Nagara River Research Articles

Genetic variability of Myxobolus nagaraensis (Bivalvulida: Myxobolidae) infecting freshwater gobies Rhinogobius Gill 1859 (Gobiiformes: Oxudercidae) from rivers in Japan

Myxobolus nagaraensis is a myxozoan parasite first reported in freshwater gobies (Rhinogobius spp.) from the Nagara River, Gifu Prefecture, Japan. Myxospores of M. nagaraensis form plasmodia in the visceral cavities of gobies, commonly presenting as distended abdomens. Although Rhinogobius is a common fish genus in Japan, details of M. nagaraensis, including genetic information, remain unknown. We compared the nucleotide sequences of the ribosomal RNA gene (rDNA) of M. nagaraensis from three different host species (R. fluviatilis, R. nagoyae, and R. similis) caught in three different rivers in Japan (Sakai, Sagami, and Kaname). The ITS region (ITS-1, 5.8S rDNA, and ITS-2) and large subunit (LSU) rDNA exhibited 49 and 55 variable sites, respectively. The highest nucleotide diversity was observed in the ITS region (0.00962), whereas that of the LSU rDNA was 0.00187. Differences in host species, rather than rivers, were a significant factor for genetic variation in both the ITS region (62.58%; P < 0.001) and LSU rDNA (55.22%; P < 0.01). Significant genetic variation was observed in M. nagaraensis from R. similis compared to R. fluviatilis (P < 0.001) or R. nagoyae (P < 0.001) from the same river. Such details are valuable for understanding parasite dispersal and its ecological impact on Rhinogobius hosts.

Manifestation of the batang banyu concept as a community communication experience

The existence of a unique concept of a river has significantly shaped the Banjarese community's relationship with it. This unique perspective, known as "Batang Banyu," portrays the river as a revered and integral aspect of their existence. The core objective of this research lies in comprehending the embodiment of the Batang Banyu concept within the regions of Martapura, Nagara, and Panggang in South Kalimantan. The research adopts a phenomenological approach, utilising an interpretive qualitative method to achieve this. The primary data is gathered through rigorous field observations and in-depth interviews with local inhabitants. The study's outcomes unveil that the Batang Banyu concept has evolved into a communicative experience, endowing the community with profound significance for the river. This significance finds manifestation in four fundamental aspects: first and foremost, the river serves as a livelihood for fishermen; secondly, it supports various livelihood-related endeavours; thirdly, it plays a crucial role in constructing homes; and lastly, it serves as a means of transportation. Remarkably, among the communities residing along the banks of the Nagara River and Panggang Lake, the Batang Banyu concept remains firmly entrenched. Conversely, for the people residing along the Martapura River, the Batang Banyu concept has been discarded, resulting in the unfortunate neglect and pollution of the Martapura River due to the accumulation of vast amounts of garbage.

Effects of fat content and fatty acid composition of Nagara River ayu on its quality as a food ingredient

Effects of fat content and fatty acid composition of Nagara River ayu on its quality as a food ingredient

Thermal Impact by Open-Loop Geothermal Heat Pump Systems in Two Different Local Underground Conditions on the Alluvial Fan of the Nagara River, Gifu City, Central Japan

An alluvial fan is a good area to install open-loop geothermal heat pump (GHP) systems due to shallower aquifers, faster groundwater flow, and fewer land subsidence risks. The natural temperature change in groundwater occurs in alluvial fans due to the recharge of river water and faster groundwater flow, and the thermal impact of the open-loop system has not been studied well in such areas. The purpose of this research is to understand the thermal impact of open-loop GHP systems on an alluvial fan. A regional 3D model of groundwater flow with heat transport was created to determine the distribution of flow velocity and temperature of groundwater. After that, two local models with different groundwater velocities were constructed to demonstrate the thermal impact of an open-loop GHP system using one extraction and one injection well. The results indicated that the local model with faster groundwater flow had a smaller thermal impact. The natural temperature change in groundwater causes groundwater temperature to be lower in the summer and higher in winter during the operation in the local model, with faster groundwater flow.

Basin-scale spatiotemporal distribution of ayu Plecoglossus altivelis and its relationship with water temperature from summer growth to autumn spawning periods

As climate warming progresses, it becomes necessary to study the effects of water temperature on the basin-scale dynamic distribution of riverine fish. This study examined the spatiotemporal distribution of Plecoglossus altivelis using the environmental DNA approach and its relationship with water temperature from summer growth to autumn spawning periods in the Nagara River basin, central Japan. The overall results of the spatiotemporal distribution of P. altivelis were consistent with the known life history: a wide-range distribution in the basin during summer and aggregation in the middle mainstem during autumn. Additionally, this study found three intriguing distribution patterns depending on water temperature. During summer (August), the warmest period, P. altivelis was distributed in the upper mainstem, one tributary, and the mainstem downstream of the tributary confluences in relation to the relatively colder water (< 25 °C). During early autumn (September–early October), it spread widely in the middle and upper mainstem without the constraint of the upper limit of water temperature. During late autumn (late October–November), it steadily aggregated to the middle mainstem because of downstream migration for spawning at water temperatures below 20 °C. This study suggests the importance of river connectivity for P. altivelis migration to suitable habitats during its freshwater life stages, upper mainstem and tributaries as summer growth habitats, and cooling effects of tributaries on the mainstem during mid-summer.

Impacts of Flood Disturbance on the Dynamics of Basin-Scale Swimming Fish Migration in Mountainous Streams

This study investigated the response of sweetfish (Plecoglossus altivelis), a species that migrates dynamically throughout a river basin, to two flood events during the summer of 2020 in the Nagara River, located in the central region of Japan. By combining multiple environmental DNA (eDNA) surveys and hydrological modeling, the spatiotemporal distribution of P. altivelis throughout a mountainous river basin was captured and analyzed. The eDNA concentrations at 42 sites in the Nagara River Basin were analyzed five times from August to early October 2020. In addition, Rainfall–Runoff–Inundation model calculations were performed using 1-km resolution precipitation data as input values to analyze the magnitude of the flood disturbance at the eDNA sites. The daily specific discharge Qs (m3/s/km2) was employed as an index of the flood magnitude. The calculation period included Flood Events 1 and 2 with 52 and 38 days of precipitation reaching 1923 and 528 mm, respectively. The results of the eDNA analysis showed that, immediately after Flood Event 1, the spatial distribution of P. altivelis was unevenly distributed in the upper reaches of the Nagara River and some of its tributaries. Subsequently, the distribution expanded to the entire mainstem. The distribution of the maximum daily specific discharge suggested that the river segments with high eDNA concentrations of P. altivelis immediately after the high-magnitude flood event were those with a relatively low intensity of flood disturbance compared with those in the other connected river segments and tributaries. The results of this study indicate that the resilience of riverine communities to extreme floods is supported by the continuity and connectivity between the mainstem and its tributaries in mountainous river basins.

Characteristics of Cormorant Fishing on the Nagara River in the Early Modern Period: Focusing on the Relationship with Owari Domain

Characteristics of Cormorant Fishing on the Nagara River in the Early Modern Period: Focusing on the Relationship with Owari Domain

About the influence of the presence of gravel mixed in the digestive tract of Nagara River Ayu on the quality as a foodstuff

About the influence of the presence of gravel mixed in the digestive tract of Nagara River Ayu on the quality as a foodstuff

Keragaman Ikan Genus Barbodes di Sungai Nagara Desa Pandak Daun Kecamatan Daha Utara

Species diversity can be defined as the number of species among the total number of individuals of all existing species. The existence of fish, especially fish of the Barbodes genus, is very important for the ecosystem, besides that, fish of the Barbodes genus also function as a source of protein for humans. The purpose of this study was to describe the diversity of fish of the genus Barbodes found in the Nagara River. This research was conducted in the Nagara River, Pandak Daun Village, North Daha District in August-January 2021. There are 2 zones to catch fish, namely settlements and vegetation using a net measuring 10 x 2 m. This research method uses descriptive method with random sampling technique. Diversity was calculated using the Shannon-Wiener diversity index. The results obtained were three types of fish of the genus Barbodes. Namely lampam putih fish (Barbodes gonionotus), lampam merah fish (Barbodes schwanenfeldii), and abang-abang fish (Barbodes altus). The highest diversity with the value H' = 1,04 and the lowest H' = 0,61.

Keragaman Jenis Ikan Familia Bagridae di Sungai Nagara Desa Pandak Daun Kecamatan Daha Utara

Species diversity can be defined as the number of species among the total number of individuals of all existing species. Fish from the Bagridae family are freshwater fish with high economic value and excellent nutritional content. The purpose of this study was to describe the diversity of fish in the Bagridae family found in the Nagara River, Pandak Daun Village, North Daha District. This research was conducted in Sungai Nagara, Pandak Daun Village, North Daha Subdistrict, in August-January 2021. There are 2 zones for catching fish, namely settlements and vegetation. This research method uses descriptive method with random sampling technique. Diversity was calculated using the Shannon-Wiener diversity index. The results obtained were three types of fish in the Bagridae family, namely Mystus mumurus, Mystus nigriceps, and Mystus gulio. The highest diversity with a value of H' = 0.88 and the lowest H' = 0.72.

A Future Scenario Focusing on Climate Change in Nagara River Watershed—Development and Application of the Integrated Future Scenario Building Methodology—

A Future Scenario Focusing on Climate Change in Nagara River Watershed—Development and Application of the Integrated Future Scenario Building Methodology—

Interaction between river water and groundwater in the Nagara River alluvial fan, Nobi plain

Interaction between river water and groundwater in the Nagara River alluvial fan, Nobi plain

Carotenoids of land-locked and sea-run types of masu salmon Oncorhynchus masou ishikawae inhabiting in the Nagara River, Japan, from the perspective of chemical ecological study

Carotenoids of the land-locked type (Amago) and sea-run type (Satsukimasu) of masu salmon Oncorhynchus masou ishikawae inhabiting the Nagara River, Gifu Prefecture, Japan were investigated from the perspective of the chemical ecological point of view. Yellow xanthophylls, 3′-epilutein, lutein, zeaxanthin, and diatoxanthin were major carotenoids in wild Amago. They were also present in the flesh of wild Amago. These carotenoids originated from aquatic insects, which wild Amago fed on. On the other hand, tunaxanthin, zeaxanthin, and salmoxanthin were major carotenoids in the integument of Satsukimasu, which migrated from the Ise Bay to the Nagara River. Astaxanthin was a major carotenoid in the flesh of Satsukimasu. These carotenoids accumulated from marine fish and crustaceans, which Satsukimasu fed on during migration in the sea. Carotenoids of Amago and Satukimasu well-reflect their ecological life history.

LONG TERM CHANGES IN FLOODING AROUND GIFU CITY

Abstract. Heavy rainfall within a short period and consequent high river discharge are results in floods which subsequently creates huge infrastructure problems for areas, such huge economic deficits in production as well as damages to existing property and goods, even loss of human lives. In about hundred years ago the flat-land around the Kiso Three Rivers system (the catchment areas of the Kiso River, Nagara River, and Ibi River are called the Kiso Three River system) included Gifu City, Gifu Prefecture of Japan, was frequently damaged by inundation after heavy rainfall. Our research aims to evaluate flood risk changes by river improvement in the Kiso Three River system fin the past hundred years. For that reason, we simulated in several times on flood inundation in the large, medium and low scale case in the urban area of Gifu city with 2D flood inundation model, and compared the distribution of flood depth. The results, the flood inundation area in urban area for small scale flood disaster dramatically is reduced from 3.82 km2 in the past time to 0.48 km2 in the current time with the progress of river infrastructure improvement. However flooded area in urban area for large and middle scale disaster show the almost same. It is suggested that flood risks in urban area are dramatically improved for only small disaster.

Underground temperature distribution and spatial suitability assessmentfor geothermal heat pumps in the alluvial fan of the Nagara River, central Japan

Underground temperature distribution and spatial suitability assessmentfor geothermal heat pumps in the alluvial fan of the Nagara River, central Japan

Characteristics of Nanoparticles in Drinking Water Treatment using Biological Activated Carbon

Characteristics of nanoparticles in drinking water treatment were performed using five types of biological activated carbon (BAC) columns (BAC1-BAC5) in continuous flow experiments. The BAC was created by covering granular activated carbon (GAC) with attached microorganisms from water samples taken from the Nagara River in Japan. The total running time was about 2000 h. The characteristics of the nanoparticles were investigated based on size distribution and volume distribution measured by Zetasizer Nano. Total dissolved organic carbon (DOC) and ultraviolet absorbance at 260 nm (UV260) were also studied. The important results in this study were that the detached nanoparticles in the effluent were within the size distribution ranges of 0.26~5.62 nm, 0.62~3.62 nm, 0.62~3.12 nm, 0.62~4.19 nm, and 0.62~6.50 for BAC 1, 2, 3, 4 and 5, respectively. The profile of peak size and peak number along the bed depth of the BAC columns was evaluated for better understanding the characteristics of the nanoparticles. This result is very important for improving drinking water treatment using granular activated carbon to remove microorganisms.

Contrasting life history patterns of the goby Rhinogobius similis in central Japan indicated by otolith Sr:Ca ratios

Rhinogobius similis a common goby, widely distributed in Far East Asia, is characterized by an amphidromous life history, adult fish inhabiting the lower reaches of rivers, and larvae in the freshwater area being swept downstream to the sea and returning to the river following a period of pelagic marine existence. Individuals were collected from 6 stations in the Ibi, Nagara and Kamo Rivers, central Japan, and their otolith strontium and calcium environmental signatures examined using electron probe microanalyses. The otolith Sr:Ca ratios of R. similis from the Kamo River suggested a typical amphidromous life history, whereas those of fish collected from the Ibi River suggested two types of migratory life history pattern: amphidromous and river resident. In contrast, the otolith Sr:Ca ratios of fish collected at two stations upriver of a dam in the Nagara River estuary suggested an artificially landlocked life history. Emergent plant vegetation in the lower reaches of the Ibi River created slow currents and pools in the river, thereby possibly enhancing the likelihood of a river resident life history. In the Nagara River, however, landlocked specimens had been obstructed in their downstream migration by the dam. It is suggested that R. similis in central Japan has a variable migratory life history pattern, allowing the species to persist in upstream habitats in large rivers.

First Announcement and Call for Papers: 20th International Drying Symposium (IDS 2016), Gifu, Japan, August 7–10, 2016

The 20th International Drying Symposium (IDS 2016) will take place during August 7–10, 2016, at the Nagaragawa (Nagara River) Convention Centre (http://www.g-ncc.jp/e-framepage.htm) in Gifu City, J...

Discrimination of the Stock Origins and Growth of Ayu Plecoglossus altivelis altivelis in the Nagara River

Discrimination of the Stock Origins and Growth of Ayu Plecoglossus altivelis altivelis in the Nagara River

Changes in the composition of stock origin and standard length of ayu Plecoglossus altivelis altivelis during the Tomozuri angling season in the Nagara River, central Japan

Delay of upward migration from the coast is considered to be a cause of stunted growth in ayu Plecoglossus altivelis altivelis in the Nagara River. To evaluate the effect of stocked seeds (hatchery reared, originating from Lake Biwa and amphidromous stock) on the growth of native ayu in the river, monthly changes in origin composition and standard lengths of territorial ayu caught by Tomozuri angling were examined. Stock origin of 94 individuals caught in the middle reaches of the river from June to October 2010 were discriminated using the otolith Sr/Ca ratio and morphological characteristics. Percentage frequency of native ayu increased with time from 4.2 % in June to 73.3 % in September and 71.4 % in October. Hatchery-reared stocks were consistently caught throughout the sampling period (26.7–41.7 %), while the catch of both Lake Biwa and amphidromous stocks were limited to before August. Native ayu were significantly smaller than the others in July; however, no significant differences were found from August. Apparent growth of stocked seed stopped after August, while native ayu stopped in September. Thus, we suggest that large stocked ayu disturb the native ayu from making territories and stunt their growth in the early part of the season.