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• Evaluating riverine environment using a hydrological model

  Cooperative Research  

  Project Year： 2010.04  -   

Papers 【 display / non-display 】

Papers 【 display / non-display 】

• Optimum condition for valuable seaweed growth to utilize treated sewage as a nutrient source

  Suzuki, Y., Nakada, K., Nukazawa, K., Yamanishi, H.

  Journal of Environmental Science and Technology   12   17 - 25   2019  [Refereed]

  Joint Work

  DOI

• A highly efficient method for concentrating DNA from river water by combined coagulation and foam separation

  Suzuki Y., Imafuku Y., Nishiyama M., Teranishi K., Jikumaru A., Nukazawa, K., Ogura Y.

  Separation Science and Technology     2019  [Refereed]

  Joint Work

• Projection of invertebrate populations in the headwater streams of a temperate catchment under a changing climate

  Nukazawa K., Arai R., Kazama S., Takemon Y.

  Science of the Total Environment   642   610 - 618   2018.11  [Refereed]

  Joint Work

  　View Summary

  Climate change places considerable stress on riverine ecosystems by altering flow regimes and increasing water temperature. This study evaluated how water temperature increases under climate change scenarios will affect stream invertebrates in pristine headwater streams. The studied headwater-stream sites were distributed within a temperate catchment of Japan and had similar hydraulic-geographical conditions, but were subject to varying temperature conditions due to altitudinal differences (100 to 850 m). We adopted eight general circulation models (GCMs) to project air temperature under conservative (RCP2.6), intermediate (RCP4.5), and extreme climate scenarios (RCP8.5) during the near (2031–2050) and far (2081–2100) future. Using the water temperature of headwater streams computed by a distributed hydrological-thermal model as a predictor variable, we projected the population density of stream invertebrates in the future scenarios based on generalized linear models. The mean decrease in the temporally averaged population density of Plecoptera was 61.3% among the GCMs, even under RCP2.6 in the near future, whereas density deteriorated even further (90.7%) under RCP8.5 in the far future. Trichoptera density was also projected to greatly deteriorate under RCP8.5 in the far future. We defined taxa that exhibited temperature-sensitive declines under climate change as cold stenotherms and found that most Plecoptera taxa were cold stenotherms in comparison to other orders. Specifically, the taxonomic families that only distribute in Palearctic realm (e.g., Megarcys ochracea and Scopura longa) were selectively assigned, suggesting that Plecoptera family with its restricted distribution in the Palearctic might be a sensitive indicator of climate change. Plecoptera and Trichoptera populations in the headwaters are expected/anticipated to decrease over the considerable geographical range of the catchment, even under the RCP2.6 in the near future. Given headwater invertebrates play important roles in streams, such as contributing to watershed productivity, our results provide useful information for managing streams at the catchment-level.

  DOI

• Simulating the Advection and Degradation of the Environmental DNA of Common Carp along a River

  Nukazawa K., Hamasuna Y., Suzuki Y.

  Environmental Science and Technology   52   10562 - 10570   2018.09  [Refereed]

  Joint Work

  　View Summary

  The environmental DNA (eDNA) method is a novel technique for precise and efficient biological surveillance. Although eDNA has been widely used to monitor various freshwater organisms, eDNA dynamics in streams remain poorly understood. In this study, we investigated the eDNA dynamics of common carp (Cyprinus carpio) in a forested headwater stream affected by the effluent from a carp farm. We evaluated the longitudinal variation in carp eDNA along a river downstream from the farm and performed a temporal eDNA decay experiment using digital polymerase chain reaction. On the basis of the resulting decay constants, we built a model to simulate the advection and degradation of eDNA along the studied river. The observed eDNA flux (concentration multiplied by flow rate) decreased exponentially with distance downstream from the farm, and eDNA was detected 3 km downstream of the farm. Although the water temperatures were similar, the eDNA decay constant was lower in autumn than in summer. The simulated eDNA concentration was markedly larger (>10 times) than the observed concentration, suggesting that eDNA removal is accelerated in the stream environment compared to in conventional experimental settings.

  DOI

• SPATIOTEMPORAL ANALYSIS OF FACTORS CONSTRAINING OVIPOSITION IN DENGUE VECTOR MOSQUITOS IN METROPOLITAN MANILA

  NUKAZAWA Kei, NISHIMOTO Shunya, SUZUKI Yoshihiro, WATANABE Kozo

  Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research)   74   I_79 - I_85   2018.09  [Refereed]

  Joint Work

  　View Summary

  Recently, as worldwide pandemic of dengue fever, researchers have attempted to predict the distribution of dengue vector mosquitoes. However, the earlier studies remained challenges in precisely understanding local prevalence of the vector mosquitos and its association with ambient environmental attributes. Here this study explored spatial and temporal oviposition patterns of the dengue vector mosquitos under heterogeneous meteorological, flooding, and land cover conditions using highly frequent data on the abundance of the dengue mosquito eggs observed throughout Metropolitan Manila. The abundance of the vector mosquito eggs (OI) tended to increase in the rainy season compared to the dry season. Spatial autocorrelation in the OI displayed a different trend depending on the seasons, suggesting that the spatial pattern of the oviposition of the vector mosquitoes are constrained by seasonally heterogeneous environmental conditions. The OI increased in response to increases in rainfall but in limited cases. In the residential area, the OI was higher than other land cover classifications.

  DOI CiNii

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Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• Eco-epidemiology of Dengue Mosquitoes in Bandung, Indonesia in Relation to Viral Tra nsmission and Climate Change

  Project Year： 2019.04  -  2022.03 

Presentations 【 display / non-display 】

Presentations 【 display / non-display 】

• Changes in Phylogroups and Antibiotic-resistant Profiles of Escherichia coli in Municipal Wastewater under Aerobic Condition

  Xie, H., Nukazawa, K., Suzuki, Y.

  第55回環境工学研究フォーラム  2018.12  -  2018.12 

• Longitudinal degradation pattern of stream environmental DNA of common carp using an advection-decay model

  Nukazawa, K., Hamasuna, Y., Suzuki, Y.

  チュニジア-日本シンポジウム2018  2018.11  -  2018.11 

• Development of High Efficiency Concentration Method of DNA from River Water by Combined Process of Coagulation and Form Separation

  Jikumaru, A., Imafuku, Y., Teranishi, K., Nukazawa, K., Ogura, Y., Suzuki, Y.

  水環境技術会議  2018.07  -  2018.07 

• Comparison of Antibiotic-Resistant Escherichia coli Collected from Uninhabited Island and Urban Ponds in Miyazaki, Japan

  Nishimura, E., Sugita, K., Sakamoto, S., Nukazawa, K., Suzuki, Y.

  水環境技術会議  2018.07  -  2018.07 

• Effect on sand supply to foreshore by beach nourishment on the Miyazaki Coast

  Miyazono, A., Ito, K., Nukazawa, K., Mitsuteru, I., Suzuki, Y.

  水環境技術会議  2018.07  -  2018.07 

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