Izu Peninsula Research Articles

Space and Cherry Blossom Viewing Users of ‘Kawazu Zakura’ (Prunus lannesiana. Wils.) Noted Place at Lower Kawazu River Basin in Izu Peninsula

Space and Cherry Blossom Viewing Users of ‘Kawazu Zakura’ (Prunus lannesiana. Wils.) Noted Place at Lower Kawazu River Basin in Izu Peninsula

Visit to valuable Water Springs (127) Valuable springs in Izu Peninsula

Visit to valuable Water Springs (127) Valuable springs in Izu Peninsula

Reinstatement of Myelophycus caespitosus (Scytosiphonaceae, Phaeophyceae) from Japan

SUMMARYReinstatement of Myelophycus caespitosus Kjellman (Ectocarpales s.l., Phaeophyceae) described from western Japan is proposed based on the comparisons of DNA sequences of Japanese Myelophycus specimens, the type specimen of Chordaria simplex and lectotypified specimen of Myelophycus caespitosus. In the genetic analyses using mitochondrial cox1 and cox3, chloroplast atpB, psbA and rbcL DNA sequences, the specimens morphologically referable to M. simplex formed two distinct clades (clade‐1 and clade‐2) supported by high statistical values. Clade‐1 was distributed on the western coast of Japan (Honshu, Shikoku and Kyushu) from the Kii Peninsula to Tsushima and the Pacific coast of Aomori, northeastern Honshu, and clade‐2 on the Pacific coast of central Honshu from Sanriku to the Kii Peninsula. Based on the cox3 DNA sequences and the location of the type locality at Shimoda, Izu Peninsula, clade‐2 was concluded to correspond to true M. simplex. There were no recognizable differences in the representative morphological features (height and diameter of sporophytes and gametophytes, number of cells comprising cortical, subcortical and medullary layers, thickness of plurilocular gametangia, or length and diameter of unilocular zoidangia) between the specimens included in the two taxa. Analyses of the specimens of the two taxa, including sympatric populations on the Kii Peninsula, using a nuclear genetic marker ocm3 did not suggest any genetic exchanges between the two taxa. On the other hand, cox3 gene sequence of the voucher specimen of Myelophycus caespitosus collected from Goto, Kyushu, western Japan housed in the UPS herbarium was included in clade‐1. In conclusion, we propose the reinstatement of M. caespitosus and to lectotypify the specimen in UPS. Korean Myelophycus specimens reported from Cheju Island and Wando were considered to belong to M. caespitosus based on the reported rbcL sequences.

Bayesian Network Analysis for the Questionnaire Investigation on Tourists’ Behavior

Tourists from abroad are increasing rapidly in Japan. Kawazu town in Izu Peninsula is famous for its cherry trees. In the cherry blossom season, many tourists visit this town. The Kawazu Cherry Blossom Festival was carried out in February 2015. Our research investigation was performed during that period. In this paper, a questionnaire investigation is executed in order to clarify tourists’ behavior, and to seek the possibility of developing regional collaboration among local government, tourism related industry and visitors. In this research, we construct the model utilizing Bayesian Network and causal relationship is sequentially chained by the characteristics of travelers, an objective to visit Izu Peninsula in Japan and the main occasion to visit them. Sensitivity Analysis for “Main occasion to visit to Izu Peninsula” was conducted and 17 cases were analyzed. These are utilized for constructing a much more effective and useful tourism service. To confirm the findings by utilizing the new consecutive visiting records would be the future works to be investigated.

A Proposal for New Analysis Method in Tourism Marketing -A Case Study of Text Mining Analysis on Tourism Attractiveness in Izu Peninsula-

A Proposal for New Analysis Method in Tourism Marketing -A Case Study of Text Mining Analysis on Tourism Attractiveness in Izu Peninsula-

The Significance of a Cooperative Medical System for Treating Decompression Illness on the Izu Peninsula in Japan

In 2011, our hospital on the Izu peninsula began to hold meetings to discuss how to manage patients with decompression illness (DCI) to establish a cooperative medical system. We retrospectively investigated the influence of these meetings and the changes subsequently effected. A medical chart review was retrospectively performed to investigate all cases between January 2005 and December 2017 in which the transport of patients with DCI via a physician-staffed helicopter emergency medical service (HEMS) was attempted. The patients were divided into 2 groups: the preprogram group and the postprogram group. There were 63 patients in the preprogram group and 65 in the postprogram group. There were no cases in which a patient's symptoms deteriorated during transportation by the HEMS. The frequency of dispatch to the scene for direct evacuation in the postprogram group (86%) was greater than that in the preprogram group (74%), but the difference was not statistically significant (P=0.09). In the postprogram group, the duration of activities at the scene or the first aid hospital was significantly shorter in comparison to the preprogram group (P=0.01). This retrospective study revealed simultaneity between the introduction of the yearly meetings and a reduced duration of the HEMS staff's activity at either the scene or the first aid hospital.

石碑の風化:伊豆半島,須崎恵比寿島における例

石碑の風化:伊豆半島,須崎恵比寿島における例

Life history of the sesarmid crab, <i>Clistocoeloma villosum</i>, on the southern coast of the Izu Peninsula, central Japan

Life history of the sesarmid crab, <i>Clistocoeloma villosum</i>, on the southern coast of the Izu Peninsula, central Japan

The Movement of Local Resourcing of<i> Citrus tachibana </i>which is Domestic Wild Citrus Fruits and Status of the Population of <i>C.</i> <i>tachibana</i> in Heta District, West Izu Peninsula.

The Movement of Local Resourcing of<i> Citrus tachibana </i>which is Domestic Wild Citrus Fruits and Status of the Population of <i>C.</i> <i>tachibana</i> in Heta District, West Izu Peninsula.

Gold Mineralization in Izu Peninsula, Central Japan, during Crustal Extension in Response to Double Subduction

AbstractIzu Peninsula in central Japan, the northern tip of the Izu‐Bonin arc, hosts numerous epithermal Au–Ag vein deposits of low‐sulfidation style. All have similar vein textures, mineralogy, and alteration. Geochemical data from fluid inclusions in vein quartz, the mineralogy and mineral chemistry of alteration, and stable isotope data indicate that auriferous hydrothermal activity occurred under subaerial conditions. The K–Ar ages of auriferous vein minerals are <1.5 Ma, indicating that the mineralization took place after extensive submarine volcanism for the host rocks. These observations suggest that Au–Ag mineralization was synchronous with the development of an extensional regime of the Izu block after its collision with the Honshu arc after 1.5 Ma. This collision resulted in the shifting of the Izu block far from the trench to the rear position, and the subduction of the Izu block along the Suruga trough to the west and along the Sagami trough to the east. The reararc position of the Izu block and double subduction resulted in crustal extension, upwelling of asthenospheric mantle, and tholeiitic magmatism reflected by mafic dyke swarms and subsequent monogenetic volcanic activity in the Izu peninsula. The timing of the Au mineralization in the Izu Peninsula during the beginning of lithospheric extension is similar to that of the Sado Au–Ag deposit on Sado island in the Japan Sea. Two mineralization events coincide with extensive tholeiitic mafic volcanism and injections of dyke swarms related to the back‐arc opening of the Japan Sea. The geological setting of the Au–Ag mineralization in Izu and Sado is also similar to that of the epithermal Au–Ag deposits in northern Nevada, where mineralization was contemporaneous with crustal extension and tholeiitic mafic magmatism derived from the asthenospheric mantle. This study suggests that epithermal Au mineralization at shallow crustal depths is a product of large‐scale lithospheric evolution.

Stress data inversion to estimate collision rate distribution and its application to the Izu Peninsula, Japan

In convergent plate boundary zones, convergent motion between adjacent plates is accommodated by fault slip along the plate interface (subduction) combined with the compressional deformation of the plates (collision). The collision rate is defined as the ratio of the long-term increase rate of the irrecoverable slip deficit at the plate interface to the full plate convergence rate in order to quantitatively represent this mechanical aspect. The distribution of the collision rate on the plate interface is a major active source that generates a tectonic stress field in the plate interior. We developed a new inversion method based on these concepts to estimate the collision rate distribution from the patterns of the intraplate tectonic stress fields. In the inversion, the analytically obtained tectonic stress data were used and a Bayesian approach was considered. The application of the inversion method to the Izu collision zone in central Japan revealed that a broad belt of high collision rates surrounded the base of the Izu Peninsula. The collision belt was divided into three parts: (1) a central strong collision zone spreading landwards at the base of the Izu Peninsula, where the value of the collision rate becomes a maximum, (2) an eastern moderate collision zone widely covering the Philippine Sea-North American plate boundary along the Sagami trough, and (3) a western moderate collision zone concentrated in a shallower part of the Philippine Sea-Eurasian plate boundary along the Suruga trough. The central collision zone coincided with the colliding front of the Izu-Ogasawara (Bonin) island arc, which indicated that the estimated collision rate distribution described the actual arc collision process. The eastern and western collision zones might imply a higher absolute strength of their corresponding large interplate seismogenic zones.

Questionnaire Investigation on Tourists’ Behavior and its Sensibility Analysis Utilizing Bayesian Network

Tourists from abroad are increasing rapidly in Japan. Kawazu town in Izu Peninsula is famous for its cherry trees. In the cherry blossom season, many tourists visit this town. In order to get much more visitors, tourists’ behavior should be investigated much further. The Kawazu Cherry Blossom Festival was carried out in February 2015. Our research investigation was performed during that period. In this paper, a questionnaire investigation is executed in order to clarify tourists’ behavior, and to seek the possibility of developing regional collaboration among local government, tourism related industry and visitors. In this research, we construct the model utilizing Bayesian Network and causal relationship is sequentially chained by the characteristics of travelers, an objective to visit Izu Peninsula in Japan and the main occasion to visit them. We analyzed them by sensitivity analysis and some useful results were obtained. Sensitivity analysis is performed by back propagation method. We have presented the paper concerning this. But the volume becomes too large, therefore we have split them and this paper shows the latter half of the investigation result by setting evidence to Bayesian Network items. These are utilized for constructing a much more effective and useful tourism service. We have obtained fruitful results. To confirm the findings by utilizing the new consecutive visiting records would be the future works to be investigated.

6. 伊豆半島は衝突したか? : マグマ活動からのアプローチ

6. 伊豆半島は衝突したか? : マグマ活動からのアプローチ

An Analysis of the Questionnaire Investigation on Tourists’ Behavior

Tourists from abroad are increasing rapidly in Japan. Particular aims of local government are to overcome the common problems of an aging population and declining birthrate through tourism-generated income and to stimulate the local society through regional exchange and migration. In order to analyze economic aspects of tourism, accurate and up-to-date statistics and information regarding tourism are needed. Specifically, this study presents opportunities for inter-regional cooperation in marketing, in light of studies of tourist behavior at events featuring seasonal flowers and held in Kawazu town, which is located on the Izu Peninsula in Shizuoka Prefecture. In this paper, a questionnaire investigation is executed in order to clarify tourists’ behavior, and to seek the possibility of developing regional collaboration among local government, tourism related industry and visitors. Hypothesis testing was executed based on that. Some interesting and instructive results were obtained.

Hypothesis Testing for the Questionnaire Investigation on Tourists’ Behavior

Tourists from abroad are increasing rapidly in Japan. Kawazu town in Izu Peninsula is famous for its cherry trees. In the cherry blossom season, many tourists visit this town. The Kawazu Cherry Blossom Festival was carried out in February 2015. Our research investigation was performed during that period. In this paper, a questionnaire investigation is executed in order to clarify tourists’ behavior, and to seek the possibility of developing regional collaboration among local government, tourism related industry and visitors. Hypothesis testing was executed based on that. We have set 10 Null hypotheses. In the hypothesis testing, 6 cases out of 10 null hypotheses were rejected and the majority of hypotheses were insisted clearly. We have obtained fruitful results.

Habitat template approach for green roofs using a native rocky sea coast plant community in Japan

The present study examined whether it is possible to simulate a local herbaceous coastal plant community on a roof, by studying the natural habitats of rocky sea coast plants and their propagation and performance on a green roof. After studying the natural habitat of coastal areas in Izu peninsula, a germination and cutting transplant study was carried out using herbaceous plants from the Jogasaki sea coast. Many plant species did not germinate at all and the use of cuttings was a better method than direct seeding. The green roof was installed in the spring of 2012 in Chiba city. Thirteen plant species from the Jogasaki sea coast, which were successfully propagated, were planted in three kinds of substrate (15 cm depth): pumice, roof tile and commercial green roof substrate. The water drainage was restricted and a reservoir with 5 cm depth of water underlaid the substrate to simulate a similar growing environment to the sea coast. Volcanic rocks were placed as mulch to create a landscape similar to that on the Jogasaki sea coast. Plant coverage on the green roof was measured every month from June 2012 to October 2014. All plants were harvested and their dry shoot weight was measured in December 2014. The type of substrate did not cause significant differences in plant survival and dry shoot weight. Sea coast plant species were divided into four categories: vigorous growth; seasonal change; disappearing after a few years; limited growth. Understanding the ecology of natural habitats was important to simulating a local landscape using native plant communities on the green roof.

Range extension of the sesarmid crab Clistocoeloma villosum along the eastern Pacific coast of the Izu Peninsula, Japan

BackgroundThe Pacific coastline along the southern Izu Peninsula, Japan, is strongly influenced by warm tropical waters of the Kuroshio Current. A new easternmost record of the near-threatened sesarmid crab Clistocoeloma villosum is reported from the southern part of Izu Peninsula.MethodsThe present study was conducted in August 2014 and February 2015, on tidal flats in the mouth of the Aono River, draining the southern part of Izu Peninsula. Crabs were collected by hand on the tidal flat substrate, under cobble stones and on the periphery of associated mangrove forests.Results and conclusionBody sizes and morphological characteristics closely matched existing descriptions of C. villosum, the distribution range having been extended ca. 350 km eastward from the Kii Peninsula (traditional eastern boundary of the species), suggesting broad northeastwardly directed planktonic larval transport by the warm Kuroshio Current along the Pacific coast of Japan. The survival and settlement of larvae of this southern species along the southern coast of the Izu Peninsula, is evidence of the suitability of the small gravel dominated tidal flats in the region as habitat for the species.

観光地化に伴う沿岸集落の変豹 : 南伊豆・石廊崎の事例

観光地化に伴う沿岸集落の変豹 : 南伊豆・石廊崎の事例

伊豆半島,多賀火山初期噴出物としての畑玄武岩類 : 静岡県丹那盆地付近の地質とK-Ar年代

伊豆半島,多賀火山初期噴出物としての畑玄武岩類 : 静岡県丹那盆地付近の地質とK-Ar年代

Postembryonic development of the sea spider Ammothella biunguiculata (Pycnogonida, Ammotheidae) endoparasitic to an actinian Entacmaea quadricolor (Anthozoa, Stichodactylidae) in Izu Peninsula, Japan

Postembryonic developmental stages of an endoparasitic pycnogonid, Ammothella biunguiculata in Izu Peninsula, Japan are described. Eleven stages were identified beginning with a protonymphon larva attached to the male oviger. We found endoparasitic individuals in the host actinian from the second to tenth instar, and forms in the ninth stage to adult were found free-living. This indicates a transition from being endoparasitic to free-living during the ninth to tenth instar stages. The first instar protonymphon attached to the adult male oviger has a gland duct on the anterior margin of each chelifore scape which completely disappears with the second instar. The disappearance of the chelifore gland duct coincides with the beginning of an endoparasitic stage in the development of this species. Although the larval morphology and the postembryonic development of pycnogonids have been summarized by several authors, the present study concludes that much remains to be learnt.