Tsushima Island Research Articles

The Role of Wild Boar as Host of Japanese Encephalitis Virus in the Absence of Domestic Pigs.

Pigs are the most common amplifying hosts of the Japanese encephalitis virus (JEV). In 2016, four residents on Tsushima Island who did not own pig farms were diagnosed with JE. Therefore, a serosurvey was conducted to estimate the risk and seroprevalence of JEV after the outbreak. Sera collected from 560 Tsushima Island residents between January and September 2017 were tested for neutralizing antibodies against JEV strains JaGAr01 (genotype 3) and Muar (genotype 5). Sera collected from six wild boars between June and July 2022 were tested. The seroprevalence rates of neutralizing antibodies against JaGAr01 and Muar were 38.8% and 24.6%, respectively. High anti-JEV neutralizing antibody titers of ≥320 were identified in 16 residents, including 3 younger than 6 years with prior JEV vaccination, 2 in their 40s, and 11 older than 70. However, no anti-JEV-specific IgM was detected. Residents who engaged in outdoor activities had higher anti-JEV antibody titers. Sera from wild boars were negative for JEV RNA, but four of six samples contained neutralizing antibodies against JEV. Therefore, JEV transmission continues on Tsushima Island, even in the absence of pig farms, and wild boars might serve as the amplifying hosts.

Spatiotemporal analysis of land-use change and its impact on surface runoff in Tsushima Island, Japan

Spatiotemporal analysis of land-use change and its impact on surface runoff in Tsushima Island, Japan

A new species of Homalernis Meyrick, 1908 (Lepidoptera, Tortricidae, Tortricinae) represents the first record of the tribe Schoenotenini in Japan

Homalernis fluctuosa Suzuki & Jinbo, sp. nov., is described and illustrated from Honshu, Shikoku, Kyushu, Tsushima Island, Amamiooshima Island, and Okinawajima Island, Japan. This is not only the first record of the genus Homalernis but also of the tribe Schoenotenini from warm temperate zones in the Palaearctic region. The association of males and females of the new species was confirmed based on the mitochondrial gene cytochrome oxidase submit 1 (COI). We discuss the taxonomic positions of two alleged Homalernis species from Malaysia and the taxonomic position of Homalernis within Schoenotenini.

Occurrence of giant migratory locust Locusta migratoria (Acrididae) on Tsushima Island, Japan

This study focused on the populations of Locusta migratoria (Linnaeus, 1758) on Tsushima Island, Japan, which exhibited the largest mean adult body size when compared to other populations from various climatic regions. Certain individuals, designated as “giant locusts,” displayed exceptionally large sizes, with females and males identified when with head widths surpassing 10.5 mm and 8.0 mm, respectively. The maximum weight recorded for a giant locust was 8.9 g, in contrast to other examined females with the maximum weight ranging from 3.1 to 5.5 g. Notably, giant females exhibited the ability to yield larger egg pods and progeny compared to their counterparts. A positive correlation emerged between body size of adult females and the number of ovarioles. To explore the potential heritability of body size, selection experiments were conducted across two generations. A significant impact of selection on adult body size was apparent at LD 12:12h, whereas this effect was not evident at LD 16:8h. Furthermore, crossing experiments showed that body size at hatching closely resembled that of the female parent or demonstrated dimensions intermediary between the two parents, suggesting a complex genetic basis for the observed body size variations. This study provides no evidence of genetic differentiation between the giant locusts and the other locusts on this island.

Real in virtual or virtual in real? Intersecting virtual and real experience in open-world video games and heritage tourism

ABSTRACT The increasing numbers of open-world games provide a sense of immersion, as if users were in a virtual world, by guaranteeing free movement within that world. One example is Ghost of Tsushima, a game developed by Sucker Punch Productions in the United States and released in 2020. The game was created by adding fictional elements to the historical facts surrounding the Mongol Empire’s invasion of the Japanese island of Tsushima in 1274. The developer implemented a virtual world as close as possible to the truth through thorough historical research into local records. This article aims to investigate the relationship and boundary between real and virtual tourism afforded by realistic virtual worlds, as well as provide a hybrid analysis of community discussions around Ghost of Tsushima on the social media forum Reddit. The community’s posts and comments suggest that the game cultivates a sense of immersion that can generate the desire to experience Tsushima, Japan in real life. However, this study also found that the game’s particular representations shape expectations in a way that influences the nature and extent of tourist initiatives.

Japan’s relations with China and Korea in the Muromachi era

The article describes the main stages and characteristics of Japanese-Korean and Japanese- Chinese relations in the Muromachi era (1333–1573). From an international relations perspective, it is an extremely important period – after six centuries, formal relations with China (Ming) and Korea (Choson) were reestablished (relations with the Korean state of Silla were interrupted in 779; the last Japanese embassy to Tang China was sent in 838), and East Asia in general experienced an explosive growth of international trade. In the early Muromachi period, Japan maintained overseas relations only with Ryukyu. Despite the sincere desire of the Ashikaga shoguns to reestablish formal relations with China (Ming) and Korea (Choson), it happened only at the beginning of the 15th century. The article deals with the main reasons why the restoration process turned out to be so long and complicated. Japan-Ming and Japan- Choson relations had both similarities and their own characteristics. There were also dramatic turns in both Japanese-Chinese and Japanese-Korean relations: breaking of diplomatic relations with Ming China under Shogun Ashikaga Yoshimochi, and even a military invasion of the Tsushima Island by Korean fleet in 1419. In Russian historiography, this topic is almost not developed, and therefore, at this stage, it seems important to characterize the key events and features of the Japanese interaction with the outside world using the example of its main partners, China and Korea. Meanwhile, a number of features of Japan’s interaction with the outside world during the Tokugawa period are rooted in the Muromachi period or inherit common East Asian cultural patterns.

한국 융기문토기의 연대 재고

Raised-design pottery is a type of pottery representative of the early Neolithic period in Korea. Particularly in the southern part of the Korean peninsula, pottery was divided into four types and created a long tradition of pottery lasting about 1,000 years. It is a well-known fact among Neolithic researchers in both countries, Korea and Japan that this type of pottery has been found in many coastal sites in the northwestern Kyushu region in Japan. In particular, the Koshitaka Site on Tsushima Island, Nagasaki Prefecture, is famous for the discovery of many pottery of the first half of the comb-patterned pottery, which is common to the southern part of the Korean peninsula, including Raised-design pottery. We, the Department of Archaeology, Kumamoto University, have conducted excavations at this site four times since 2015, jointly with the Tsushima Board of Education, and have obtained various information about the characteristics of the site that were not well understood until now. This paper examines the revision of the age of Raised-design pottery, one of the results of excavations that could not be fully explained due to the limited number of characters in the previous report, by adding new materials. In analyzing the dating values, we studied the types of charcoal, seeds, and charcoal attached to pottery, examined the presence or absence of a marine reservoir effect by the C value, and performed calibration using IntCal 20 and Marine 20. As a result, the age values indicated by the plant samples showed the most reliable age values, and in the case of Korean Neolithic sites located on the coast, it was reconfirmed that the influence of the marine reservoir effect is large. Although Raised-design pottery in southern Korea and Tsushima follow almost the same pattern changes, we concluded that the existing chronology of Raised-design pottery in Korea is about 400 years older than the new chronology based on reliable age values and that a revision is necessary.

Taxonomic reassessment of salamanders (genus Hynobius) from Tsushima Islands, Japan, with a resurrection of Hynobius tagoi Dunn, 1923 (Amphibia: Caudata).

To clarify the taxonomic status of salamanders from Tsushima Islands, Japan, we examined two species of salamanders, Hynobius tsuensis and Hynobius sp. from Tsushima Islands, and compared them with H. nebulosus from Kyushu. We found that the three taxa differ from each other in nuclear DNA, adult morphology, and egg-sac shape, and consider them to be independent species. Based on the investigation of type specimens of the synonyms, we identified Hynobius sp. as H. tagoi Dunn, 1923 and redescribe it herein. Also, we designate a neotype for H. tsuensis and redescribe H. tsuensis. The distribution areas of the two species partly overlap but they were distinguishable by their body colorations: H. tsuensis has uniformly blackish tail sides and a distinct yellow stripe on the upper tail edge; whereas H. tagoi has brown tail sides with numerous dark stippling and without a distinct yellow stripe on the upper tail edge.

Neoplasia in captive Tsushima leopard cats (Prionailurus bengalensis euptilurus)

The Tsushima leopard cat (Prionailurus bengalensis euptilurus) is a subspecies of the mainland leopard cat that lives on the small island of Tsushima, Japan. Captive breeding has been attempted in zoos in Japan because only approximately 100 animals remain in the wild and the Tsushima leopard cat is an endangered species. There are very few reports on diseases, including tumours, of this species. We analysed the deaths of 58 Tsushima leopard cats and confirmed that nine had neoplastic disease. The average age at death of the animals with neoplasia was 14 years and tumours were the primary cause of death in all animals. Eight of the nine cases involved primary tumours of the pancreas, liver, gallbladder, tongue and salivary glands, suggesting that Tsushima leopard cats may have a predilection for digestive system tumours. This is the first report of neoplastic disease in the Tsushima leopard cat.

The Japanese Neolithic: The Sea at the Origins of the Jōmon Culture and the Iriae Archaeological Excavations on Tsushima Island

Archaeology & Anthropology:Open Access The Japanese Neolithic: The Sea at the Origins of the Jōmon Culture and the Iriae Archaeological Excavations on Tsushima Island Daniele Petrella* International Research Institute for Archaeology and Ethnology, Italy *Corresponding author: Daniele Petrella, International Research Institute for Archaeology and Ethnology, Via Mezzocannone 109, Naples, Italy Submission: March 06, 2023Published: March 28, 2023 DOI: 10.31031/AAOA.2023.04.000612 ISSN: 2577-1949 Volume4 Issue4

Feline Foamy Virus Transmission in Tsushima Leopard Cats (Prionailurus bengalensis euptilurus) on Tsushima Island, Japan.

Tsushima leopard cats (TLC; Prionailurus bengalensis euptilurus) only inhabit Tsushima Island, Nagasaki, Japan and are critically endangered and threatened by infectious diseases. The feline foamy virus (FFV) is widely endemic in domestic cats. Therefore, its transmission from domestic cats to TLCs may threaten the TLC population. Thus, this study aimed to assess the possibility that domestic cats could transmit FFV to TLCs. Eighty-nine TLC samples were screened, and FFV was identified in seven (7.86%). To assess the FFV infection status of domestic cats, 199 domestic cats were screened; 14.07% were infected. The phylogenetic analysis revealed that the FFV partial sequence from domestic cats and TLC sequences clustered in one clade, suggesting that the two populations share the same strain. The statistical data minimally supported the association between increased infection rate and sex (p = 0.28), indicating that FFV transmission is not sex dependent. In domestic cats, a significant difference was observed in FFV detection in feline immunodeficiency virus (p = 0.002) and gammaherpesvirus1 infection statuses (p = 0.0001) but not in feline leukemia virus infection status (p = 0.21). Monitoring FFV infection in domestic cats and TLC populations is highly recommended as part of TLC surveillance and management strategies.

Numerical estimation of the hotspot positions of floating plastic debris in the Tsushima Strait using the adjoint marginal sensitivity method

Marine plastic has become a global problem and the situation is also very serious in the Sea of Japan. Tsushima Island, Japan is one of the areas encountering severe problems with beach plastics, followed by many other beaches facing the Sea of Japan. The total cost of beach cleanup is nontrivial for municipalities facing the sea. Offshore recovery of floating large debris at its concentrated areas, or hotspots, could be less burdensome and more economical than the beach cleanup. For this purpose, it is necessary to confirm the presence of hotspots in a target sea, and identifying offshore hotspots using a suitable numerical method can aid in the recovery of large floating plastics. In this study, we estimated the hotspot position of floating plastic bags in the Tsushima Strait using the adjoint marginal sensitivity method and measurement data in the Sea of Japan. The numerical results were found to be moderately comparable with satellite images using indices of large floating plastics.

Increased Risk of Infection with Severe Fever with Thrombocytopenia Virus among Animal Populations on Tsushima Island, Japan, Including an Endangered Species, Tsushima Leopard Cats.

To investigate the seroprevalence of severe fever with thrombocytopenia syndrome (SFTS) among wild and companion animals on Tsushima Island, Japan, SFTS virus (SFTSV)-specific ELISA and virus-neutralizing tests were conducted on 50 wild boars, 71 Sika deer, 84 dogs, 323 domestic cats, and 6 Tsushima leopard cats. In total, 1 wild boar (1.8%), 2 dogs (2.4%), 7 domestic cats (2.2%), and 1 Tsushima leopard cat (16.7%) were positive for anti-SFTSV antibodies. Among the 11 positive animals, 10 were collected after 2019, and all were found on the southern part of the island. SFTSV, thus far, seems to be circulating within a limited area of Tsushima Island. To protect humans and animals, including endangered Tsushima leopard cats, from SFTSV infection, countermeasures are needed to prevent the spread of SFTSV on Tsushima Island.

Preliminary research on the relationship between tick and deer abundance on Tsushima Islands, western Japan

Preliminary research on the relationship between tick and deer abundance on Tsushima Islands, western Japan

죠몬시대 후기 북부큐슈의 묘제와 한반도의 관계

This paper provides an overview of the burials of the late Jomon period in Kyushu, and examines the influence of the Korean Peninsula. But, even on Tsushima Island(対馬島), which had the most contact with the Korean Peninsula, the clear relationship couldn't pointed out. In the Jomon period, there were few exchanges related to spiritual sphere between Korea and Japan, so it is thought that the influence on the burials was small. However, it is necessary to continue to review the problem of stone covered burials(覆石葬) and shell bracelets. The Kogawashima (小川島) Shell midden Tomb No. 4 appears to have the pottery of the latest phase of Korean Neolithic, but it is assumed to be related to Tsushima Island. It is also possible to point out the possibility that pottery of the Korean Peninsula may have had a symbolic meaning to those traveling to and from the Islands around the Genkainada(玄界灘).

縄文時代後半期北部九州の墓制と韓半島との関係

This paper provides an overview of the burials of the late Jomon period in Kyushu, and examines the influence of the Korean Peninsula. But, even on Tsushima Island(対馬島), which had the most contact with the Korean Peninsula, the clear relationship couldn't pointed out. In the Jomon period, there were few exchanges related to spiritual sphere between Korea and Japan, so it is thought that the influence on the burials was small. However, it is necessary to continue to review the problem of stone covered burials(覆石葬) and shell bracelets. The Kogawashima (小川島) Shell midden Tomb No. 4 appears to have the pottery of the latest phase of Korean Neolithic, but it is assumed to be related to Tsushima Island. It is also possible to point out the possibility that pottery of the Korean Peninsula may have had a symbolic meaning to those traveling to and from the Islands around the Genkainada(玄界灘).

Investigating terrestrial and oceanic environmental conditions to identify possible factors influencing seaweed bed distribution in Tsushima Islands, Japan

A decrease in seaweed beds has been a serious problem in the coastal areas of the Tsushima Islands, and other areas in Japan and worldwide. In the Tsushima Islands, certain coastal areas in the northeastern (NE) area contain seaweed beds, while their depletion is of serious concern in other areas. The influence of terrestrial and oceanic waters, and their relationship with seaweed bed distribution in the Tsushima Islands, Japan was examined to understand the marine environmental conditions. We conducted comprehensive investigations based on water sampling and their analyses in this study. Water qualities including total iron, dissolved iron, nitrate nitrogen, nitrite nitrogen and phosphate-phosphorus, and carbon stable isotope ratios of particulate organic matter (POM) in seawaters and river waters in the NE and southwestern (SW) areas of the Tsushima Islands were seasonally monitored. The seawater quality results showed no distinct differences between the NE and SW areas. This observation indicates that the materials, including iron supplied from terrestrial areas, were not the primary factors characterizing the seaweed bed distribution, despite the seaweed bed distribution in the NE area being larger than that in the SW area. Meanwhile, the seasonal variations in the δ13C values of POM in the NE area were more evident than those in the SW area. This implies the significant contribution of oceanic POM in the NE area, possibly due to the existence of island-induced current and cyclonic eddies, and its influence on the coastal water qualities. These environmental properties have been suggested to potentially influence the characteristics of seaweed bed distribution in the Tsushima Islands.

Comparison of the Genetic Diversity of the Captive and Wild Populations of the Tsushima Leopard Cat Using a GRAS-Di Analysis.

Simple SummaryThe Tsushima leopard cat (Prionailurus bengalensis euptilurus) is exclusively found on the Tsushima Island in Japan; however, its population has been declining in recent years and is in danger of extinction. Hence, effort is underway for both in situ and ex situ conservation. Genetic management is also important in the management of captive populations, and various studies are being conducted regarding the same. In our previous study, we developed a reference genome of the Tsushima leopard cat and used GRAS-Di analysis, a genome-wide analysis, to genetically evaluate the wild populations. In this study, we attempted to improve the Tsushima leopard cat reference genome and compared the captive and wild populations by GRAS-di analysis. The results showed that the captive population had almost the same genetic diversity as the wild population and managed to remain in good condition.The Tsushima leopard cat (Prionailurus bengalensis euptilurus) (TLC) is a regional population of the Amur leopard cat (P. bengalensis euptilurus) that lives only on the Tsushima Island in Japan and is threatened with extinction. Because the TLC population is small, genetic management is important. In this study, we obtained the draft genome of the TLC and identified single-nucleotide polymorphism (SNP) markers using a genotyping by random amplicon sequencing-direct (GRAS-Di) analysis. We genotyped 31 captive individuals and 50 wild individuals, of which 48 were from a previous study. The identified SNPs were used to clarify the genetic diversity and genetic structure of the wild and captive populations of the TLC. The size of the genome was estimated to be about 2.42 Gb. The number of SNP markers developed was 139, and although PID and probability of exclusion obtained using these SNP markers were not as high as those reported in the studies of other wild species, these SNP markers could be used to identify individuals and parentage. Moreover, the genetic diversity indices of the captive population were similar to those of the wild population. These SNP markers will be useful for understanding the ecology of the TLC and planning conservation strategies.

SURVEY OF ANCIENT TOMB-LIKE TOPOGRAPHY IN THE NORTH CAPE OF ORONO-SHIMA ISLAND －ORIGINS OF THE ANCIENT TOMB SYSTEM IN JAPAN?－

Abstract. Orono-shima Island is a remote Island in the Tsushima Strait, it is 4.3km around. Since ancient times, it has been a landmark when crossing from the Korean Peninsula to Japanese archipelago via Tsushima Island and Iki Island. However, large-scale ruins and burial mounds are not known on Orono-shima Island until now. During my four years on the island, the author walked all over the island for terrain survey. As a result, the author discovered a topography like keyhole tomb which is a characteristic Japanese burial mound, on the northern cape of the island. It could be up to 150m in size, one of the largest around Kyusyu Island. There is no burial mound comparable to this on a remote island in Japan. Therefore, we created a 3D image using a drone Laser surveying of this terrain and we compared the results with another keyhole tomb. In addition, we analyzed the image of infrared radiation of Orono-shima Island took by Landsat8. In conclusion, it was speculated that this topography was the prototype of the oldest type of keyhole cairn tomb in Japan. The topography of the northern part of Orono-shima could be regaining the missing link between the cairn on the Korean Peninsula of the first century and the oldest type of keyhole cairn tomb in Japan of the third century.

Differentiated historical demography and ecological niche forming present distribution and genetic structure in coexisting two salamanders (Amphibia, Urodela, Hynobiidae) in a small island, Japan.

BackgroundThe climatic oscillations in the Quaternary period considerably shaped the distribution and population genetic structure of organisms. Studies on the historical dynamics of distribution and demography not only reflect the current geographic distribution but also allow us to understand the adaption and genetic differentiation of species. However, the process and factors affecting the present distribution and genetic structure of many taxa are still poorly understood, especially for endemic organisms to small islands.MethodsHere, we integrated population genetic and ecological niche modelling approaches to investigate the historical distribution and demographic dynamics of two co-existing salamanders on Tsushima Island, Japan: the true H. tsuensis (Group A), and Hynobius sp. (Group B). We also examined the hypothesis on the equivalency and similarity of niches of these groups by identity and background tests for ecological niche space.ResultsOur result showed that Group A is considered to have undergone a recent population expansion after the Last Glacial Maximum while it is unlikely to have occurred in Group B. The highest suitability was predicted for Group A in southern Tsushima Island, whereas the northern part of Tsushima Island was the potential distribution of Group B. The results also suggested a restricted range of both salamanders during the Last Interglacial and Last Glacial Maximum, and recent expansion in Mid-Holocene. The genetic landscape-shape interpolation analysis and historical suitable area of ecological niche modelling were consistent, and suggested refugia used during glacial ages in southern part for Group A, and in northern part of Tsushima Island for Group B. Additionally, we found evidence of nonequivalence for the ecological niche of the two groups of the salamanders, although our test could not show either niche divergence or conservatism based on the background tests. The environmental predictors affecting the potential distribution of each group also showed distinctiveness, leading to differences in selecting suitable areas. Finally, the combination of population genetics and ecological modeling has revealed the differential demographic/historical response between coexisting two salamanders on a small island.