Kumamoto Prefecture Research Articles

Food sources are more important than biomagnification on mercury bioaccumulation in marine fishes

Marine animals often accumulate various harmful substances through the foods they ingest. The bioaccumulation levels of these harmful substances are affected by the degrees of pollution in the food and of biomagnification; however, which of these sources is more important is not well-investigated for mercury (Hg) bioaccumulation. Here we addressed this issue in fishes that inhabit the waters around Minamata Bay, located off the west coast of Kyushu Island in Kumamoto Prefecture, Japan. The total Hg concentration (hereafter [THg]) and carbon and nitrogen stable isotope ratios (δ13C and δ15N) were analyzed in the muscle tissue of 10 fish species, of which more than five individuals were caught by gillnet. Except one species, each was separated into two trophic groups with respective lower and higher δ13C values ranging from −17‰ to −16‰ and −15‰ to −14‰, which suggested that the fishes depended more on either phytoplankton- and microphytobenthos-derived foods (i.e., pelagic and benthic trophic pathways), respectively. Linear mixed effects models showed that the Hg levels were significantly associated with both δ15N and the differences in the trophic groups. [THg] increased with δ15N (i.e., indicative of higher trophic levels), but the slopes did not differ between the two trophic groups. [THg] was significantly higher in the group with higher δ13C values than in those with lower δ13C values. The effect size from marginal R squared (R2) values showed that the variation in [THg] was strongly ascribed to the trophic group difference rather than δ15N. These results suggest that the substantial Hg bioaccumulation in the fishes of Minamata Bay is mainly an effect of ingesting the microphytobenthos-derived foods that contain Hg, and that the subsequent biomagnification is secondary.

Detailed mapping of surface ruptures associated with the 2016 Kumamoto earthquake and faulting history of the conjugated fault in Dozon, Mashiki Town, Kumamoto Prefecture

Detailed mapping of surface ruptures associated with the 2016 Kumamoto earthquake and faulting history of the conjugated fault in Dozon, Mashiki Town, Kumamoto Prefecture

Recent efforts about countermeasures for sediment-related disaster in Kumamoto Prefecture

Recent efforts about countermeasures for sediment-related disaster in Kumamoto Prefecture

ミカン市場の環境変化と三角産地の展開

This study investigates the Misumi production area in the Kumamoto prefecture, an emerging citrus production area led by the Misumi Agricultural Cooperative Society (hereinafter referred to as the Misumi region).

Sediment disasters in Kumamoto Prefecture by a heavy rainfall in July 2020

Sediment disasters in Kumamoto Prefecture by a heavy rainfall in July 2020

Construction of Multi-regional Input-Output table in Kumamoto Prefecture and its Analysis

熊本県産業連関表を基に，ノンサーベイアプローチにより県内を熊本市，県北，県南の三地域に分割し，県外を加えた四地域間産業連関表を作成した．そして，それを用いて当該地域間の経済構造及び「くまモン」関連グッズ売上による経済波及効果の分析を行った．その結果，熊本市は都市型産業，県北は製造業，県南は電力・ガス・熱供給に特化していることが示された．地域間交易を見ると，熊本市は県外からの製造業製品の移入及びサービス業の県内移出，県北はサプライチェーンを通じた県外・海外との製造業製品取引，県南は電力・ガス・熱供給の県内移出がそれぞれ大きかった．また，「くまモン」関連グッズ売上1,409億円の経済波及効果は熊本市内648億円，県北556億円，県南636億円，県外1,287億円の計3,128億円と推計され，県内外に大きな効果をもたらすことが示された．

熊本県西原村布田における布田川断層の2016年熊本地震（Mw7.0）時上下変位と活動性

熊本県西原村布田における布田川断層の2016年熊本地震（Mw7.0）時上下変位と活動性

Hydrological changes after the 2016 Kumamoto earthquake, Japan

The 2016 Kumamoto earthquake, whose main shock was an M7.3 event on April 16, 2016, 28 h after a foreshock of M6.5, caused severe damage in and around Kumamoto Prefecture, Japan. It also caused postseismic hydrological changes in Kumamoto Prefecture. In this study, we analyzed daily streamflow data collected by eight observation stations from 2001 to 2017 in regions that experienced strong ground motion during the 2016 Kumamoto earthquake. We also surveyed 11 water springs in the region several times after the main shock. Streamflow had no or slight change immediately after the earthquake; however, large increases were recorded at some of the eight stations following a heavy rainfall that occurred 2 months after the earthquake. A decrease in the water-holding capacity of the catchment caused by earthquake-induced landslides can explain this delayed streamflow increase. Conversely, earthquake-related changes to the spring flow rate were not so clear. Water temperature and chemical composition of spring waters were also hardly changed. Only the concentration of NO3−, which is usually considered to be supplied from the surface, changed slightly just after the earthquake. These results show that the postseismic hydrological changes were caused mainly by earthquake-induced surface phenomena and that there was little contribution from hydrothermal fluid.

Clinical Features of Patients With Acute Aortic Dissection After an Earthquake: Experience from the Kumamoto Earthquake 2016.

While there is a concern about the increase in the occurrence of acute aortic dissection (AAD) caused by the worsening of hypertension, mental stress, etc., there is a lack of data regarding the influence of disasters on this event. The aim of this study was to address this issue in the acute-subacute phase after the Kumamoto Earthquake occurred on 14 April 2016. We retrospectively investigated the impacts of the Kumamoto Earthquake on various cardiovascular diseases, including AAD, utilizing the medical records of patients in 16 hospitals in Kumamoto Prefecture during the period from 14 April to 30 June (78 days) in 2014, 2015, 2016, and 2017. The occurrence of heart failure and venous thromboembolism increased significantly in the acute-subacute phase after the earthquake. When comparing the earthquake year (2016) to the non-earthquake years (2014, 2015, and 2017), the difference in the occurrences and mortalities of AADs were not significant. When other characteristics of the patients were compared between the earthquake year and the non-earthquake years, there were no differences. It might be possible that the Kumamoto Earthquake did not affect the incidence of AAD or deaths from AAD, possibly because the climate was mild and the preventive efforts based on previous experience were successful. University Hospital Medical Information Network (UMIN)-CTR (http://www.umin.ac.jp/ctr/). UMIN000023864. Opt-out materials were available at the following website: http://www.kumadai-junnai.com/home/wp-content/uploads/shinsai.pdf.

Detection of Earthquake-Induced Landslides during the 2018 Kumamoto Earthquake Using Multitemporal Airborne Lidar Data

A series of earthquakes hit Kumamoto Prefecture, Japan, continuously over a period of two days in April 2016. The earthquakes caused many landslides and numerous surface ruptures. In this study, two sets of the pre- and post-event airborne Lidar data were applied to detect landslides along the Futagawa fault. First, the horizontal displacements caused by the crustal displacements were removed by a subpixel registration. Then, the vertical displacements were calculated by averaging the vertical differences in 100-m grids. The erosions and depositions in the corrected vertical differences were extracted using the thresholding method. Slope information was applied to remove the vertical differences caused by collapsed buildings. Then, the linked depositions were identified from the erosions according to the aspect information. Finally, the erosion and its linked deposition were identified as a landslide. The results were verified using truth data from field surveys and image interpretation. Both the pair of digital surface models acquired over a short period and the pair of digital terrain models acquired over a 10-year period showed good potential for detecting 70% of landslides.

Tourism and natural disaster management process: perception of tourism stakeholders in the case of Kumamoto earthquake in Japan

ABSTRACT Tourism has a reciprocal relationship with natural disasters. The study aims to investigate the role of tourism as a strategy in the disaster phases based on (2001. Towards a framework for tourism disaster management. Tourism Management, 22, 135–147) and Ritchie (2004. Chaos, crises and disasters: A strategic approach to crisis management in the tourism industry. Tourism Management, 25 , 669–683)’s disaster management frameworks in the case of the earthquake occurred in Kumamoto Prefecture in Japan in April 2016. The analysis was based on interviews with twelve informants and stakeholders in tourism development collected in Kumamoto in summer 2018. The results suggest that the tourism industry contributes differently across the phases of a disaster but is mainly significant in terms of information provisions, communications and emergency accommodations for tourists. More fundamental changes may be observed in the long-term recovery and resolution phases, whereby tourism is most important in information collection, experience learning in disaster, institutional reform and strategy of sustainable tourism development and poster-disaster destination marketing. The study further advances the existing disaster management framework through the enrichment of knowledge from tourism stakeholder perspective. Empirically, the research findings inform tourism development and sustainability strategy of Kumamoto area after a rarely occurred earthquake disaster. Highlights The significance of tourism’s contributions to all phases of the disaster process is different. The tourism industry mainly contributes to information provisions, communications, and preparation targeting at tourists. Tourism can function in an emergency to provide tourists with news about safety, immediate evacuation and emergency accommodation. In long-term recovery, tourism contributes to more fundamental changes in initiating strategy of sustainable tourism development.

Perinatal self-report of thoughts of self-harm, depressive symptoms, and personality traits: Prospective study of Japanese community women.

The aim of this study was to identify women with thoughts of self-harm preceded by suicidal ideation, during the perinatal period, on cluster analysis and to clarify their psychological correlates. A secondary analysis was conducted using the data from a longitudinal study involving 18 obstetric clinics between 2011 and 2012 in Kumamoto Prefecture (Japan). Self-administered questionnaires including demographic data, Edinburgh Postnatal Depression Scale, Temperament and Character Inventory, and the Postnatal Bonding Questionnaire were distributed during the third trimester of pregnancy (wave 1), at 5 days (wave 2), and 1 month postpartum (wave 3). On cluster analysis using the data of participants who answered all observational points, the participants were divided into two groups: cluster 1, normal (n = 201); and cluster 2, thoughts of self-harm (n = 42). Low self-directedness, low cooperativeness, higher anxiety, depression, and lack of affection and anger and rejection towards the baby were associated with cluster 2. The finding that low self-directedness and low cooperativeness were related to the cluster 2 group suggests that immature personality traits may work as a predisposing factor mediating between anxiety, depression and thoughts of self-harm.

Mercury speciation in preserved historical sludge: Potential risk from sludge contained within reclaimed land of Minamata Bay, Japan

In the latter half of the 1950s, a large amount of methylmercury (MeHg) was discharged directly into Minamata Bay, Japan by a chemical factory, resulting in the contamination of the fish and shellfish. Ultimately, an outbreak of MeHg intoxication, called Minamata disease, occurred. From 1977 to 1988, the Kumamoto Prefectural Government dredged and transferred sediments exceeding 25 μg/g of total mercury (THg, dry basis) into a strictly segregated area of the bay near the wastewater outlet, then this area was landfilled. We conducted analyses of the mercury speciation in preserved Minamata Bay sludge samples (collected from inside of the bay prior to the termination of the remediation project; n=4) and recent Minamata Bay sediments (collected outside the dredging area of the bay; n=5) to evaluate the potential risk of the sludge/sediment leakage from the reclaimed land to the Minamata Bay. Median THg (dry basis) concentrations were 241 μg/g for the preserved sludge, 6.1 μg/g for the recent Minamata Bay sediments, and 0.18 μg/g for a single control sample; median MeHg concentrations (percentage of MeHg in THg) were 108 ng/g (0.031%), 3.7 ng/g (0.12%), and 0.71 ng/g (0.41%), respectively. In all the samples, the MeHg% decreased exponentially with increasing THg concentration. The extractability of THg from each sample into seawater was shown to be much lower than that of MeHg. The extracted MeHg was 0.86% for the preserved sludge, 4.57% for the recent Minamata Bay sediments, and 7.89% for the control. The predominant chemical form of mercury in the preserved sludge containing the highest THg concentration was found to be stable β-mercury sulfide (HgS) based on transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) and X-ray absorption fine structure (XAFS) analyses.

Eucoleus garfiai (Gállego et Mas-Coma, 1975) (Nematoda: Capillariidae) infection in wild boars (Sus scrofa leucomystax) from the Amakusa Islands, Japan

We examined lingual tissues of Japanese wild boars (Sus scrofa leucomystax) captured in the Amakusa Islands off the coast of Kumamoto Prefecture. One hundred and forty wild boars were caught in 11 different locations in Kamishima (n = 36) and Shimoshima (n = 104) in the Amakusa Islands, Japan between January 2016 and April 2018. Lingual tissues were subjected to histological examinations, where helminths and their eggs were observed in the epithelium of 51 samples (36.4%). No significant differences in prevalence were observed according to maturity, sex or capture location. Lingual tissues positive for helminth infection were randomly selected and intact male and female worms were collected for morphological measurements. Based on the host species, site of infection, and morphological details, we identified the parasite as Eucoleus garfiai (Gállego et Mas-Coma, 1975) Moravec, 1982 (syn. Capillaria garfiai). This is the first report from outside Europe of E. garfiai infection in wild boars. Phylogenetic analysis of the parasite using the 18S ribosomal RNA gene sequence confirmed that the parasite grouped with other Eucoleus species, providing additional nucleotide sequence for this genus. Since wild boar populations are widely distributed in Japan, continuing surveys on the epidemiology of the parasite and identifying possible intermediate host candidates are crucial for elucidating the transmission route of the parasite.

Genome-Wide Association Studies (GWAS) for Yield and Weevil Resistance in Sweet potato (Ipomoea batatas (L.) Lam).

We apply the GWAS to sweet potato genome, and identified the SNPs associated with yield and weevil resistance. The sweet potato (Ipomoea batatas (L.) Lam) is a highly heterozygous, outcrossing, polyploid species, which presents challenges for genetic analysis. Therefore, we considered that genome-wide association studies (GWAS) may be applied to the study of the sweet potato genome. The yield of two sweet potato varieties [Purple Sweet Lord (PSL) and 90IDN-47] was assessed at two locations (Kumamoto and Okinawa prefectures) in Japan in 2013 and the yield scores were used for GWAS. The results showed that there were several single nucleotide polymorphisms (SNP) above the significance thresholds in PSL; two peaks were detected in Kumamoto and Okinawa on the Ib03-3 and Ib01-4 linkage groups of PSL, respectively. As for 90IDN-47, one relatively high peak was detected in Kumamoto on the Ib13-8 linkage group. Interestingly, although high peaks above significance thresholds were detected in Kumamoto and Okinawa in PSL, the peaks were located in different linkage groups. This result suggests that the genetic regions controlling yield may change in response to environmental conditions. Additionally, we investigated the degree of weevil damage to the plants, which is the greatest problem in sweet potato cultivation in Okinawa. In this experiment, no SNPs were identified above the significance thresholds. However, one relatively high peak was found in the 90IDN-47 genotype, which showed resistance to weevils. On the other hand, one relatively high peak was also detected in the PSL genotype, which showed susceptibility to weevils. These results suggest that two regions could affect weevil resistance and may contain the gene(s) controlling weevil resistance.

Relationships between perceived health status and ambient air quality parameters in healthy Japanese: a panel study

BackgroundThere has been growing global concern about air pollution due to its great risk to public health. In Japan, although industrial- and traffic-related air pollution has been decreasing, concerns about particulate matter air pollution has been growing in recent years. In this study, we examined the effects of air pollution on symptoms and the health status of healthy subjects in Japan.MethodsParticipants (n = 2887) who visited healthcare centers in Kumamoto or Niigata prefectures in February from 2010 to 2015 were asked to fill out a questionnaire, which was a self-completed booklet containing questions on the characteristics of participants, their respiratory symptoms, and questionnaires on their health status in February, May, and July. Generalized estimating equation analyses were performed to predict the factors associated with the symptoms and health status using two-week averages of air quality parameters obtained from 49 monitoring stations as independent variables.ResultsOnly allergy was associated with air quality in both areas. Prevalence of the other respiratory symptoms were correlated with air quality only in Kumamoto. The health statuses including the ‘physical fitness’, ‘daily activities’, and ‘social activities’ domains were related only to time spent outdoors. The ‘overall health’ was associated with time spent outdoors and concentrations of nitrogen dioxide and suspended particulate matters (SPM) in Kumamoto, and with temperatures and SPM in Niigata. The ‘pain’ score was correlated with temperature and carbon monoxide concentration only in Kumamoto. In Kumamoto, the ‘quality of life (QoL)’ was worse in those who spent shorter hours outdoors, were exposed to lower humidity, higher concentrations of oxidants, SPM, and PM2.5, and who experienced more Asian sand dust (ASD) events. In Niigata, a worsened ‘QoL’ was associated with time spent outdoors, temperature, and SPM.ConclusionsThe associations between air quality and the health status was found mainly in the comprehensive domain of the health status such as ‘overall health’ and ‘QoL’. The effect of short-term exposure to larger particles, such as SPM, on health status was observed when compared to smaller particles such as PM2.5 and gaseous pollutants.

Epidemiology of post-earthquake dizziness in Kumamoto prefecture

Epidemiology of post-earthquake dizziness in Kumamoto prefecture

Activities to support victims of the Kumamoto earthquakes by the Mifune Public Health Center in the Kumamoto prefecture: Infection control, prevention of food poisoning, and management of nutrition and daily meals

Activities to support victims of the Kumamoto earthquakes by the Mifune Public Health Center in the Kumamoto prefecture: Infection control, prevention of food poisoning, and management of nutrition and daily meals

Features and Paleoecological Significance of the Shark Fauna from the Upper Cretaceous Hinoshima Formation, Himenoura Group, Southwest Japan

The shark fauna of the Upper Cretaceous Hinoshima Formation (Santonian: 86.3–83.6 Ma) of the Himenoura Group (Kamiamakusa, Kumamoto Prefecture, Kyushu, Japan) was investigated based on fossil shark teeth found at five localities: Himedo Park, Kugushima, Wadanohana, Higashiura, and Kotorigoe. A detailed geological survey and taxonomic analysis was undertaken, and the habitat, depositional environment, and associated mollusks of each locality were considered in the context of previous studies. Twenty-three species, 15 genera, 11 families, and 6 orders of fossil sharks are recognized from the localities. This assemblage is more diverse than has previously been reported for Japan, and Lamniformes and Hexanchiformes were abundant. Three categories of shark fauna are recognized: a coastal region (Himedo Park; probably a breeding site), the coast to the open sea (Kugushima and Wadanohana), and bottom-dwelling or near-seafloor fauna (Kugushima, Wadanohana, Higashiura, and Kotorigoe). The shark fauna of the Hinoshima Formation is similar to that of the Yezo and Futaba groups, and also to faunas from Angola, Australia, and Antarctica. However, based on the composition of taxa, the fauna differs from that of the Upper Cretaceous shark fauna of the Western Interior Seaway and Europe. The Upper Cretaceous shark fauna of Japan, including the Hinoshima Formation, contained active pelagic (Squalicorax and Cretoxyrhina mantelli) and bentho-pelagic (e.g. Notidanodon, Chlamydoselachus, Sphenodus) predators. These taxa probably coexisted, as they occupied different ecological niches. The characteristics of the Late Cretaceous shark fauna in Japan are similar to those of the contemporaneous Southern Hemisphere fauna (e.g. Angola, Australia, and Antarctica). This shows that the characteristic shark fauna (e.g. Notidanodon, Chlamydoselachus, Sphenodus) of the Southern Hemisphere had spread to the middle latitudes of the Northern Hemisphere by the Late Cretaceous.

地域内外における持続的交流システムの形成 : 観光・地域振興へ向けた人づくり : 熊本県氷川町宮原のまちづくりを事例として

地域内外における持続的交流システムの形成 : 観光・地域振興へ向けた人づくり : 熊本県氷川町宮原のまちづくりを事例として