Japan Aqua Restoration Research Center

Gifu, Japan

Japan Aqua Restoration Research Center

Gifu, Japan
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Nagayama S.,Japan Aqua Restoration Research Center | Nakamura F.,Hokkaido University
Limnology | Year: 2017

This study examined the structure and function of habitats for fish, the contribution to fish populations, and the effects of channel modification on habitats and fish populations in the lowland meandering Shibetsu River, northern Japan. Electrofishing and environmental measurements were conducted in bank areas of habitats constituting natural meandering and modified reaches. All types of habitats in a meandering reach highly contributed to the fish population(s). In particular, the contributions of lateral and wood habitats to fish populations were generally high, despite the low spatial extent of these habitats. The modified reach was simplified and had fewer types of habitats with uniform currents, and there was a low abundance of most fish within these habitats. Abundance of each fish group (taxa) was negatively affected by the changes in the habitats and/or channel shortening (i.e., decrease in the absolute abundance of habitat) due to river modification, which was implemented during 1950–1978. This study suggests that the recovery of all the habitat types is important in meander restoration and that the changes in habitat types and abundance should be examined in monitoring meander restoration and channel shortening. © 2017 The Japanese Society of Limnology

Nagayama S.,Japan Civil Engineering Research Institute for Cold Region | Nagayama S.,Japan Aqua Restoration Research Center | Nakamura F.,Hokkaido University
Landscape and Ecological Engineering | Year: 2010

To provide river managers and researchers with practical knowledge about fish rehabilitation, various studies of fish habitat rehabilitation that used wood were reviewed. The review focuses on fish responses, wood installation methods, and geomorphic features of the rehabilitation sites. Most studies were conducted in moderately sized (small and medium) streams with relatively high bed gradients and aimed to improve the habitats of salmonid species. In this stream type, structures spanning the full (log dam) and partial (log deflector) width of the river were most common, and wood structures that created pools and covers were successful in improving fish habitat. Some projects were conducted in moderately sized low-gradient streams, in which wooden devices used to create instream cover were effective for fish assemblages. There were few studies in other aquatic ecosystems. However, well-designed large wood structures, known as engineered log jams, were used in rehabilitation projects for large rivers. In slack-water or lentic systems such as side-channels, estuaries, and reservoirs, small and large wood structures that created cover were used to improve habitat for many fish species. For successful fish habitat rehabilitation projects, the hydrogeomorphic conditions of rehabilitation sites should be carefully examined to avoid physical failure of wood structures. Although artificial wood structures can be used to improve fish habitat in various aquatic ecosystems, they should be considered to be a complementary or interim habitat enhancement technique. The recovery of natural dynamic processes at the watershed scale is the ultimate target of restoration programs. © 2009 International Consortium of Landscape and Ecological Engineering and Springer.

Kume M.,Japan Aqua Restoration Research Center | Kitano J.,Fred Hutchinson Cancer Research Center | Mori S.,Gifu Keizai University | Shibuya T.,Akkeshi Waterfowl Observation Center
Journal of Evolutionary Biology | Year: 2010

When two closely related species migrate to divergent spawning sites, divergent use of spawning habitats can directly reduce heterospecific mating. Furthermore, adaptations to divergent spawning habitats can promote speciation as a by-product of ecological divergence. Here, we investigated habitat isolation and ecological divergence between two anadromous forms of threespine stickleback (Gasterosteus aculeatus), the Japan Sea and Pacific Ocean forms. In several coastal regions of eastern Hokkaido, Japan, these forms migrate to the same watershed to spawn. Our field surveys in a single watershed revealed that segregation of distinct spawning sites between the two forms was maintained within the watershed across multiple years. These spawning sites diverged in salinity and predator composition. Morphological and physiological divergence between the forms also occurs in the direction predicted by ecological differences between the spawning sites. Our data indicate that migration into divergent spawning habitats can be an important mechanism contributing to speciation and phenotypic divergence in anadromous fishes. © 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology.

Doi H.,Hiroshima University | Mori T.,Japan Aqua Restoration Research Center
Oikos | Year: 2013

Species-abundance distribution (SAD) is one of the most basic descriptions of an ecological community. Vigorous controversy surrounded SAD from the 1940s to 1960s, and has since persisted. Isao Motomura first published a notable paper in 1932 to describe findings on SAD, and to provide an empirical model; nevertheless, this work has often been overlooked or incorrectly cited, probably due to being published in Japanese. Here, we introduce the works of Motomura with an English translation of the paper, and the subsequent research history of SAD. We also introduce the work of Numata et al., another Japanese paper, which provided the biological explanation for Motomura's model of SAD, although it was rarely cited by subsequent studies. We summarize that Motomura was the first to fit a statistical model to observed SAD, and that Numata et al. attempted to explain the observed SAD via underlying biological mechanisms. © 2013 The Authors. Oikos © 2013 Nordic Society Oikos.

Mori T.,Japan Aqua Restoration Research Center | Saitoh T.,Hokkaido University
Ecology | Year: 2014

The effects of both abiotic factors and biotic interactions among guilds (i.e., inter-guild effects) have been suggested to be important for understanding spatial variation in species diversity; however, compared to the abiotic effects, the processes by which the interguild effects are mediated have been little described. Hence, we investigated stream invertebrate assemblages on Hokkaido Island, Japan, and assessed how the processes of determining regional patterns in species diversity differed among guilds (collector-filterers, collectorgatherers/ shredders, scrapers, and predators) by taking both inter-guild and abiotic effects into consideration using Bayesian networks. Collector-gatherers/shredders, collector-filterers, and predators exhibited significant regional gradients in taxonomic richness. Gradients in the former two guilds can be generated by variation in flood disturbance regardless of interactions with other guilds. The gradient in predator taxonomic richness was indirectly related to the disturbance and was directly generated by bottom-up effects through their prey (collectorgatherers/ shredders and collector-filterers). We found that not only environmental factors, but also inter-guild effects may be essential for forming the regional gradient in predators, unlike those for collector-gatherers/shredders and collector-filterers. The processes underlying the regional variation in taxonomic richness of the three guilds are interpreted in terms of the "more individuals" hypothesis, facilitation, and predator-prey relationships. © 2014 by the Ecological Society of America.

Kume M.,Hokkaido University | Kume M.,Japan Aqua Restoration Research Center
Zoological Studies | Year: 2011

Clutch and egg sizes of two migratory forms of the threespine stickleback Gasterosteus aculeatus in eastern Hokkaido, Japan. Zoological Studies 50(3): 309-314. Clutch and egg sizes were compared between the Japan Sea and Pacific Ocean forms of the threespine stickleback collected from the Bekanbeushi River in eastern Hokkaido, Japan. The Japan Sea form produced many small-sized eggs, whereas the Pacific Ocean form produced fewer large-sized eggs, suggesting the existence of a trade-off between clutch and egg sizes in both forms. A previous study revealed that the 2 forms diverged in their breeding habitats by using different salinity regimes within a single watershed. These findings suggest that the Japan Sea and Pacific Ocean forms have evolved different reproductive strategies and characteristics in response to differing salinities and properties of their respective environments.

Negishi J.N.,Japan Aqua Restoration Research Center | Negishi J.N.,Hokkaido University | Nagayama S.,Japan Aqua Restoration Research Center | Kume M.,Japan Aqua Restoration Research Center | And 3 more authors.
Ecological Indicators | Year: 2013

We tested the hypothesis that globally imperiled freshwater mussels (Order: Unionoida) can be used as an indicator of fish communities in lowland aquatic systems for relatively small geographic areas (i.e.; <100 km 2). The survey was conducted in 13 reaches within a network of agricultural drainage channels and in 9 floodplain backwaters in Central Japan. In each site, the fish community was examined on four seasonal occasions (spring to early summer, mid-summer, fall to early winter, and winter) and related to the mussel community. Total abundance, taxon richness, and diversity index were used to characterize fish communities. Mussel community variables predicted some aspects of fish communities, but such patterns were seasonally limited. In both systems, mussel community variables had no predictive power for the total abundance of fishes. In drainage channels, taxon richness of mussels was a good predictor of all fish community variables except for total abundance in early summer. In winter, mussel abundance predicted well the taxon richness of the fish community, while taxon richness predicted the diversity index of the fish community. In backwaters, mussel abundance was a good predictor of fish community variables except total abundance in mid-summer. A relatively minor portion (<23%) of fish-mussel relationships was attributable to direct commensalism between mussels and bitterlings. A conceptual framework was provided to help identify the mechanisms behind fish-mussel relationships. Our findings validated the use of mussels as an indicator of high-quality summer rearing habitats in backwaters and wintering and reproduction habitats of fishes in drainage channels. © 2012 Elsevier Ltd. All rights reserved.

Negishi J.N.,Japan Aqua Restoration Research Center | Negishi J.N.,Hokkaido University | Sagawa S.,Japan Aqua Restoration Research Center | Kayaba Y.,Japan Aqua Restoration Research Center | And 3 more authors.
Freshwater Biology | Year: 2012

Understanding mechanisms behind the distribution of organisms along a gradient of hydrological connectivity is crucial for sustainable management of river-floodplain systems. We tested the hypothesis that frequency of flood pulses exerts a direct influence on the distribution of freshwater mussels (Unionoida) by creating a local environment that limits their fitness. Multiscale habitat analyses combined with transplant-rearing experiments were carried out with a focus on abundance, presence/absence, survival rates and growth rates of mussels. Sixty-nine floodplain waterbodies (FWBs) were surveyed within a 15-km lowland segment of the Kiso River in Japan. The abundance of mussels significantly increased with increased frequency of inundation associated with flood pulses at the among-FWB scale, while the probability of occurrence of mussels was negatively predicted by the amount of benthic organic matter at the within-FWB scale. Field-rearing experiments showed that survival rates were low and growth rates nearly zero in infrequently inundated FWBs (these FWBs had no naturally occurring resident mussels). In such FWBs, hypoxia (DO<2mgL -1) was frequently observed near the bottom when temperature was optimal for mussel growth (>15°C). These findings demonstrated that flood pulse frequency was the most important factor in determining mussel distribution in FWBs because it directly limits mussels' fitness by mediating local environmental factors, possibly dissolved oxygen (DO) levels. Successful restoration efforts for mussel habitat conservation should focus on processes that lead to improved local conditions. © 2012 Blackwell Publishing Ltd.

Doi H.,Ehime University | Doi H.,Carl von Ossietzky University | Takahashiz M.,Hokkaido University | katano I.,Carl von Ossietzky University | katano I.,Japan Aqua Restoration Research Center
Global Change Biology | Year: 2010

Climate change is inducing changes in the phenological timings of organisms. Genetic diversity could influence phenological responses to climate change, but empirical evidence is very limited. We estimated the regional variation across Japan in flowering and leaf budburst dates of plants based on a dataset of phenological timings from 1953 to 2005. The observed plants' genetic diversities varied according to human cultivation. The within-species variations of phenological response to temperature as well as regional variations were less in the plant populations with lower genetic diversity. Thus, genetic diversity influences the variation in phenological responses of plant populations. Under increased temperatures, low variation in phenological responses may allow drastic changes in the phenology of plant populations with synchronized phenological timings. Our findings indicate that we should pay attention to maintaining genetic diversity of populations to alleviate changes in phenology due to future climate change. © 2009 Blackwell Publishing Ltd.

Negishi J.N.,Japan Aqua Restoration Research Center | Negishi J.N.,Hokkaido University | Kayaba Y.,Japan Aqua Restoration Research Center
Ecological Research | Year: 2010

Despite the dwindling populations and an urgent need for conservation of unionid freshwater mussels in Japan, there are gaps in our understating of their fundamental ecology. This study examined size-dependent annual growth rates, elucidated size-specific intra-annual growth patterns, and estimated age and longevity of P. japanensis individuals for two locally isolated populations in agricultural drainage channels. Annual growth rates of P. japanensis were strongly size-dependent, with growth rates being exponentially decelerated with increasing shell length. Irrespective of sizes, individuals ceased to grow in winter when water temperature fell below 10°C. Intra-annual growth patterns were weakly explained by the changes in water temperature and differed among size classes; juveniles (<25 mm) maximized growth rate in May whereas the growth rates were the highest in June or July for larger individuals. Only adult individuals exhibited growth cessation in the July-August period, suggesting that energy investment was directed towards reproductive activities. Adults also showed negative growth rates (shrinkage of individuals) in winter, suggesting possible dissolution of shell margins. Age estimation based on two 1-year periods suggests that large numbers of P. japanensis individuals were >10 years old, and the oldest individuals were >20 years old for both study populations. Our findings suggest that anthropogenic activities conducted in spring may have strong influences on juveniles and population dynamics of P. japanensis and underscore the need for accurately determining age and longevity of remaining populations of unionid mussels. © The Ecological Society of Japan 2009.

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