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Focusing on green infrastructure (GI), which utilizes nature’s diverse resources, we developed urban flood control measures on three small-scale private tracts in Tokyo and Fukuoka in Japan, experiencing high rainfall. In addition, we implemented these measures and verified the possibility of introduction. Using a target rainfall of 100 mm/h and previous rainfall data, we set our goal of reducing runoff from each site below the capacity of a public sewage pipe. Implementation was conducted by assessing the soil infiltration rate and developing and installing rain gardens and storage layers using crushed stones. These measures satisfied the initially set goals, drastically reducing runoff at all three sites. The target installation cost was set at 100,000 yen per cubic meter of runoff reduction. The target costs were met in the two Fukuoka sites but not at the Tokyo site. The key reasons were the high costs of removing non-permeable surfaces or improving the soil of compacted surfaces, which called for a process to balance the runoff reduction and cost to determine the most effective plan for implementing GI in urban areas. The development and implementation processes were conducted in collaboration with the house owners and concerned parties; the workshops produced constructive ideas being unconstrained by conventional thinking. Visitors highly appreciated ideas related to using water because the techniques were derived from the Japanese culture of lifestyle. Thus, introducing attractive and effective GI may be possible through collaboration. Additionally, sharing experiences led to the formation of new community ties, supporting post-implementation site maintenance.

Saint Martin’s Island is a tiny island located in Bangladesh that is rich in biodiversity but threatened by many natural disasters, and it is often neglected due to being far from the mainland. Ecosystem-based disaster risk reduction (Eco-DRR) is the most urgently required provision for Bangladesh as it is a very easy and inexpensive way to survive natural adversities. In this study, attempts were made to quantify the capacity of an existing Pandanus forest on Saint Martin’s Island to reduce the storm surge disaster risk. For this, satellite images were processed with ErdasImagine and ArcGIS software, and land use and land cover changes were analyzed to determine the changes related to Pandanus trees over time. Storm surge wave height reduction was analyzed using the Bao regression model equation. The results show that the Pandanus tree population increased almost 3-fold from 2010 to 2021, and that the Pandanus trees can reduce the surge height, which will ultimately preserve 75% of the area of the island (2021). The minimum required patch width for the Pandanus tree belt was identified as 4.53 m. The areas highly vulnerable to flooding were also identified in this study.

In this study, we collated the number of deaths caused by disasters that took place in the Chikugo River middle basin on the island of Kyushu, Japan, from the 1600s to 2017. The compilation of quantitative statistics of floods in Japan began in the modern era, while the statuses of previous disasters are described by vague indices and are thus difficult to quantify. In this study, we geographically restricted our investigation to the Chikugo River middle basin. We quantified the scale of each disaster by using the number of deaths recorded in historical documents. We then compared the disasters that took place in the area since the 1600s to identify the potential disaster risks harbored by our study area. During the period examined, the great famine from 1732 to 1733 was the greatest disaster and caused the most deaths. However, this is the only recorded famine for which fatalities were documented. Meanwhile, floods occurred frequently through this period, 26 of which resulted in fatalities: they had a total death toll of 292. Thus, famines occur infrequently but cause severe damage, whereas floods occur frequently but cause relatively minor damage. During the approximately 400 years examined, there were four floods with death tolls exceeding 30 people. Three of these occurred after 1868, when the modern era of Japan began. Meanwhile, there have been almost no small-scale floods during and after the modern era. By quantitatively assessing the disasters’ scales, we were able to establish that the 2017 northern Kyushu torrential rainfall was the fourth gravest water-related disaster, in terms of its death, toll since the 1600s. If only the north bank of the Chikugo River middle basin is considered, it was the greatest flood disaster to occur in this period.

The Japanese archipelago extends over a large distance from north to south exposed to the effects of climate change. The aim of this study was to assess the impacts of climate change on env...

The purpose of this chapter is to review progress in our understanding of human behavior and decision-making relevant to future earth research agenda, and propose Decision Science as a hub of knowledge networks connecting disciplinary and interdisciplinary sciences with the practice of problem-solving. This review is composed of four sections. First, we describe the conceptual framework of “decision science for a sustainable society” and argue that evolutionary biology of the human nature is key to construct this framework. Second, we review how our group decision-making often fails due to various cognitive biases and argue that participatory approaches of co-design and co-production do not guarantee reasonable decision-making. Third, we review success stories of problem-solving in local communities and consider how we can connect those successes in local communities to successful national and global decision-making. Fourth, learning from both failures and successes, we argue that the adaptive learning of society is a process enabling us to transform our society toward a sustainable future. We review some positive global trends toward sustainability and consider the cognitive processes and behavioral mechanisms behind those trends that would provide clues for finding successful ways to transform our society.

Correction to Chapter 1 in: Yahara T. et al. (2021) Decision Science for Future Earth: A Conceptual Framework. In: Yahara T. (eds) Decision Science for Future Earth. Springer, Singapore. 10.1007/978-981-15-8632-3_1

This article focuses on how ecosystem-based approaches could be mainstreamed in recovery and reconstruction after large scale, rare and infrequent coastal hazards. In doing so, this study reviews historical practices of disaster management in rivers and coasts as well as reconstruction process after the Great East Japan Earthquake (GEJE). It reveals how ecosystem approaches are integrated in river and coast works and highlights some of the relevant policies, technical guidance and guidelines and good practices on the ground. This study also documents how Eco-DRR policy evolved and implemented after the GEJE and addresses some of the challenges in its implementation. In order to draw additional insights, the reconstruction processes of Hurricane Sandy in the United States (US) was also reviewed as GEJE and Sandy shares some common features. Experience from Sandy suggests the importance of the participatory planning process rather than technical guidance or guidelines. Although it is too early to judge whether either reconstruction process was better or not, nor difficult to generalize the conclusion from only two samples, these two experiences suggest only technical guidance and guidelines is not sufficient to mainstream Eco-DRR/CCA in the reconstruction from large scale, rare and infrequent disasters. It is also suggested that the critical role of participatory planning process with cross-sector, cross-professional and interactive design approach may lead more innovative solutions.

Ensuring access to affordable, reliable, sustainable modern energy is a key challenge in reducing poverty in developing countries. Off-grid rural electrification based on decentralized renewable energy has been recognized as an effective way to increase access to energy in remote areas. However, there is some doubt about its long-term sustainability. Previous studies have indicated that once renewable energy generation facilities are installed, the responsibility for operation and maintenance is often handed over to the local community, and, eventually, the project fails because of a lack of maintenance budget. This paper discusses issues related to the sustainability of MHP-based rural electrification as a case study in a remote village in West Java, Indonesia, that is deeply steeped local traditions. A complementary approach between the community and a private company was introduced to improve the economic sustainability of MHPPs while simultaneously conserving local traditions and livelihoods.

Large-scale disasters, such as hurricanes, cyclones, tsunamis, and forest fires, have caused considerable damage in recent years. This study investigated two case studies of discontinuous open levees (kasumi-tei), which are a traditional Japanese river technology, on the Matsuura River at the sites of Okawano and Azame-no-se, and evaluated the advantages of these levees from the perspective of ecosystem-based disaster risk reduction (Eco-DRR). These case studies were conducted through literature surveys, flood observations, and oral interviews. The systems in both the cases were flood control systems utilizing ecosystem services. The traditional river technology (the flood plain open levee) served as an effective Eco-DRR in both cases. Additionally, the flood plain levee technology enhanced the ecosystem services at both sites, including not only flood control capabilities, but also other ecosystem services. Furthermore, the open levees offered substantial cost advantages over their alternatives. These results suggest that other traditional Japanese river technologies may also be effective in strengthening Eco-DRR.

Selecting sites for river restoration projects or performing ex post evaluation must be done in ecoregions with comparable biological integrity. Moreover, to evaluate the integrity of a river ecosystem that varies from the headwater to downstream regions, adjustments of the ecoregion according to the longitudinal change in biota must be made. We defined regions where biota are identical according to the direction of change along the stream path as “segment-based ecoregions.” We delineated segment-based ecoregions using fish fauna data for two ecoregions in Japan: the northeast Kyushu, and south Kyushu. The northeast Kyushu ecoregion was divided into three segment-based ecoregions, and south Kyushu ecoregion into five segment-based ecoregions. Classifying fish fauna within the same ecoregion enables classification by differences in the longitudinal change in the stream path rather than by differences in watersheds. Specific topographic regions such as the amphitheater areas of the south Kyushu ecoregion was classified as independent segment-based ecoregions. We further defined indicator fish species for each segment-based ecoregion. Indicator fish species reflected the fish fauna of each ecoregion in the midstream area, such as migratory Gobiidae of the south Kyushu ecoregion. Applying the segment-based ecoregion concept helps compare the biological integrity of fish fauna depending on a common environmental type between watersheds.

Frequent inundation has become a serious problem in urban areas. It is necessary to improve rainwater retention/infiltration in the urban watershed. The purpose of this study is to report how private rainwater-retention/harvesting facilities can be spread gradually but steadily in the city by citizen-initiated activities. Rainwater harvesting tanks were installed intensively and a rainwater harvesting house was constructed in the city of Fukuoka, Japan after the city experienced a flood disaster. The former enhanced users’ daily preparedness for emergency, and the latter inspired construction of a rainwater-harvesting housing complex. A public elementary school is in use from April 2016, which is inspired by these facilities. The school premises are located on the land reclaimed from an old irrigation pond. Thus the school needs to be adapted to this condition. 3000 m 3 of rainwater can be retained within the premises. The amounts of retention and discharge are monitored, and the data is utilized for science education. In big cities, people tend to depend too much on the top-down, mega-system, which invites more impervious surfaces in urban areas. Bottom-up, individual/collaborative approaches should be adopted in order to achieve multiple purposes of preventing/mitigating disasters, preserving/conserving ecosystems and nurturing/rebuilding communities in the city.

Intensive rainfall and frequent inundation have become a serious problem in urban areas all over the world. Climate change and heat island effect may be the cause of the phenomena. Widespread impervious pavement/surface of the ground makes things worse. In order to promote an effective river basin management in urban areas and reduce runoff, a registration system called “Safety Plan for 100mm/h-Rainfall” (“100mm/h Anshin Plan” in Japanese), a scheme for preventing and mitigating inundation caused by extremely heavy, short-term rainfall (such as 100mm/h-rainfall) was established in April 2013 by the central government in Japan. This study carried out a questionnaire survey to examine how municipalities effectively utilize the registration scheme for their watershed management. As a result, it is found that there are municipalities who have started/revised subsidizing installation of private rainwater retention/infiltration facilities in association with the registration system; however, municipalities in general are not so active in promoting runoff reduction by subsidizing private facilities. In addition, in the plans emphasizing public works for runoff reduction, public involvement is not so active, whereas in the plans devised with relatively new committees of watershed management, public involvement as well as private retention activities tend to be active. Based on the results, prospects of how a safety plan should be utilized in an urban watershed are discussed and examined from practicality’s point of view.

Although many significant policies and legislation have been put forth by the Chinese government aiming toward “ecological civilization” for the aquatic environment, in practice, the situation is still undesirable. A pioneering multi-year study has since been conducted on the East Tiaoxi River (a major tributary of the renowned Yangtze River), focusing on fish distribution, influencing factors and habitat requirements, and river health as well. This revealed certain key species, hotspot protection areas, negative impacts of local anthropogenic activities, and inappropriate perceptions and practices of conservation and restoration. We found that not all fish species were equally conserved and that the supposedly ecological engineering measures were initiated without regard for ecological integrity. Our exemplary study appreciates scientific basis and truly ecological notion, and urgently advocates comprehensive and continuous basin-scale scientific investigation of fish biodiversity, and “ecological river”-oriented conservation and restoration action for the Yangtze River Basin and broader areas of China.

The continuous warming observed in recent decades as a result of climate change is posing significant threats to the environment, particularly for freshwater ecosystems. Therefore, it is highly important to predict the impact of this phenomenon on habitat suitability. However, such prediction requires the use of an integrated framework in which different parameters can be incorporated. While 1D modelling has been commonly used in river habit suitability simulations, most 1D mathematical models either do not provide enough information for the area along the rivers or do not consider the impact of river basin management on the river flow characteristics. This study seeks to develop such an integrated framework is in which water temperature and hydrologic-hydraulic parameters are jointly applied to simulate habitat suitability. The modeling setup is based on a combination of the Soil and Water Assessment Tool (SWAT) and international river interface cooperative (iRIC) models, and, due to the importance of the water temperature, the water temperature module in SWAT was modified. To examine the effectiveness of this method, Kikuchi basin is selected as the case study, and two different general circulation models, namely HadGEM2-ES and MICRO5, under two representative concentration pathways are applied to evaluate river habitat suitability under climate change conditions. The results showed a reduction in the river flows, water depths and velocities that have slightly positive effects on the habitat suitability of the Kikuchi river. However, this reduction causes some parts of the river to become dry, so that some of the habitats may disappear as a result of climate change. Moreover, it is shown that the downstream section of the Kikuchi river is more vulnerable to climate change. Therefore, migration of fishes to its upstream section is predicted. Finally, the proposed methodology is strongly recommended for use in modeling of other regions suffering water scarcity.

The establishment of a conservation strategy or restoration goal for river estuaries requires knowledge of potential biota or possible habitat characteristics. In this study, we investigated the relationship between estuarine fauna and macro scale physical indicators on Kyushu Island, Japan to provide basic information for estuarine conservation. As a result of the classification of shellfish fauna by similarity, the Kyushu region was divided into three groups, namely, 1) southern Kyushu with high wave exposure, long fetch, and low tidal variation; 2) the Ariake and Yatsushiro seas with low wave exposure, short fetch, and high tidal variation; and 3) northern Kyushu with an intermediate fetch and tidal variation. In addition, a number of sites, such as Nakatsu Port, Sone tideland, and the Honmyou River, were classified into geographically different groups. This is because the physical characteristics of these sites were similar to classified groups or shellfish fauna were significantly altered by artificial impacts. As a result of discriminant analysis, the discrimination hit rate of species inhabiting the inner bay or tidal flat was high, whereas that for species using a wide variety of bottom sediment environment was low. To improve the accuracy of the discriminant model, it is necessary to collect more detailed physical information, such as habitat type, salinity concentration, or grain diameter of bottom sediment. To establish a conservation or restoration strategy, there is a need for classifying taxonomic groups or physical characteristics.

For the utilization of renewable energy from sources widely distributed in low-density non-urban areas the grid augmentation for its transmission to urban areas of high population density is often discussed under the premise that the present demand distribution remains invariant. Instead of grid augmentation, this study examined an alternative option of creating a power demand close to renewable sources and inducing population movements (i.e., Renewable Energy Exodus). First, the capacity of renewable energy to maintain populations in hilly and mountainous farming areas of Japan was evaluated from two perspectives: Task (1) a challenging nationwide balance based on possible energy demand saving scenario for the future, and Task (2) a conservative nationwide balance based on the current per capita energy demand and on the region-by-region generation–consumption matching concept. Because Task (2) indicated that Hokkaido, the northern-most island, has a huge capacity, Task (3) was conducted for Hokkaido by examining both energy balance and economic evaluation including job creation for the following two scenarios: (A) a supply to Tokyo scenario and (B) a local demand generation scenario, keeping the same conservativeness as Task (2) by using the current data for energy consumption per capita. The nationwide Renewable Energy Exodus estimates gave 48 million people for Task (1) (with the future per capita energy demand) and 10 million people for Task (2) (with the current per capita energy demand and region-by-region self-sustained balance), respectively. For Hokkaido Task (3) (with an additional economic assessment) gave 1 million people. The Renewable Energy Exodus concept combined with the green economy promotion was found to have a significant merit for a sustainable future of countries like Japan where economic and social disparities are serious between urban areas and non-urban areas.

River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.

Wetland plays important roles in river ecosystems. However, the area of wetland decreased considerably due to excessive construction and land use with economic development. For recovering river ecosystem, the wetland named Azame-no-se was restored in the Matsuura River, which is located in Saga Prefecture in Kyushu, Japan. Anodonta lauta, a freshwater mussel that lives in the lentic water of wetlands, played an important role in a river. However, A. lauta lost its habitat and became endangered in Japan. A. lauta was found surviving in the Azame-no-se Wetland; however, only recently researchers have begun to understand the mechanisms that allow this mussel to now prosper there. This study investigated mussel survival mechanisms in the restored Azame-no-se Wetland. Mussel motility, coverage of Trapa japonica (an aquatic plant) and water quality were investigated in three pools (Shitaike, Ueike, and Tomboike) of the Azame-no-se Wetland and in still water in the Matsuura River (May 2011–2012). A feeding behavior experiment was also conducted in Ueike Pool two times in 2012. Results showed that this pool had abundant nutrients (thanks to its high flood frequency) that supported the growth of certain phytoplankton species possibly important for A. lauta. Dissolved oxygen was another important factor. Although Shitaike Pool shared similar conditions with Ueike Pool, the mussel became extinct when the dissolved oxygen decreased because of the lush growth of T. japonica in Shitaike Pool. This study indicated that the factors essential for A. lauta’ survival in the restored wetland were dissolved oxygen (DO), nutrients, and phytoplankton species. These results could be helpful for understanding functions of restored wetland and further offer suggestions for managing river–floodplain system.

Small scale hydropower energy goes a long way to fire up community development. Until 1920-30s, Japanese hydropower techniques had been established on a global level in each local area. However, after the second World War, the main energy resource was changed. This has resulted in a local decline in micro-hydro technical expertise and fewer waterwheel makers throughout Japan. At the present, we are going to work to re-make small scale hydropower technologies and markets. In this paper, we discuss and propose improvements to the “Japanese” small scale hydropower technology and production techniques, especially Pelton type wheel. The Pelton wheel technology of Nepal was freely available in the public domain so we decided to design a system based on that. We decided to designed by 3D-CAD and to make our Pelton buckets using a 3D printer. We compared the power generation capacity of our waterwheel with one purchased from New Zealand to investigate its effectiveness and efficiency. In our results of the experiment, the power generation curves for each turbine are approximately equal. The power increases continuously with increases in the flow rate. The maximum power generated by each turbine is approximately the same. This shows that it is possible to design a Pelton bucket that has a power generation efficiency comparable to a purchased bucket. The next step, the Pelton turbine designed in this study was chosen to be included in the Itoshima micro-hydro power generation system. So we scaled up and redesigned the Pelton turbine. In addition, we conducted a survey involving waterwheel makers regarding connecting to cost reduction. Using a 3D printer has the following advantages: 1.) Design deficiencies and failed designs can be identified at an early stage. 2.) Different forms of waterwheel can be made at low cost and in a short amount of time, which can then be used to run water experiments.

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.

Various investigations about the flood condition and dam operation have been conducted on 2011 Chao Praya river flooding. Investigations about the lower reaches of the Chao Praya river, which was heavily damaged, have been conducted, but investigation reports about the flood form of the midstream Chao Praya river, i.e., upstream where the Ping and Nan rivers meet, have hardly been reported. This investigation sorts out the conditions of flooding and the reservoir of the midstream Chao Praya river and the reflow into river channels fromthe floodplain, which is reflooding, inspects them based on field investigations and considers the possibility of reducing flood damage in the lower reaches using the floodplain in the midstream area.

In Japan, floods occur frequently in urban areas because non-infiltrating areas are seeing increased urbanization. To prevent floods, urban basins must improve the infiltration capacity and water retention of the whole basin. There are several basic technologies for river basin management, such as infiltration trenches or rainwater storage. However, a method of soil amendment that prevents flood disasters has not been established. This study aims to evaluate the infiltration capacity and water retention potential of soil amendments using bamboo charcoal and humus. A constant-head infiltration test and rainfall simulation were conducted to evaluate the properties of the soil amendments. The combination ratios of the improved soils used in the experiment were (1) 100% decomposed granite, (2) mixed with 10% bamboo charcoal, (3) mixed with 20% bamboo charcoal, (4) mixed with 30% bamboo charcoal, (5) mixed with 10% humus, (6) mixed with 20% humus, and (7) mixed with 30% humus. The constanthead infiltration test's results showed that soils mixed with 30% humus had the greatest potential for influencing initial and final infiltration rates, and the more the mixing rates of bamboo charcoal and humus were increased, the higher the water retention capacity. The results of the rainfall simulation showed that soils mixed with 30% humus had the highest final infiltration rates and lowest multiplication spillage. To reduce the runoff volume using soil amendment technology, it is important to delay overland flow, and the hydraulic properties of the soils mixed with bamboo charcoal and humus were as effective as those of granite soils.

The distribution patterns of loaches (Teleostei: Cobitoidea) were revealed in the River East Tiaoxi in China. Eight loach species (Cobitis sinensis, C. dolichorhynchus, C. laterimaculata, Misgurnus anguilicaudatus, Paramisgurnus dabryanus, Leptobotia tchangi, Vanmanenia pingchowensis and V. stenosoma) were found in field surveys at 90 sites. A macroscale analysis of the geographical distribution showed that related species were segregated in accordance with longitudinal alterations along the river course. M. anguillicaudatus was widely distributed from the middle reaches to upstream of the river whereas the related species, P. dabryanus, was distributed only downstream. Three spined loaches, namely C. dolichorhynchus, C. sinensis, and C. laterimaculata, were distributed in the middle reaches, the middle to upstream reaches, and the upstream section of the river, respectively. The distribution of V. pingchowensis was further upper stream than that of V. stenosoma in the upstream section. More detailed microscale analysis revealed that L. tchangi and the two Vanmanenia species, V. stenosoma and V. pingchowensis were mostly found in the ‘Riffle’ (lotic) habitats, whereas the two spined loaches, C. laterimaculata and C. sinensis preferred the ‘Pool’ (lentic) habitats. These results demonstrated that related loach species preferred similar habitat units in the River East Tiaoxi system.

Throughout Japan, numerous restoration projects and efforts to conserve the river environment are underway. However, in spite of such efforts, effective measures to conserve the river ecosystem or post-evaluation of restoration projects remain insufficient due to a lack of environmental indicators. In many European countries and the United States, a number of biological indicators have been developed and adapted. However, it appears to be difficult to directly apply these indicators to Japan, because its biota is finely classified according to its many islands and peninsulas. The ultimate goal of this study is to comprehensively evaluate indicators of aquatic biodiversity from both physical and biological aspects. We divided the Kyushu region in Japan into several ecoregions as a preliminary step to establish an indicator. We delineated the ecoregions of the Kyushu region using the fish fauna data of 21 rivers within the Kyushu region. Presence–absence (0/1) data for each fish species were used to run a two-way indicator species analysis (TWINSPAN analysis). As a result, the Kyushu region was divided into four ecoregions (A: northwest Kyushu, B1: northeast Kyushu, B2: south Kyushu, and C: Amami-Oshima Island). Each ecoregion was characterized by the following fish species: (A) Cyprinidae, in particular Acheilognathinae, is abundant; (B1) Gobiidae is abundant, while Cyprinidae such as Tanakia limbata (not confirmed in B2) are also present; (B2) Gobiidae is abundant, while Rhingobius sp. DA and Rhingobius sp. CO (not confirmed in B1) are present. These results indicate that the fish fauna of the Kyushu region is finely delineated, and that an assessment standard for biological integrity should be established, based on differences in fish fauna.

We provide the first evidence for navigation impact on resident river fish in China. The survey was conducted in the East Tiaoxi River that discharges into Lake Taihu near Shanghai, on which cargo ship traffic has dramatically increased in the recent economic development period. Water turbidity, ship traffic and other environmental factors were evaluated at 29 sites on the river. In a multiple regression model with the stepwise method, turbidity was significantly correlated with ship traffic (R 2 = 0.53). Another survey was conducted at 46 sites in the same area of the river, in which environmental factors were evaluated and fish individuals were electrofished. A generalised linear model with the stepwise method was applied to predict ecological indicators of the fish assemblage (species richness, individual density and Shannon’s diversity index) based on environmental factors. The results showed that the indicators were negatively correlated with turbidity and presence of artificial shore embankment structures. Another analysis further showed that the negative effect of turbid water was especially considerable for fish of smaller size. In conclusion, cargo ship traffic has a negative impact on fish assemblage, especially on smaller individuals, in the East Tiaoxi River. A higher profile for conservation actions and consideration of environmental impacts of such traffic should be given increasing focus for this and other similar East Asian water courses.

Riverine floodplains play many important roles in river ecosystems. However, many floodplains have suffered degradation or loss of ecological function due to excessive river improvements or through changes in agricultural systems. As a result, many floodplain restoration projects are being conducted worldwide. One of the many methods being implemented to restore floodplain vegetation is flood water seed dispersal. In this technique, precisely estimating the effect of seed dispersal by flood water is important in order to achieve successful floodplain revegetation. Here, we focus our attention on sediment transport by flood water into the Azamenose Swamp, a restored floodplain. We attempt to estimate the function of seed deposition in the restored floodplain and explain how the seeds are deposited in the floodplain by flood water. The result suggests that the restored floodplain functions as a more appropriate deposition site for seeds than the riverbanks of the main river. It was also found that the distance from the inflow site and the weight of the sediment were related to seed deposition.

We validated the effects of a passive integrated transponder (PIT) tagging process on the oriental weather loach Misgurnus anguillicaudatus. Laboratory experiments were conducted to assess the effects of PIT tagging on fish survival, growth, wound healing, and tag omission. Two tagging protocols, standard syringe injection versus insertion through a small hole pierced by a fine needle-shaped awl, were compared using a 12.5 × 2.07 mm2 tag. A control group was also included. In comparison with the awl technique, syringe injection heightened the mortality of the loach and delayed healing of the wound caused by tag insertion. No effects of either PIT tagging method were detected on the growth of surviving loach. We also field-tested similarly tagged populations within a river-based irrigation system of Sado Island, Japan. Two different sized tags (long, 12.5 × 2.07 mm2; short, 8.5 × 2.12 mm2) were compared by using antenna loggers which detected fish movement through gates and automatically logged tagged fish’s tag IDs and timestamps. By comparing logged data and actual fish collection surveys both below and above the gates, 77% and 30% of actual loach movements were confirmed to have been successfully logged for the long and short tags, respectively. The awl insertion technique with the longer tag is therefore recommended for use in similar studies of smaller fish species.

Genetic endemism of island organisms and the threat to such organisms provided by artificially introduced genes are aspects of major interest in evolutionary and conservation studies of fishes. In this paper the genetic population structure of the oriental weatherloach, Misgurnus anguillicaudatus, in Sado Island of Japan was elucidated by phylogeographic analysis based on partial mitochondrial control region sequences. The specimens were sampled at 62 sites in Sado Island and 14 sites on the mainland close to the island. We found various haplotypes of different origins, most of which had already been reported from the mainland and other places of Japan. This suggests that the loach has been historically introduced to the island from various regions of Japan. Of the 62 sites on the island, cultured/nonnative individuals were confirmed to have been stocked at eight specific sites for feeding of re-introduced Japanese crested ibis (Nipponia nippon). By a Mantel test, geographical and genetic distances were not significantly correlated among the local populations in Sado Island. However a significant correlation was found when the eight stocked local populations were excluded from the analysis. This implied that the genetic distribution pattern of the loach on the island has been disturbed by the stocking. In addition, the nucleotide diversity values of stocked local populations were significantly higher than those of other local populations, also a likely outcome of the stocking. In conclusion, the loach on the island likely had their origins in multiple historical introductions and colonizations, where more recent stocking for the ibis has caused further genetic disturbance to their local populations.