Effects of sediment replenishment on riverbed environments and macroinvertebrate assemblages downstream of a dam.

Riverbeds downstream of dams are starved of sediment, impacting habitat structure and ecological function. Despite the implementation of sediment management techniques, there has been no evaluation of their conservational effectiveness; the impacts on high trophic level organisms remain unknown. This study examined the effects of sediment replenishment on riverbeds and macroinvertebrates in a dammed river before and after sediment replenishment. We evaluated the particle sizes of replenished sediments and the case material of a case-bearing caddisfly. We observed significant changes in macroinvertebrate assemblages before and after sediment replenishment, and between the upstream and tributary references and downstream of the dam. The percentages of Ephemeroptera, Plecoptera, and Trichoptera, and the number of inorganic case-bearing caddisflies downstream of the dam following sediment replenishment, were significantly higher than the upstream and tributary reference sites. The particle size of case materials used by case-bearing caddisfly corresponded to the size of the replenished sediment. Dissimilarity results after replenishment showed that assemblages downstream of the dam differed from upstream sites, although they were similar to the tributary sites. The dissimilarity between the tributary and downstream of the dam was the same as that between the upstream and tributary. Sediment replenishment was observed to reduce the harmful effects of the dam, and partly restore benefits such as increasing species diversity and altering community assemblages, similar to the effects of tributary inflows.

Habitat suitability maps for juvenile tri-spine horseshoe crabs in Japanese intertidal zones: A model approach using unmanned aerial vehicles and the Structure from Motion technique.

The tri-spine horseshoe crab, Tachypleus tridentatus, is a threatened species that inhabits coastal areas from South to East Asia. A Conservation management system is urgently required for managing its nursery habitats, i.e., intertidal flats, especially in Japan. Habitat suitability maps are useful in drafting conservation plans; however, they have rarely been prepared for juvenile T. tridentatus. In this study, we examined the possibility of constructing robust habitat suitability models (HSMs) for juveniles based on topographical data acquired using unmanned aerial vehicles and the Structure from Motion (UAV-SfM) technique. The distribution data of the juveniles in the Tsuyazaki and Imazu intertidal flats from 2017 to 2019 were determined. The data were divided into a training dataset for HSM construction and three test datasets for model evaluation. High accuracy digital surface models were built for each region using the UAV-SfM technique. Normalized elevation was assessed by converting the topographical models that consider the tidal range in each region, and the slope was calculated based on these models. Using the training data, HSMs of the juveniles were constructed with normalized elevation and slope as the predictor variables. The HSMs were evaluated using the test data. The results showed that HSMs exhibited acceptable discrimination performance for each region. Habitat suitability maps were built for the juveniles in each region, and the suitable areas were estimated to be approximately 6.1 ha of the total 19.5 ha in Tuyazaki, and 3.7 ha of the total 7.9 ha area in Imazu. In conclusion, our findings support the usefulness of the UAV-SfM technique in constructing HSMs for juvenile T. tridentatus. The monitoring of suitable habitat areas for the juveniles using the UAV-SfM technique is expected to reduce survey costs, as it can be conducted with fewer investigators over vast intertidal zones within a short period of time.

Comprehensive flood control involving citizens in a Japanese watershed.

In July 2009, the city of Fukuoka, Japan experienced a flood disaster along the Hii River, which runs through densely populated, concrete-covered areas of the city. The drainage system was overwhelmed and the river overflowed due to heavy rainfall and rapid runoff. The event led citizens in its watershed to plan and implement comprehensive flood control. The plan aims not only to mitigate floods but also to revitalize the river environment and populated communities in urban areas. This study reports the activities led by the citizens. They organized and carried out civic forums, workshops, and fieldwork to share views as to how the flood disaster was caused, how floods in the watershed should be controlled, and how the river environment should be rehabilitated. This study illuminates how people, including the flood victims and municipal engineers, can change drastically and communicate effectively in the course of discussing and implementing the comprehensive flood control measures.

Continuous-flow chemical processing on a microchip by combining microunit operations and a multiphase flow network.

A new design and construction methodology for integration of complicated chemical processing on a microchip was proposed. This methodology, continuous-flow chemical processing (CFCP), is based on a combination of microunit operations (MUOs) and a multiphase flow network. Chemical operations in microchannels, such as mixing, reaction, and extraction, were classified into several MUOs. The complete procedure for Co(II) wet analysis, including a chelating reaction, solvent extraction, and purification was decomposed into MUOs and reconstructed as CFCP on a microchip. Chemical reaction and molecular transport were realized in and between continuous liquid flows in a multiphase flow network, such as aqueous/aqueous, aqueous/organic, and aqueous/organic/aqueous flows. When the determination of Co(II) in an admixture of Cu(II) was carried out using this methodology, the determination limit (2sigma) was obtained as 18 nM, and the absolute amount of Co chelates detected was 0.13 zmol, that is, 78 chelates. The sample analysis time was faster than that of a conventional processing system. Moreover, troublesome operations such as phase separation and acid and alkali washing, all necessary for the conventional system, were simplified. The CFCP methodology proposed here can be applied to various on-chip applications.

[Mycobacterium abscessus infection complicated with diabetes mellitus].

We report a case of Mycobacterium abscessus infection complicated with diabetes mellitus. A 38-year-old man with diabetes mellitus as an underlying disease, was admitted to our hospital because of a productive cough. He had had pulmonary tuberculosis two years before. Chest radiography revealed infiltration in both lung apices and chest CT showed a cavitary lesion in the left upper lobe. Gaffky 2 was found on a sputum smear. However, in the examination of PCR on sputum, not only M. tuberculosis but M. avium complex was negative, and repeated cultures of sputum were positive for M. abscessus. On the basis of the diagnosis of an M. abscessus infection, the patient was initially treated with amikacin, imipenem/cilastatin and levofloxacin during hospitalization while receiving insulin for diabetes mellitus. The smear and culture of sputum became negative for Mycobacterium, and the findings of chest radiography and chest CT improved. After discharge, treatment was continued with clarithromycin and levofloxacin. It is considered that the choice of effective drugs and the additional treatment of an underlying disease are very important for the treatment of a Mycobacterium abscessus infection.