Eastern Japan Research Articles

First record of the rare spoon worm <i>Ikedosoma elegans</i> (Annelida: Echiura: Thalassematidae) from Shikoku Island, Japan

Ikedosoma elegans (Ikeda, 1904) (Annelida: Echiura: Thalassematidae) is a rare, large deep-burrowing spoon worm that has been observed only in Japan. This species was first described based on the specimens collected from Misaki, Sagami Bay (Kanagawa Prefecture), eastern Japan, in 1902. Since the first description, this species has not been collected until the recent studies, which reported that I. elegans was collected from Hamana Lake (Shizuoka Prefecture), Boso Peninsula (Chiba Prefecture), and probably Amakusa, Ariake Sea (Kumamoto Prefecture). Furthermore, the specimen collected from Takasu, Seto Inland Sea (Okayama Prefecture) in 1975 was identified to be I. elegans. In this study, we present a new locality of this species in Japan. We collected a large individual of I. elegans with a probably commensal scale worm (Polynoidae: Polynoinae) by using a yabby pump in a mud flat in the Doki River Estuary, which is facing the Seto Inland Sea, in Marugame (Kagawa Prefecture), northern Shikoku Island. To the best of our knowledge, the present study is the first record of I. elegans from Shikoku Island and the second record from the Seto Inland Sea, following a 42-year-old record from Takasu, Okayama.

Ichthyofaunal changes in Lake Kitaura, eastern Japan, over the past 50 years

Ichthyofaunal changes in Lake Kitaura, eastern Japan, over the past 50 years

The size and health of old-aged Tokyo cherries in the Eastern Japan

The size and health of old-aged Tokyo cherries in the Eastern Japan

The Thoughts of an Elder Who Lives in a Fishing Village after the Great Eastern Japan Earthquake

The Thoughts of an Elder Who Lives in a Fishing Village after the Great Eastern Japan Earthquake

Distinct responses of East Asian and Indian summer monsoons to astronomical insolation during Marine Isotope Stages 5c and 5e

Loess and stalagmite records in China show different responses of Asian monsoon to the astronomical insolation during Marine Isotope Stage (MIS) 5c and 5e, raising the question whether the amplitudes of the whole Asian monsoon are linearly controlled by the astronomical summer insolation changes and whether the regional differences exist. In this study, a set of numerical experiments are conducted for these stages to examine the sensitivity of Asian summer monsoon to changes in the astronomical parameters. The results highlight a complicated response changing with regions and signals. The East Asian monsoon is remarkably stronger during MIS-5e, which is characterized by southerly winds, primarily due to the anomalous anticyclone over northwestern Pacific. The intensified East Asian monsoon leads to less precipitation in the eastern China and Japan but more in the further north and northwest. However, the Indian monsoon circulation does not vary significantly while the precipitation over Arabian Sea is significantly promoted by the upward air motion. Change in water vapor sources of Indian and Pacific Oceans qualitatively explains the observed differences in stalagmite δ18O records, implying that these proxy changes are primarily controlled by the water vapor delivery from oceans, at least on the astronomical timescale.

Effects of local and landscape factors on the abundance of an endangered multivoltine butterfly at riverbanks

AbstractPlebejus argyrognomon is one of the grassland‐dwelling butterflies undergoing rapid decline in recent decades. Grassland habitats for butterflies are generally threatened by fragmentation and invasive species, hence are among the most vulnerable ecosystems. We studied the seasonal abundance of P. argyrognomon at habitat patches along the banks of the Kinugawa River in eastern Japan, to identify environmental factors suitable for population persistence of this species, including habitat patch connectivity. Results showed that the patch's host plant cover had a positive effect on abundance in all three seasons, while the shading of the host plants by surrounding non‐host plants and nearby forested area showed negative effects. Additionally, habitat patch connectivity and nectar richness could be considered as positive factors in autumn and summer, respectively. Analysis of habitat connectivity also showed that the Kinugawa River did not appear to act as a dispersal barrier for P. argyrognomon. Our findings emphasize the importance of understanding environmental factors that may vary among seasons, and such understanding could contribute to habitat management of multivoltine butterflies in fragmented landscapes.

Radiocesium dynamics in the aquatic ecosystem of Lake Onuma on Mt. Akagi following the Fukushima Dai-ichi Nuclear Power Plant accident

Understanding ecosystem dynamics of radionuclides is necessary to ensure effective management for food safety. The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 released large amounts of radiocesium (134Cs and 137Cs) and contaminated the environment across eastern Japan. In this study, we aimed to elucidate the temporal dynamics of 137Cs in the aquatic ecosystem of Lake Onuma on Mt. Akagi. The effective ecological half-life (Teff) of 137Cs in fishes, western waterweed (Elodea nuttallii), seston (phytoplankton and zooplankton), and lake water was estimated using survey data of 137Cs concentration collected from 2011 to 2016, and single- and two-component decay function models (SDM and TDM, respectively). The decay processes of 137Cs concentrations in wakasagi (Hypomesus nipponensis), pale chub (Zacco platypus), phytoplankton, and total 137Cs concentrations of the water column (WC) in the lake were well suited by the TDMs. The Teff in the fast component of the TDMs in these samples ranged from 0.49 to 0.74years. The Teff in the slow component of the TDMs could converge towards the physical half-life of 137Cs. Nearly five and a half years after the FDNPP accident, we concluded that 137Cs concentrations approached a state of dynamic equilibrium between some aquatic organisms (wakasagi, pale chub, and phytoplankton) and the environment (lake water). However, the decay processes of 137Cs concentrations in Japanese dace (Tribolodon hakonensis), western waterweed, zooplankton, and particulate- and dissolved-forms in the WC were better predicted for the SDM. The total 137Cs concentrations in inflowing river and spring waters were one to two orders of magnitude lower than lake water under normal flow conditions. However, particulate 137Cs contamination level in the river water was high after heavy rains. Overall, 137Cs contamination levels have significantly decreased in Lake Onuma, but monitoring surveys should be continued for further understanding of the reduction processes.

Sulfur accumulation rates in volcanic soils of eastern Japan over the last millennium based on tephrochronology

Soils have an important role as a reservoir of essential elements for forest ecosystems. Although previous chronosequence studies have determined accumulation rates of several elements in soils, they have not focused on sulfur (S), a secondary macronutrient. We investigated S accumulation rates in five volcanic soils, dated by the use of tephras from the following volcanoes: Mt. Komagatake (tephra Ko-a, 1929 CE), Mt. Tarumae (tephra Ta-a, 1739 CE), Mt. Fuji (tephra F-Ho, 1707 CE), Towada caldera (tephra To-a, 915 CE), and Mt. Haruna (tephra Hr-FP520, 520 CE). The soils were sampled from A horizons formed above the tephra layer, and total S and pedogenic minerals (Ald, Fed, Alo, and Feo) were analyzed to determine the relationships between their estimated pools and soil age. The fractionation of S by oxidation state was determined by S K-edge XANES analysis in constituents of soils from Mt. Komagatake and Mt. Haruna. Our results showed that the S accumulation rate was almost constant over the last millennium. To extend our analysis to longer soil formation times, we extrapolated the S accumulation–age relationship to 10cal. ka and compared the resulting values with previously reported S data from horizons that likely developed during that time period in soils from Mt. Nantai dated by tephra Nt-S (14–15cal. ka). The similarity of the extrapolated values to the Nantai soil values suggests that the S accumulation rate may have been constant since 10cal. ka. In addition, the growth of the S pool with soil age was linearly proportional to the growth of pedogenic mineral pools. Sulfur isotope composition of soil total S depended not on soil age, but rather on the soil origin as indicated by location. The predominant oxidation state of the S fraction changed from reduced to oxidized with soil age during the Holocene. These results suggest that the constant S accumulation rate may reflect the variable influence of exogenous S sources as well as the association of S compounds with pedogenic minerals. Sulfur compounds may accumulate at a constant rate in Japanese volcanic soils as the result of biological transformation followed by retention of S in association with the pedogenic minerals.

Plant remains from the Middle–Late Jurassic Daohugou site of the Yanliao Biota in Inner Mongolia, China

AbstractA late Middle–early Late Jurassic fossil plant assemblage recently excavated from two Callovian–Oxfordian sites in the vicinity of the Daohugou fossil locality in eastern Inner Mongolia, China, was analysed in detail. The Daohugou fossil assemblage is part of the Callovian–Kimmeridgian Yanliao Biota of north-eastern China. Most major plant groups thriving at that time could be recognized. These include ferns, caytonialeans, bennettites, ginkgophytes, czekanowskialeans and conifers. All fossils were identified and compared with species from adjacent coeval floras. Considering additional material from three collections housed at major palaeontological institutions in Beijing, Nanjing and Pingyi, and a recent account in a comprehensive book on the Daohugou Biota, the diversity of the assemblage is completed by algae, mosses, lycophytes, sphenophytes and putative cycads. The assemblage is dominated by tall-growing gymnosperms such as ginkgophytes, czekanowskialeans and bennettites, while seed ferns, ferns and other water- or moisture-bound groups such as algae, mosses, sphenophytes and lycophytes are represented by only very few fragmentary remains. The floral composition underlines the Callovian–Kimmeridgian age of the Yanliao Biota. The Daohugou/Yanliao flora is a typical member of the Middle to Late JurassicConiopteris-Phoenicopsisassemblage of north-eastern China, differing from the Early Cretaceous Jehol flora. Both floras probably belong to the same cycle of volcanism and sedimentation, although the Daohugou Bed is older than the Yixian Formation. The Yanliao fossil assemblage is placed in a larger palaeo-phytogeographical context and its relationships with Middle–Late Jurassic floras from north-eastern China, north-eastern and eastern Siberia and Japan are evaluated.

佐藤博信著, 『中世東国政治史論』, 塙書房, 二〇〇六・一〇刊, A5, 四三六頁, 一一〇〇〇円

佐藤博信著, 『中世東国政治史論』, 塙書房, 二〇〇六・一〇刊, A5, 四三六頁, 一一〇〇〇円

Noting as Learning: Its Significance for Teaching and Learning Japanese in Volunteer Language Classrooms for Migrants

This paper discusses problems in volunteer Japanese classrooms as a field of teaching foreign language for special purposes, which is to enhance migrant learners in the neighbourhood to participate in the host society through the target language. The data on which the discussion is based was collected from a case study conducted in a volunteer Japanese classroom in eastern Japan. From the point of view of “noting” in the Language Management Theory (LMT; cf. Neustupný 1985, 1994; Jernudd and Neustupný 1987), the findings suggest that although all the learners in the classroom intend to stay in Japan permanently, they appear to be reluctant to interact with local Japanese and to expand their Japanese social network due to the inability to note deviations from norms underlying in Japanese speech situations. In the second half of the paper, I raise an example of teaching materials to illustrate that noting as learning can be enhanced through systematic classroom activities. It is suggested that the ability to become sensitive about possible problems when interacting with local Japanese people can help foreigners in the neighbourhood to be more prepared and thus more confident to use the target language in real life.

佐々木虔一著 『古代東国社会と交通』 (歴史科学叢書) (校倉書房 一九九五・九刊 A5 三九八頁 九〇〇〇円)

佐々木虔一著 『古代東国社会と交通』 (歴史科学叢書) (校倉書房 一九九五・九刊 A5 三九八頁 九〇〇〇円)

Altitudinal characteristics of atmospheric deposition of aerosols in mountainous regions: Lessons from the Fukushima Daiichi Nuclear Power Station accident

To understand the formation process of radiologically contaminated areas in eastern Japan caused by the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, the deposition mechanisms over complex topography are the key factors to be investigated. To characterize the atmospheric deposition processes of radionuclides over complex mountainous topography, we investigated the altitudinal distributions of the radiocesium deposited during the accident. In five selected areas, altitudinal characteristics of the air dose rates observed using airborne surveys were analyzed. To examine the deposition mechanisms, we supplementarily used vertical profiles of radiocesium deposition in each area calculated in the latest atmospheric dispersion model. In southern Iwate, the vertical profile of the observed air dose rate was uniform regardless of altitude. In western Tochigi, the areas with the highest levels of contamination were characteristically distributed in the middle of the mountains, while in southern Fukushima, the areas with the highest contamination levels were enhanced near the summits of mountains. In central Fukushima, high air dose rates were limited to the bottoms of basin-like valley. In the region northwest of FDNPS, the air dose rate was the highest at the bottom of valley topography and decreased gradually with altitude. The simulation results showed that calculated wet deposition and observed vertical profiles of total deposition were similar in areas of southern Iwate and northwest of FDNPS qualitatively, suggesting that the dominant deposition mechanism was wet deposition. In contrast, the atmospheric dispersion model failed to reproduce either the timing of precipitation events or vertical profiles of radiocesium deposition in three other areas. Although it was difficult to elucidate the deposition mechanisms in these areas due to uncertainties of the present model results, potential mechanisms such as cloud water deposition were still proposed based on circumstantial evidences of limited meteorological data during the early stage of the accident.

Measuring Long-term Effects of the Fukushima Daiichi Nuclear Power Plant Accident on Real Estate Prices

The Fukushima Daiichi Nuclear Power Plant accident was caused by the Great East Japan Earthquake in March, 2011. Widespread areas in eastern Japan were contaminated by the huge release of radioactive materials. We analyze the long-term effects of the accident on land prices by estimating the hedonic equation with regional fixed effects. Our estimation results show that the soil contamination by cesium-134/137 affected the surrounding land prices negatively; however, this effect disappeared after only one year. This implies that we should discreetly interpret the results in estimating the cost of the Fukushima nuclear accident by the hedonic approach.

Characterization of Ornithobacterium rhinotracheale from commercial layer chickens in eastern Japan.

From a total of 72 commercial layer and pullet farms that were monitored in the eastern Japan area, 4 farms had mild to severe respiratory disease accompanied by decreased feed intake and drop in egg production. Microbiological analysis showed that 3 of the 4 farms, particularly from Fukushima, Tochigi, and Ibaraki prefectures, were positive for Ornithobacterum rhinotracheale (ORT). Out of 65 birds examined, ORT was isolated in 21 birds (32.31%). All isolates were Gram-negative pleomorphic rods with a colony size of 0.05mm, translucent with grayish coloration, and with butyric smell after 48 h of incubation in 10% chicken blood agar at 37°C under microaerophilic conditions. All isolates reacted positively in the p-nitrophenyl-β-d-galactopyranoside test within 3 h and were positive in cytochrome oxidase tests with an API 20NE identification system biocode of 0-0-2-0-0-0-4. An agar gel precipitation test showed that all isolates were serotype-A. All strains were positive in PCR by yielding a 784bp amplicon of the 16S rRNA gene. All strains were resistant to amikacin, colistin, gentamicin, kanamycin, neomycin, polymyxin b, streptomycin, and sulfamethoxazole trimethoprim and susceptible to amoxicillin clavulanic acid, ampicillin, doxycycline, spectinomycin, and tetracycline. This study is the first characterization of ORT from commercial layer chickens in eastern Japan.

東日本大震災から考えるメディアとサバルタニティ( 震災後のメディア研究,ジャーナリズム研究)

東日本大震災から考えるメディアとサバルタニティ( 震災後のメディア研究,ジャーナリズム研究)

Density economies and transport geography: Evidence from the container shipping industry

By exploiting the 1995 Hanshin earthquake in western Japan as an exogenous shock to the container traffic of Northeast Asia, our study shows that economies of density in the transportation sector can influence transport geography. This earthquake caused great damage to the port of Kobe, resulting in a diversion of its container traffic to the nearby port of Busan, which increased markedly after this windfall. The strengthened economies of transport density therefore allowed Busan to expand its hinterland to regions whose container shipping operations had not even been directly affected by the earthquake, such as eastern Japan. The empirical evidence from the port choice dynamics in eastern Japan supports this mechanism. Substantial diversions of container traffic occurred after 1995 from the major ports in this region to the port of Busan. Furthermore, these unintended container shipping diversions led to a structural change in the manufacturing sector of related regions after the late 1990s.

Fabian Drixler, Mabiki: Infanticide and Population Growth in Eastern Japan, 1660-1950 (Asia: Local Studies/Global Themes), Oakland, Calif., University of California Press, 2013, 439p

Fabian Drixler, Mabiki: Infanticide and Population Growth in Eastern Japan, 1660-1950 (Asia: Local Studies/Global Themes), Oakland, Calif., University of California Press, 2013, 439p

Interpopulational variation in pupal diapause of the butterfly Atrophaneura alcinous (Klug) (Lepidoptera, Papilionidae) in the Kanto District, eastern Japan

Interpopulational variation in pupal diapause of the butterfly Atrophaneura alcinous (Klug) (Lepidoptera, Papilionidae) in the Kanto District, eastern Japan

Molecular survey of Bartonella henselae and Bartonella clarridgeiae in pet cats across Japan by species-specific nested-PCR.

Cats are known to be the main reservoir for Bartonella henselae and Bartonella clarridgeiae, which are the agents of 'cat-scratch disease' in humans. In the present study, we investigated the prevalence of the two Bartonella species on 1754 cat bloods collected from all prefectures in Japan during 2007-2008 by a nested-polymerase chain reaction (PCR) targeting the 16S-23S rRNA internal transcribed spacer region. Overall, Bartonella DNA was detected in 4·6% (80/1754) of the cats examined. The nested-PCR showed that 48·8% (39/80) of the positive cats were infected with B. henselae mono-infection, 33·8% (27/80) with B. clarridgeiae mono-infection and 17·5% (14/80) were infected with both species. The prevalence (5·9%; 65/1103) of Bartonella infection in the western part of Japan was significantly higher than that (2·3%; 15/651) of eastern Japan (P < 0·001). Statistical analysis of the cats examined suggested a significant association between Bartonella infection and FeLV infection (OR = 1·9; 95% CI = 1·1-3·4), but not with FIV infection (OR = 1·6; 95% CI = 1·0-2·6).