ and Cl⁻ were determined in the rain water sampled at the summit, possibly because of the long-range transport of sea-salt particles raised by a typhoon through the middle troposphere. The vertical transport of sea-salt particles would influence the cloud microphysical properties in the middle troposphere. Significant loss of Mg²⁺ was seen in the rain water at the summit. The concentrations of peroxides in the fog and rain water were relatively large (10–105 μM). The potential capacity for SO₂ oxidation seems to be strong from summer to early autumn at Mt. Fuji. The fog water peroxide concentrations displayed diurnal variability. The peroxide concentrations in the nighttime were significantly higher than those in the daytime.     

Seasonal and spatial variation in the denitrifying activity in estuarine and lagoonal sediments

We have elucidated the seasonal and spatial variation in the potential denitrifying activity in estuarine and coastal lagoonal sediments in Lakes Shinji and Nakaumi, Japan. The denitrifying activity increased from summer through autumn and was positively correlated with the temperature of the overlying water at all sites except one, where the bottom was always more reductive than at the other sites and there was no NO₃ ⁻ as a substrate for denitrification from spring to autumn. Moreover, the relationship between the denitrifying activity and the distance from the sea showed different trends in estuarine and lagoonal sediments. These spatial differences indicate that different factors regulate the denitrification in estuarine and lagoonal sediments. Denitrifying activity in estuarine sediment was regulated by the discharge of freshwater containing NO₃ ⁻ or organic matter, while in the lagoonal sediments the occurrence of nitrification via the intrusion of oxic seawater into the reductive sediment appears to be a key requirement for the process of denitrification. Therefore, the denitrifying activity in the lagoonal sediment appears to be greater near the sea. Water intrusion is one of the key factors controlling denitrification in coastal marine ecosystems by affecting the supply of substrate available for denitrification.     

Heterogeneity in supraglacial debris thickness and its role in glacier mass changes of the Mount Gongga

In the Tibetan Plateau, many glaciers have extensive covers of supraglacial debris in their ablation zones, which affects glacier response to climate change by altering ice melting and spatial patterns of mass loss. Insufficient debris thickness data make it difficult to analyze regional debris-cover effects. Maritime glaciers of the Mount Gongga have been characterized by a substantial reduction in glacier area and ice mass in recent decades. The thermal property of the debris layer estimated from remotely sensed data reveals that debris-covered glaciers are dominant in this region, on which the proportion of debris cover to total glacier area varies from 1.74% to 53.0%. Using a physically-based debris-cover effect assessment model, we found that although the presence of supraglacial debris has a significant insulating effect on heavily debris-covered glaciers, it accelerates ice melting on ~10.2% of total ablation zone and produces rapid wastage of ~25% of the debris-covered glaciers, leading to the similar mass losses between the debris-covered and debris-free glaciers. Widespread debris cover also facilitates the development of active terminus regions. Regional differences in debris-cover effects are apparent, highlighting the importance of debris cover for understanding glacier mass changes in the Tibetan Plateau and other mountain ranges around the world.     

Climate disaster resilience of the education sector in Thua Thien Hue Province, Central Vietnam

Recognizing the importance of building disaster resilience for education sector, this study aims to develop a methodology to measure the level of educational resilience to cope with natural disasters and is then applied in Central Vietnam. The assessment tool in this paper is developed through a combination of climate disaster resilience indexes and the 16 tasks of Hyogo framework for action designed for education sector. It looks at five dimensions namely physical conditions, human resources, institutional issues, external relationships, and natural conditions, with each dimension characterized by three parameters and five variables. Findings from this study provide important insights into enhancing resilience of the education system in Thua Thien Hue at the provincial, local, and school levels. By giving the overall resilience situation, it can help policy-makers and practitioners in developing an effective plan to increase the level of educational resilience. In addition, it provides the School Management Board with a means to assess the school??s resilience level and set out priorities that need to be focused on with regard to the improvement of school safety and disaster risk reduction education.     

Atmospheric helium isotope ratio: Possible temporal and spatial variations

The atmospheric ³He/⁴He ratio has been considered to be constant on a global scale, because the residence time of helium is significantly longer than the mixing time in the atmosphere. However, this ratio may be decreasing with time owing to the anthropogenic release of crustal helium from oil and natural gas wells, although this observation has been disputed. Here, we present the ³He/⁴He ratios of old air trapped in historical slags in Japan and of modern surface air samples collected at various sites around the world, measured with a newly developed analytical system. In air helium extracted from metallurgical slag found at refineries in operation between AD 1603 and 1907 in Japan, we determined a mean ³He/⁴He ratio of (5106 ± 108) × 10^-5 R_HESJ (where R_HESJ is the ³He/⁴He ratio of the Helium Standard of Japan), which is consistent with the previously reported value of (5077 ± 59) × 10^-5 R_HESJ for historical slags in France and United Arab Emirates and about 4% higher than that of average modern air, (4901 ± 4) × 10^-5 R_HESJ. This result implies that the air ³He/⁴He ratio has decreased with time as expected by anthropogenic causes. Our modern surface air samples revealed that the ³He/⁴He ratio increases from north to south at a rate of (0.16 ± 0.08) × 10^-5 R_HESJ/degree of latitude, suggesting that the low ³He/⁴He ratio originates in high-latitude regions of the northern hemisphere, which is consistent with the fact that most fossil fuel is extracted and consumed in the northern hemisphere.     

K‐Th‐Ti systematics and new three‐component mixing model of HED meteorites: Prospective study for interpretation of gamma‐ray and neutron spectra for the Dawn mission

Abstract– The Dawn spacecraft carries a gamma‐ray and neutron detector (GRaND), which will measure and map the abundances of selected elements on the surface of asteroid 4 Vesta. We compare the variability of moderately volatile/refractory incompatible element ratios (K/Th and K/Ti) in howardite, eucrite, and diogenite (HED) meteorites with those in other achondrite suites that represent asteroidal crusts, because these ratios may be accurately measured by GRaND and likely reflect initial chemical compositions of the HED parent body. The K/Th and K/Ti variations can differentiate HED meteorites from angrites and some unique eucrite‐like lithologies. The results suggest that K, Th, and Ti abundances determined from GRaND data could not only confirm that Vesta is the parent body of HED meteorites but might also allow recognition of as‐yet unsampled compositional terranes on Vesta. Besides the K‐Th‐Ti systematics study, we propose a new three‐component mixing model for interpretation of GRaND spectra, required because the spatial resolution of GRaND is coarser than the spectral (compositional) heterogeneity of Vesta’s surface. The mixing model uses abundances of K, Ti, Fe, and Mg that will be analyzed more accurately than other prospective GRaND‐analyzed elements. We examine propagated errors due to GRaND analytical uncertainties and intrinsic errors that stem from an assumption introduced into the mixing model. The error investigation suggests that the mixing model can adequately estimate not only the diogenite/eucrite mixing ratio but also the abundances of most major and minor elements within the GRaND propagated errors.     

Cooling and inferred exhumation history of the Ryoke metamorphic belt in the Yanai district, south-west Japan: Constraints from Rb–Sr and fission-track ages of gneissose granitoid and numerical modeling

Abstract The Ryoke metamorphic belt in south-west Japan consists mainly of I-type granitoids and associated low-pressure/high-temperature metamorphic rocks. In the Yanai district, it has been divided into three structural units: northern, central and southern units. In this study, we measured the Rb–Sr whole-rock–mineral isochron ages and fission-track ages of the gneissose granodiorite in the central structural unit. Four Rb–Sr ages fall in a range of ca 89–87 Ma. The fission-track ages of zircon and apatite are 68.9 ± 2.6 Ma and 57.4 ± 2.5 Ma (1σ error), respectively. Combining the newly obtained ages with previously reported (Th–)U–Pb ages from the same unit, thermochronologic study revealed two distinctive cooling stages; 1) a rapid cooling (> 40°C/Myr) for a period (~7 Myr) soon after the peak metamorphism (~ 95 Ma) and 2) the subsequent slow cooling stage (~ 5°C/Myr) after ca 88 Ma. The first rapid cooling stage corresponds to thermal relaxation of the intruded granodiorite magma and its associated metamorphic rocks, and to the uplift by a displacement along low-angle faults which initiated soon after the intrusion of the magma. Uplift by the later stage deformation having formed large-scale upright folds resulted in progress of the exhumation during the first stage. The average exhumation velocity of the stage is ≥ 2 mm/yr. During the second stage, the rocks were not accompanied by ductile deformation and were exhumed with the rate of 0.1–0.2 mm/yr. The difference in the exhumation velocity between the first and second cooling stages resulted from the difference in the thickness of the crust and in the activity of ductile deformation between the early and later stages of the orogenesis.     

Suppressive Effects of Traditional Mulching Using Japanese Knotweed (Fallopia japonica) on Solanaceae Crop Diseases

Poaceae plant species, such as silver grass, are commonly used in mulching activities Japan. In contrast, local farmers have traditionally used Japanese knotweed (Fallopia japonica) mulch in the cultivation of solanaceous crops in the Nishi-Awa area of Japan, which is a Globally Important Agricultural Heritage Systems site. We have previously evaluated the positive effects of Japanese knotweed mulching on solanaceous crops, such as eggplants, tomato, and potato. In the present study, we observed that the naturally occurring diseases in the solanaceous crops tended to decrease when the knotweed mulching system was adopted, in comparison to when Poaceae mulch was adopted. In eggplants, leaf mold and powdery mildew decreased under Japanese knotweed mulching. We further evaluated the effects of Japanese knotweed mulching by inoculating test plants with Pseudomonas cichorii. We observed suppression of bacterial disease and tomato mosaic virus under Japanese knotweed mulching and following spraying with Japanese knotweed extracts. In addition, disease-resistance genes were expressed at high levels in Arabidopsis thaliana, a model plant, following treatment with Japanese knotweed extracts. The results suggest that Japanese knotweed has potential applications in future sustainable agriculture activities.