Researchers Database

WATANABE, Kozo

    Center for Marine Environmental Studies Professor
Contact: watanabe.kozo.mjehime-u.ac.jp
Last Updated :2021/03/05

Researcher Information

Degree

  • Doctor of Engineering(2005/03 Tohoku University, Japan)

URL

Research funding number

  • 80634435

ORCID ID

J-Global ID

Profile

  • 【Biodiversity】Development of Next-Generation Sequencing (NGS)-based Technologies for Accurate, Rapid and Cost effective Assessment of Freshwater Species and Genetic Diversities

    【Evolution】Adaptive Evolution of Freshwater Biodiversity at Gene and Species Levels Associated with Spatio-temporal Environmental Variation (e.g. Climate Change)

    【Eco-Health】 Molecular Genetic Approach for Control of Vector-borne Diseases (e.g. Population Genetics and Virus Surveys of Dengue Mosquito in the Philippines and Indonesia)

    【International】 Study Fields Widely Cover Japan, Italian Alps, Swiss, Indonesia and Philippines. Active International Collaboration!

    Keywords: Phylogenetics, Population Genetics, Freshwater Ecosystems, Vector-borne Diseases, Next-Generation Sequencing (NGS)

Research Interests

  • DNA   進化生物学   系統発生   底生動物   河川生態学   分子生態学   デング熱   熱帯感染症   次世代シークエンサー   土木環境システム   生物多様性   分類学   ノロウイルス   

Research Areas

  • Social infrastructure (civil Engineering, architecture, disaster prevention) / Civil engineering (environmental systems)
  • Environmental science/Agricultural science / Social-ecological systems

Academic & Professional Experience

  • 2020/04 - Today  Ehime UniversityCenter for Marine Environmental Studies (CMES)Professor
  • 2019/11 - Today  Ehime University Satellite Office Philippinesat De La Salle University Laguna CampusDirector
  • 2019/04 - Today  Ehime UniversityResearch Unit for Environmental and Health Studies in Southeast AsiaDirector
  • 2019/04 - Today  Ehime UniversityEndowed Chair of the Sumitomo Electric Industries Group Corporate Social Responsibility Foundation ‘Eco-epidemiological Control of Mosquito-borne Disease in Southeast Asia"Professor
  • 2018/04 - Today  Yamagata UniversityFaculty of AgricultureVisiting Professor
  • 2017/04 - Today  De La Salle University, Philippines,Biological Control Research Unit (BCRU)Visiting Professor
  • 2017/04 - 2020/03  Ehime UniversityCenter for Marine Environmental StudiesProfessor
  • 2017/04 - 2020/03  Ehime UniversityGraduate School of Science and EngineeringProfessor
  • 2017/08 - 2017/10  Berlin Center for Genomics in Biodiversity Research, GermanyVisiting Professor
  • 2015/10 - 2017/03  De La Salle University, Philippines,Biology Department,Visiting Scholar
  • 2015/04 - 2017/03  Ehime UniversityCenter for Marine Environmental StudiesAssociate Professor
  • 2012/04 - 2017/03  Ehime UniversityGraduate School of Science and EngineeringAssociate Professor
  • 2010/04 - 2012/03  Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB),GermanyEU Marie-Curie Research Fellow
  • 2009/04 - 2010/03  Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), GermanyJSPS postdoctoral fellow for research abroad
  • 2006/04 - 2009/03  Tohoku UniversityGraduate school of engineeringJSPS postdoctoral research fellow
  • 2005/04 - 2006/03  Tohoku UniversityGraduate school of engineeringResearch Assistant
  • 2002/04 - 2005/03  Tohoku UniversityGraduate school of engineeringJSPS research fellow (DC1)

Education

  • 2002/04 - 2005/03  Tohoku University  Graduate school of engineering  Department of civil and environmental engineering, Doctor's course
  • 2000/04 - 2002/03  Tohoku University  Graduate school of engineering  Department of civil and environmental engineering
  • 1996/04 - 2000/03  Tohoku University  Faculty of engineering  Department of civil engineering

Published Papers

  • Megumi Sato, Sumire Ikeda, Reiko Arai, Miwako Kato, Junko Aoki, Akiko Nishida, Kaori Watanabe, Chika Hirokawa, Kozo Watanabe, Maria Angenica F. Regilme, Mami Sato, Marcello Otake Sato, Tsutomu Tamura
    Ticks and Tick-borne Diseases 12 (3) 101683  1877-959X 2021/05 [Peer-reviewed]
     Scientific journal
  • Von Ralph Dane Marquez Herbuela, Tomonori Karita, Thaddeus Marzo Carvajal, Howell Tsai Ho, John Michael Olea Lorena, Rachele Arce Regalado, Girly Dirilo Sobrepeña, Kozo Watanabe
    JMIR Public Health and Surveillance 7 (3) e19034  2021/03 [Peer-reviewed]
     Scientific journal 
    Background While early detection and effective control of epidemics depend on appropriate surveillance methods, the Philippines bases its dengue fever surveillance system on a passive surveillance method (notifications from barangay/village health centers, municipal or city health offices, hospitals, and clinics). There is no available mHealth (mobile health) app for dengue fever that includes all the appropriate surveillance methods in early detection of disease outbreaks in the country. Objective This study aimed to evaluate the usability of the Mozzify app in terms of objective quality (engagement, functionality, aesthetics, information) and app subjective and app-specific qualities and compare total app mean score ratings by sociodemographic profile and self and family dengue fever history to see what factors are associated with high app mean score rating among school-based young adult samples and health care professionals. Individual interviews and focus group discussions were also conducted among participants to develop themes from their comments and suggestions to help structure further improvement and future development of the app. Methods User experience sessions were conducted among participants, and the Mobile Application Rating Scale (MARS) professional and user versions (uMARS) were administered followed by individual interviews and focus group discussions. Descriptive statistical analysis of the MARS and uMARS score ratings was performed. The total app mean score ratings by sociodemographic and dengue fever history using nonparametric mean difference analyses were also conducted. Thematic synthesis was used to develop themes from the comments and suggestions raised in individual interviews and focus group discussions. Results Mozzify obtained an overall >4 (out of 5) mean score ratings in the MARS and uMARS app objective quality (4.45), subjective (4.17), and specific (4.55) scales among 948 participants (79 health care professionals and 869 school-based samples). Mean difference analyses revealed that total app mean score ratings were not significantly different across ages and gender among health care professionals and across age, income categories, and self and family dengue fever history but not gender (P<.001) among the school-based samples. Thematic syntheses revealed 7 major themes: multilanguage options and including other diseases; Android version availability; improvements on the app’s content, design, and engagement; inclusion of users from low-income and rural areas; Wi-Fi connection and app size concerns; data credibility and issues regarding user security and privacy. Conclusions With its acceptable performance as perceived by health care professionals and school-based young adults, Mozzify has the potential to be used as a strategic health intervention system for early detection of disease outbreaks in the Philippines. It can be used by health care professionals of any age and gender and by school-based samples of any age, socioeconomic status, and dengue fever history. The study also highlights the feasibility of school-based young adults to use health-related apps for disease prevention.
  • Maria Angenica F. Regilme, Thaddeus M. Carvajal, Ann–Christin Honnen, Divina M. Amalin, Kozo Watanabe
    PLOS Neglected Tropical Diseases 15 (2) e0009139  2021/02 [Peer-reviewed]
     Scientific journal 
    Dengue is endemic in tropical and subtropical countries and is transmitted mainly by Aedes aegypti. Mosquito movement can be affected by human-made structures such as roads that can act as a barrier. Roads can influence the population genetic structure of Ae. aegypti. We investigated the genetic structure and gene flow of Ae. aegypti as influenced by a primary road, España Boulevard (EB) with 2000-meter-long stretch and 24-meters-wide in a very fine spatial scale. We hypothesized that Ae. aegypti populations separated by EB will be different due to the limited gene flow as caused by the barrier effect of the road. A total of 359 adults and 17 larvae Ae. aegypti were collected from June to September 2017 in 13 sites across EB. North (N1-N8) and South (S1-S5) comprised of 211 and 165 individuals, respectively. All mosquitoes were genotyped at 11 microsatellite loci. AMOVA FST indicated significant genetic differentiation across the road. The constructed UPGMA dendrogram found 3 genetic groups revealing the clear separation between North and South sites across the road. On the other hand, Bayesian cluster analysis showed four genetic clusters (K = 4) wherein each individual samples have no distinct genetic cluster thus genetic admixture. Our results suggest that human-made landscape features such as primary roads are potential barriers to mosquito movement thereby limiting its gene flow across the road. This information is valuable in designing an effective mosquito control program in a very fine spatial scale.
  • Ruslan La Ane, Von Ralph Dane M. Herbuela, Isra Wahid, Andi Susilawaty, Hasanuddin Ishak, Erniwati Ibrahim, Ming-Chih Chiu, Kozo Watanabe
    Research Square (Preprint) 2021/02 Research society 
    Abstract Background: High water demand accompanied with an unreliable piped water supply has forced urban residents to store water in containers. This situation potentially increases the number of breeding sites for mosquito vectors, such as Aedes. Method: This study aimed to test the hypothesis if piped water connection availability, tap water use, and highly stable tap water supply can help minimize the use of water storage containers as well as the presence of larvae and number of adult Aedes mosquitoes. We conducted a community-based entomological survey of 343 households from 36 neighborhoods or Rukun Tetangga in Makassar City, Indonesia. Our model based on the hypothesis was tested by piecewise structural equation modeling analysis. Results: A significant negative correlation was found between the stability of tap water supply and the number of water storage containers (−0.16, P < 0.05). Of the two categories of water storage containers, the unintentional water storage containers demonstrated a significantly (P < 0.001) higher effect on larval prevalence than the intentional one. Further, both container categories have significant indirect effects on the number of adult mosquitoes mediated by larval presence. Conclusion: Improving water supply condition, particularly by assuring a stable tap water supply, could minimize the use of intentional water storage containers. Furthermore, a regular community-wide health education program that targets the elimination of unintentional water storage containers, which can be breeding grounds for Aedes larvae mosquitoes, is necessary.
  • Reiko Arai, Megumi Sato, Miwako Kato, Junko Aoki, Akiko Nishida, Kaori Watanabe, Chika Hirokawa, Sumire Ikeda, Kozo Watanabe, Maria Angenica F. Regilme, Marcello Otake Sato, Tsutomu Tamura
    Scientific Reports 11 2595  2021/01 [Peer-reviewed]
     Scientific journal 
    AbstractJapanese spotted fever, a tick-borne disease caused by Rickettsia japonica, was firstly described in southwestern Japan. There was a suspicion of Rickettsia japonica infected ticks reaching the non-endemic Niigata Prefecture after a confirmed case of Japanese spotted fever in July 2014. Therefore, from 2015 to 2017, 38 sites were surveyed and rickettsial pathogens were investigated in ticks from north to south of Niigata Prefecture including Sado island. A total of 3336 ticks were collected and identified revealing ticks of three genera and ten species: Dermacentor taiwanensis, Haemaphysalis flava, Haemaphysalis hystricis, Haemaphysalis longicornis, Haemaphysalis megaspinosa, Ixodes columnae, Ixodes monospinosus, Ixodes nipponensis, Ixodes ovatus, and Ixodes persulcatus. Investigation of rickettsial DNA showed no ticks infected by R. japonica. However, three species of spotted fever group rickettsiae (SFGR) were found in ticks, R. asiatica, R. helvetica, and R. monacensis, confirming Niigata Prefecture as a new endemic area to SFGR. These results highlight the need for public awareness of the occurrence of this tick-borne disease, which necessitates the establishment of public health initiatives to mitigate its spread.
  • Billy Joel M. Almarinez, Mary Jane A. Fadri, Richard Lasina, Mary Angelique A. Tavera, Thaddeus M. Carvajal, Kozo Watanabe, Jesusa C. Legaspi, Divina M. Amalin
    Insects 12 (1) 26  2021/01 [Peer-reviewed]
     Scientific journal 
    Comperiella calauanica is a host-specific endoparasitoid and effective biological control agent of the diaspidid Aspidiotus rigidus, whose outbreak from 2010 to 2015 severely threatened the coconut industry in the Philippines. Using the maximum entropy (Maxent) algorithm, we developed a species distribution model (SDM) for C. calauanica based on 19 bioclimatic variables, using occurrence data obtained mostly from field surveys conducted in A. rigidus-infested areas in Luzon Island from 2014 to 2016. The calculated the area under the ROC curve (AUC) values for the model were very high (0.966, standard deviation = 0.005), indicating the model’s high predictive power. Precipitation seasonality was found to have the highest relative contribution to model development. Response curves produced by Maxent suggested the positive influence of mean temperature of the driest quarter, and negative influence of precipitation of the driest and coldest quarters on habitat suitability. Given that C. calauanica has been found to always occur with A. rigidus in Luzon Island due to high host-specificity, the SDM for the parasitoid may also be considered and used as a predictive model for its host. This was confirmed through field surveys conducted between late 2016 and early 2018, which found and confirmed the occurrence of A. rigidus in three areas predicted by the SDM to have moderate to high habitat suitability or probability of occurrence of C. calauanica: Zamboanga City in Mindanao; Isabela City in Basilan Island; and Tablas Island in Romblon. This validation in the field demonstrated the utility of the bioclimate-based SDM for C. calauanica in predicting habitat suitability or probability of occurrence of A. rigidus in the Philippines.
  • Faridah, L, S. Ekawardhani, H. L. Wiraswati, N. Fauziah, F. R. Rinawan, W. Mayasarid, K. Watanabe
    Systematic Reviews in Pharmacy 12 (1) 1340 - 1342 2021/01 [Peer-reviewed]
     Scientific journal
  • Thaddeus M. Carvajal, Divina M. Amalin, Kozo Watanabe
    Infection, Genetics and Evolution 87 104676  1567-1348 2021/01 [Peer-reviewed]
     Scientific journal
  • Levente-Péter Kolcsár, Daichi Kato, Maribet Gamboa, Kozo Watanabe
    ZooKeys 1000 71 - 105 1313-2989 2020/12 [Peer-reviewed]
     Scientific journal 
    Japanese species of the genus Nipponomyia Alexander, 1924 are revised. Two new species, Nipponomyia okinawensis Kolcsár &amp; Kato, sp. nov. and N. yakushimensis Kolcsár &amp; Kato, sp. nov. are described from the Ryukyu Islands. Images of habitus and wings, illustrations of male and female terminalia, and distribution maps are provided for the Japanese species. A key to the world species of Nipponomyia is added. DNA barcodes of three Japanese Nipponomyia are provided, representing the first barcodes from the genus.
  • Ming‐Chih Chiu, Bin Li, Kei Nukazawa, Vincent H. Resh, Thaddeus Carvajal, Kozo Watanabe
    Diversity and Distributions 26 (12) 1813 - 1824 1366-9516 2020/12 [Peer-reviewed]
     Scientific journal
  • Ming‐Chih Chiu, Kei Nukazawa, Thaddeus Carvajal, Vincent H. Resh, Bin Li, Kozo Watanabe
    Ecography 43 (12) 1891 - 1901 0906-7590 2020/12 [Peer-reviewed]
     Scientific journal
  • Daichi Kato, Kozo Watanabe, Levente-Péter Kolcsár
    ZooKeys 999 147 - 163 1313-2989 2020/11 [Peer-reviewed]
     Scientific journal 
    Japanese species of the genus Ulomorpha Osten Sacken, 1869 are revised and U. amamiana Kato &amp; Kolcsár, sp. nov. and U. longipenis Kato &amp; Kolcsár, sp. nov. are described. A key to the four Japanese species of the genus is provided, with images of habitus and wings, and drawings of their male terminalia. Ulomorpha amamiana Kato &amp; Kolcsár, sp. nov. is the first representative of the genus discovered from the Oriental region.
  • Jean Claude Balingit, Thaddeus M. Carvajal, Mariko Saito-Obata, Maribet Gamboa, Amalea Dulcene Nicolasora, Ava Kristy Sy, Hitoshi Oshitani, Kozo Watanabe
    Parasites & Vectors 13 (1) 594  2020/11 [Peer-reviewed]
     Scientific journal 
    Abstract Background Vector control measures are critical for the prevention and reduction of dengue virus (DENV) transmission. Effective vector control is reliant not only on knowledge of mosquito abundance, but also on the timely and accurate detection of mosquito-borne infection. Mosquito-based virus surveillance programs typically rely on pool-based mosquito testing, although whether individual-based mosquito testing is a feasible alternative to this has not been widely studied. Applying an individual-based mosquito testing approach, we conducted a 1-month surveillance study of DENV in adult Aedes aegypti mosquitoes in homes of suspected dengue patients during the 2015 peak dengue season in Tarlac City, Philippines to more accurately assess the mosquito infection rate and identify the DENV serotypes and genotypes concurrently co-circulating in mosquitoes and patients there. Methods We performed a one-step multiplex real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for the simultaneous detection and serotyping of DENV in patients and individual female Ae. aegypti mosquitoes. Additionally, we performed sequencing and phylogenetic analyses to further characterize the detected DENV serotypes in mosquitoes and patients at the genotype level. Results We collected a total of 583 adult Ae. aegypti mosquitoes, of which we individually tested 359 female mosquitoes for the presence of DENV. Ten (2.8%) of the 359 female mosquitoes were positive for the presence of DENV. We detected DENV-1, DENV-2, and DENV-4 in the field-collected mosquitoes, which was consistent with the serotypes concurrently found in infected patients. Sequencing and phylogenetic analyses of the detected DENV serotypes based on the partial sequence of the evelope (E) gene revealed three genotypes concurrently present in the sampled mosquitoes and patients during the study period, namely DENV-1 genotype IV, DENV-2 Cosmopolitan genotype, and DENV-4 genotype II. Conclusions We demonstrated the utility of a one-step multiplex real-time RT-PCR assay for the individual-based DENV surveillance of mosquitoes. Our findings reinforce the importance of detecting and monitoring virus activity in local mosquito populations, which are critical for dengue prevention and control.
  • Billy Joel M. Almarinez, Alberto T. Barrion, Mario V. Navasero, Marcela M. Navasero, Bonifacio F. Cayabyab, Jose Santos R. Carandang, Jesusa C. Legaspi, Kozo Watanabe, Divina M. Amalin
    Insects 11 (11) 745  2020/10 [Peer-reviewed]
     Scientific journal 
    The coconut scale insect, Aspidiotus rigidus Reyne, caused a major pest outbreak in coconut plantations and stands in the Southern Tagalog region of Luzon Island in the Philippines between 2010 and 2015. To determine if parasitism by Comperiella calauanica Barrion, Almarinez and Amalin, a native encyrtid, could have been a factor in the eventual management of the outbreak by 2015, we estimated and assessed its parasitization levels on A. rigidus colonies on field-collected samples from selected points in three provinces in the Southern Tagalog Region across three sampling periods. We observed that C. calauanica consistently occurred only in areas where A. rigidus populations occurred, with high parasitization levels in the Southern Tagalog sites from 2014 to 2015. Results of correlation and regression of total scale count against parasitized scale count suggest putative host density-dependent parasitism by C. calauanica in the field. A marked decrease in the abundance of A. rigidus was recorded concurrently with visually observable recovery of coconut trees from the third quarter of 2014 up to the second quarter of 2016. Similar results of significant reduction in A. rigidus populations concurrent with high percent parasitization by mass-reared and released C. calauanica were found in the Zamboanga Peninsula from 2018 to 2020. Our findings and observations altogether suggest that host-specific parasitization by C. calauanica effected biological control, which may have contributed to the eventual management of the A. rigidus outbreak in the Southern Tagalog Region, and also in the Zamboanga Peninsula where similar recovery of coconut trees were observed within a year after inoculative releases of C. calauanica.
  • Joeselle M Serrana, Kozo Watanabe
    bioRxiv 2020/10 Scientific journal 
    Sequential membrane filtration as a pre-processing step for the isolation of microorganisms could provide good quality and integrity DNA that can be preserved and kept at ambient temperatures before community profiling through culture-independent molecular techniques, e.g., 16s rDNA amplicon sequencing. Here, we assessed the impact of pre-processing sediment samples by sequential membrane filtration (from 10, 5 to 0.22 μm pore size membrane filters) for 16s rDNA-based community profiling of sediment-associated microorganisms. Specifically, we examined if there would be method-driven differences between non- and pre-processed sediment samples regarding the quality and quantity of extracted DNA, PCR amplicon, resulting high-throughput sequencing reads, microbial diversity, and community composition. We found no significant difference in the quality and quantity of extracted DNA and PCR amplicons between the two methods. Although we found a significant difference in raw and quality-filtered reads, read abundance after bioinformatics processing (i.e., denoising and the chimeric-read filtering steps) were not significantly different. These results suggest that read abundance after these read processing steps were not influenced by sediment processing or lack thereof. Although the non- and pre-processed sediment samples had more unique than shared amplicon sequence variants (ASVs), we report that their shared ASVs accounted for 74% of both methods' absolute read abundance. More so at the genus level, the final collection filter identified most of the genera (95% of the reads) captured from the non-processed samples, with a total of 51 false-negative (2%) and 59 false-positive genera (3%). Accordingly, the diversity estimates and community composition were not significantly different between the non- and pre-processed samples. We demonstrate that while there were differences in shared and unique taxa, both methods revealed comparable microbial diversity and community composition. We also suggest the inclusion of sequential filters (i.e., pre- and mid-filters) in the community profiling, given the additional taxa not detected from the non-processed and the final collection filter. Our observations highlight the feasibility of pre-processing sediment samples for community analysis and the need to further assess sampling strategies to help conceptualize appropriate study designs for sediment-associated microbial community profiling.
  • Rachel L. Malison, Bonnie K. Ellis, Amanda G. DelVecchia, Hailey Jacobson, Brian K. Hand, Gordon Luikart, H. Arthur Woods, Maribet Gamboa, Kozo Watanabe, Jack A. Stanford
    The Bulletin of the Ecological Society of America 101 (4) e01767  0012-9623 2020/10 Scientific journal
  • Sakiko Yaegashi, Tatsuo Omura, Kozo Watanabe
    AoB PLANTS 12 (5) plaa043  2020/10 [Peer-reviewed]
     Scientific journal 
    The black locust Robinia pseudoacacia (Robinieae, Fabaceae) is a common invasive riparian tree in Japan. There are less effective management strategies to remove the tree from the riparian area because of its quickly established high population. We investigated the expansion patterns of R. pseudoacacia through sympatric (i.e. between high- and low-water channel (HWC/LWC) within a study site) and allopatric (i.e. along river corridor) dispersal in the Tama River (Tokyo, Japan). Four microsatellites were used to examine the effects of gene flow on six populations in three sites. These subpopulations showed small genetic distance (i.e. no barrier or slightly limited) and genetically mixed population structure. It indicated that both sympatric and allopatric dispersals were active. Many migrants were younger individuals (i.e. <5 years old) and were found in the LWC area. Thus, the LWC could receive more migrants than the HWC through both types of dispersals. In addition, our age and genetic structure analyses reveal that recruited individuals likely settled immediately after the clearing project of R. pseudoacacia through sympatric dispersal. It appears that the migration by allopatric dispersal occurred following this. For the effective management of R. pseudoacacia, migrants should be removed regularly following initial removal of invaders during site restoration.
  • Rachel L. Malison, Bonnie K. Ellis, Amanda G. DelVecchia, Hailey Jacobson, Brian K. Hand, Gordon Luikart, H. Arthur Woods, Maribet Gamboa, Kozo Watanabe, Jack A. Stanford
    Ecology 101 (10) e03127  0012-9658 2020/10 [Peer-reviewed]
     Scientific journal
  • Maribet Gamboa, Yusuke Gotoh, Arnelyn D Doloiras-Larano, Kozo Watanabe
    bioRxiv 2020/09 Scientific journal 
    Latitudinal variation has been known to create strong selection pressure for genomic variation that enables the adaptation and survival of organisms. By altering gene expression patterns, organisms can modify their adaptive potential to heterogeneous environmental conditions along a latitudinal gradient; however, there is a gap in our understanding of how physiological consequences in wild species are affected and how changing environmental conditions act on multiple species. Here, we investigated how seven stream stonefly species sampled from four geographical regions in Japan differ in their responses to latitudinal variations by measuring gene expression (RNA-sequencing) differences within species and gene co-expression among species. We found that a large number of genes (622) were differentially expressed along the latitudinal gradient. The high species-specific gene expression diversity found at higher latitude regions was probably associated with low temperatures and high water discharge, which suggests the adaptive potential of stonefly specie. In contrast, similar gene expression patterns among species was observed at lower latitudes, which suggests that strong environmental stress occurs in warmer regions. Weighted gene co-expression network analysis (WGCNA) identified 22 genes with similar expression patterns among species along the latitudinal gradient. Among the four geographical regions, high differential expression patterns in the co-expressed genes from two regions were found, suggesting that the local environment strongly affects gene expression patterns among species in these regions. Respiration, metabolism, and developmental co-expressed genes exhibited a latitudinal cline, showing clear evidence of divergent adaptive responses to latitude. Our findings demonstrate that stonefly species are differentially adapted to local environmental conditions, and imply that adaptation in gene expression could be shared by multiple species under environmental stress conditions. This study highlights the importance of considering multiple species when evaluating the consequences of environmental changes on aquatic insect communities, and possible mechanisms to cope with environmental changes.
  • Francisco, M. E, T. M. Carvajal, M. Ryo, K. Nukazawa, D. M. Amalin, K. Watanabe
    bioRxiv 2020/09 Scientific journal 
    ABSTRACTBackgroundDengue is an endemic vector-borne disease influenced by environmental factors such as landscape and climate. Previous studies separately assessed the effects of landscape and climate factors on mosquito occurrence and dengue incidence. However, both factors interact in time and space to affect mosquito development and dengue disease transmission. For example, eggs laid in a suitable environment can hatch after being submerged in rain or flood water. ObjectivesThis study aimed to investigate the combined influences of landscape and climate factors on mosquito occurrence and dengue incidence. MethodsEntomological, epidemiological, and landscape data from the rainy season (July-December) were obtained from respective government agencies in Metro Manila, Philippines, from 2012 to 2014. Temperature, precipitation, and vegetation data were obtained through remote sensing. A random forest algorithm was used to select the landscape and climate variables. Afterwards, using the identified key variables, a model-based (MOB) recursive partitioning was implemented to test the combinatory influences of landscape and climate factors on the ovitrap index and dengue incidence. ResultsThe MOB recursive partitioning for the ovitrap index indicated that mosquito occurrence was higher in high residential density areas, where industrial areas also exist and are well connected with roads. Precipitation was another key covariate modulating the effects of landscape factors, possibly by expanding breeding sites and activating mosquito reproduction. Moreover, the MOB recursive partitioning indicated that precipitation was the main predictor of dengue incidence, with a stronger effect in high residential density and commercial areas. DiscussionPrecipitation with floods has epidemiologically important implications by damaging shelters and causing population displacement, thus increasing exposure to dengue vectors. Our findings suggest that the intensification of vector control during the rainy season can be prioritized in residential and commercial areas to better control dengue disease dynamics.
  • Somar Israel D. Fernando, Khristina G. Judan Cruz, Kozo Watanabe
    BioNanoScience 10 (3) 696 - 704 2191-1630 2020/09 [Peer-reviewed]
     Scientific journal 
    © 2020, Springer Science+Business Media, LLC, part of Springer Nature. The inevitable occurrence of diseases caused by bacterial pathogens is one of the main constraints in tilapia industry that has resulted in major economic losses. The study reveals the advantages of quorum sensing inhibition through nanotechnology in developing antivirulence drugs to control aquaculture pathogens using scientifically untapped medicinal plants, the ethnobotanicals. The ethnobotanical crude extracts (CEs) and biologically synthesized gold nanoparticles (CEs + AuNPs) of the Ilongot-Eǵongot community exhibit quorum sensing inhibition (QSI) activity through inhibition of the biofilm formation against gram-positive Streptococcus agalactiae. Furthermore, ethnobotanical CEs + AuNPs show much greater activity than its counterpart CEs in antibacterial and biofilm formation assay in S. agalactiae which is molecularly confirmed by gene expression analysis. The results indicate the potential of these ethnobotanicals for therapeutic approach in which it showed minimal expression of agrA gene linked in biofilm formation and connotes maximal inhibition of QS in S. agalactiae thereby can possibly inhibit bacterial resistance and virulence.
  • Bin Li, Sakiko Yaegashi, Thaddeus M. Carvajal, Maribet Gamboa, Ming Chih Chiu, Zongming Ren, Kozo Watanabe
    Ecology and Evolution 10 (13) 6677 - 6687 2020/07 [Peer-reviewed]
     Scientific journal 
    © 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Adaptive divergence is a key mechanism shaping the genetic variation of natural populations. A central question linking ecology with evolutionary biology is how spatial environmental heterogeneity can lead to adaptive divergence among local populations within a species. In this study, using a genome scan approach to detect candidate loci under selection, we examined adaptive divergence of the stream mayfly Ephemera strigata in the Natori River Basin in northeastern Japan. We applied a new machine-learning method (i.e., random forest) besides traditional distance-based redundancy analysis (dbRDA) to examine relationships between environmental factors and adaptive divergence at non-neutral loci. Spatial autocorrelation analysis based on neutral loci was employed to examine the dispersal ability of this species. We conclude the following: (a) E. strigata show altitudinal adaptive divergence among the populations in the Natori River Basin; (b) random forest showed higher resolution for detecting adaptive divergence than traditional statistical analysis; and (c) separating all markers into neutral and non-neutral loci could provide full insight into parameters such as genetic diversity, local adaptation, and dispersal ability.
  • Thaddeus M. Carvajal, Kohei Ogishi, Sakiko Yaegeshi, Lara Fides T. Hernandez, Katherine M. Viacrusis, Howell T. Ho, Divina M. Amalin, Kozo Watanabe
    PLOS Neglected Tropical Diseases 14 (5) e0008279 - e0008279 1935-2727 2020/05 [Peer-reviewed]
     Scientific journal
  • RaoRao Mo, Maribet Gamboa, Kozo Watanabe, GuoQuan Wang, WeiHai Li, Ding Yang, Dávid Murányi
    PLOS ONE 15 (3) e0229120 - e0229120 2020/03 [Peer-reviewed]
     Scientific journal
  • Lia Faridah, Fedri Ruluwedrata Rinawan, Nisa Fauziah, Wulan Mayasari, Angga Dwiartama, Kozo Watanabe
    International Journal of Environmental Research and Public Health 17 (5) 1661-7827 2020/03 [Peer-reviewed]
     Scientific journal 
    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This study was performed to evaluate the health information system regarding the dengue surveillance system in Indonesia. Major obstacles to the implementation of an effective health information system regarding dengue cases in Bandung are examined, and practical suggestions on measures to overcome them are discussed. The study utilized a mixed-method research design using qualitative approaches: document analysis, key informants and focus group interviews. Thirty key informants were selected, comprised of policymakers, senior managers, and staff at the Ministry of Health. Data from documents and transcripts were evaluated through a modified Institutional Analysis and Development (IAD) framework described by Ostrom. Through this study, we have identified several issues that hinder the effective implementation of the health information system in the case of dengue in Bandung. In the end, we propose several recommendations for reform that encompasses motivational, strategic, and structural approaches to each component of the analysis. Through evaluation of the health information system for dengue surveillance in Indonesia, we conclude that well-coordination in multi-level governance in a country as large as Indonesia is the key in the implementation of the health information system in different levels of agencies. Furthermore, the adaptability of human resources in adopting a new information system also plays an important part.
  • Serrana, J. M., B. Li, T. Sumi, Y. Takemon, and K. Watanabe
    bioRxiv doi: https://doi.org/10.1101/2020.01.25.919381 2020/01 Scientific journal
  • Von Ralph Dane Marquez Herbuela, Tomonori Karita, Micanaldo Ernesto Francisco, Kozo Watanabe
    JMIR Formative Research 4 (1) e16424  2020/01 [Peer-reviewed]
     Scientific journal 
    Background For the last 10 years, mobile phones have provided the global health community with innovative and cost-effective strategies to address the challenges in the prevention and management of dengue fever. Objective The aim is to introduce and describe the design and development process of Mozzify, an integrated mobile health (mHealth) app that features real-time dengue fever case reporting and mapping system, health communication (real-time worldwide news and chat forum/timeline, within-app educational videos, links to local and international health agency websites, interactive signs and symptoms checker, and a hospital directions system), and behavior modification (reminders alert program on the preventive practices against dengue fever). We also aim to assess Mozzify in terms of engagement and information-sharing abilities, functionality, aesthetics, subjective quality, and perceived impact. Methods The main goals of the Mozzify app were to increase awareness, improve knowledge, and change attitudes about dengue fever, health care-seeking behavior, and intention-to-change behavior on preventive practices for dengue fever among users. It was assessed using the Mobile Application Rating Scale (MARS) among 50 purposively sampled individuals: public health experts (n=5), environment and health-related researchers (n=23), and nonclinical (end users) participants (n=22). Results High acceptability and excellent satisfaction ratings (mean scores ≥4.0 out of 5) based on the MARS subscales indicate that the app has excellent user design, functionality, usability, engagement, and information among public health experts, environment and health-related researchers, and end users. The app’s subjective quality (recommending the app to other people and the app’s overall star rating), and specific quality (increase awareness, improve knowledge, and change attitudes about dengue fever; health care-seeking behavior; and intention-to-change behavior on preventive practices for dengue fever) also obtained excellent satisfaction ratings from the participants. Some issues and suggestions were raised during the focus group and individual discussions regarding the availability of the app for Android devices, language options limitations, provision of predictive surveillance, and inclusion of other mosquito-borne diseases. Conclusions Mozzify may be a promising integrated strategic health intervention system for dengue fever case reporting and mapping; increase awareness, improve knowledge, and change attitude about dengue fever; and disseminating and sharing information on dengue fever among the general population and health experts. It also can be an effective aid in the successful translation of knowledge on preventive measures against dengue fever to practice.
  • Dávid Murányi, Maribet Gamboa, Kozo Watanabe
    Zootaxa 4718 (1) 57 - 66 1175-5326 2020/01 [Peer-reviewed]
     Scientific journal 
    Copyright © 2020 Magnolia Press A new species of the genus Protonemura Kempny, 1898 (Plecoptera: Nemouridae: Amphinemurinae) is described from the Ishizuchi Range of Shikoku Island, Japan, based on the male, female and Co1 sequences. Protonemura shimizui Murányi & Gamboa sp. n. belongs to the P. orbiculata species group sensu Shimizu, 1998. The new species appears to be limited to the higher elevations of the Ishizuchi Range. Faunistic survey of the high elevation rheocrenes of the Ishizuchi Range is also presented.
  • Von Ralph Dane M. Herbuela, Ferdinand S. de Guzman, Girly D. Sobrepeña, Andrew Benedict F. Claudio, Angelica Cecilia V. Tomas, Carmina M.Arriola Delos Reyes, Rachele A. Regalado, Mariama M. Teodoro, Kozo Watanabe
    International Journal of Environmental Research and Public Health 17 (1) 99  1661-7827 2020/01 [Peer-reviewed]
     Scientific journal 
    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. Background: Psychiatric symptoms have been reported in adult patients with dengue fever (DF); however, information on pediatric patients remains inadequate. We sought to identify the prevalence and predictors of depressive and anxiety symptoms and identify other psychiatric symptoms among pediatric patients with DF. This case-control study involved pediatric in-patients (n = 225) who had clinical or serologic-confirmed DF and healthy school-based controls (n = 260). Participants completed the Revised Child Anxiety and Depression Scale (RCADS). Results: The prevalence of depressive (13.3%) and anxiety (34.2%) symptoms among pediatric patients with DF was significantly (p < 0.001) higher than that among controls (3.5% and 16.2%, respectively). Multiple linear regression analysis found that age, family history of DF, ≤2 days of hospitalization, myalgia, and arthralgia were predictors of increased depressive and anxiety symptoms among the patients. Further, 26.7% of pediatric patients reported irritability, agitation, visual hallucinations, and aggressiveness. Conclusion: Pediatric patients present depressive and anxiety symptoms whose levels were associated with social and clinical factors. However, whether these symptoms are present only during the infection or may still persist after recovery or are brought by children’s adverse reactions to hospitalization are unknown, and thus, further studies are needed.
  • Von Ralph Dane M. Herbuela, Ferdinand S. de Guzman, Girly D. Sobrepeña, Andrew Benedict F. Claudio, Angelica Cecilia V. Tomas, Carmina M.Arriola Delos Reyes, Rachele A. Regalado, Mariama M. Teodoro, Kozo Watanabe
    International Journal of Environmental Research and Public Health 16 (23) 4705  1661-7827 2019/12 [Peer-reviewed]
     Scientific journal 
    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. Background: Knowledge, attitude, and practice (KAP) of in-patients with dengue fever (DF) through hospital-based surveillance has not been done. This study aimed to assess and compare the KAP, identify its predictors, correlation, and protective factors among pediatric and adult patients with DF and community-based controls to structure proactive community-wide DF prevention and control programs. Methods: This case-control study involved clinically or serologically confirmed patients (pediatrics n = 233; adults n = 17) with DF admitted in three public hospitals and community-based controls in Metro Manila, Philippines. A pretested structured KAP questionnaire was administered to participants to assess their KAP. Results: Pediatric and adult patients had significantly lower mean scores in the practice (p < 0.001) domain compared with the pediatric and adult controls. Being in senior high school, having had days in hospital, and rash were predictors of KAP among pediatric patients. Knowledge and attitude of patients with DF did not correlate with their practices against DF. Use of mosquito-eating fish, screen windows, and dengue vaccine were protective factors against DF. Conclusion: The study highlights the importance of behavioral change for knowledge and attitude to have significant effect to practices against DF. Thus, we recommend two comprehensive health programs, Communication for Behavioral Impact (COMBI) and Health Belief Model (HBM).
  • Takahashi, S, Y. Takemon, T. Omura, K. Watanabe
    bioRxiv doi.org/10.1101/870717 2019/12 Research society
  • Regilme, M. A. F, M. Sato, T. Tamura, R. Arai, M. O. Sato, S. Ikeda, M. Doi, K. Tanaka, M. Gamboa, M. T. Monaghan, K. Watanabe
    bioRxiv doi.org/10.1101/862904 2019/12 Research society
  • Joeselle M Serrana, Naoto Ishitani, Thaddeus M Carvajal, Billy Joel M Almarinez, Alberto T Barrion, Divina M Amalin, Kozo Watanabe
    Insects 10 (11) 374  2019/10 [Peer-reviewed]
     Scientific journal 
    Despite the fact that massive outbreaks of the coconut scale insect pest, Aspidiotus rigidus Reyne (Hemiptera: Diaspididae) are inflicting significant economic losses to the Philippines' coconut industry, little is known about the population and dispersal history of this invasive pest in the country. Here, we examined the genetic diversity, structure and demographic history of A. rigidus sampled from localities with reported outbreaks from 2014 to 2017. We analyzed the genetic structure of the outbreak populations using mitochondrial COI and nuclear EF-1α markers. Both markers and all methods of population genetic structure analyses indicate clear differentiation among the A. rigidus populations separating the north from the southern regions of the Philippines. Very low or no genetic differentiation was observed within and amongst the populations per geographic region indicating two unrelated outbreak events of the pest originating from two genetically uniform populations isolated in each respective region. Historical data supports the resurgence of an established A. rigidus population in the south which could have been driven by sudden climatic changes or human-induced habitat imbalance. Our study provides valuable information on the genetic differentiation of the two A. rigidus groups that would be useful for developing and implementing biological control strategies against this pest in the Philippines.
  • Gamboa, M, J. Serrana, Y. Takemon, M. T. Monaghan, K. Watanabe
    bioRxiv doi.org/10.1101/765578 2019/09 Research society
  • Thaddeus M. Carvajal, Kazuki Hashimoto, Reza Kurniawan Harnandika, Divina M. Amalin, Kozo Watanabe
    Parasites & vectors 12 (1) 361 - 361 2019/07 [Peer-reviewed]
     Scientific journal 
    BACKGROUND: Recent reports reveal the presence of Wolbachia in Ae. aegypti. Our study presents additional support for Wolbachia infection in Ae. aegypti by screening field-collected adult mosquitoes using two Wolbachia-specific molecular makers. METHODS: A total of 672 Ae. aegypti adult mosquitoes were collected from May 2014 to January 2015 in Metropolitan Manila. Each individual sample was processed and screened for the presence of Wolbachia by selected markers, Wolbachia-specific 16S rDNA and its surface protein (wsp), under optimized PCR conditions and sequenced. RESULTS: Totals of 113 (16.8%) and 89 (13.2%) individual mosquito samples were determined to be infected with Wolbachia using the wsp and 16S rDNA markers, respectively. The Ae. aegpyti wsp sample sequences were similar or identical to five known Wolbachia strains belonging to supergroups A and B while the majority of 16S rDNA sample sequences were similar to strains belonging to supergroup B. Overall, 80 (11.90%) individual mosquito samples showed positive amplifications in both markers and 69% showed congruence in supergroup identification (supergroup B). CONCLUSIONS: By utilizing two Wolbachia-specific molecular makers, our study demonstrated the presence of Wolbachia from individual Ae. aegypti samples. Our results showed a low Wolbachia infection rate and inferred the detected strains belong to either supergroups A and B.
  • Faridah, L, N. Fauziah, S Ekawardhani, Riyadi, K. Watanabe
    Journal of Clinical and Diagnostic Research 13 (7) DC20 - DC23 2019/07 [Peer-reviewed]
     Scientific journal
  • Joeselle M. Serrana, Yo Miyake, Maribet Gamboa, Kozo Watanabe
    ECOLOGICAL INDICATORS 101 963 - 972 1470-160X 2019/06 [Peer-reviewed]
     Scientific journal 
    Conventional morphology-based identification is commonly used for routine assessment of freshwater ecosystems. However, cost and time efficient techniques such as high-throughput sequencing (HTS) based approaches may resolve the constraints encountered in conducting morphology-based surveys. Here, we characterized stream macroinvertebrate species diversity and community composition via metabarcoding and morphological analysis from environmental samples collected from the Shigenobu River Basin in Ehime Prefecture, Japan. We compared diversity metrics and assessed both approaches' ability to evaluate the relationship between macroinvertebrate community and environmental variables. In total, we morphologically identified 45 taxa (3 families, six subfamilies, 31 genera, and five species) from 8,276 collected individuals from ten study sites. We detected 44 species by metabarcoding, with 35 species collapsed into 11 groups matching the morphologically identified taxa. A significant positive correlation between logged depth (number of HTS reads) and abundance of morphological taxa was observed, which implied that quantitative data could be used for subsequent analyses. We recovered a considerably high rate of relative abundance detection of the morphologically identified samples. Recovery of samples by incidence or presence/absence count were considerably low, with a high rate of false-negative detection specifically for species with scarce representation in the community sample. Given the low taxonomic resolution of the morphological assignment in this study, we report that metabarcoding does not reflect the majority of the species naturally occurring in our site, which could further be proven by performing refined morphological assessment of the samples. However, abundance-based detection proved to be efficient with 92% of the individuals correctly demonstrated. We conclude that DNA metabarcoding provides a practical and cost-effective approach especially for rapid biological monitoring of freshwater macroinvertebrate communities, but further improvements in the detection of scarce samples should be considered to increase the sensitivity of detecting most, if not all, of the species present in the environment.
  • Maribet Gamboa, Kozo Watanabe
    BMC Genomics 20 (1) 84 - 84 2019/01 [Peer-reviewed]
     Scientific journal 
    © 2019 The Author(s). Background: Environmental heterogeneity continuously produces a selective pressure that results in genomic variation among organisms; understanding this relationship remains a challenge in evolutionary biology. Here, we evaluated the degree of genome-environmental association of seven stonefly species across a wide geographic area in Japan and additionally identified putative environmental drivers and their effect on co-existing multiple stonefly species. Double-digest restriction-associated DNA (ddRAD) libraries were independently sequenced for 219 individuals from 23 sites across four geographical regions along a nationwide latitudinal gradient in Japan. Results: A total of 4251 candidate single nucleotide polymorphisms (SNPs) strongly associated with local adaptation were discovered using Latent mixed models; of these, 294 SNPs showed strong correlation with environmental variables, specifically precipitation and altitude, using distance-based redundancy analysis. Genome-genome comparison among the seven species revealed a high sequence similarity of candidate SNPs within a geographical region, suggesting the occurrence of a parallel evolution process. Conclusions: Our results revealed genomic signatures of local adaptation and their influence on multiple, co-occurring species. These results can be potentially applied for future studies on river management and climatic stressor impacts.
  • Maribet Gamboa, David Muranyi, Shota Kanmori, Kozo Watanabe
    PLoS ONE 14 (1) e0210269  2019/01 [Peer-reviewed]
     Scientific journal 
    © 2019 Gamboa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The generation of the high species diversity of insects in Japan was profoundly influenced by the formation of the Japanese Archipelago. We explored the species diversification and biogeographical history of the Nemouridae Billberg, 1820 family in the Japanese Archipelago using mitochondrial DNA and nuclear DNA markers. We collected 49 species among four genera: Indonemoura Baumann, 1975; Protonemura Kempny, 1898; Amphinemura, Ris 1902 and Nemoura Latreille, 1796 in Japan, China, South Korea and North America. We estimated their divergence times—based on three molecular clock node calibrations—using Bayesian phylogeography approaches. Our results suggested that Japanese Archipelago formation events resulted in diversification events in the middle of the Cretaceous (<120 Ma), speciation in the Paleogene (<50 Ma) and intra-species diversification segregated into eastern and western Japan of the Fossa Magna region at late Neogene (20 Ma). The Indonemoura samples were genetically separated into two clades—that of Mainland China and that of Japan. The Japanese clade clustered with the Nemouridae species from North America, suggesting the possibility of a colonisation event prior to the formation of the Japanese Archipelago. We believe that our results enhanced the understanding both of the origin of the species and of local species distribution in the Japanese Archipelago.
  • Joeselle M. Serrana, Sakiko Yaegashi, Shunsuke Kondoh, Bin Li, Christopher T. Robinson, Kozo Watanabe
    Scientific Reports 8 (1) 10185 - 10185 2018/12 [Peer-reviewed]
     Scientific journal 
    © 2018 The Author(s). Sediment bypass tunnels (SBTs) are guiding structures used to reduce sediment accumulation in reservoirs during high flows by transporting sediments to downstream reaches during operation. Previous studies monitoring the ecological effects of SBT operations on downstream reaches suggest a positive influence of SBTs on riverbed sediment conditions and macroinvertebrate communities based on traditional morphology-based surveys. Morphology-based macroinvertebrate assessments are costly and time-consuming, and the large number of morphologically cryptic, small-sized and undescribed species usually results in coarse taxonomic identification. Here, we used DNA metabarcoding analysis to assess the influence of SBT operations on macroinvertebrates downstream of SBT outlets by estimating species diversity and pairwise community dissimilarity between upstream and downstream locations in dam-fragmented rivers with operational SBTs in comparison to dam-fragmented (i.e., no SBTs) and free-flowing rivers (i.e., no dam). We found that macroinvertebrate community dissimilarity decreases with increasing operation time and frequency of SBTs. These factors of SBT operation influence changes in riverbed features, e.g. sediment relations, that subsequently effect the recovery of downstream macroinvertebrate communities to their respective upstream communities. Macroinvertebrate abundance using morphologically-identified specimens was positively correlated to read abundance using metabarcoding. This supports and reinforces the use of quantitative estimates for diversity analysis with metabarcoding data.
  • Thaddeus Carvajal, Jayson Dale Capistrano, Kazuki Hashimoto, Kristin Joyce Go, Maria Angeline Isabelle Cruz, Monique Johanne Lourdee Martinez, Vincent Stefano Tiopianco, Divina Amalin, Kozo Watanabe
    Journal of Vector Borne Diseases 55 (4) 265 - 270 0972-9062 2018/12 [Peer-reviewed]
     Scientific journal 
    © 2018 E-Flow Wolters Kluwer Medknow Publications. All rights reserved. Background & objectives: Culex quinquefasciatus is a peridomestic mosquito known for its ability to transmit pathogenic diseases such as filariasis and Japanese encephalitis. The development and use of novel and innovative vector control measures such as the utilization of Wolbachia, along with the existing ones, are necessary to prevent the transmission of these diseases. Studies exploring the diversity of Wolbachia, particularly in Cx. quinquefasciatus are very limited in the Philippines. Thus, the aim of the study was to detect the presence, distribution, and phylogenetic relationship of Wolbachia infections in Cx. quinquefasciatus in Metropolitan Manila, Philippines. Methods: Adult Cx. quinquefasciatus mosquitoes were collected using a commercially available light-trap from May 2014-January 2015. Based on their sampling grids (n = 51), the adult mosquito abdomens were pooled and subjected to Wolbachia surface protein (wsp) gene amplification assay. Five selected wsp-positive samples were then sequenced and further analyzed to infer their phylogenetic relationship with known Wolbachia strains. Results: A total of 1090 adult Cx. quinquefasciatus mosquitoes were collected. Pooled abdomens (n = 53) were then sorted based on their sampling grids for subsequent screening of wsp gene. Wolbachia infection rate was 59% (31/53). These infections were located at 29 (57%) sampling grids, and were observed to be widely distributed in the study area. Phylogenetic analysis indicated that the sample sequences were Wolbachia pipientis isolated from known hosts, Cx. pipiens and Cx. quinquefasciatus belonging to supergroup B clade. Interpretation & conclusion: The study was able to demonstrate the prevalence and distribution of Wolbachia in Cx. quinquefasciatus in Metropolitan Manila, Philippines. The findings of this study are geared towards proposing a vector control program that utilizes the potential of Wolbachia as a biological control agent in preventing the transmission of Culex-borne diseases.
  • Howell T. Ho, Thaddeus M. Carvajal, John Robert Bautista, Jayson Dale R. Capistrano, Katherine M. Viacrusis, Lara Fides T. Hernandez, Kozo Watanabe
    Tropical Medicine and Infectious Disease 3 (4) 118  2018/11 [Peer-reviewed]
     Scientific journal 
    © 2018 by the authors. Dengue is a major public health concern and an economic burden in the Philippines. Despite the country's improved dengue surveillance, it still suffers from various setbacks and needs to be complemented with alternative approaches. Previous studies have demonstrated the potential of Internet-based surveillance such as Google Dengue Trends (GDT) in supplementing current epidemiological methods for predicting future dengue outbreaks and patterns. With this, our study has two objectives: (1) assess the temporal relationship of weekly GDT and dengue incidence in Metropolitan Manila from 2009–2014; and (2) examine the health-seeking behavior based on dengue-related search queries of the population. The study collated the population statistics and reported dengue cases in Metropolitan Manila from respective government agencies to calculate the dengue incidence (DI) on a weekly basis for the entire region and annually per city. Data processing of GDT and dengue incidence was performed by conducting an ‘adjustment' and scaling procedures, respectively, and further analyzed for correlation and cross-correlation analyses using Pearson's correlation. The relative search volume of the term ‘dengue' and top dengue-related search queries in Metropolitan Manila were obtained and organized from the Google Trends platform. Afterwards, a thematic analysis was employed, and word clouds were generated to examine the health behavior of the population. Results showed that weekly temporal GDT pattern are closely similar to the weekly DI pattern in Metropolitan Manila. Further analysis showed that GDT has a moderate and positive association with DI when adjusted or scaled, respectively. Cross-correlation analysis revealed a delayed effect where GDT leads DI by 1–2 weeks. Thematic analysis of dengue-related search queries indicated 5 categories namely; (a) dengue, (b) sign and symptoms of dengue, (c) treatment and prevention, (d) mosquito, and (e) other diseases. The majority of the search queries were classified in ‘signs and symptoms' which indicate the health-seeking behavior of the population towards the disease. Therefore, GDT can be utilized to complement traditional disease surveillance methods combined with other factors that could potentially identify dengue hotspots and help in public health decisions.
  • マニラ首都圏におけるデング熱媒介蚊の産卵活動に関わる因子の時空間的分析
    糠澤桂, 西元竣哉, 鈴木祥広, 渡辺幸三
    土木学会論文集G(環境) Vol.74, No.5, pp.I_79-I_85, (No.5) I_79 - I_85 2018/09 [Peer-reviewed]
     Scientific journal
  • Andri Taruna Rachmadi, Masaaki Kitajima, Kozo Watanabe, Sakiko Yaegashi, Joeselle Serrana, Arata Nakamura, Toyoko Nakagomi, Osamu Nakagomi, Kazuhiko Katayama, Satoshi Okabe, Daisuke Sano
    Applied and Environmental Microbiology 84 (13) e00244-18  0099-2240 2018/07 [Peer-reviewed]
     Scientific journal 
    © 2018 American Society for Microbiology. Human noroviruses are excreted in feces from infected individuals and included in wastewater. It is critical to remove/inactivate them in wastewater treatment processes, particularly in the disinfection step, before release to aquatic environments. However, the high mutation rates of human noroviruses raise concerns about the emergence of strains that are less susceptible to disinfectants and can survive even after wastewater treatment. This study aimed to demonstrate the strain-dependent susceptibility of norovirus to free chlorine. A population originated from the murine norovirus strain S7-PP3, a surrogate for human noroviruses in environmental testing, was exposed to free chlorine and then propagated in a host cell. This cycle of free chlorine exposure followed by propagation in cells was repeated 10 times, and populations with lower susceptibility to free chlorine were obtained from two independent trials of chlorine exposure cycles. Open reading frame 2 (ORF2) and ORF3 of the murine norovirus genome were analyzed by next-generation sequencing, and a unique nonsynonymous mutation (corresponding to a change from phenylalanine to serine) at nucleotide (nt) 7280 in ORF3, which encodes the minor capsid protein VP2, was found in chlorine-exposed populations from both trials. It was confirmed that all of the clones from the chlorine-treated population had lower susceptibility to free chlorine than those from the control population. These results indicate that exposure to free chlorine and dilution exert different driving forces to form murine norovirus (MNV) quasispecies, and that there is a selective force to form MNV quasispecies under free chlorine exposure.
  • Thaddeus M. Carvajal, Katherine M. Viacrusis, Lara Fides T. Hernandez, Howell T. Ho, Divina M. Amalin, Kozo Watanabe
    BMC Infectious Diseases 18 (1) 183 - 183 2018/04 [Peer-reviewed]
     Scientific journal 
    © 2018 The Author(s). Background: Several studies have applied ecological factors such as meteorological variables to develop models and accurately predict the temporal pattern of dengue incidence or occurrence. With the vast amount of studies that investigated this premise, the modeling approaches differ from each study and only use a single statistical technique. It raises the question of whether which technique would be robust and reliable. Hence, our study aims to compare the predictive accuracy of the temporal pattern of Dengue incidence in Metropolitan Manila as influenced by meteorological factors from four modeling techniques, (a) General Additive Modeling, (b) Seasonal Autoregressive Integrated Moving Average with exogenous variables (c) Random Forest and (d) Gradient Boosting. Methods: Dengue incidence and meteorological data (flood, precipitation, temperature, southern oscillation index, relative humidity, wind speed and direction) of Metropolitan Manila from January 1, 2009 - December 31, 2013 were obtained from respective government agencies. Two types of datasets were used in the analysis; observed meteorological factors (MF) and its corresponding delayed or lagged effect (LG). After which, these datasets were subjected to the four modeling techniques. The predictive accuracy and variable importance of each modeling technique were calculated and evaluated. Results: Among the statistical modeling techniques, Random Forest showed the best predictive accuracy. Moreover, the delayed or lag effects of the meteorological variables was shown to be the best dataset to use for such purpose. Thus, the model of Random Forest with delayed meteorological effects (RF-LG) was deemed the best among all assessed models. Relative humidity was shown to be the top-most important meteorological factor in the best model. Conclusion: The study exhibited that there are indeed different predictive outcomes generated from each statistical modeling technique and it further revealed that the Random forest model with delayed meteorological effects to be the best in predicting the temporal pattern of Dengue incidence in Metropolitan Manila. It is also noteworthy that the study also identified relative humidity as an important meteorological factor along with rainfall and temperature that can influence this temporal pattern.
  • Bin Li, Yang Yang, Sai Wang, Ming Wang, Kozo Watanabe
    Wetlands 38 (2) 391 - 399 0277-5212 2018/04 [Peer-reviewed]
     Scientific journal 
    © 2017, Society of Wetland Scientists. Constructed wetlands (CWs) for wastewater treatment had drawn much attention for their additional function of conserving freshwater ecosystems. The purpose of this study was to evaluate the macroinvertebrate biodiversity of two subsurface-flow and surface-flow hybrid CW systems (Qimei CW system (QCWS) and Kejiyuan CW system (KCWS)) under high and low pollutant stress in China. Nonmetric multidimensional scaling (NMDS) and canonical correspondence analysis (CCA) were used to analyze the water quality and aquatic macroinvertebrates community data. The results indicated that the subsurface-flow CW could conserve significant macroinvertebrate biodiversity (total taxon richness 17). The community structure was influenced by habitat types (i.e., subsurface-flow vs. surface-flow CWs) under low pollutant stress, and this influence was somehow masked by influence of water quality under high pollutant stress. Good pollutant removal rates were obtained in decreasing the concentrations of total nitrogen (66.37% and 27.28%), total phosphorus (58.93% and 37.55%), and loadings of biochemical oxygen demand (28.38% and 73.71%) in QCWS and KCWS, respectively. This study implied that subsurface-flow CWs could achieved good performance in both water purification and biodiversity conservation, which could provide a more solid basis for the application of subsurface-flow CWs.
  • Andri Taruna Rachmadi, Masaaki Kitajima, Kozo Watanabe, Satoshi Okabe, Daisuke Sano
    Environmental science & technology 52 (5) 2434 - 2435 0013-936X 2018/03 [Peer-reviewed]
     Scientific journal
  • Maribet Gamboa, Maria Claret Tsuchiya, Suguru Matsumoto, Hisato Iwata, Kozo Watanabe
    Archives of insect biochemistry and physiology 96 (3) 0739-4462 2017/11 [Peer-reviewed]
     Scientific journal 
    Proteome variation among natural populations along an environmental gradient may provide insights into how the biological functions of species are related to their local adaptation. We investigated protein expression in five stream stonefly species from four geographic regions along a latitudinal gradient in Japan with varying climatic conditions. The extracted proteins were separated by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption/ionization of time-of-flight (MALDI TOF/TOF), yielding 446 proteins. Low interspecies variation in the proteome profiles was observed among five species within geographical regions, presumably due to the co-occurring species sharing the environments. However, large spatial variations in protein expression were found among four geographic regions, suggesting strong regulation of protein expression in heterogeneous environments, where the spatial variations were positively correlated with water temperature. We identified 21 unique proteins expressed specifically in a geographical region and six common proteins expressed throughout all regions. In warmer regions, metabolic proteins were upregulated, whereas proteins related to cold stress, the photoperiod, and mating were downregulated. Oxygen-related and energy-production proteins were upregulated in colder regions with higher altitudes. Thus, our proteomic approach is useful for identifying and understanding important biological functions related to local adaptations by populations of stoneflies.
  • 八重樫咲子, 細川大樹, 渡辺幸三
    土木学会論文集G(環境) 73 (7) III_139 - III_147 2017/11 [Peer-reviewed]
  • Kozo Watanabe, Michael T Monaghan
    Evolution; international journal of organic evolution 71 (7) 1755 - 1764 0014-3820 2017/07 [Peer-reviewed]
     Scientific journal 
    A fundamental question linking population genetics and community ecology is how adaptive processes (e.g., natural selection) and neutral processes (e.g., drift-migration equilibrium) underpin the species-genetic diversity correlation (SGDC). Here, we combine genome scans and outlier loci detection with community analysis to separately test for neutral and nonneutral SGDCs in four species of stream insect. We sampled 60 localities in Japan and examined the relationships among population AFLP band richness (Br), taxon richness of the total community (S) and of the trophic guild (Str ), and 15 habitat parameters that could potentially drive adaptation and influence richness. Neutral Br was positively correlated with S only in the dominant species of these communities, suggesting Br may be constrained when intraspecific competition is pronounced. Nonneutral Br was correlated with Str in a species restricted to high elevations where habitat heterogeneity was highest. Community distance and genetic distance (β-SGDC) was correlated in two of the four species at both neutral and nonneutral loci. Distance-based redundancy analysis found geographic isolation and elevation to drive divergence of both communities and populations. This suggests that both neutral and adaptive divergence occurred through the shared influences of geographic isolation and local adaptation at the two levels of diversity.
  • Weihai Li, Dávid Murányi, Maribet Gamboa, Ding Yang, Kozo Watanabe
    Zootaxa 4243 (1) 165 - 176 1175-5326 2017/03 [Peer-reviewed]
     Scientific journal 
    © 2017 Magnolia Press. The species of Leuctridae (Plecoptera) from Guangxi, China are reviewed. Two species of Rhopalopsole are described as new to science, R. cestroidea sp. nov. and R. triangulis sp. nov., belonging to the R. vietnamica group and the R. magnicerca group, respectively. Six species of Leuctridae are now known for Guangxi including two additional species of Rhopalopsole and one Paraleuctra recorded for the first time. The previously unknown female of R. duyuzhoui Sivec &Harper, 2008 is described from specimens from Guangxi. Characters are illustrated for the separation of R. furcospina (Wu, 1973) and R. sinensis Yang &Yang, 1993. Mitochondrial sequences of five Rhopalopsole species support their specific recognition.
  • Kei Nukazawa, So Kazama, Kozo Watanabe
    ECOHYDROLOGY 10 (1) e1778  1936-0584 2017/01 [Peer-reviewed]
     Scientific journal 
    Species distribution models were developed to predict the spatial patterns of the species diversity and the genetic diversity of stream organisms using a distributed hydrological model. We derived annual metrics of water depth and flow velocity in rivers using a hydrological model covering an entire catchment in northeastern Japan. We acquired geospatial data throughout the catchment and the presence records of six taxa within the part of the catchment. Subsequently we derived habitat suitability indices (HSIs) for these taxa using a frequency analysis or the maximum-entropy approach (MaxEnt) to predict three metrics of species diversity. The Shannon-Wiener's diversity index based on MaxEnt (Shannon_MaxE) most effectively represented empirical taxon richness. Subsequently, by comparing Shannon_MaxE and empirical genetic diversity for the four species of stream insects, we evaluated species-genetic diversity correlations (SGDCs). Of the four species, only one caddisfly species (Hydropsyche orientalis) displayed significant positive SGDCs. The result reflects the broad habitat range of this taxon throughout the catchment and its poor dispersal ability, whereas the other three species lacked SGDCs and displayed either a strong dispersal potential (Stenopsyche marmorata and Ephemera japonica) or a narrower habitat range within upstream domains (Hydropsyche albicephala). Finally, we estimated the spatial distribution of genetic diversity of H. orientalis populations based on the calculated Shannon_MaxE using the positive SGDC. This framework is promising for projecting future biodiversity in the context of anthropogenic perturbations such as climate change.
  • Fuminari Miura, Toru Watanabe, Kozo Watanabe, Kazuhiko Takemoto, Kensuke Fukushi
    Journal of environmental sciences (China) 50 13 - 20 1001-0742 2016/12 [Peer-reviewed]
     Scientific journal 
    Diarrheal diseases can be transmitted via both primary infection due to exposures to contaminated materials from the environment and secondary infection due to person-to-person contacts. Usually, the importance of secondary infection is empirically assessed by fitting mathematical models to the epidemic curves. However, these empirical models may not be applicable to other epidemic cases because they are developed only for the target epidemics and they don't consider the detail routes of infection. In our previous study, we developed a theoretical model taking into account the various routes of infection that commonly occur in households (e.g., shaking hands, food handling, and changing diapers). This model was made flexible and applicable to any epidemics by means of adjusting model parameters. In this study, we proposed a new index "Vulnerability indicator to secondary infection (VISI)", which expressed a ratio of secondary infection to primary infection risks and calculated this index in a simulated norovirus (NoV) epidemic that involved 10,000 households. The results demonstrated that households composed of more than three members including infant(s) had much higher levels of VISI (5-45) than two-member-households with VISI (0.1-4). These results concluded that the infants were likely to be a hub of secondary infections in highly dense families and therefore careful handling of diapers was deemed indispensible in such families to effectively control the secondary infections.
  • 渡辺幸三, 近藤俊介, 泉昂佑, 八重樫咲子
    土木学会論文集G(環境) 72 (7) III_489 - III_496 2016/12 [Peer-reviewed]
     Scientific journal
  • 八重樫咲子, 泉昴佑, 三宅洋, 渡辺幸三
    土木学会論文集G(環境) 72 (7) III_115 - III_122 2016/12 [Peer-reviewed]
     Scientific journal
  • Thaddeus M. Carvajal, Lara Fides T. Hernandez, Howell T. Ho, Menard G. Cuenca, Biancamarie C. Orantia, Camille R. Estrada, Katherine M. Viacrusis, Divina M. Amalin, Kozo Watanabe
    Journal of Vector Borne Diseases 53 (2) 127 - 135 0972-9062 2016/06 [Peer-reviewed]
     Scientific journal 
    Background & objectives: Aedes aegypti (L.) is an efficient vector for arboviral diseases such as dengue. The wings of Ae. aegypti has been extensively studied in order to investigate population heterogeneity and structure by utilizing a landmark based geometric morphometrics (GMs) approach. The aim of this study was to examine and assess the wing geometry of Ae. aegypti in Metropolitan Manila. Methods: In total, 312 Ae. aegypti mosquitoes were collected from 98 sampling points using a mosquito light-trap from May 2014 to January 2015. A complete coverage of the wing was achieved by removing wing scales with chemical and physical treatment, leading to identification of 26 landmarks. Geometric morphometric analyses were employed and the spatial distance pattern was estimated using isolation by distance (IBD) and spatial autocorrelation (SA). Results: The results of the GM analyses revealed population heterogeneity and structuring in Ae. aegypti populations for both sexes using principal component and canonical variate analyses respectively. Moreover, IBD and SA only detected significant spatial structure in male Ae. aegypti populations while female population structures were homogeneous throughout the geographical area. Interpretation & conclusion: The newly modified wing preparation procedure was able to capture a complete coverage of the wings of Ae. aegypti, thus providing a stronger separation power for very close populations in an urban area. It is also noteworthy that the results of IBD and SA supported the findings of GM in the population structuring of male and female Ae. aegypti. The outcome of the study increases our understanding of the vector, which would be useful in developing effective control strategies.
  • Bin Li, Kozo Watanabe, Dong-Hwan Kim, Sang-Bin Lee, Muyoung Heo, Heui-Soo Kim, Tae-Soo Chon
    WATER 8 (5) 2073-4441 2016/05 [Peer-reviewed]
     Scientific journal 
    Water quality maintenance should be considered from an ecological perspective since water is a substrate ingredient in the biogeochemical cycle and is closely linked with ecosystem functioning and services. Addressing the status of live organisms in aquatic ecosystems is a critical issue for appropriate prediction and water quality management. Recently, genetic changes in biological organisms have garnered more attention due to their in-depth expression of environmental stress on aquatic ecosystems in an integrative manner. We demonstrate that genetic diversity would adaptively respond to environmental constraints in this study. We applied a self-organizing map (SOM) to characterize complex Amplified Fragment Length Polymorphisms (AFLP) of aquatic insects in six streams in Japan with natural and anthropogenic variability. After SOM training, the loci compositions of aquatic insects effectively responded to environmental selection pressure. To measure how important the role of loci compositions was in the population division, we altered the AFLP data by flipping the existence of given loci individual by individual. Subsequently we recognized the cluster change of the individuals with altered data using the trained SOM. Based on SOM recognition of these altered data, we determined the outlier loci (over 90th percentile) that showed drastic changes in their belonging clusters (D). Subsequently environmental responsiveness (E-k') was also calculated to address relationships with outliers in different species. Outlier loci were sensitive to slightly polluted conditions including Chl-a, NH4-N, NOX-N, PO4-P, and SS, and the food material, epilithon. Natural environmental factors such as altitude and sediment additionally showed relationships with outliers in somewhat lower levels. Poly-loci like responsiveness was detected in adapting to environmental constraints. SOM training followed by recognition shed light on developing algorithms de novo to characterize loci information without a priori knowledge of population genetics.
  • Kei Wakimura, Yasuhiro Takemon, Atsushi Takayanagi, Shin-ichi Ishiwata, Kozo Watanabe, Kazumi Tanida, Nobuyoshi Shimizu, Mikio Kato
    DNA Barcodes 4 1 - 25 2016/04 [Peer-reviewed]
     Scientific journal 
    We have determined nucleotide sequences of three genes encoding histone H3, 18S rRNA, and mitochondrial cytochrome oxidase subunit I (COI) from the mayfly community in Eastern Asia. All sequence data collected from 303 specimens comprising 80 taxa (63 identified to species, 14 to genus, and 3 to family) were deposited in GenBank/ EMBL/ DDBJ International Databases for further expansion of DNA barcoding projects of mayflies. Phylogenetic analysis based on the neighborjoining method among the three genes found that COI and H3 genes had relatively high evolutionary rates, and were not suitable in inferring phylogenetic relationships among families within the orders but were useful in identifying species (i.e., DNA barcoding). In contrast, the more conserved 18S rRNA gene was adequately informative for elucidating inter-family divergence, but not suitable for species identification.
  • 糠澤 桂, 風間 聡, 渡辺 幸三
    水工学論文集 Annual journal of Hydraulic Engineering, JSCE 土木学会 60 Ⅰ_433 - 438 1880-8751 2016/03 [Peer-reviewed]
  • Kei Nukazawa, So Kazama, Kozo Watanabe
    11TH INTERNATIONAL SYMPOSIUM ON ECOHYDRAULICS 2016 [Peer-reviewed]
     International conference proceedings 
    Among key components threatening global biodiversity in the future, such as land use alterations, climate changes can be primary stressors on stream ecosystems. Although many studies in the discipline of landscape genetics have tried to explore genetic consequences of oncoming climate change, most of them used anonymous genes, even though the majority of these genetic regions are just known to be "neutral" (no relation) to natural selection. In this study, we projected adaptive genetic variations and species distributions in four stream insect species under climate change scenarios, using a distributed hydrothermal model and 8 global climate models (GCM). We used non-neutral AFLP (Amplified Fragment Length Polymorphism) loci, which were statistically defined to be subject to natural selection, in the target species found at 11-31 out of 45 sampling localities. For modeling species distributions, we used presence data of the studied insects at the same sites as above. We acquired bias-corrected air temperature and precipitation data of 3 RCP (Representative Concentration Pathways) scenarios from the GCMs. Then, these climatic data were used to calculate annual metrics of current velocity, water depth and water temperature using the hydrothermal model. Models describing adaptive genetic variation, which is represented as linear response of allele frequency at each locus to environmental predictors, have been constructed based on current hydrothermal variables in a previous work. We used the model for estimating future ranges of the allele frequency along changing climate gradients. Finally, we projected spatial pattern of genetic diversity (heterozygosity) for the studied species. Also, we employed maximum entropy model (Maxent) to predict present and future distributions of the studied species. Degraded pattern of genetic diversity in a caddisfly species (Stenopsyche marmorata) was more notable under extreme climate scenarios when comparing with the current climate, depending on higher air temperature projected in the future. While genetic diversity in catchment scale only decreased in S. marmorata, habitat range, which was predicted by species distributions, severely contracted more in other three species than for S. marmorata.
  • YAEGASHI Sakiko, FUWA Naoto, YAMAZAKI Kumiko, MIYAKE Yo, WATANABE Kozo
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 71 (7) III_115 - III_121 2185-6648 2015 
     We investigated gene flow of Epeorus latifolium in Shigenobu River (Ehime, Japan) fragmented by 3 types of barriers (i.e. one reservoir dam, 98 weir&check dam, intermittent flow). 112 individuals (13 - 15 individuals / population, average = 14) were collected from 8 populations and genotyped using Cytochrome Oxidase subunit I region in mitochondrial DNA. Among the 3 types of habitat barriers, the weir&check dams showed significant and the highest pairwise Fst between fragmented populations. In addition, the number of weir&check dams was significantly and positively correlated to the level of pairwise Fst (R = 0.81, p < 0.05), suggesting that gene flow of E. latifolium tends to be interrupted in sections with large number of weir&check dams (at least > 14). However, this genetic differentiation found in mountain area could be also explained by the potential process of local adaptation of the populations to the different environmental conditions associated to elevational variation between sites (e.g. water temperature, water flow velocity, UV, oxygen concentration). E. latifolium did not show significant genetic differentiation in the other barrier types of reservoir dam and intermittent flow. It suggests that E. latifolium adults fly over the small-size reservoir dam that we studied (< 0.5 km2) and have adapted life history strategy to migrate across the intermittent sections.
  • Kei Nukazawa, So Kazama, Kozo Watanabe
    JOURNAL OF BIOGEOGRAPHY 42 (1) 103 - 113 0305-0270 2015/01 [Peer-reviewed]
     Scientific journal 
    AimA central question in landscape genetics is how local adaptation among heterogeneous environments leads to genetic variation in natural populations. This article has two aims: (1) to examine associations between non-neutral genetic diversity of stream insect populations and environmental heterogeneity simulated by a hydrothermal model; and (2) to establish a novel framework for simulating the spatial distribution of adaptive genetic variation at catchment scale. LocationNatori River basin, north-eastern Japan. MethodsA distributed hydrothermal model was used to simulate current velocity, water depth and water temperature throughout the basin. We used empirical genetic data from 6-21 non-neutral amplified fragment length polymorphism (AFLP) loci in four target stream insect species found at 45 sampling sites. We constructed multiple regression models using allele frequencies at the non-neutral loci as objective variables and the hydrothermal and geographical parameters as candidate explanatory variables. ResultsOf the four species, one caddisfly species provided strong evidence of local adaptation to the annual maximum water temperature. Assuming a priori that the regression models were applicable throughout the study area, we visualized the geographical distributions of genetically similar groups - UPGMA (unweighted pair group method with arithmetic mean) clusters based on genetic distance - and local genetic diversity along the simulated hydrothermal gradients. The UPGMA clusters of two caddisfly species (Hydropsyche orientalis and Stenopsyche marmorata) showed clear spatial turnover along an elevational gradient. Local genetic diversities of these species showed lower genetic diversity in lowland areas. Main conclusionsThe predicted spatial patterns along an elevational gradient could be explained by a hypothetical mechanism whereby lowland habitats only accommodate genotypes adapted to severe thermal conditions. Our approach of combining a hydrothermal simulation with genome-wide scans of non-neutral loci is promising for the identification of evolutionary associations of adaptive loci to the temporal regime of hydrothermal conditions, such as maxima and temporal variability.
  • Kozo Watanabe, Sakiko Yaegashi, Hiro Tomozawa, Shunichi Koshimura, Tatsuo Omura
    FRESHWATER BIOLOGY 59 (7) 1474 - 1483 0046-5070 2014/07 [Peer-reviewed]
     Scientific journal 
    The 2011 Great East Japan Earthquake generated extreme tsunami waves that entered river mouths, causing strong and long-distance propagation along the water corridors. This study reports the first empirical survey of this rare and extreme ecological impact of tsunami propagation on river communities. We sampled macroinvertebrate communities at 15 river sites on the Sendai Plain in Northeast Japan along a gradient of tsunami disturbance intensity [i.e. altitude: range=1-29m above sea level (a.s.l.)] two and 16months after the earthquake. In comparison with data collected before the tsunami, we found evidence of significant reductions in taxon richness (-54% on average) and total abundance (-91%) after the tsunami in inundated river reaches (up to 25km from the river mouth). There were large spatial variations in local impacts, with altitudes of 7-9m a.s.l. separating heavily damaged inundated communities from intact non-inundated communities. The degraded communities exhibited variable recovery rates extending beyond 16months after the tsunami. Mobility trait analysis revealed a relatively rapid recovery of swimmers (e.g. Baetis), reflecting their high mobility and active drift behaviours in the recolonisation phase. We observed the rare phenomenon of upstream drift' of marine worms (Phyllodocidae) to freshwater rivers in three of the 10 inundated sites. These survived in fresh water for up to 14months, suggesting that some marine-derived immigrants can persist in fresh water for extended periods.
  • NUKAZAWA Kei, KAZAMA So, TAKASE Akihiko, WATANABE Kozo
    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS Japan Society of Civil Engineers 70 (4) I_1405 - I_1410 2185-467X 2014/03 [Peer-reviewed]
     Scientific journal 
    We evaluated the linkage between genetic diversity and habitat suitability index (HSI) of aquatic animals including freshwater fishes, amphibians and macroinvertebrates in the Natori River basin located at the middle of Miyagi prefecture. The HSI has been structured by variables calculated from a distributed hydro-thermal model and GIS based geographical variables. We found a strong positive correlation between genetic diversity and HSI in one caddisfly (Hydropsychidae), indicating that a prospective habitat (i.e., locality which has high HSI) might contribute to increase in genetic diversity. The genetic diversity of one caddisfly (Hydropsychidae) had significant positive correlations with the HSIs of predatory fishes and aquatic insects. This result suggests that exposures to predation pressure can enhance genetic diversity. We derived negative correlations between genetic diversity and the HSIs within niche competitors, suggesting inter-species selective pressure constrains intra-species genetic diversity.
  • Sakiko Yaegashi, Kozo Watanabe, Michael T. Monaghan, Tatsuo Omura
    FRESHWATER SCIENCE 33 (1) 172 - 180 2161-9549 2014/03 [Peer-reviewed]
     Scientific journal 
    Most population genetic studies in streams infer long-term patterns of gene flow by calculating fixation indices (e. g., F-ST) among sampled populations. In more-recent analytical methods, the need to assign individuals to populations a priori (clustering algorithms) is relaxed, and spatial autocorrelation analysis of allele frequencies (SA) is used to infer finer-scale and potentially short-term dispersal distances. We applied multiple methods to study the population genetic structure of the riverine caddisfly Stenopsyche marmorata (Trichoptera:Stenopsychidae) from 4 adjacent catchments in northeastern Japan. We genotyped larval individuals (N = 532) from 30 sites at 8 polymorphic microsatellite loci. Fixation indices suggested low levels of genetic differentiation among populations (global F-ST = 0.062, p < 0.01), and significant isolation-by-distance (IBD) indicated populations were in drift-migration equilibrium. Bayesian clustering separated S. marmorata into distinct upland (> 250 m asl) and lowland populations, with different F-ST values (upland F-ST = 0.048, p < 0.01; lowland F-ST = 0.029, p < 0.01) and significant IBD only among upland populations. Allele frequencies were significantly positively autocorrelated (Moran's I > 0, p < 0.05) at distances up to 18 km along streams and up to 12 km across terrestrial habitat. These values were similar to directly observed flight distance in a single generation for this species in the field. We conclude that the multiple-method approach revealed: 1) unexpected population subdivision between upland and lowland areas that may result from local adaptation, differences in phenology, and historical colonization by multiple lineages; and 2) fine-scale estimates of dispersal that match direct observations of flight and suggest gene flow is more pronounced along water
  • TAKASE Akihiko, NUKAZAWA Kei, KAZAMA So, WATANABE Kozo
    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS Japan Society of Civil Engineers 70 (4) I_1297 - I_1302 2185-467X 2014 [Peer-reviewed]
     
    This study quantitatively evaluated Habitat Suitability Index (HSI) and species diversity of benthic invertebrates using a distributed hydro-thermal model and observed benthic samples from 45 localities in the Natori River basin, Northeast of Japan. We applied probability density function and histogram analysis to the Suitability Index (SI) model analysis. To evaluate basin-scaled habitat values of invertebrate families, we used the index Weight Usable Ratio (WUR). From the viewpoint of repeatability in the multiple modeling manners, Diptera had the highest WUR in basin. We estimated spatial distribution of Shannon-Weiner diversity index based on the HSIs to evaluate species diversity throughout the basin. Results in the both applications showed that regions found in the top 80% of the diversity index were allocated from the upper to the middle stream.
  • MIURA Fuminari, WATANABE Toru, WATANABE Kozo, FUKUSHI Kensuke
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 70 (7) III_295 - III_304 2185-6648 2014 
     To predict transmission pattern of Norovirus gastroenteritis at regional scale, we've constructed an infectious disease transmission model that considers secondary infection in households. In the model, a household-scale submodel that could simulate secondary infection within family members was independently and in parallel applied to all households in the modeled region. The result of simulation showed that the effect of the secondary infection on the spread of the Norovirus gastroenteritis was larger than the primary infection. In particular, households of more than four family members including infant(s) showed ten times higher infectious risk of the secondary infection. Based on comparisons with empirical epidemiological data in the modeled region, our approach demonstrated a high utility ofthe model in estimating the exposure time fromthe primary infection time.
  • Kozo Watanabe, So Kazama, Tatsuo Omura, Michael T Monaghan
    PloS one 9 (3) e93055  1932-6203 2014 [Peer-reviewed]
     Scientific journal 
    A central question linking ecology with evolutionary biology is how environmental heterogeneity can drive adaptive genetic divergence among populations. We examined adaptive divergence of four stream insects from six adjacent catchments in Japan by combining field measures of habitat and resource components with genome scans of non-neutral Amplified Fragment Length Polymorphism (AFLP) loci. Neutral genetic variation was used to measure gene flow and non-neutral genetic variation was used to test for adaptive divergence. We identified the environmental characteristics contributing to divergence by comparing genetic distances at non-neutral loci between sites with Euclidean distances for each of 15 environmental variables. Comparisons were made using partial Mantel tests to control for geographic distance. In all four species, we found strong evidence for non-neutral divergence along environmental gradients at between 6 and 21 loci per species. The relative contribution of these environmental variables to each species' ecological niche was quantified as the specialization index, S, based on ecological data. In each species, the variable most significantly correlated with genetic distance at non-neutral loci was the same variable along which each species was most narrowly distributed (i.e., highest S). These were gradients of elevation (two species), chlorophyll-a, and ammonia-nitrogen. This adaptive divergence occurred in the face of ongoing gene flow (Fst = 0.01-0.04), indicating that selection was strong enough to overcome homogenization at the landscape scale. Our results suggest that adaptive divergence is pronounced, occurs along different environmental gradients for different species, and may consistently occur along the narrowest components of species' niche.
  • 八重樫咲子, 渡辺幸三, 大村達夫
    環境工学研究論文集 50 III.489-III.494  1341-5115 2013/11 [Peer-reviewed]
  • Scharnweber K, Watanabe K, Syväranta J, Wanke T, Monaghan MT, Mehner T
    BMC evolutionary biology 13 132  2013/06 [Peer-reviewed]
  • Akihiko Takase, Kei Nukazawa, So Kazama, Kozo Watanabe
    PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS I AND II 2611 - 2617 2013 [Peer-reviewed]
     International conference proceedings 
    We evaluated spatial variations of habitat suitability of nine aquatic insects in the Natori River basin, Northeast Japan quantitatively combining dual approaches of using Habitat Suitability Index (HSI) model analysis and hydrothermal simulation model. We also developed a new index of the Weighted Usable Ratio (WUR) for evaluating the overall habitat suitability throughout the catchment for each species. The results of spatial distributions of HSI showed species-specific patterns such as wide distribution of digit grids with high HSI throughout the catchment in habitat generalists (for example, Baetis, WUR=0.55) while the constrained distribution in habitat specialists (for example, Limnocentropus insolitus, WUR=0.06). Overall, the spatial variation of HSI showed good consistency with the empirical habitat distributions, supporting the accuracy of our model approach.
  • TAKAHASHI Shinji, TAKEMON Yasuhiro, OMURA Tatsuo, WATANABE Kozo
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 69 (7) III_547 - III_555 2185-6648 2013 
     Dams often supply large amount of Fine Particulate Organic Matters (FPOM) orginated from dam reservoirs (called "dam-POM") to their downstream reaches. It potentially leads to a shift of trophic sources of stream faunal communities from the stream-origins (e.g., periphyton and terrestrial input) to the dam-origin organic matters. However, the lentic habitats at dam outlet reaches such as backwater and isolated pool may receive a lot of terrestrial and autochthnous organic matters, thus we need habitat-specific tests regarding the trophic dependency on dam-POM. The aim of this study is to qularify the spatial variation of trophic contribution of dam-POM between lotic and lentic habitats at dam downstream reaches. The proportion of contribution of dam-POM to Suspended FPOM and Benthic FPOM was quantified at each habitat using a mixing source model with carbon and nitrogen stable isotopic data. The results support the habitat specific patterns showing higher contribution of dam-POM to Suspended FPOM in lotic habitats than lentic habitats. It suggests the ecologically important role of lentic habitats in locally sustaining insitu trophic structures of stream ecosystem in the impacted reaches by dams.
  • YAEGASHI Sakiko, WATANABE Kozo, OMURA Tatsuo
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 69 (7) III_489 - III_494 2185-6648 2013 
     Environmental heterogeneity among habitats may be one of the factors causing adaptive genetic divergence in wild populations. We examined the effect of natural selection on genetic diversity of Stenopsyche marmorata population in middle of Miyagi, Japan. Eight microsatellites were employed to draw genetic structure and tested for their neutrality. Three microsatellites were estimated to be presumably under the selection and 4 microsatellites were nuetrall. Genetic diversity at selective loci showed significant positive partial correlations with food condition (SS, FPOM, chlorophyll a within surface biofilm, FBOM) and riverbed heterogeneity (average size of pebbles, uniform coefficient of sediment). It support that linked geanes with lower fitness could exist under habitats with abundand foods and variable sediments. This results suggest a risk of decrease of genetic diversity by artificial environment disruption.
  • NUKAZAWA Kei, KAZAMA So, WATANABE Kozo
    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS Japan Society of Civil Engineers 69 (4) I_1303 - I_1308 2185-467X 2013 [Peer-reviewed]
     
    In accordance with a most recent report in discipline "landscape genetics", simulation studies to predict spatial genetic variation are urgently required. We evaluated relationships between genetic diversities of caddisfly Hydropsyche orientalis and species diversity calculated from Habitat Suitability Index (HSI) of aquatic animals and discussed outliers in the correlation diagrams in the Natori River basin located at the middle of Miyagi prefecture. Omitting two significant outliers, we developed spatial genetic diversity distribution maps on the basis of linear regression models in the correlation diagrams. At the catchment scale, the longitudinal distribution of genetic diversity had high peak in the middle stream. The result is identical with the observed pattern of genetic diversity for the species. The prediction has advantages which can be applied to future planning in respect of dam removal, urban planning, and zoning in view of genetic diversity.
  • TAKASE Akihiko, NUKAZAWA Kei, KAZAMA So, WATANABE Kozo
    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 公益社団法人 土木学会 69 (4) I_1255 - I_1260 2185-467X 2013 
    We evaluated spatial variations of habitat suitability of nine aquatic insects in the Natori River basin, Northeast Japan quantitatively combining dual approaches of using Habitat Suitability Index (HSI) model analysis and hydrothermal simulation model. We also developed a new index of the Weighted Usable Ratio (WUR) for evaluating the overall habitat suitability throughout the catchment for each species. The results of spatial distributions of HSI showed species-specific patterns such as wide distribution of digit grids with high HSI throughout the catchment in habitat generalists (e.g., Baetis, WUR=0.55) while the constrained distribution in habitat specialists (e.g., Limnocentropus insolitus, WUR=0.06). Overall, the spatial variation of HSI showed good consistency with the empirical habitat distributions, supporting the accuracy of our model approach.
  • 八重樫咲子, 渡辺幸三, 高橋真司, 永峯賢人, 大村達夫
    環境工学研究論文集 49 III.611-III.616  1341-5115 2012/11 [Peer-reviewed]
  • 高橋真司, 渡辺幸三, 竹門康弘, 大村達夫
    応用生態工学 15 (1) 121 - 130 1344-3755 2012/07 [Peer-reviewed]
  • BERTOLDI W., GURNELL A.M., TOCKNER K.
    京都大学防災研究所年報 京都大学防災研究所 (56) 691 - 698 0386-412X 2012 
    Biodiversity of lentic habitats in river channels generally depends on a frequency of connection with channels and the time since the habitat was born. The Tagliamento River in the north Italy has a steep basin with high sediment supply and thus its middle reaches form braided channels changing frequently with flow fluctuations. To understand relations of species diversity of aquatic animal communities to age of lentic habitats, the temporal dynamics of the habitats in two reaches of the river were recorded by fixed cameras installed on the cliff tops beside the reaches. A total of 89 habitats were chosen to collect aquatic animals and to measure environment factors in April to May, 2011. This paper revealed that lentic species increase with the age of habitats while lotic species decrease with the age. Considering with specificity of habitat preference, we discussed on the age and longevity of the lentic habitats required for maximize biodiversity of habitats scale and reach scale.
  • Shinji Takahashi, Kozo Watanabe, Yasuhiro Takemon, Tatsuo Omura
    Ecology and Civil Engineering 15 (1) 121 - 130 1882-5974 2012 [Peer-reviewed]
     Scientific journal 
    Spatial structures of 7 types of aquatic habitat at the reach scale were delineated using a high precision Global Position System (GPS) in 3 dam-impacted and 6 reference riverrine reaches in Miyagi Prefecture, Japan. Taxonomic and functional compositions of quantitative benthic invertebrate samples were also investigated. Out of the three dams, two indicated decreased levels of habitat diversity indexes (S, H', a, and E) at the outlet reaches due to reduced sediment supply and reduced hydraulic variation through dam-operation but one dam connected to meandering outlet reach did not. Percentage of total area of lentic habitats (i. e., backwater and isolated pool) at the dam-impacted reaches (mean= 1.5%) was significantly lower than reference reaches (mean=5.5%). The taxon richness, abundance of swimmers, predators, attachers and crawlers increased with the percentage of lentic habitat area (P< 0.05, n=9), which suggests that lentic habitats contribute to maintain species diversity and the functional groups at the reach scale. Our data indicated a high application potential of the GPS-based evaluation of habitat structure for biodiversity conservation in rivers.
  • BERTOLDI W., GURNELL A.M., TOCKNER K.
    京都大学防災研究所年報(CD-ROM) 京都大学防災研究所 (56) 691 - 698 0386-412X 2012 
    Biodiversity of lentic habitats in river channels generally depends on a frequency of connection with channels and the time since the habitat was born. The Tagliamento River in the north Italy has a steep basin with high sediment supply and thus its middle reaches form braided channels changing frequently with flow fluctuations. To understand relations of species diversity of aquatic animal communities to age of lentic habitats, the temporal dynamics of the habitats in two reaches of the river were recorded by fixed cameras installed on the cliff tops beside the reaches. A total of 89 habitats were chosen to collect aquatic animals and to measure environment factors in April to May, 2011. This paper revealed that lentic species increase with the age of habitats while lotic species decrease with the age. Considering with specificity of habitat preference, we discussed on the age and longevity of the lentic habitats required for maximize biodiversity of habitats scale and reach scale.
  • YAEGASHI Sakiko, WATANABE Kozo, TAKAHASHI Shinji, NAGAMINE Kento, OMURA Tatsuo
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 68 (7) III_611 - III_616 2185-6648 2012 
     Spatial environmental heterogeneity may favorably sustain genetic diversity of wild populations through adaptive divergence. We empirically examined the relationship between habitat structure and genetic diversity of stream mayfly Ephemera strigata populations at riverine reach scale. The habitat structure was delineated by a high precision GPS among 11 riverine sites in the Natori River, Miyagi Japan and genetic diversity was quantified at nine loci presumably under selection identified through a genome wide scan of 319 AFLP loci. Out of the nine adaptive loci, two had a strong association with the index of habitat structure, indicating a significant variation of allele frequency and genetic diversity along a gradient of the percentage of the total area of lentic habitats (i.e., backwater and isolated pool, range = 0.0 - 11.2 %). Particular environmental features reserved in these lentic habitats such as low current and high amount of deposited organic matters may enhance local adaptation of specific genotypes, leading to higher adaptive genetic variation within reaches. Our result highly suggests the importance of conservation of lentic habitats in river to sustaining genetic diversity of aquatic organisms.
  • NUKAZAWA Kei, KAZAMA So, WATANABE Kozo
    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 公益社団法人 土木学会 68 (7) III_603 - III_610 2185-6648 2012 
     Relationships between species diversity calculated from Habitat Suitability Index (HSI) of aquatic animalms and genetic diversities of four species of aquatic insect (three caddisflies and one mayfly) were examined in the Natori River basin, middle of Miyagi prefecture Japan. The HSI has been evaluated for six riverine animals based on current velocity and water depth calculated from an existing distributed runoff model and geographical data (eg., landuse, slope, and urban ratio) by Kazama et al. (2007). As a result, three out of four genetic diversity indices of one caddisfly (Hydropsyche orientalis) showed significant positive correlation to the HSI based taxa richness. This result suggests a sharing influence of immigration on community and population levels is potentially high in the locations where many species can coinhabit. Accordingly, parallel effects of gene flow and habitat heterogeneity on species and genetic diversity through environmental filtering and local adaptation of genotypes of focal species would contribute to the enhancement of biodiversity.
  • マイクロサテライトマーカーを用いたヒゲナガカワトビケラの流域内および流域間移動分散の評価
    八重樫咲子, 渡辺幸三, 大村達夫
    土木学会論文集G(環境) 67 (7) III_99 - III_106 2011/11 [Peer-reviewed]
     Scientific journal
  • 八重樫咲子, 渡辺幸三, 大村達夫
    環境工学研究論文集 48 III.99-III.106  1341-5115 2011/11 [Peer-reviewed]
  • K. Nukazawa, S. Kazama, K. Watanabe, J. Kang
    WIT Transactions on Ecology and the Environment 146 263 - 274 1743-3541 2011 [Peer-reviewed]
     Scientific journal 
    In order to assess the impacts of sabo dam (check dam) construction, species diversity of benthic faunal communities and genetic diversity of caddisfly Stenopsyche marmorata were investigated using microsatellite analysis along the Oisawa River, Japan. The Oisawa River is fragmented by two slit sabo dams and one unslit sabo dam. Over the slit dams, Shannon-Weiner diversity indices and number of taxa ranged from 0.90 to 1.02 and 13 to 15 respectively in the upstream region, and also from 0.98 to 1.18 and 13 to 20 respectively in the downstream region. Through microsatellite analysis of S. marmorata, we found two selective alleles, which show clear genetic differentiation among three upstream sites and four downstream sites in the study area. Longitudinal change of mean heterozigosities Ho showed a decreasing pattern of genetic diversity in the downstream site (=0.486 - 0.678), and it showed the highest diversity at the highest upstream site, which receives no effect of the unslit dam. Differences of community's species compositions between sites were correlated to geographical distances whereas genetic distances between sites were not correlated to geographical distances, suggesting that species compositions of the communities were determined through the process of species adaptation to the local environment. We concluded that increments of species diversity at the inlet reaches of the slit dam were caused by the recovery of habitats, and by the continuousness of the stream which allows the flowing of particulate organic matters and sediments to the downstream area. In part of some loci, genetic selection might occur by the different velocities caused by sabo dam constructions, because S marmorata (filter-feeder) has the habit of constructing nets to filter and collect fine particulate organic matter (FPOM) from water flow. © 2011 WIT Press.
  • Species diversity of benthic faunal communities along a mountain stream fragmented by slit and unslit dam
    Kei Nukazawa, So Kazama, Kozo Watanabe
    Proceedings of the 5th conference of Asia Pasific Association of Hydrology and Water Resources(APHW) 48 - 55 2010/11 [Peer-reviewed]
     International conference proceedings
  • Kozo Watanabe, Michael T. Monaghan, Yasuhiro Takemon, Tatsuo Omura
    AQUATIC CONSERVATION-MARINE AND FRESHWATER ECOSYSTEMS 20 (5) 574 - 579 1052-7613 2010/07 [Peer-reviewed]
     Scientific journal 
    1. The dispersal ability of species and the geographic scale of habitat fragmentation both may influence the extent of gene flow between fragments, but their interactions have rarely been tested, particularly among co-occurring species. 2. Population genetic structures of three species of aquatic insect were compared in streams fragmented by reservoirs and in unfragmented streams in north-eastern Japan, using 52, 37, and 58 RAPD markers. The three species studied included a strong disperser Cincticostella elongatula (Ephemeroptera: Ephemerellidae), an intermediate disperser Stenopsyche marmorata (Trichoptera: Stenopsychidae), and a weak disperser Hydropsyche orientalis (Trichoptera: Hydropsychidae). 3. The patterns of genetic isolation by distance (IBD) supported a priori hypotheses of dispersal ability. The strong disperser (C. elongatula) exhibited significant IBD only at the largest spatial scale studied (among drainages, r = 0.50, P < 0.01). The intermediate disperser (S. marmorata) showed IBD both within (r = 0.22, P < 0.01) and among (r = 0.45, P < 0.01) drainages. The weak disperser (H. orientalis) did not exhibit significant IBD at any scale. 4. Pairwise genetic differentiation (theta) indicated that neither the weak disperser nor the strong disperser were genetically differentiated above and below reservoirs when compared with reference sites. This was in contrast to previous results for S. marmorata, for which subpopulations were genetically fragmented across larger (>4.1 km), but not smaller (<2.9 km) reservoirs. 5. We suggest that intermediate dispersers, i.e. those at equilibrium between migration and genetic drift within drainages, are more likely to be affected by fragmentation than either strong or weak dispersers. Intermediate dispersers could therefore be used as indicator species in studies aimed at detecting the effects of distance between habitat fragments (e. g. reservoir size) for conservation planning. Copyright (C) 2010 John Wiley & Sons, Ltd.
  • 糠澤桂, 風間聡, 渡辺幸三
    水工学論文集(CD-ROM) 54 ROMBUNNO.215  1880-8751 2010/02 [Peer-reviewed]
  • 高橋真司, 五十嵐夏奈, 伊藤歩, 渡辺幸三, 相澤治郎, 大村達夫, 海田輝之
    環境工学研究論文集 46 1 - 8 1341-5115 2009/11 [Peer-reviewed]
  • 鈴木祥一, 渡辺幸三, 八重樫咲子, 大村達夫
    環境工学研究論文集 46 529 - 536 1341-5115 2009/11 [Peer-reviewed]
  • L. G. Abercrombie, C. M. Anderson, B. G. Baldwin, I. C. Bang, R. Beldade, G. Bernardi, A. Boubou, A. Branca, F. Bretagnolle, M. W. Bruford, A. Buonamici, R. K. Burnett, D. Canal, H. Cardenas, C. Caullet, S. Y. Chen, Y. J. Chun, C. Cossu, C. F. Crane, S. Cros-Arteil, R. Cudney-Bueno, R. Danti, J. A. Davila, G. Della Rocca, S. Dobata, L. D. Dunkle, S. Dupas, N. Faure, M. E. Ferrero, B. Fumanal, G. Gigot, I. Gonzalez, S. B. Goodwin, D. Groth, B. D. Hardesty, E. Hasegawa, E. A. Hoffman, M. L. Hou, A. F. J. Jamsari, H. J. Ji, D. H. Johnson, L. Joseph, F. Justy, E. J. Kang, B. Kaufmann, K. S. Kim, W. J. Kim, A. V. Koehler, B. Laitung, P. Latch, Y. D. Liu, M. B. Manjerovic, E. Martel, S. S. Metcalfe, J. N. Miller, J. J. Midgley, A. Migeon, A. J. Moore, W. L. Moore, V. R. F. Morris, M. Navajas, D. Navia, M. C. Neel, P. J. G. de Nova, I. Olivieri, T. Omura, A. S. Othman, J. Oudot-Canaff, D. R. Panthee, C. L. Parkinson, I. Patimah, C. A. Perez-Galindo, J. B. Pettengill, S. Pfautsch, F. Piola, J. Potti, R. Poulin, P. T. Raimondi, T. A. Rinehart, A. Ruzainah, S. K. Sarver, B. E. Scheffler, A. R. R. Schneider, J. F. Silvain, M. N. Siti Azizah, Y. P. Springer, C. N. Stewart, W. Sun, R. Tiedemann, K. Tsuji, R. N. Trigiano, G. G. Vendramin, P. A. Wadl, L. Wang, X. Wang, K. Watanabe, J. M. Waterman, W. W. Weisser, D. A. Westcott, K. R. Wiesner, X. F. Xu, S. Yaegashi, J. S. Yuan
    MOLECULAR ECOLOGY RESOURCES 9 (5) 1375 - 1379 1755-098X 2009/09 [Peer-reviewed]
     Scientific journal 
    This article documents the addition of 283 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Agalinis acuta; Ambrosia artemisiifolia; Berula erecta; Casuarius casuarius; Cercospora zeae-maydis; Chorthippus parallelus; Conyza canadensis; Cotesia sesamiae; Epinephelus acanthistius; Ficedula hypoleuca; Grindelia hirsutula; Guadua angustifolia; Leucadendron rubrum; Maritrema novaezealandensis; Meretrix meretrix; Nilaparvata lugens; Oxyeleotris marmoratus; Phoxinus neogaeus; Pristomyrmex punctatus; Pseudobagrus brevicorpus; Seiridium cardinale; Stenopsyche marmorata; Tetranychus evansi and Xerus inauris. These loci were cross-tested on the following species: Agalinis decemloba; Agalinis tenella; Agalinis obtusifolia; Agalinis setacea; Agalinis skinneriana; Cercospora zeina; Cercospora kikuchii; Cercospora sorghi; Mycosphaerella graminicola; Setosphaeria turcica; Magnaporthe oryzae; Cotesia flavipes; Cotesia marginiventris; Grindelia Xpaludosa; Grindelia chiloensis; Grindelia fastigiata; Grindelia lanceolata; Grindelia squarrosa; Leucadendron coniferum; Leucadendron salicifolium; Leucadendron tinctum; Leucadendron meridianum; Laodelphax striatellus; Sogatella furcifera; Phoxinus eos; Phoxinus rigidus; Phoxinus brevispinosus; Phoxinus bicolor; Tetranychus urticae; Tetranychus turkestani; Tetranychus ludeni; Tetranychus neocaledonicus; Tetranychus amicus; Amphitetranychus viennensis; Eotetranychus rubiphilus; Eotetranychus tiliarium; Oligonychus perseae; Panonychus citri; Bryobia rubrioculus; Schizonobia bundi; Petrobia harti; Xerus princeps; Spermophilus tridecemlineatus and Sciurus carolinensis.
  • WATANABE Kozo, YAEGASHI Sakiko, KIKUCHI Yuji, TAKEMON Yasuhiro, KAZAMA So, OMURA Tatsuo
    Journal of Japan Society on Water Environment 社団法人日本水環境学会 32 (5) 253 - 258 0916-8958 2009/05 
    Population connectivity of aquatic organisms is an important factor for sustaining the robustness of metapopulation in a basin-scale as well as for interpreting the properties of respective local populations. We examined the genetic structure of 30 Stenopsyche marmorata (Tricoptera) local populations in 4 catchments in South-Central Miyagi Prefecture, Japan using AFLP markers, and evaluated their dispersal pattern. We constructed a dendrogram using q, and found that 7 populations in headwater were isolated from another area in the basins. Although previous studies on S. marmorata adult flight within streams reported most of the females fly upstream along a watercourse after mating, our results indicated high possibility of non-directional adult dispersal due to wind. The results also suggested a strong potential for DNA polymorphic analysis to enhance understanding of the population connectivity and dispersal patterns of aquatic organisms in a basin scale.
  • Mano Akira, Omura Tatsuo, Udo Keiko, Wtanabe Kozo, Shirotori Yoshiyuki, Kotake Shota
    Annual report of the Society for the Promotion of Construction Engineering 東北大学 44 (44) 51 - 52 0288-9994 2009/04
  • Yoshiyuki Shirotori, Kozo Watanabe, Keiko Udo, Akira Mano
    Advances in Geosciences: Volume 11: Hydrological Science (HS) 223 - 235 2009/01 [Peer-reviewed]
     In book 
    On the upstream of Atago weir, Hirose River, Japan, the sedimentation phenomenon is complex due to the coexistence of the weir and channel bend. Moreover, fine sediment accumulates on the river bed notably. From the observed results, it is found that silt is the major component in the flood water and accumulates significantly in the discharge increasing stage by the backwater of the weir. From the theoretical computation considering the settling and resuspension of the suspended sediment, the cohesion of fine sediment is an important factor of the net deposition process.
  • Yoshiyuki Shirotori, Kozo Watanabe, Keiko Udo, Akira Mano
    ADVANCES IN WATER RESOURCES AND HYDRAULIC ENGINEERING, VOLS 1-6 815 - 820 2009 [Peer-reviewed]
     International conference proceedings 
    On the upstream of Atago weir, Hirose River, Japan, the sedimentation phenomenon is complex due to the coexistence of the weir and channel bend. Moreover, fine sediment accumulates on the river bed notably not only the floodplain. In this study, we conducted field observation and numerical computation. From the observation results, we found that fine sediment is the major component in the flood water and accumulates significantly close to the inner bank (silt and clay= 55% in the maximum). In the numerical computation, we calculated the flow using finite volume method with unstructured grid. The suspended-sediment transport was calculated by the advection-diffusion equation considering settling and resuspension. By considering the weir and cohesivity of the fine sediment, we reproduced the settling-resuspension characteristics of the fine sediment. From this calculation result, the deposition and erosion region was indicated.
  • Kozo Watanabe, Michael T. Monaghan, Tatsuo Omura
    AQUATIC SCIENCES 70 (4) 377 - 387 1015-1621 2008/12 [Peer-reviewed]
     Scientific journal 
    Small local populations may have low levels of genetic diversity, although widespread gene flow may counteract genetic drift and maintain high local diversity. At a larger spatial scale, a relationship between population size and genetic diversity could have important effects on the longitudinal genetic patterns in riverine corridors. We examined the genetic structure of 15 subpopulations of the caddisfly Hydropsyche orientalis in four rivers within the Natori River system in Japan using 78 polymorphic RAPD loci. Six subpopulations were fragmented by reservoirs and thus may be smaller, genetically isolated, or both. Pairwise F (ST) values were generally high throughout the study, and a higher mean value across the reservoirs (mean=0.219) relative to unfragmented streams 0.157) indicated reduced gene flow. Genetic diversity was not consequently reduced in these subpopulations; however, genetic diversity was positively correlated with larval density at all sites (percentage of polymorphic loci, %P = 46.3-59.1; expected heterozygosity H (exp) = 0.163-0.225). The longitudinal distribution of genetic diversity exhibited a unimodal pattern, with a peak in middle reaches. Correlation with larval density was a significant factor, although the presence of cryptic species as well as unimodally distributed environmental variables (e.g., habitat heterogeneity) provide alternative hypotheses. We suggest that studies examining longitudinal patterns of genetic diversity will provide a better understanding of the principal mechanisms that create and maintain biodiversity in rivers and streams.
  • Kozo Watanabe, Michael T. Monaghan, Yasuhiro Takemon, Tatsuo Omura
    SCIENCE OF THE TOTAL ENVIRONMENT 394 (1) 57 - 67 0048-9697 2008/05 [Peer-reviewed]
     Scientific journal 
    Analysis of carbon (delta C-13) and nitrogen (delta N-15) stable isotopes provides an increasingly important means of understanding the complex trophic structure of macroinvertebrate communities in streams. We coupled a stable isotope approach with a contaminant analysis of six metals (Pb, Ag, Zn, Hg, Cu, As) to trace the accumulation and dilution of metals from an abandoned mine across trophic levels of the benthic community in Ginzan Creek, Japan. The delta N-15 signature increased with trophic level, with mean increases of 4.70%. from producers to primary consumers and 3.06%. from primary to secondary consumers. Tissue Pb and Ag concentrations were negatively correlated with delta N-15, indicating biodilution of both metals through the food web. Although macroinvertebrate taxon body mass was negatively correlated with tissue metal concentration at several sites, it did not increase with trophic level (as delta N-15) in any of the sites, suggesting that changes in body mass were not the cause of biodilution. Our findings suggest invertebrates at higher trophic levels may exhibit increasingly efficient excretion of metals. Autotrophic epilithon (mean delta C-13 =-21.3%.) had a much higher concentration of mined metals than did riparian vegetation (mean delta C-13 = -29.3%.); nonetheless, a carbon-mixing model indicated that taxa. feeding on autochthonous carbon sources did not accumulate more metal than allochthonous feeders. It is likely that the notably high metal concentration of allochthonous FPOM plays an important role in the trophic transfer of metals. Our data suggest the strong potential for stable isotope analysis to enhance our understanding of metal transfer through stream macroinvertebrate food webs. (c) 2008 Elsevier B.V. All rights reserved.
  • 渡辺幸三, 白鳥喜之, 有働恵子, 真野明, 大村達夫
    水工学論文集(CD-ROM) 52 ROMBUNNO.194  1880-8751 2008/02 [Peer-reviewed]
  • 浜本洋, 風間聡, 渡辺幸三, 沢本正樹, 大村達夫
    水工学論文集(CD-ROM) 52 ROMBUNNO.196  1880-8751 2008/02 [Peer-reviewed]
  • WATANABE Kozo, KIKUCHI Yuji, KAZAMA So, OMURA Tatsuo
    Journal of Japan Society on Water Environment 公益社団法人 日本水環境学会 31 (1) 31 - 37 0916-8958 2008/01 
    The genetic diversity of Stenopsyche marmorata was investigated in three spatial hierarchies, among catchments, among reaches within catchments, and among individuals within reaches, by AFLP analysis of 306 individuals in 12 reaches in 3 catchments in Eastern Japan. The analysis of molecular variance revealed that the diversity within reaches accounted for the highest percentage (86%) of the total genetic variation in the three hierarchies. The genetic diversity between reaches increased with geographical distance between reaches on a small spatial scale (=2-74km); however, it did not increase on a large spatial scale (=74-450km). The level of gene flow among adjacent catchments (=55-74km) was lower than that between reaches within catchments (=2-19km). The genetic diversity within reaches (as the percentage of polymorphic loci and expected heterozygosity) positively correlated with altitude, suggesting that altitude is an environmental factor in determining the local population size of S. marmorata in each reach.
  • Kozo Watanabe, Tatsuo Omura
    WATER SCIENCE AND TECHNOLOGY 58 (3) 503 - 512 0273-1223 2008 [Peer-reviewed]
     Scientific journal 
    The trophic structure of a macro invertebrate community was investigated using carbon and nitrogen stable isotopes analysis (delta C-13 and delta N-15) at three longitudinal sites along the main channel of the Hirose River, Japan, and at an outlet site of the tributary reservoir. Along the main channel, primal food supply gradually changed from allochthonous to autochthonous source. The percentage of autochthonous origin of the macroinvertebrate community calculated by a carbon-mixing model ( = 38-83%) increased with that of suspended fine particulate organic matter (FPOM = 21-67%), a main resource for filtering-collectors that dominated the communities. The lowest percentage of autochthonous in the lake outlet community ( = 21%) was a result of the notably low percentage autochthonous of FPOM due to the decomposition of allochthonous coarse particulate organic matter (e.g., leaf) strained in the reservoir. Predators had higher mean delta N-15 than non-predators in three sites. The average enrichments of delta N-15 signature per trophic level for all sites were 3.82 parts per thousand from producers to first consumers and 1.24 parts per thousand from first to second consumers. Our data suggest the strong potential for stable isotope analysis to enhance our understanding of the trophic structure of stream macroinvertebrate community.
  • 渡辺幸三, 草野光, 大村達夫
    環境工学研究論文集 44 83 - 92 1341-5115 2007/11 [Peer-reviewed]
  • 菊池祐二, 渡辺幸三, 風間聡, 大村達夫, 沢本正樹
    環境工学研究論文集 44 99 - 106 1341-5115 2007/11 [Peer-reviewed]
  • 城戸和寿, 後藤勝洋, 佐合純造, 大村達夫, 渡辺幸三
    リバーフロント研究所報告 (18) 159 - 166 1348-9356 2007/09
  • 渡辺幸三, 大村達夫
    土木学会論文集 G 63 (2) 93 - 101 2007/07 [Peer-reviewed]
  • Kozo Watanabe, Tatsuo Omura
    BIOLOGICAL CONSERVATION 136 (2) 203 - 211 0006-3207 2007/04 [Peer-reviewed]
     Scientific journal 
    Reservoirs have the potential to block the gene flow of stream macroinvertebrates along a Received 27 February 2006 channel, which takes place via larval drift and adult flight, resulting in genetic differentiation Received in revised form above and below the reservoirs. Gene flow across the reservoirs may be strongly obstructed if 15 November 2006 the area of standing water is larger. Using random amplified polymorphic DNA markers, we Available online 17 January 2007 investigated the genetic structure of Stenopsyche marmorata (Stenopsychidae: Trichoptera) populations found above and below the reservoirs, and the reference stream of six reservoirs Keywords: with small to large water surface area ranging from 0.12 km(2) to 6.00 km(2). As a result, the two largest reservoirs with a standing water area larger than 3.27 km(2) showed significant differ flow ences in pairwise 0 between fragmented and reference streams, whereas the other four res fragmentation ervoirs with a standing water area smaller than 1.64 km(2) showed insignificant differences. Genetic diversity The genetic differentiations in the two largest reservoirs did not result in the reduction of Population size genetic diversities in the fragments. Based on the significant correlation between relative population size and mean expected heterozygosity, we concluded that local genetic diversities were constrained in smaller populations due to the effect of genetic drift. (C) 2006 Elsevier Ltd. All rights reserved.
  • 白鳥喜之, 渡辺幸三, 有働恵子, 真野明
    東北地域災害科学研究 43 199 - 204 2007/03 [Peer-reviewed]
  • 広瀬川愛宕堰上流における堆積環境の実態解明
    白鳥喜之, 渡辺幸三, 有働恵子, 真野明
    土木学会東北支部技術研究発表会 44 Ⅱ-29  2007 Research society
  • 渡辺幸三, 草野光, 大村達夫
    土木学会論文集 G 63 (3) 186-194 (J-STAGE)  2007 [Peer-reviewed]
  • WATANABE Kozo, OMURA Tatsuo
    Doboku Gakkai Ronbunshuu G 公益社団法人 土木学会 62 (1) 94 - 104 1880-6082 2006/04 
    Based on RAPD, the genetic structures of Stenopsyche marmorata, Hydropsyche orientalis, and Ephemerella nigra populations found above and below reservoirs with various water surface areas were investigated. The results of the genetic distance showed that amongst the six reservoirs, the genetic differentiations of H. orientalis were found in the third smallest and in the largest reservoirs while those of S. marmorata were shown in the two largest reservoirs. The size of reservoir influenced the genetic differentiations for S. marmorata, but did not for H. orientalis. The expected heterosygosity indicated that genetic diversities of H. orientalis were constrained by both effects of habitat fragmentation and population size while the rest of the species were constrained only by the latter's effect.
  • WATANABE Kozo, OMURA Tatsuo
    土木学会論文集 土木学会 (811) 49 - 59 0289-7806 2006/02
  • WATANABE Kozo, YAMAMOTO Naoki, KUSANO Hikaru, OMURA Tatsuo
    Journal of Japan Society on Water Environment 日本水環境学会 28 (12) 737 - 744 0916-8958 2005/12 
    Concentrations of Ag, Pb, and Hg in samples of aquatic insects and feeding sources such as algae and leaves were determined at four sites along the Ginzan River, Which receives drainage from a mined land. Nitrogen (δ15N) and carbon (δ13C) isotope analyses of the samples were carried out to assess whether feeding sources or the trophic level influenced metal accumulation in each faunal taxon. The individual dry mass was also measured to examine the effect of body size on metal accumulation. The relationship between metal concentrations and level of δ15N in fauna indicated biodilutions for Pb (3 sites) and Ag (1 site) through the food webs. This must be caused by high concentrations of metals in algae and fine particulate organic matter (FPOM) as the main feeding sources for harvivores and detorivores. The relative contribution of autochthonous and allochthonous energy sources to each taxon's biomass had no effect on the concentrations of Ag, Pb, and Hg in the fauna. The individual dry mass was negatively correlated with the concentrations of Ag (3 sites), Pb (1 site), and Hg (4 sites) in fauna.
  • K Watanabe, C Yoshimura, T Omura
    ECOLOGICAL MODELLING 189 (3-4) 396 - 412 0304-3800 2005/12 [Peer-reviewed]
     Scientific journal 
    A macroinvertebrate community having been pre-assessed to have lower resilience against anthropogenic pulse-disturbance in river (e.g. muddy water from construction site) should be given intensive preservation efforts. Using stochastic population dynamics model with density-dependant and environmental fluctuation, a recovery prediction model for macroinvertebrates' total biomass following its decline due to pulse-stressors have been developed. In this recovery model, the inherent resilience was determined by three parameters: carrying capacity, specific growth rate and environmental fluctuation intensity. The parameters were estimated from the time-series data of the total biomass. Using the application of the recovery model for a hypothesized scenario, the recovery index (RI) and the ecological time loss (ETL) were calculated. Both RI and ETL can evaluate the recovery process of the total biomass after an anthropogenic pulse-disturbance. A case study was done in 70 communities in Tokyo using the indexes of both RI and ETL. Recovery processes were simulated by administering a virtual pulse stressor to decrease the total biomass to 8%. As a result, 80% among the total number of communities performed a higher resilience within 3 years of the ETL. RI revealed that geographically neighboring community possesses extra-high resilience. Multiple regression analysis also proved that ETL was significantly explained by five environmental variables: specific conductivity, width of low-water channels, catchment area, suspended solid and stream order. As the results implied, macroinvertebrate community can recover quickly in total biomass when supplied from non-damaged upstream reaches. The case study also demonstrated the high potentialities of RI and the ETL for impact assessments in the river ecosystems. (c) 2005 Elsevier B.V. All rights reserved.
  • YAMAMOTO Naoki, WATANABE Kozo, KUSANO Hikaru, OMURA Tatsuo
    Journal of Japan Society on Water Environment 日本水環境学会 28 (6) 385 - 392 0916-8958 2005/06 
    The trophic structures of benthic faunal communities in a river are expected to respond to the relative amounts of autochthonous and allochthonous energy sources in the environment. Using isotopic analysis of δ13C, we investigated the percentage of autochthonous energy of benthic fauna at 3 sites longitudinally sited along the Hirose River, and at a site at the outlet of the Okura reservoir in a tributary. The relative trophic level of each taxon was also estimated from δ15N, and a biomass pyramid for each community was produced. As a result, the percentage of autochthonous energy of benthic faunal community formed a longitudinal distribution along the river, showing a high peak midstream with lower values both upperstream and downstream. This profile was similar to a longitudinal pattern of that of Fine Particulate Organic Matters (FPOM) in flowing water, a main resource for filtering-collectors that dominate these communities. At the Okura reservoir outlet, the percentage of autochthonous energy of the community was the lowest among the four sites, reflecting a low percentage of autochthonous energy in FROM due to the decomposition of allochthonous organic matter in standing water. The biomass pyramid for each community showed an energy peak in the middle trophic level.
  • WATANABE Kozo, OMURA Tatsuo
    Doboku Gakkai Ronbunshu 公益社団法人 土木学会 (790) 49 - 58 0289-7806 2005/05 
    Reservoir obstructs gene flow of stream invertebrates along a channel, which takes place via larval drift and adult flight. It may result in genetic differentiation between above and below reservoir, which would reduce genetic diversities in fragments. Gene flow across a reservoir may be more strongly obstructed if the area of standing water is larger. Using RAPD, we investigated the genetic structure of Stenopsyche marmorata populations found above and below the reservoir, and the reference stream of 6 reservoirs in small to large water surface area. As a result, out of the 6 reservoirs, significant genetic differentiations were detected in the biggest 2 reservoirs with an area of standing water larger than 3.27 km2. However, these genetic differentiations did not result in the reduction of genetic diversities in the fragments.
  • WATANABE Kozo, YOSHIMURA Chihiro, OGAWARA Takashi, OMURA Tatsuo
    Doboku Gakkai Ronbunshu 公益社団法人 土木学会 (748) 67 - 79 0289-7806 2003/11 
    The population dynamics model describes the annual change of total biomass of benthic animals in river. We developed a recovery model assessing the influence of an artificial pulse type (temporal) impact with two evaluation indexes, i. e. Recovery Rate and Ecological Loss Time. Recovery simulations from a virtual impact were performed in 70 river sites in Tokyo with an assumption that the biomass decreases to 0.08 times just after the impact in each site. This recovery model confirmed the tendency of high resilience of macroinvertebrate as well as the effectiveness of the two indexes for impact assessments in river ecosystem.
  • WATANABE Kozo, YOSHIMURA Chihiro, OGAWARA Takashi, OMURA Tatsuo
    土木学会論文集 土木学会 734 (734) 99 - 110 0289-7806 2003/05
  • OGAWARA Takashi, WATANABE Kozao, YOSHIMURA Chihiro, OMURA Tatsuo
    Journal of Japan Society on Water Environment 日本水環境学会 26 (4) 223 - 229 0916-8958 2003/04 
    It has been reported that several floras and faunas in rivers are genetically impaired by artificial structures such as dams and cities because of the fragmentation and the reduced heterogeneity of their habitats. However, the investigations on genetic diversities of Trichoptera in rivers have been few to date. In this study, therefore, the genetic investigation of Hydropsyche orientalis was conducted at 13 stations in the Natori River System in Miyagi Prefecture, Japan from Dec. 2000 to May 2001. The Okura and Kamafusa dams, and the Sendai urban area are located upstream and downstream of the rivers. The DNA polymorphisms of Hydropsyche orientalis collected at the 13 stations were analyzed with the appropriate primer, OPA-11, for calculating the genetic diversity index. The result of statistical analysis of the index showed a significantly higher level of genetic diversity of Hydropsyche orientalis in the natural area than in the areas around the dams. Moreover, the effect of urbanization on its genetic diversity was indicated based on the estimation of its migration from the results of the cluster analysis of the DNA polymorphisms.

Books etc

  • Health in Ecological Perspectives in the Anthropocene
    Carvajal, T. M, H. T. Ho, L. F. T. Hernandez, K. M. Viacrusis, D. M. Amalin, K. Watanabe (Joint work, An Ecological Context towards Understanding Dengue Disease Dynamics in Urban Cities: a Case Study in Metropolitan Manila, Philippines)
    Springer 2018/11 9789811325267 159

Conference Activities & Talks

MISC

Awards & Honors

  • 2014/09 土木学会 平成26年度地球環境優秀講演賞
     
    受賞者: 糠澤桂;風間聡;渡辺幸三
  • 2010/09 日本水環境学会 日本水環境学会平成21年年間優秀論文賞(メタウォーター賞)
     
    受賞者: 渡辺幸三;八重樫咲子;竹門康弘;風間聡;大村達夫
  • 2009/06 財)建設工学研究振興会 平成20年度建設工学研究奨励賞
     
    受賞者: 渡辺幸三
  • 2005/03 東北大学 平成16年度東北大学総長賞
     
    受賞者: 渡辺幸三
  • 2004/10 応用生態工学会 応用生態工学会第8回大会ポスター賞(選考委員会部門
     
    受賞者: 渡辺幸三
  • 2004/10 応用生態工学会 応用生態工学会第8回大会ポスター賞(一般投票部門)
     
    受賞者: 渡辺幸三
  • 2004/09 土木学会 土木学会第59回年次学術講演会優秀講演者
     
    受賞者: 渡辺幸三
  • 2004/05 土木学会 平成15年度土木学会論文奨励賞
     
    受賞者: 渡辺幸三

Research Grants & Projects

  • Biological Control of Dengue Disease Using Symbiotic Wolbachia Bacteria: Environmentally Safe and Inexpensive Approach
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
    Date (from‐to) : 2019/10 -2022/03 
    Author : 渡辺 幸三, 糠澤 桂, 八重樫 咲子, ガンボア・メンデス マリベット・アリアナ
  • Prediction and integrated assessment of health risks due to heat-induced disorders and infectious diseases under climate change
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 福士 謙介, 渡部 徹, 渡辺 幸三
  • Quantitative Meta-barcoding for Rapid and Accurate Assessment of Species Diversity: Application to Community and eDNA samples
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 渡辺 幸三, 加藤 幹男, 竹門 康弘
  • ノロウイルス感染症制御を可能とする水インフラの実現
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2018/04 -2022/03 
    Author : 大村 達夫, 李 玉友, 片山 浩之, 渡部 徹, 渡辺 幸三
     
    本研究は、「ノロウイルス感染症制御を可能とする水インフラ」の実現を目指すものである。充実した水インフラが整備されている先進諸国であっても、ノロウイルス感染症は制御不可能な状況にある。これは、水インフラの整備が遅れている開発国において病原性の高いノロウイルスの遺伝系統が容易に発生するためと推測される。そこで本研究では、「水インフラ環境が異なる地域間でノロウイルスの進化速度が異なる」との仮説を立て、その実証を試みることを目的としている。 研究初年度である平成30年度は、マウスノロウイルスを用いた精密膜ろ過及び消毒処理による環境選択実験により、精密膜ろ過により除去されにくいマウスノロウイルスの遺伝系統と、消毒剤耐性を有するマウスノロウイルスの遺伝系統を取得すること、及び下水・汚水由来のノロウイルス遺伝子取得を目的とした実験を行った。消毒剤耐性を有するマウスノロウイルスに関しては、遊離塩素に対し有意な耐性を保持する集団の取得に成功した。得られた遊離塩素耐性マウスノロウイル集団、および遊離塩素を用いずに希釈と培養のみを繰り替えした対照マウスノロウイルス集団に対し全ゲノム解析を行ったところ、遊離塩素耐性マウスノロウイルス集団に特異的な遺伝子変異を同定することに成功した。そのうちの1つはVP2と呼ばれるマイナー外殻タンパク質をコードする遺伝子中に存在しており、この変異によりマウスノロウイルス粒子の安定性が向上しているものと推測された。下水・汚水由来のノロウイルス遺伝子取得に関しては、仙台市内の下水処理場で採取した未処理下水から得られたノロウイルス遺伝子配列の取得に成功した。
  • Genome Scan for Genes underlying Global Warming Adaptation Using Next-generation Sequencing: Application to Genetic Diversity Projection
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Challenging Research (Exploratory)
    Date (from‐to) : 2019/06 -2021/03 
    Author : 渡辺 幸三
  • Assessment of Dengue Risk under Climate Change: A New Approach based on Genetic Analysis of Mosquito
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2019/04 -2021/03 
    Author : 渡辺 幸三, CARVAJAL Thaddeus Marzo
  • Why noroviruses are accumulated in oysters: To unravel the mechanisms
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Challenging Research (Pioneering)
    Date (from‐to) : 2017/06 -2020/03 
    Author : 大村 達夫, 藤井 学, 三浦 尚之, 渡辺 幸三, 佐野 大輔
     
    カキを養殖している内湾の河口から沖に向かった縦断方向に位置する5地点において海水200~560Lに含まれる植物および動物プランクトン試料を採取用ネット(目合0.1mmおよび目合0.072mm)をそれぞれ用いて採取した。また,5地点のうち1地点では,養殖カキも同じ日に採取した。調査は2018年11月6日、12月20日、2019年2月4日にそれぞれ行った。プランクトン採取時のばらつきを評価するため,各地点において濃縮試料(約40mL)のレプリケートを3~4本採取した。採取したプランクトン試料は顕微鏡下で,動物,植物プランクトンに形態学的にソーティングした。カキ試料からは中腸線を取り出し,湿重量を計量したのちに,定量PCRによるノロウイルスの検出および定量,そしてDNAメタバーコーディングによるカキの食性解析のために冷凍保存した。 形態学的ソーティングの結果,採取用ネットの目合(0.1mmおよび0.072mm)の違いに依らず,動植物プランクトンが混在した形で採取されていることが確認された。ただし,割合としては,0.072mm目合ネットの方が植物プランクトンの個体数の割合が全体的に高まっていた。リアルタイムPCRによるノロウイルスの検出の結果,一部サンプルからノロウイルスが検出された。サンプル中の動物および植物プランクトンの個体数を形態学的に定量した結果,動物プランクトンの個体数の割合が高い地点のサンプルほど,ノロウイルス濃度が低下している相関関係が観察された。また,カキ中腸線のDNAメタバーコーディング解析を行い,カキが動物および植物プランクトンの双方を捕食していることも確認された。
  • Development of database for health and environment in southeast Asia
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2017/04 -2020/03 
    Author : 福士 謙介, 渡部 徹, 渡辺 幸三
     
    【暑熱環境班】暑熱環境の解析をベトナム(ハイフォン、フエ、ダナン)、インドネシア(メダン市、スラバヤ市、デンパサール市、北スマトラ州、東ジャワ州、バリ州)において、現在、将来に関して実施し、計算結果、計算するために必要なデータの収集と整理を行った。一方、国立環境研究所・気候変動適応センターとアジア太平洋気候変動適応情報プラットホーム(AP-PLAT)における本事業で収集整理したデータの効率的な格納方法、表示方法に関して検討し、2020年までには同プラットホーム上で本事業の成果を公表可能にする方向で検討することとなった。 【水系感染症班】ベトナム・フエを対象に、カウンターパートの協力を得ながら、洪水時の溢水のサンプリングを実施した。また,洪水時と平常時の感染症発生状況を把握するため、都市下水のサンプリングも実施した。そこで採取したサンプルからは、感染症リスク評価に必要な糞便汚染指標細菌(大腸菌、腸球菌)やノロウイルスの検出をそれぞれ行った。さらに、農作物の汚染を介した間接的な感染症リスクを検討するために、都市下水に起因する都市近郊農地の汚染に関する情報収集も行った。 【ベクター感染症班】前年度から継続して、インドネシア全土およびフィリピン全土から各国のカウンターパートと協力して、デング患者の疫学データを国際機関と国の保健機関から収集した。また、デング熱小児患者の心理的負担(うつ病率等)についてのデータも収集し、約2割のデング熱小児患者がうつ病を発症していることを明らかにした。さらに、トラップを使った蚊生息数データの収集を、マニラおよびバンドンで継続的に行った。蚊に刺された場所と時間データをスマートフォンを介して広範囲から収集するアプリを開発できた。インドネシアを網羅する約8割の県を対象として、各県の気象変数からデング熱感染リスクを予測する機会学習モデルを作成した。
  • Ecological evaluation of river restoration projects below dams by combination management of flow and sediment regimes
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2017/04 -2020/03 
    Author : 角 哲也, 竹門 康弘, 渡辺 幸三
     
    平成29年度にトリニティ川で調査した「河川管理(流況・土砂供給)」,「生息場構造」「生物多様性 」「水質浄化機能」の4要素間の関係を分析するとともに、天竜川と木津川を中心とした国内河川で同様の調査を行って比較分析を行った。平成30年度は、平成29年度に実施した、課題1の河川管理の違いが生息場構造や河床状態に及ぼす影響の解明、および、課題2の河川管理の結果形成された生息場構造が生物多様性(魚類・底生動物)に及ぼす影響に加えて、課題3の砂州フィルタリングによる水質浄化機能に及ぼす影響について取り組んだ。 課題1に関しては,ルイストンダム下流区間ならびに天竜川船明ダム下流区間の調査結果をもとに,面積比,頻度比,生息場多様度等の生息場構造指標を評価し,「流量変動や土砂供給量が中程度の状況下で生息場構造の多様性や河床間隙が最も高まる」という仮説を検証した。 課題2では,生息場ごとに底生動物と魚類の種多様性,種構成,個体数,エネルギー寄与率等の生態学的指標を評価するために ,課題1で明らかにされた生息場構造指標,砂州形状特性値や河床材料に関するデータとの定量関係を回帰分析で導き,流況や 土砂管理による生息場の改善が生態学的指標の変化に繋がっているのかを定量的に検証した。 課題3では,生息場構造の水質浄化機能を評価するために, 平成29年度に行った調査結果をもとに,濁度,懸濁成分量(SS, 強熱減量),粒状有機物の安定同位体比,溶存酸素や栄養塩等の水質項目について,砂州内流下方向の変化を評価するとともに ,河床内に生息する微生物群集の種組成について,次世代シーケンサーを用いたメタゲノム解析で種を同定した。そして,砂州リフレッシュによる微生物群集組成の更新と共に,生物学的な水質浄化機能の改善に繋がっている分類群等を特定し,砂州形状や河床間隙率の違いが水質浄化機能に及ぼす影響を明らかにした。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Challenging Research (Exploratory)
    Date (from‐to) : 2017/06 -2019/03 
    Author : Watanabe Kozo
     
    Dengue viruses are biologically transmitted among humans through the bite of infected female Aedes aegypti mosquitoes. However, gene-based processes occuring in viral infected mosquitoes are not clear yet. Next-generation sequencing based transcriptome analysis (RNAseq) is a powerful technique for assessing the differential expression of genes. Using this technique, we compared gene expression patterns among mosquito individuals infected with 1) Dengue virus, 2) asymbiotic bacteria Wolbachia, and 3) neither of these, using Aedes aegypti samples collected from the Philippines. Before the RNAseq analysis, we screened Dengue virus or Wolbachia positive individuals using PCR or RT-PCR assays. Through the RNAseq analysis, we found 69 genes, which are potentially related to biological process concurring in Dengue infected mosquito bodies. These genes are estimated to be related to many biological functions such as serine-type endopeptidase activity, ATP binding, and odorant binding protein.
  • Vulnerability Assessment of Stream Invertebrates to Global Warming Using Gene Expression Analysis
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2017/04 -2019/03 
    Author : 渡辺 幸三, GAMBOA MENDEZ MARIBET ARIANA
     
    【研究背景】膨大なゲノムには水質・水温・流速等の様々な環境因子の自然選択を受けた遺伝子が数多く存在する。この環境選択性遺伝子を同定できれば,生物の適応的進化の理解が促進される。この遺伝子と環境を直接関連付ける適応的進化の理解により,将来の気候変動や土地利用変化などの環境変化後の遺伝的多様性の劣化をより正確に予測することが可能となる。 【研究目的】水温の変化に敏感な河川水生昆虫カワゲラを対象に,日本列島の寒冷~亜熱帯の気候勾配に沿った適応的なRNAレベルの遺伝構造の変化を調べて,将来の気候変動(地球温暖化)に伴う遺伝的多様性の劣化や種の絶滅の可能性を予測する. 【方法】札幌,仙台,岐阜,松山の日本列島の気候条件に沿った4地域の流域において,河川水生昆虫カワゲラの幼虫個体を採取した。生物個体の採取と共に,遺伝的な適応に関係する可能性のある気温・水温・流速・河床材料などの物理的環境の現地調査,GISを使った土地利用状況(農地,山林等)や都市化率の定量化など,環境条件を多岐に渡って調査した。さらに,次世代シークエンサー(HiSeq 4000)を使ったゲノムワイドのトランスクリプトーム解析により,DNAから翻訳されたmRNAライブラリーの配列データを取得した。 【結果および考察】次世代シーケンス解析から353,352配列が得られた.その内,BLAST検索でヒットしたのは1732配列,411個の遺伝子がアノテーションされた.地域間において共通の遺伝子領域は1つのみだったが,特異な遺伝子領域は390個とはるかに多かった.特に札幌では他3地域より約40個多い131個の遺伝子領域が特異だった.アノテーションされた遺伝子領域が札幌において143個で他3地域より40個以上多かったことから,極端な環境状態に適応するためにカワゲラはより多くの遺伝子を発現する必要があると推測された.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2016/04 -2019/03 
    Author : Watanabe Kozo
     
    We developed a new method for parallel assessment of genetic dversity across multiple species in riverine invertebrate communities using next-generation sequencing technology. We applied the develop method to the Shigenobu River Basin and tested its utility and feasibility. In this case study, we investigated gene flow among localities in the basin for 15 species of aquatic insects (3 of Ephemeroptera species; 12 of Diptera, Chironomidae species) in parallel. Cytochrome Oxidase subunit I region in mitochondrial DNA were amplified with DNA tag for each sampling site and were genotyped using NGS amplicon analysis. Comparison of pairwise Fsts between flagmented sited and between non-flagmented sited by intermittend interval showed that most spesies were not interrupted by intermittent interval other than Baetis sp. and Chironomus kiiensis. Overall, we could demonstrate a high potential of the developed method in accelerating assessment of genetic diversity in wild populations.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2016/04 -2019/03 
    Author : Watanabe Kozo
     
    We detected Dengue virus and symbiotic bacteria Wolbachia from Aedes aegypti samples collected from the Philippines. Out of 359 female aduult Ae. aegypti tested for the presence of the Dengue virus using an individual-based serotype-specific multiplex real-time RT-PCR assay, ten female mosquitoes (2.8 %) were confirmed to be positive for the presence of the DENV. Different serotypes were found between mosquito and human in same villages, suggesting that spatial transmission of dengue virus is occurring in a large space (i.e., among villages). In addition, out of 627 adult Ae. aegypti individuals collected from Metro Manila, 80 (12%) were found to be Wolbachia positive based on PCR and sequencing analysis of wsp and 16S rDNA markers. We also developed a machine learning model that predicts the weekly change of Dengue Incidence in Metro Manila based on meteorological and hydrological observational data.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2016/04 -2019/03 
    Author : SATO MEGUMI, Nakao Minoru
     
    Tick collection was conducted during 2016 to 2018, and tick prevalence Niigata prefecture was reviled. 10 tick species were recorded in this research. Some of them are ticks in hot area, and have never seen in Niigata in 1950's. Tick born diseases pathogens; Rickettsia spp. and Borrelia spp. detection was done, and host-pathogen specificity was observed. 3 species of Rickettsia were detected, namely R. asiatica, R. helvetica, R. monacensis. For Borrelia, B. japonica,B. miyamotoi and unknown species of Borrelia were detected from collected ticks.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2015/04 -2018/03 
    Author : Omura Tatsuo
     
    We investigated the adaptive evolution of gastroenteritis viruses under the repeated disinfection with free chlorine. Murine norovirus (MNV) and Rhesus rotavirus (RRV) were used as surrogates for human norovirus and rotavirus. As a result, resistant populations of these viruses to free chlorine were successfully acquired by the repeated treatment with free chlorine. The single nucleotide polymorphisms revealed that specific mutations were found in outer capsid proteins of these viruses, which implied that some mutations in structural proteins may contribute to the virion stability and lead to the change in free chlorine susceptibility. Based on these results, it was concluded that the free chlorine disinfection can be regarded as a selection pressure on gastroenteritis viruses.
  • 日本産河川昆虫カワゲラの種多様性の系統発生学的再評価:DNAと形態に基づく種分類
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2015/04 -2017/03 
    Author : 渡辺 幸三, MURANYI DAVID
     
    本研究は、ヨーロッパ,北アメリカ,日本広域を網羅する東アジアから採取した成虫標本を用いて、カワゲラ目クロカワゲラ科の属ならびに種の定義を見直した。形態学的分析とDNA塩基配列に基づいて、(1)クロカワゲラ類の時間的,地理的な進化過程を明らかにすること,(2) クロカワゲラ類の属間の形態形質の進化パターンを明らかにすること, (3) DNAデータベースの充実化に向けクロカワゲラ類のCOI塩基配列とHistone H3塩基配列を解読し決定することを目的とした解析を行った.主な結論を以下にまとめる. (1) クロカワゲラ科224サンプルから形態同定により未記載属7属,未記載種15種が確認された.形態だけでなく分子系統樹においてもこれらの属の単系統が示されたことにより,形態同定の正確性が裏付けられた.なお,未記載属Aのアメリカ産と日本産は系統の異なる別属であることが示唆された.日本産クロカワゲラ科のいずれの種も,現在のCapnia属の狭義の形態学的定義には当てはまらないことが明らかになった。これらは我々が定義しようとしている新たな属に分類されるものと考えられる。 (2) ベイズ推定法による分子系統樹からクロカワゲラ類の時間的,地理的な進化過程が推定された.日本産の属の多くが単系統群に当てはまり,日本産クロカワゲラは大きく分けて3つの系統から成ることが示された.. (3) 遺伝距離と形態形質の距離の間に正の相関があることが示された.クロカワゲラ科は遺伝的な差が大きくなるほど形態も異なっている. (4) クロカワゲラ科19属62種のCOI配列を220配列,Apteroperla(ハダカカワゲラ)属6種のHistone H3配列を28配列解読した.これらの配列データをDNAデータベースに登録し,DNAバーコーディングの精度向上に役立てられるものと考えられる.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2014/04 -2017/03 
    Author : Fukushi Kensuke
     
    Models for quantitative risk assessment of infectious diseases induced by urban flood were developed, considering effects of climate and societal changes, in some cities in Asian developing countries. One of the developed model was a QMRA-based model which enabled us to estimate risk of norovirus infection taking human behaviors in flood setting and human-to-human transmission in households into account. Another model to estimate risk of dengue fever based on climatic parameters, focusing on seasonal and spatial changes of its prevalence in cities, was developed using an algorithm for machine learning. We also clarified infectious diseases which happen frequently in flood settings and inhabitants’ feeling to the diseases by means of interview surveys in the target cities. According to the result, the method to calculate DALY lost by the infectious diseases was modified and finally the economic loss due to the diseases induced by urban flood was quantified.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2014/04 -2017/03 
    Author : SUMI TETSUYA, Boes Robert
     
    1. Regarding sediment bypass tunnels in Japan and Switzerland, data of the shape of tunnel, design flow velocity, gran size distributions of passing gravel, rock quality, yearly operation days, passing sediment volume, etc. were collected. 2. (1) Data on abrasion performance of Asahi Dam of Kansai Electric Power Co., Inc. was collected. We compared the prediction accuracy of abrasion prediction formula widely used in Japan (Ishibashi formula) and Swiss Federal Institute Technology. (2) In the observation technique of sediment transport rate, a plate type hydrophone has been developed which can withstand the impact of high flow velocity and large particle diameter. By physical experiments, we have determined the measurable sediment particle size range and the signal (gain) optimum for estimating sediment load. It was revealed that the detection rate of passing gravel by hydrophone is represented by saturation rate and collision rate.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2014/04 -2017/03 
    Author : MIYAKE Yo, INOUE Mikio, WATANABE Kozo, YOSHIMURA Kento, OKADA Yusei, IZUMI Teppei, WATANABE Yuya, MUKUDA Yuki
     
    We aimed to elucidate the relationship between flow regime and river faunal composition across Japanese rivers. Our results showed that the duration of high flow events and the magnitude of spring flood have strong influence on the community structure of stream-dwelling invertebrate and fish in Japanese rivers. We concluded that environmental flow management, such as improvement of dam operation and mitigation of the impact of human land use, is essential for river ecosystem conservation.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Watanabe Kozo
     
    We projected adaptive genetic variations of four species of stream insect under climate change scenarios, using the distributed hydrothermal model and 8 global climate models. We modeled 11-31 selective AFLP loci per species, which were statistically identified to be subject to natural selection. We acquired bias-corrected air temperature and precipitation data of 3 RCP scenarios (CP2.6、RCP4.5、RCP8.5) from the GCMs. Then, these climatic data were used to calculate annual metrics of current velocity, water depth and water temperature using the hydrothermal model. Models describing adaptive genetic variation, which is represented as linear response of allele frequency at each locus under natural selection to environmental predictors, have been constructed based on current hydrothermal variables. Using the models, we estimated future changes of the allele frequency along changing climate gradients.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2013/04 -2017/03 
    Author : TAKEMON YASUHIRO
     
    River ecosystems should be managed as a dynamic habitat mosaic system. This study clarified the disturbance regimes required for creating suitable habitat structure by a series of field monitoring of riverbed geomorphology and ecological functions from the aspect of habitat longevity. Suitable spawning redds of Ayufish were created by big floods of 4.5 year return period and degenerated by middle and small floods less than 1 year return period in the Tenryu River. Whereas flood plain ponds suitable for bitterlings and unionid mussels had the mud deposition of 5-10cm in depth and an inundation frequency less than three time per year at the moment of two years before (ponds at relative height of inundation period of 8-22days/year at present conditions) . corresponded to the amount of annual mean sediment load of 40,000-60,000m3/year in the Kizu River.
  • 河川水生昆虫カワゲラの環境適応と遺伝的分化:ゲノムとタンパク質の進化
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2013/04 -2016/03 
    Author : GAMBOA Maribet
     
    気候勾配に沿った札幌・仙台・岐阜・松山の4地域の河川から,45種・1457個体の水生昆虫カワゲラの幼生個体を採取した。また,現地で補足的に行った成虫のサンプリングにより,12種から成る89個体の成虫個体も採取した。 RADシークエンシングにより,42種の計384カワゲラ個体から,合計約160億塩基のゲノムワイドのDNA塩基配列データを収集することに成功した。解読されたゲノム上の約300万塩基において,気候勾配に沿って設定した調査地域間における一塩基多型(SNP)が検出され,気候勾配に沿った遺伝的変異がゲノム上の広域で起きていることが解明された。 タンパク質レベルのプロテオーム解析では,2次元電気泳動によるタンパク分画解析から,気温の季節間変動が大きな札幌と岐阜では,他地域よりも多様なタンパク質を発現していることが分かった.解析をした7種のカワゲラのうち,Nemoura sp. ,Rhabiopteryx japonica ,Eucanopsis sp. ,Perlodini incertaeの4種は4地域で最も温暖な松山で特異的に発現したタンパク質数が他の地域より多いことから,温暖な地域に適応的な種である可能性が示された.一方,Amphinemoura sp. とHaploperla japonica の2種は札幌で特異的に発現したタンパク質数が多いことから,寒冷な地域に適応的な種と推察された.さらに,各地域に固有に発現していた計111種類(スポット)のタンパク質を選択して,更に高度なアミノ酸配列情報等を取得するMALDI-TOF/TOFを行い,タンパク質を同定した. ゲノムワイドのmRNAの発現をトランスクリプトーム解析で調べた。7種の計46個体のカワゲラから,合計約6300万塩基のゲノムワイドのmRNA塩基配列データを収集し,411個の遺伝子のうち11個はもっとも寒冷な札幌で特異的に検出されていることがわかった.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2013/04 -2016/03 
    Author : Watanabe Kozo, OMURA Tatsuo, KATO Mikio, MIYAKE Yo
     
    Using high-throughput Next-generation Sequencing (NGS), we rapidly assessed species richness of stream macroinvertebrate communities among 10 sites in the Shigenobu River catchment in Ehime Prefecture Japan. A conventional morphological taxonomic identification found 64 taxa among 8921 individuals collected from the catchment. Our NGS analysis produced 165,508 reads of mitochondrial COI amplicons. Based on DNA barcoding analysis of the NGS data, 39,337 was hit and 128 species were identified. Further, we found a significant positive correlation between numbers of sequence reads and morphology-based abundance among 33 taxonomic groups (1 class, 3 orders, and 30 families). We also applied DNA taxonomy analysis using PTP model, and the presence of 298 species in the catchment was estimated.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2013/04 -2016/03 
    Author : Watanabe Kozo, OMURA Tatsuo, WATANABE Toru, OSHITANI Hitoshi, SAITO Mariko
     
    We assessed the spatial population genetic structure of dengue vector mosquito Aedes aegypti in Metro Manila and Tarlac city in the Philippines. The analysis inferred a strong dispersal activity of Ae aegypti based on the observed low genetic differentiation among populations. However, fine scale population structuring was also detected based on the generated dendrogram and the identification of 3 genetic populations. Based on auto-correlation among local populations, their flight distance was estimated < 5km. In addition, we also developed a GIS-based prediction model of local dengue risk focusing on flood intensity and land use classification in all 604 administrative district in Metro Manila. Using these data, we constructed a regression tree model that describes the spatial variation of dengue infection rate of the administrative section. The model was estimated with high accuracy, and flooding has also been shown that a high contribution as a risk factor.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2013/04 -2015/03 
    Author : DAISUKE Sano, WATANABE Kozo
     
    The objective of this study was to investigate the mechanism of acquiring free chlorine-resistance of noroviruses. As a result, it was confirmed that a population of murine norovirus acquired the relatively high resistance against free chlorine treatment by repeatedly exposing to free chlorine, owing to the dominance of free chlorine-resistant mutants in the population. Based on these results, the project leader was honored (Encouraging Award for Young Researchers) in the 55th Conference of Japanese Society of Clinical Virology.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2012/04 -2015/03 
    Author : OMURA Tatsuo, YOSHIMURA Chihiro, TAKEMON Yasuhiro, KAZAMA So, NISHIMURA Osamu, WATANABE Kozo
     
    The purpose of this project is to indicate the target image of biodiversity and its formation mechanism for suitable river restoration in the European Alps through an intensive investigations of reference semi-natural basins remained in northeast Italy. We clarified the true species richness of stream invertebrate communities in the basins by addressing the potential problem of poor morphological taxonomy (e.g., many undescribed species) applying an new technique of DNA sequence based taxonomy. We found the ecological importance of spatial environmental heterogeneity among habitats and microhabitats (e.g. large woody debris) in sustaining the high biodiversity in the natural river system. In addition, satellite and mountain camera image analyses for tracing the temporal change of river geomorphology at reach scale allow us to understand significant role of large and frequent flood disturbances in sustaining the high species diversity in the natural floodplain system.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity start-up
    Date (from‐to) : 2012/08 -2014/03 
    Author : 渡辺 幸三
     
    愛媛県重信川流域の15地点において,2012年5月,8月,11月,2月に環境調査と河川底生動物群集の採取を行った。これらの調査地点は「流域」,「セグメント(流程)」,そして「リーチ(蛇行区間)」の3つの異なる空間階層スケールで種多様性を評価するデザインで選択した。環境調査は,水質,餌資源,流速,水深,河床材料など幅広く行った。2012年8月に採取した底生動物群集サンプルを,従来の顕微鏡観察に基づく形態学的種分類に基づく種多様性評価を完了したのちに,次世代DNAシークエンシング解析に用いた。このDNA分析では,まず各地点の生物群集試料から一度にDNAを抽出し,雑多な種が混在するDNAを対象にして,マルチプレックスPCRでミトコンドリアDNAのCOI領域(672bp)を増幅した。その後,雑多な種のPCR産物(アンプリコン)を,Roche 454 Sequencerを用いたパイロシークエンシング法に基づき,次世代DNAシークエンシング解析した。その結果,平均400bp長の塩基配列データを約17万配列を一度に作成することに成功した。この大規模DNAデータベースは引き続き実施される各調査地点の種多様性(種数)の評価に用いられる。具体的には,進化モデルと絶滅モデルを融合したGeneralized Mixed Yule-Coalescent(GMYC)モデルに適用することで,塩基配列間の非類似性に基づいて種の境界を定義して種数を定量化する。
  • 水生昆虫集団の個体群動態の履歴に因る遺伝構造の形成と生息地分断による遺伝的分化
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2006 -2008 
    Author : 渡辺 幸三
     
    宮城県中南部地域4水系の源流から下流の30地点に分布するヒゲナガカワトビケラ局所個体群の遺伝構造をAFLPマーカーおよびミトコンドリアDNA(COI領域)マーカーで解析し,局所個体群間の移動分散パターンを評価した。地点間の遺伝距離に基づく系統樹の結果から,源流の局所個体群が中流以降の大部分の個体群から遺伝的に隔離されていることが明らかになった。ヒゲナガカワトビケラは,雌成虫が河道に沿って産卵遡上する行動が観察されているが,本研究の結果は,風分散により方向性を持たない成虫の移動が起きている可能性を示した。また,ミトコンドリアDNAの塩基置換数から,源流の多くの個体に見られた遺伝子群は,中流以降に多く見られる遺伝子群から約70万年前に独自に進化した特殊な遺伝子群と推定された。源流域はヒゲナガカワトビケラに高い遺伝的多様性を残すために極めて重要な地域であるが,上述したように強く隔離されているため,個体群の存続が困難になっていることが明らかにされた。 成虫の分散能力が異なるウルマーシマトビケラ(分散力低い),ヒゲナガカワトビケラ(中),オオクママダラカゲロウ(高)の3種を対象に,規模が大きく異なる7つのダム(湖長=0.1〜5km)上下流間の分集団間の遺伝子類似性を調べた。その結果,分散能力が中程度で,一世代当たりの異動距離がダム湖の長さとほぼ一致するヒゲナガカワトビケラのみ,ダムにより地域交流が遮断されている可能性が示された。さらに,ヒゲナガカワトビケラの集団遺伝構造を感度良くかつ安価に調べることを可能にするマイクロサテライト領域を増幅するPCRプライマーを10ペア開発した。本研究により,局所個体群間の繋がりや移動分散パターンに関する理解を深めるツールとして,DNA多型解析は高いポテンシャルを有することが示された。
  • 年周期性を考慮したダム放流水が河川底生動物相に与える影響メカニズムの解明
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2002 -2004 
    Author : 渡辺 幸三
     
    本研究は河川底生動物に対するダム放流水の影響メカニズムを解明し,河川底生動物相への影響を最小化するダムの運転・管理手法の提案を目的としている. 本年度は昨年度に引き続き、主にダム湖の上下流側に生息する底生動物個体群のDNA多型をRAPD調査し,ダム湖による生息地の分断化がダム湖上下流間の遺伝子流動(遺伝子の個体群間の移動)の低下に及ぼす影響評価を行った.調査は田瀬ダム,遠野ダム(岩手県),大倉ダム(宮城県),下久保ダム(群馬県),刀利ダム,室牧ダム(富山県)の計6つのダムを対象に行った.これらのダム湖は湛水面積が大きく異なるため,生息地分断の規模が遺伝子流動の阻害度に影響するかの検証に適している.遺伝子流動の阻害の有無は,ダム上下流地点間のNeiの遺伝距離を、ダムで分断された河川に隣接するコントロール河川(ダムで分断されていない河川)の遺伝距離と比較することで評価した.対象種はヒゲナガカワトビケラである. 解析の結果、6つのダム湖のうち,湛水面積が3.27km^2以上の2つのダム湖において統計的に有意な遺伝的分化が起きていることがわかった.また,遺伝的多様性を低下させる要因として,ダムによる遺伝子流動の低下よりも,各地点の集団サイズの低下がより強く影響していることが明らかになった.これらの研究成果は土木学会第59回年次学術講演会(2004年9月愛知県)で発表し、さらに土木学会論文集への掲載が決定された.

Committee Membership

  • 2014/05 - Today   Benthological Society of Asia (BSA)   Executive Board Members

愛媛大学教員活動実績

教育活動(B)

担当授業科目(B01)

  • 2019, the first semester, under graduate, 技術英語I
  • 2019, the first semester, under graduate, 建設倫理
  • 2019, the first semester, master course, 生物多様性と人間活動
  • 2019, the first semester, master course, 技術英語プレゼンテーション


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