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Last Updated :2024/10/31

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Master

Affiliation (Master)

  • Faculty of Environmental Earth Science　Integrated Environmental Science　Practical and Earth Sciences for Environment

Affiliation (Master)

  • Faculty of Environmental Earth Science　Integrated Environmental Science　Practical and Earth Sciences for Environment

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Negishi

  • Name (Kana)

    Junjiro

  • Name

    201501041678793586

Alternate Names

Achievement

Research Interests

  • 底生動物   氾濫原   湧水   生息環境   河床低下   生態系保全   保全   水生生物   生態系管理   底性動物   流域管理   河川   生物多様性   流域保全   森林渓流生態系   生物濃縮   鳥類   放射性セシウム   農地生態系   森林農地生態系   放射性物質の移行   撹乱   有機物動態   森林生態系   放射性核種   食物網解析   渓流生態系   淡水魚類   河川生態系   河川流出   

Research Areas

  • Environmental science/Agricultural science / Biological resource conservation
  • Life sciences / Forest science
  • Environmental science/Agricultural science / Landscape science
  • Environmental science/Agricultural science / Environmental agriculture

Research Experience

  • 2011 - Today Hokkaido University

Published Papers

  • Shohei Yamashita, Junjiro N. Negishi, Tomohiro Nakagawa, Nozomi Aruga, Kazuhiro Toyoda, Futoshi Nakamura
    Environmental Pollution 125101 - 125101 0269-7491 2024/10
  • S. D. Tiegs, K. A. Capps, D. M. Costello, J. P. Schmidt, C. J. Patrick, J. J. Follstad Shah, C. J. LeRoy, Vicenç Acuña, Ricardo Albariño, Daniel C. Allen, Cecilia Alonso, Patricio Andino, Clay Arango, Jukka Aroviita, Marcus V.M. Barbosa, Leon A. Barmuta, Colden Baxter, Brent Bellinger, Luz Boyero, Lyubov Bragina, Lee E. Brown, Andreas Bruder, Denise A. Bruesewitz, Francis Burdon, Marcos Callisto, Antonio Camacho, Cristina Canhoto, María M. Castillo, Eric Chauvet, Joanne Clapcott, Fanny Colas, Checo Colón-Gaud, Julien Cornut, Verónica Crespo-Pérez, Wyatt F. Cross, Joseph Culp, Michael Danger, Olivier Dangles, Elvira de Eyto, Alison M. Derry, Veronica Díaz Villanueva, Michael M. Douglas, Arturo Elosegi, Andrea C. Encalada, Sally Entrekin, Rodrigo Espinosa, Verónica Ferreira, Carmen Ferriol, Kyla M. Flanagan, Alexander S. Flecker, Tadeusz Fleituch, André Frainer, Nikolai Friberg, Paul C. Frost, Erica A. Garcia, Liliana García-Lago, Pavel Ernesto García Soto, Mark O. Gessner, Sudeep Ghate, Darren P. Giling, Alan Gilmer, José Francisco Gonçalves, Rosario Karina Gonzales, Manuel A.S. Graça, Mike Grace, Natalie A. Griffiths, Hans-Peter Grossart, François Guérold, Vlad Gulis, Pablo E. Gutiérrez-Fonseca, Luiz U. Hepp, Scott Higgins, Takuo Hishi, Joseph Huddart, John Hudson, Moss Imberger, Carlos Iñiguez-Armijos, Mark W. Isken, Tomoya Iwata, David J. Janetski, Andrea E. Kirkwood, Aaron A. Koning, Sarian Kosten, Kevin A. Kuehn, Hjalmar Laudon, Peter R. Leavitt, Aurea L Lemes da Silva, Shawn Leroux, Peter J. Lisi, Richard MacKenzie, Amy M. Marcarelli, Frank O. Masese, Peter B. McIntyre, Brendan G. McKie, Adriana Medeiros, Kristian Meissner, Marko Miliša, Shailendra Mishra, Yo Miyake, Ashley Moerke, Shorok Mombrikotb, Rob Mooney, Timothy Moulton, Timo Muotka, Junjiro Negishi, Vinicius Neres-Lima, Mika L. Nieminen, Jorge Nimptsch, Jakub Ondruch, Riku Paavola, Isabel Pardo, Edwin T.H.M. Peeters, Jesus Pozo, Aaron Prussian, Estefania Quenta, Brian Reid, John S. Richardson, Anna Rigosi, José Rincón, Geta Risnoveanu, Christopher T. Robinson, Lorena Rodríguez-Gallego, Todd V. Royer, James A. Rusak, Anna C. Santamans, Géza B. Selmeczy, Gelas Simiyu, Agnija Skuja, Jerzy Smykla, Ryan Sponseller, Kandikere R. Sridhar, Aaron Stoler, Christopher M. Swan, Franco Teixeira de Mello, Jonathan D. Tonkin, Sari Uusheimo, Allison M. Veach, Sirje Vilbaste, Lena B.-M. Vought, Chiao-Ping Wang, Jackson R. Webster, Paul B. Wilson, Stefan Woelfl, Guy Woodward, Marguerite A. Xenopoulos, Adam G. Yates, Chihiro Yoshimura, Catherine M. Yule, Yixin Zhang, Jacob A. Zwart
    Science 384 (6701) 1191 - 1195 0036-8075 2024/06/14 
    Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a predictive model (81% variance explained) for cellulose decomposition rates across 514 globally distributed streams. A large number of variables were important for predicting decomposition, highlighting the complexity of this process at the global scale. Predicted cellulose decomposition rates, when combined with genus-level litter quality attributes, explain published leaf litter decomposition rates with high accuracy (70% variance explained). Our global map provides estimates of rates across vast understudied areas of Earth and reveals rapid decomposition across continental-scale areas dominated by human activities.
  • Bingguo Dai, Shin ichiro S. Matsuzaki, Junjiro N. Negishi, Zhijun Xia, Md Khorshed Alam, Zhongguan Jiang
    Diversity and Distributions 30 (6) 1366-9516 2024/06 
    Aim: This study aimed to illustrate the changing diversity patterns of native freshwater fish in the past two centuries and to identify priority locations for native fish conservation to counter future degradation. Location: Japanese archipelago. Methods: We used the published native fish fauna data in 39 lakes across Japan, analysing historical and current diversity and projecting future distribution patterns based on the Japanese Red List. We assessed fish assemblages' taxonomic, phylogenetic, and functional alpha and beta diversity across different periods. Additionally, we proposed a cumulative diversity index that incorporated taxonomic, phylogenetic and functional facets, and then examined its relationship with the latitudinal positioning of the lakes across periods. Results: We observed a significant decrease in the richness of native freshwater fish since historical periods. Accompanying this decline were significant reductions in both phylogenetic relatedness and functional redundancy. Fish beta diversity increased from the past to the present and is predicted to decline drastically, indicating an ongoing homogenization process. Using the cumulative diversity index, we identified Hokkaido and Kyushu as crucial habitats for endemic fishes. These islands, with unique biogeographical backgrounds, contributed substantially to the national dissimilarity patterns of native fish assemblages in the historical period. However, the contribution is diminishing due to the ongoing decline in fish endemism. Main Conclusions: The conservation priority of native freshwater fish in Japan should be assigned to Hokkaido and Kyushu due to the inhabited endemic species. The proposed framework for assessing the cumulative diversity of biotic communities presented the potential to aid macroecological explorations that underpin biodiversity conservation.
  • Gyo Yoshinari, Kazuhisa Inada, Masaki Takenaka, Koji Tojo, Junjiro N. Negishi
    Limnology 1439-8621 2024 
    Taxonomical and ecological knowledge of stoneflies (Order: Plecoptera) is important biological indicator of riverine environments. A genus Utaperla was established by Ricker in 1952 when he described U. sopladora Ricker 1952. The Utaperla stoneflies have been recorded in North America, Russia and China and consists of the species, U. sopladora, U. orientalis Nelson and Hanson 1969, U. lepnevae (Zhiltzova 1970), U. gaspesiana Harper and Roy 1975. None of these species were previously observed in Japan. We recently discovered adult specimens of U. orientalis during a survey of riverine benthos in Hokkaido, Japan, and report here on their collection sites, morphological characteristics, genetic information, and adult emergence patterns in comparison with other sympatric species. Although their abundance appeared to be low, with an emergence period limited to early summer, this finding contributes to an improved database for biodiversity conservation in the region.
  • Izumi Katano, Hideyuki Doi, Junjiro N. Negishi, Tomoko Minagawa, Yuichi Kayaba
    River Research and Applications 1 - 14 2023/11 [Refereed]
  • Shigeya Nagayama, Morihiro Harada, Junjiro N. Negishi, Jyun-ichi Kitamura, Terutaka Mori, Seiichi Mori
    Restoration Ecology 2023/10/25 [Refereed]
  • Kazuki Miura, Nobuo Ishiyama, Junjiro N. Negishi, Keita Kawajiri, Hokuto Izumi, Daisetsu Ito, Futoshi Nakamura
    2023/05/22 
    Abstract Recruitment failure is a major threat to freshwater mussel (Order Unionoida) populations worldwide. Assessments of the recruitment status and determining the bottleneck factors of mussel recruitment are crucial for preventing future declines in mussel populations. In this study, we investigated the recruitment status (i.e., size structure and the proportion of juveniles within a population) of the endangered freshwater pearl musselMargaritifera laevisin 22 rivers in eastern Hokkaido, northern Japan. We also quantified the density of the host fishOncorhynchus masou masouand examined the relationship between the proportion of juveniles and host-fish density to assess host-limitation threats toM. laevisrecruitment. Our assessments showed that 13 (59.1%) rivers had no signs of recent recruitment within 10 years, with a low mean proportion of juveniles (mean:0.02 [range:0.00–0.09] fraction), indicating that these populations are threatened by sustained recruitment failure. The proportion of juveniles was positively associated with host-fish density, suggesting that host-fish limitation could be a bottleneck factor forM. laevisrecruitment. These results highlight the urgent need for prompt conservation measures, including the enhancement of host-fish availability, to sustainM. laevispopulations in the study region.
  • Nobuo Ishiyama, Masanao Sueyoshi, Jorge García Molinos, Kenta Iwasaki, Junjiro N. Negishi, Itsuro Koizumi, Shigeya Nagayama, Akiko Nagasaka, Yu Nagasaka, Futoshi Nakamura
    The Bulletin of the Ecological Society of America 0012-9623 2023/03/15
  • Nobuo Ishiyama, Masanao Sueyoshi, Jorge García Molinos, Kenta Iwasaki, Junjiro N. Negishi, Itsuro Koizumi, Shigeya Nagayama, Akiko Nagasaka, Yu Nagasaka, Futoshi Nakamura
    Ecological Monographs 93 (2) 0012-9615 2023/02/16
  • Bingguo Dai, Junjiro N. Negishi, Kazuya Fujii, Md Khorshed Alam, Zhongguan Jiang
    NeoBiota 85 101 - 123 1619-0033 2023 
    The introduction of non-native fish species poses a threat to native assemblages in floodplain systems. Establishing oxbow lake-based conservation areas has been proposed as a practical approach to mitigate this threat. Previous studies have extensively discussed the effects of lateral connectivity between oxbow lakes and main channels on fish communities but overlooked the spatial longitudinal gradients of oxbow lakes on a broader spatial scale. Over the course of about ten years, the temporal changes in fish community diversity were estimated in 28 oxbow lakes along the Ishikari River in Hokkaido, Japan. The associations between these temporal variations and the locations of the lakes were then explored along a longitudinal spatial gradient. The results showed that upstream oxbow lakes underwent mild alterations to their species composition and maintained a high level of native uniqueness. In contrast, downstream oxbow lakes experienced intense species turnover and increased non-native fish diversity. Additionally, the dominance of non-native fish in downstream areas rapidly expanded upstream to a location 110 km from the source of the Ishikari River over the decade. It is emphasized that the lakes in the upper reaches were the only remaining refuges for native fish and should be prioritized in conservation efforts. Our study proposes the application of location and species contributions to regional community heterogeneity as indicators for highlighting native fish conservation areas.
  • Masaru Sakai, Yumiko Ishii, Hideki Tsuji, Asuka Tanaka, Jaeick Jo, Junjiro N. Negishi, Seiji Hayashi
    Environmental Pollution 315 120474 - 120474 0269-7491 2022/12
  • J. N. Negishi, M. K. Alam, M. A. T. M. T. Rahman, R. Kawanishi, H. Uno, G. Yoshinari, K. Tojo
    Hydrobiologia 849 (19) 4203 - 4219 0018-8158 2022/11
  • Janine Rodulfo Tolod, Junjiro N. Negishi, Nobuo Ishiyama, Md. Khorshed Alam, Mirza A. T. M. Tanvir Rahman, Pongpet Pongsivapai, Yiyang Gao, Masanao Sueyoshi, Futoshi Nakamura
    Hydrobiologia 2022/09/07
  • Kei Uchida, Azumi Okazaki, Takumi Akasaka, Junjiro N. Negishi, Futoshi Nakamura
    Journal of Environmental Management 317 115467 - 115467 0301-4797 2022/09
  • Izumi Katano, Junjiro N. Negishi, Tomoko Minagawa, Hideyuki Doi, Yôichi Kawaguchi, Yuichi Kayaba
    Scientific Reports 11 (1) 7525 - 7525 2021/12 [Refereed]
     
    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.
  • Luz Boyero, Naiara López-Rojo, Alan M. Tonin, Javier Pérez, Francisco Correa-Araneda, Richard G. Pearson, Jaime Bosch, Ricardo J. Albariño, Sankarappan Anbalagan, Leon A. Barmuta, Ana Basaguren, Francis J. Burdon, Adriano Caliman, Marcos Callisto, Adolfo R. Calor, Ian C. Campbell, Bradley J. Cardinale, J. Jesús Casas, Ana M. Chará-Serna, Eric Chauvet, Szymon Ciapała, Checo Colón-Gaud, Aydeé Cornejo, Aaron M. Davis, Monika Degebrodt, Emerson S. Dias, María E. Díaz, Michael M. Douglas, Andrea C. Encalada, Ricardo Figueroa, Alexander S. Flecker, Tadeusz Fleituch, Erica A. García, Gabriela García, Pavel E. García, Mark O. Gessner, Jesús E. Gómez, Sergio Gómez, Jose F. Gonçalves, Manuel A.S. Graça, Daniel C. Gwinn, Robert O. Hall, Neusa Hamada, Cang Hui, Daichi Imazawa, Tomoya Iwata, Samuel K. Kariuki, Andrea Landeira-Dabarca, Kelsey Laymon, María Leal, Richard Marchant, Renato T. Martins, Frank O. Masese, Megan Maul, Brendan G. McKie, Adriana O. Medeiros, Charles M.M’ Erimba, Jen A. Middleton, Silvia Monroy, Timo Muotka, Junjiro N. Negishi, Alonso Ramírez, John S. Richardson, José Rincón, Juan Rubio-Ríos, Gisele M. dos Santos, Romain Sarremejane, Fran Sheldon, Augustine Sitati, Nathalie S.D. Tenkiano, Scott D. Tiegs, Janine R. Tolod, Michael Venarsky, Anne Watson, Catherine M. Yule
    Nature Communications 12 (1) 3700 - 3700 2021/12 [Refereed]
     
    The relationship between detritivore diversity and decomposition can provide information on how biogeochemical cycles are affected by ongoing rates of extinction, but such evidence has come mostly from local studies and microcosm experiments. We conducted a globally distributed experiment (38 streams across 23 countries in 6 continents) using standardised methods to test the hypothesis that detritivore diversity enhances litter decomposition in streams, to establish the role of other characteristics of detritivore assemblages (abundance, biomass and body size), and to determine how patterns vary across realms, biomes and climates. We observed a positive relationship between diversity and decomposition, strongest in tropical areas, and a key role of abundance and biomass at higher latitudes. Our results suggest that litter decomposition might be altered by detritivore extinctions, particularly in tropical areas, where detritivore diversity is already relatively low and some environmental stressors particularly prevalent.
  • Junjiro N. Negishi, Tomohiro Nakagawa, Futoshi Nakamura
    Aquatic Ecology 56 (1) 325 - 330 1386-2588 2021/10/13 [Refereed]
     
    This study tested the hypothesis that color affects the behavior of Ephemeroptera, Plecoptera, and Trichoptera (EPT) adults in the riparian zone of a gravel-bed river in northern Japan. EPT abundance was measured using plot scale surveys and a color-choice experiment that utilized non-shiny sticky traps in two contrasting colors, yellow and blue. Chloroperlidae and Hydrobiosidae were caught more abundantly in yellow and blue traps, respectively, whereas other taxa exhibited little or no color-affected responses. We proposed that Chloroperlidae responses were driven by relatively strong diurnal activity compared with those of other taxa. Hydrobiosidae's preference of blue remained unknown. Understanding the evolutionary background of color preferences in relation to other possibly interfering factors, such as reflection-polarization characteristics, at the species level will help advance the visual sensory ecology of aquatic insects.
  • Kazuki Miura, Nozomi Watanabe, Yuuka Takagi, Nobuo Ishiyama, Junjiro N. Negishi
    Hydrobiologia 0018-8158 2021/10/05 [Refereed]
  • Kazuki Miura, Nobuo Ishiyama, Junjiro N. Negishi, Daisetsu Ito, Keita Kawajiri, Hokuto Izumi, Takahiro Inoue, Masahiro Nakaoka, Futoshi Nakamura
    2021/09/23 
    AbstractMultiple stressors can interactively affect the population of organisms; however, the process by which they affect recruitment efficiency remains unclear for empirical populations. Recruitment efficiency can be regulated at multiple stages of life, particularly in organisms with complex life cycles. Understanding the interactive effects of multiple stressors on recruitment efficiency and determining the bottleneck life stages is imperative for species conservation. The proportion of <20-year-old juveniles of the endangered freshwater pearl mussel Margaritifera togakushiensis, which has an obligate parasitic larval stage, was investigated in 24 rivers from eastern Hokkaido, northern Japan to reveal the influence of nutrients, fine sediment, and their combined effects on juvenile recruitment efficiency. The following indices for recruitment at adult, parasitic, and post-parasitic juvenile stages were obtained from 11 of these rivers: gravid female density, glochidia density (the number of glochidia infections per stream area), and juvenile survival rate. This study explored the bottleneck stages of recruitment efficiency and the interactive effects of the two stressors on these stages. Twenty-four population status assessments determined that the proportion of juveniles ranged from 0.00 to 0.53, and juveniles were absent from four rivers. The results showed that the parasitic and post-parasitic juvenile stages were bottlenecks for recruitment efficiency. Juvenile survival rates had a more significant positive effect on recruitment efficiency in rivers with a high glochidia density. Juvenile survival rate was decreased by the synergistic interaction of nutrients and fine sediment, although factors limiting glochidia density were not found. The nutrient concentration of rivers in the study region was well explained by the proportion of agricultural land cover and urban areas in the watersheds, but no relationship was detected between fine sediment abundance and land use. This study suggests that nutrient management at a catchment scale can be effective for re-establishing the recruitment of M. togakushiensis, particularly in rivers with a high content of fine sediments. The results also emphasise the importance of considering both parasitic and post-parasitic juvenile stages of mussels to maximise the positive effects of stressor mitigation.
  • Hitoshi Kitaichi, Junjiro N. Negishi, Daisetsu Ito, Kazuki Miura, Hirokazu Urabe
    Ecological Research 36 (5) 803 - 814 0912-3814 2021/09 [Refereed]
     
    Understanding the limiting factors of the reproduction process in host–affiliate relationships is a high priority. We examined the effects of habitat location on the reproductive process of freshwater pearl mussels Margaritifera laevis (Bivalvia, Unionida) as a parasite using sympatric and allopatric Oncorhynchus masou masou (Actinopterygii, Salmoniformes) as a host fish. Initial infection rates of parasitic larvae (glochidia) and transformation rates to cysts (encysted glochidia) were examined for all parasite-host combinations from three habitat locations (a total of nine combinations) to test the hypothesis that sympatric pairs of mussels and fish result in the highest success rates of glochidia infection and encystment. Measurements of glochidia-infected fish reared in flow-through experimental indoor tanks were taken at the initial infection point as well as at encystment, 2 weeks after the infection. Results disagreed with our hypothesis. Instead, an unexpected heterogeneity in a pathological deformity in gills explained a greater amount of variance in these processes. This deformity was responsible for reducing the initial infection rate and increasing the metamorphosis rates of initially attached glochidia to cysts. The field-measured prevalence of the gill deformity was low in all habitat locations, indicating that the deformity occurred during the acclimation period before infection for relatively small-sized host fish more susceptible to infection. Our results did not show the local adaptation of parasitic freshwater mussels to host fish but shed light on one of the least studied factors, providing an empirical underpinning of the importance of pathologically diversified host conditions in the reproductive processes of unionid mussels.
  • Kengo Okada, Masaru Sakai, Takashi Gomi, Aimu Iwamoto, Junjiro N. Negishi, Masanori Nunokawa
    ECOLOGICAL RESEARCH 0912-3814 2021/09 [Refereed]
     
    Understanding the factors influencing Cs-137 concentrations in freshwater salmonids is crucial for reviving inland fisheries in polluted regions. We studied seasonal variations of Cs-137 concentration in charr (Salvelinus leucomaenis) through uptake and metabolism in forested headwaters at Fukushima and Gunma sites. Charr consumed both terrestrial and aquatic animals, and terrestrial prey was predated more in summer at both sites. The Cs-137 concentrations in litter, which is a dominant basal food resource of both forest and stream ecosystems, differed between forest and stream due to Cs-137 leaching effect on litter submerged in streams. The concentration difference in both litter and prey was greater at Fukushima site than at Gunma site. The estimated prey Cs-137 concentration at Fukushima site peaked in summer when terrestrial preys are most available, whereas it remained relatively constant at Gunma site because of the small difference of Cs-137 concentrations in between terrestrial and aquatic preys. The specific metabolic rate of charr was commonly changed with stream water temperature, greatest in summer, and lowest in winter at both sites. Because both prey Cs-137 concentrations and specific metabolic rates peaked in summer, the combination of uptake and metabolism at Fukushima site largely negated seasonal Cs-137 fluctuations in charr, whereas specific metabolic rate fluctuations could be the major determinant of charr Cs-137 concentrations at Gunma site. Our results suggested that Cs-137 concentrations in prey items, whose seasonality are varied due to initial Cs-137 fallout volume, were expected to be an important determinant for Cs-137 concentrations in charr.
  • Mirza A. T. M. Tanvir Rahman, Junjiro N. Negishi, Md. Khorshed Alam, Gao Yiyang, Janine Rodulfo Tolod, Pongpet Pongsivapai
    LIMNOLOGICA 89 0075-9511 2021/07 [Refereed]
     
    The life-history traits of amphibitic insects are not well understood. These insects inhabit saturated interstitial areas below the riverbed (hyporheic zone) at the larval stage, mate in terrestrial habitats, and return to rivers for oviposition, but there is no knowledge concerning their dispersal characteristics. We sought to address this by examining how far amphibitic insects disperse away from the channel (laterally) and along upstream or downstream (longitudinally) in a gravel-bed river. Alloperla ishikariana was selected as the focal species because it numerically dominates other amphibites in an 18-km study segment of a 4th-order gravel-bed river in Hokkaido, Northern Japan. Malaise traps were set at various distances from the channel towards the riparian forest to estimate lateral dispersal distances. An elevated stable nitrogen isotope ratio in downstream larvae, caused by the influence of effluent from a wastewater treatment plant, was used to assess longitudinal dispersal by identifying and tracking adult movements. Laterally, 50th and 90th percentile dispersal distances were 11.66 and 35.09 m for female A. ishikariana and 20.59 and 59.20 m for male, respectively; this overlapped with distances previously estimated for other aquatic benthic taxa. Longitudinally, 50th and 90th percentile dispersal distances were 0.74 and 1.43 km for female and 3.11 and 7.87 km for male, respectively. Alloperla ishikariana had one of the longest upstream traveling distances compared with other aquatic insects, and the longest among Plecoptera taxa known thus far where male exhibited a greater dispersal distance. A higher number of adults demonstrated upstream movement, suggesting an upstream bias in the longitudinal dispersal of A. ishikariana. Overall, amphibitic stoneflies did not exhibit distinct dispersal characteristics compared with the results of previous reports on presumably benthic taxa. Our findings support an improved visualization of a multi-dimensionally connected river ecosystem in terms of material flow, including vertical connectivity.
  • Md Khorshed Alam, Junjiro N. Negishi, Pongpet Pongsivapai, Shohei Yamashita, Tomohiro Nakagawa
    Water (Switzerland) 13 (10) 2021/05/02 [Refereed]
     
    Despite the fact that leaf decomposition constitutes an important function in rivers, how multiple environmental stressors simultaneously affect it remains largely unknown. This study investigated the interactive effects of fine sediments (particle size: <2 mm; experimentally manipulated) and a specific nutrient (i.e., nitrate) on subsurface (hyporheic) leaf litter decomposition rate and macroinvertebrates in a gravel-bed river and its tributary in eastern Hokkaido, Japan. The experiment was conducted by measuring leaf litter decomposition of dried Alnus japonica leaves (3 ± 0.05 g) in benthic and hyporheic zones with and without sediment treatments at four sites that had a gradient of nitrate concentration. The decomposition rate was comparable between the two zones but was slowed down by sediment addition in the hyporheic zone. The functional responses were highly predictable for the individual stressors. Detritivore invertebrates were the main driving component of decomposition in the decreased leaf litter decomposition rate under a higher fine sediment condition, whereas higher nitrate accelerated the leaf litter decomposition rate by stimulated microbe-driven decomposition as well as detritivore feeding. Overall, the negative effect of fine sediment could be offset in the presence of nitrate while considering gross functional responses. We demonstrated the additive effects of fine sediment and nitrate on leaf litter decomposition in the hyporheic zone.
  • Mirza A. T. M. Tanvir Rahman, Junjiro N. Negishi, Takumi Akasaka, Futoshi Nakamura
    ECOLOGY AND EVOLUTION 11 (9) 4656 - 4669 2045-7758 2021/05 [Refereed]
     
    Hyporheic zone (HZ) locates below the riverbed providing habitat for macroinvertebrates from where the winged adult insects (i.e., hyporheic insects, HIs) emerge and bring out aquatic resources to the riparian zone. This study estimated mean daily flux as dry biomass (BM), carbon (C), and nitrogen (N) deriving from the dominant HI species Alloperla ishikariana (Plecoptera, Chloroperlidae) for a 4th-order gravel-bed river during the early-summer to summer periods. We hypothesized that HIs were an important contributor in total aquatic resources to the riparian zone. In 2017 and 2018, we set parallelly (May to August) and perpendicularly (June to October) oriented Malaise traps to catch the lateral and longitudinal directional dispersing winged adults of A. ishikariana, and other Ephemeroptera, Plecoptera, Trichoptera, and Diptera from the river and estimated the directional fluxes of them. We further split the directional fluxes as moving away or back to the channel (for lateral) and from down- to upstream or up- to downstream (for longitudinal). Alloperla ishikariana was similar to other Plecoptera species and differed clearly from Ephemeroptera and Trichoptera in directional characteristics of resources flux, suggesting that the extent and directions of HZ-derived resource transfer depend on taxon-specific flight behaviors of HIs. Contributions of A. ishikariana to the riparian zone in total aquatic C and N transfer seasonally varied and were lower in May (5%-6%) and August (2%-4%) and the highest in July (52%-70%). These conservative estimates largely increased (9% in May) after the supplementary inclusion of Diptera (Chironomidae and Tipulidae), part of which were considered HIs. We demonstrated that HZ could seasonally contribute a significant portion of aquatic resources to the riparian zone and highlighted the potential importance of HZ in nutrient balance in the river-riparian ecosystem.
  • Luz Boyero, Javier Pérez, Naiara López-Rojo, Alan M. Tonin, Francisco Correa-Araneda, Richard G. Pearson, Jaime Bosch, Ricardo J. Albariño, Sankarappan Anbalagan, Leon A. Barmuta, Leah Beesley, Francis J. Burdon, Adriano Caliman, Marcos Callisto, Ian C. Campbell, Bradley J. Cardinale, J. Jesús Casas, Ana M. Chará-Serna, Szymon Ciapała, Eric Chauvet, Checo Colón-Gaud, Aydeé Cornejo, Aaron M. Davis, Monika Degebrodt, Emerson S. Dias, María E. Díaz, Michael M. Douglas, Arturo Elosegi, Andrea C. Encalada, Elvira De Eyto, Ricardo Figueroa, Alexander S. Flecker, Tadeusz Fleituch, André Frainer, Juliana S. França, Erica A. García, Gabriela García, Pavel García, Mark O. Gessner, Paul S. Giller, Jesús E. Gómez, Sergio Gómez, Jose F. Gonçalves, Manuel A.S. Graça, Robert O. Hall, Neusa Hamada, Luiz U. Hepp, Cang Hui, Daichi Imazawa, Tomoya Iwata, Edson S.A. Junior, Samuel Kariuki, Andrea Landeira-Dabarca, María Leal, Kaisa Lehosmaa, Charles M’Erimba, Richard Marchant, Renato T. Martins, Frank O. Masese, Megan Camden, Brendan G. McKie, Adriana O. Medeiros, Jen A. Middleton, Timo Muotka, Junjiro N. Negishi, Jesús Pozo, Alonso Ramírez, Renan S. Rezende, John S. Richardson, José Rincón, Juan Rubio-Ríos, Claudia Serrano, Angela R. Shaffer, Fran Sheldon, Christopher M. Swan, Nathalie S.D. Tenkiano, Scott D. Tiegs, Janine R. Tolod, Michael Vernasky, Anne Watson, Mourine J. Yegon, Catherine M. Yule
    Science Advances 7 (13) 2021/03 [Refereed]
     
    Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.
  • Pongpet Pongsivapai, Junjiro N. Negishi, Hokuto Izumi, Paolo A. Garrido, Kanta Kuramochi
    WATER 13 (4) 2021/02 [Refereed]
     
    Sediments are potentially the internal source that supply nutrients to water in lentic to semi-lentic ecosystems. The understanding of factors that cause temporal changes in sediment properties is critical for the internal source management. This study investigated the spatial variations and temporal changes in sediment properties in relation to their controlling factors in water bodies of the Ishikari River, Northern Japan. Sediment data in 29 water bodies were measured twice (around 2005 and 2019) to study the temporal changes in sediment properties, and were compared using Generalized Linear Mixed Models (GLMMs). The controlling factors of sediment properties including catchment and morphometry were examined by partial least square (PLS) regression. Our results showed that the temporal change in sediment properties over decades was largely driven by morphometry, while land use in the catchment played a relatively minor role in those changes. The rate of change in organic matter (OM) differed among water bodies depending on their morphometry. The small and shallow water bodies provided suitable habitat for macrophytes that led to OM deposits, resulting to an increase in OM and OM to total nitrogen (TN) ratio over time. The consequences of these changes are important for internal source management and biodiversity conservation.
  • Md Khorshed Alam, Junjiro N. Negishi, Mirza A.T.M.Tanvir Rahman, Janine Rodulfo Tolod
    Ecological Indicators 118 1470-160X 2020/11 
    Bio-assessment protocols for the subsurface domain of river channels (i.e. hyporheic zone) are scarce despite of the known importance of its ecological function in river ecosystems. The larvae of the Alloperla ishikariana Plecoptera species inhabit the hyporheic zone. Therefore, we examined whether emergent adult A. ishikariana could serve as proxy indicators of the effects of pollution in the hyporheic food web. The study site comprised a 15-km stretch of a gravel bed river in Hokkaido, Japan, from which all invertebrates were collected from the riverbed at a depth of 30–50 cm, and emergent A. ishikariana adults were sampled in riparian zones. Water quality changed gradually along the river owing to the effects of a wastewater treatment plant and surrounding land uses. Nitrogen and carbon stable isotope ratios (SIRs) of epilithic biofilms, hyporheic particulate organic matter (POM), benthic POM, and invertebrates were used to determine the major basal carbon sources, the effects of water pollution on the hyporheic zone, and the trophic positions of dominant invertebrates. Generalized linear (mixed) models were used for statistical testing and modeling. Amphipoda and the larvae of A. ishikariana were considered as top predators and secondary consumers in the hyporheic food web, respectively. The observed similarity in water quality between the hyporheic and surface water suggested a large degree of hydrological exchange between the two zones, and resulted in positive increases in the nitrogen SIRs of hyporheic invertebrates, including A. ishikariana larvae, in proportion to nitrate levels in the surface water. The nitrogen SIRs of A. ishikariana adults were significantly correlated with the nitrogen SIRs of their larvae within the same location (adjusted R2 = 0.78), indicating that emerged adults can provide information on the longitudinal variability of the effects of synthetic nitrogen. In contrast, the carbon SIRs of adults did not predict those of their larvae, possibly reflecting the diverse feeding habitats of larvae. Overall, we demonstrated that adult aquatic insects emerging from the hyporheic zone can be used as indirect indicators of pollution-associated nutrient assimilation as well as the spatial heterogeneity of dietary carbon resources in hyporheic food web.
  • Futoshi Nakamura, Yasuharu Watanabe, Junjiro Negishi, Takumi Akasaka, Yuki Yabuhara, Akira Terui, Satoshi Yamanaka, Miwa Konno
    Ecological Engineering 157 0925-8574 2020/10/01 [Refereed]
     
    A braided gravel-bed river provides essential habitats for various plants and animals. However, human regulation of rivers, such as dams, channelization, and other engineering works, alter flow and sediment regimes, which generally cause the degradation of river and riparian ecosystems. One of the prominent changes prevailing in Japanese rivers is forest expansion over gravel bars, and many native plants and animals that depend on gravel-bar habitat are now endangered. The Satsunai River is typical of rivers experiencing forest expansion, so the Japanese government launched a restoration project in 2012 to partially restore its riparian ecosystems. This is a large-scale experiment developed jointly by an interdisciplinary science team and river managers, who conduct monitoring and evaluation under an adaptive management scheme. The main measure to restore gravel bed habitat was an artificial flood regime, releasing a maximum water volume of 120 m3/s, which was a 2-year return period flood before dam construction. A unique feature of the project is that we considered the role of high-magnitude floods with recurrence intervals greater than 20 years after dam construction. We hypothesize that the artificial floods can be timed seasonally to create sites for regeneration and nesting of riparian species, and the high-magnitude floods contribute to maintaining a shifting mosaic structure of floodplain forest and unvegetated gravel-bar patches. We also used critical non-dimensional shear stress analysis to define “flood-disturbance areas” that can be disturbed under the artificial flow regime created by a dam. Artificial floods have been initiated once a year since 2012 at the end of June, synchronized with the seed dispersal period of Salix arbutifolia, which is endangered and a high conservation priority in the project. Thus far, the idea of setting floodplain-disturbance areas and the strategy of using both artificial and high-magnitude floods to restore a shifting mosaic of floodplain habitat patches is appropriate, as we found successful regeneration of S. arbutifolia and an exponential decay curve of the age distribution of floodplain forest patches. However, the sediment regime regulated by the dam was not addressed in this research, so future monitoring should track changes in river morphology associated with reduced sediment supply caused by the dam.
  • Hokuto Izumi, Junjiro Negishi, Kazuki Miura, Daisetsu Ito, Pongpet Pongsivapai
    Ecology and Civil Engineering 23 (1) 1 - 20 1344-3755 2020/09/28 [Refereed]
     
    Despite of the importance of floodplain waterbodies for biodiversity and ecosystem services, human activities have degraded their quality as habitat for biological communities. Detailed understanding of life-history traits and population dynamics of organisms is crucial to the development and realization of effective management practices for the conservation of biodiversity. This study examined the distribution, reproductive traits, and host-fish utilizations of Unionoid mussels in floodplain waterbodies of the Ishikari River, northern Japan, and highlighted challenges in ecosystem management. Three target species exhibited the differences in habitat preferences, with Anemina arcaeformis Heude, 1877 being disproportionately most abundant in marsh-type waterbodies. Two species, Sinanodonta lauta Martens, 1877 and Unio douglasiae nipponensis Martens, 1877, were gravid in summer July and August while A. arcaeformis was more gravid in fall and winter October and November The low abundances of immature small individuals and the absence of parasitic attachments of mussel larvae to field-collected fish suggested the reduced levels of recent recruitments. The proliferations of invasive fish species such as Rhodeus ocellatus ocellatus, which comprised 30-70% of the total abundances of fish and were not suitable as host for the parasitic larvae of mussels, might be a possible cause of poor recruitment rates. Recognition of the diversity of waterbody types as a driver of species diversity, continued monitoring of population sizes and further elucidations of habitat quality as well as other aspects of life-history processes will contribute to improved ecosystem-based management of floodplain waterbodies in the Ishikari River.
  • Nobuo Ishiyama, Kazuki Miura, Satoshi Yamanaka, Junjiro N. Negishi, Futoshi Nakamura
    Journal of Applied Ecology 57 (3) 548 - 558 0021-8901 2020/03/01 [Refereed]
     
    Habitat fragmentation, which involves habitat size reduction and isolation, is a major cause of biodiversity decline. However, interest in small isolated habitats has increased among ecosystem managers because these fragments can serve as remnant refuges for unique and/or endangered species in human-altered landscapes. In a fragmented floodplain of northern Japan, we demonstrate how habitat fragmentation and habitat quality shape the refuges for a unique endangered minnow Rhynchocypris percnurus sachalinensis from biological invasions. We focused on two invasive minnows, topmouth gudgeon Pseudorasbora parva and rosy bitterling Rhodeus ocellatus ocellatus, which are the dominant invasive species. By using a graph theoretical approach and structural equation modelling, we elucidated the relationships among habitat fragmentation, habitat quality and the abundance of invasive minnows with the endangered swamp minnow. We found that the invasion of topmouth gudgeon, which has a high mobility and environmental tolerance, negatively affected swamp minnow populations. The invasive species may outcompete the native species in their overlapping trophic niche. Analyses indicated that habitat fragmentation (decreasing habitat size and connectivity) indirectly and positively affected the population abundance of swamp minnow by reducing the potential for invasion by topmouth gudgeon. We further found an interaction between the indirect effects of habitat fragmentation and local habitat quality: the indirect effects became more apparent in the relatively deeper habitats that were of better quality for natives. This result was likely attributed to the strong control effect of the abiotic stressor. Interspecific competition between the two minnows would be masked in shallow ponds because the native populations are primarily restricted by the abiotic factor, and its abundance is inherently limited regardless of pressure by invaders. Synthesis and applications. In fragmented landscapes, evenly conserving all small fragments within a limited budget is difficult. The change in importance of small isolated ponds across a pond-depth gradient suggests that conservation priorities for small fragments should be established by considering local habitat quality. Our findings do not justify habitat fragmentation but suggest that both landscape-scale and local-scale perspectives synergistically aid in the management of biological invasions in modified habitat networks.
  • Kousuke Ikeda, Hideyuki Doi, Shigeharu Terui, Atsuko Kato, Takashi Mitsuzuka, Tadashi Kawai, Junjiro N. Negishi
    Freshwater Science 38 (3) 629 - 641 2161-9549 2019/09/01 [Refereed]
     
    The signal crayfish, Pacifastacus leniusculus, is non-native to Japan, and its invasion may have contributed to the habitat loss of the endemic Japanese crayfish, Cambaroides japonicus. We assessed the distribution of the signal crayfish and the Japanese crayfish in small streams that flow into Lake Akan (Hokkaido, Japan), which the signal crayfish inhabits. We conducted this survey with 2 methods: analysis of environmental DNA (eDNA) and hand capture. Of the 17 streams we surveyed, we detected signal crayfish DNA in 16 streams and Japanese crayfish DNA in 9 streams. In contrast, with our hand-capture survey of the same 17 streams, we found signal crayfish in 9 streams and Japanese crayfish in 4 streams. These results suggest that the signal crayfish may have invaded almost all the small streams with culverts around Lake Akan. The presence of signal crayfish was also confirmed on the upstream side of a 69-cm-high road-crossing culvert. There were only 2 culverts above which the absence of signal crayfish was supported by eDNA analysis, suggesting that culverts have limited effectiveness against signal crayfish invasion in our study site. Active species-specific removal projects may be an effective management option to minimize the negative impacts of signal crayfish where they are already present. eDNA has great potential as a cost-effective tool to monitor crayfish range expansion.
  • Kazuki Miura, Nobuo Ishiyama, Keita Kawajiri, Keisuke Atsumi, Michikusa Tachibana, Yu Nagasaka, Yoshiyasu Machida, Gao Yiyang, Junjiro N. Negishi, Itsuro Koizumi, Futoshi Nakamura
    Ecological Research 34 (5) 667 - 677 0912-3814 2019/09/01 [Refereed]
     
    Species identification is a fundamental process for ecological studies and conservation practices, and simple nonlethal identification criteria are important for endangered species. This study developed species identification criteria for two endangered freshwater pearl mussels (Margaritifera laevis and Margaritifera togakushiensis) based on linear discriminant functions (LDFs) that were established considering intraspecific regional morphological differences from sites at Hokkaido, northern Japan. We collected a total of 1,110 mussels from 52 rivers across 32 watersheds in two geographical regions (east and west). Shell morphologies (length, height, and width) of the collected mussels were measured, followed by species identification with gel electrophoresis banding patterns of 16S rRNA polymerase chain reaction products. LDFs were constructed for two size classes (≥40 mm and < 40 mm) using forward stepwise procedures to determine key morphological differences between the two species and consideration of whether regional morphological differences improved identification accuracies. The LDFs revealed that the morphologies of the two species were clearly distinguished by the relationship between height and length for both size classes. Region-specific LDFs produced better identification accuracies. Regardless of region, the maximum length of M. laevis exceeded 100 mm, whereas all M. togakushiensis were < 100 mm in length. Identification accuracies of the established LDFs were high for each of the five length classes (0–20 mm, 20–40 mm, 40–60 mm, 60–80 mm, and 80–100 mm) with 85–96% (mean: 92%) accuracy in the east and 67–96% (mean: 80%) in the west. These criteria for species identification will progress future ecological studies and conservation practices for freshwater mussels.
  • Junjiro N. Negishi, Aiko Hibino, Kazuki Miura, Ryota Kawanishi, Nozomi Watanabe, Kazuhiro Toyoda
    FRESHWATER SCIENCE 38 (3) 591 - 604 2161-9549 2019/09 [Refereed]
     
    Interactions between the hyporheic and benthic zones play a vital role in maintaining the integrity of river ecosystems, but simultaneous assessments of hyporheic and benthic macroinvertebrate responses to surface water pollution are limited. We examined how hyporheic (50 cm below surface) and benthic (surface) invertebrates responded to water pollution that originated from a point source (wastewater treatment plant) in a gravel-bed river in Hokkaido, Japan. Dissolved nutrient levels and algal biomass were significantly higher at sample sites down- than upstream of the point source. Furthermore, nitrate concentrations increased gradually from up- to downstream sites, which suggest the presence of diffuse pollution sources in the surrounding areas. Closely synchronized fluctuations of water temperature and similar water quality in the surface and hyporheic zones indicated that the hyporheic zone was highly hydrologically interactive with the surface water. Chloroperlidae (mostly Alloperla ishikariana) had a disproportionately high abundance in the hyporheic zone relative to the benthic zone, regardless of the surface water quality. Numerically dominant invertebrate taxa increased in abundance below the point source of pollution in both the benthic and hyporheic habitats. High N stable isotope ratios (SIR) of the invertebrates in both habitat types indicated that invertebrates assimilated anthropogenic N via the ingestion of pollution-contaminated food resources. End-member mixing analyses based on C SIR demonstrated that assimilation of anthropogenic N occurred because of the increase in available food resources originating from the biofilm. The trophic structure of invertebrates changed less markedly in the hyporheic zone than in the benthic zone, suggesting that the hyporheic assemblage was less sensitive than the benthic assemblage to the changes in surface water quality. Overall, our findings showed that the numeric responses of the invertebrate assemblage to anthropogenic changes in surface water quality were similar and coupled between the benthic and hyporheic zones.
  • Junjiro N. Negishi, Akira Terui, Badrun Nessa, Kazuki Miura, Takeaki Oiso, Keizo Sumitomo, Tomoko Kyuka, Mitsuaki Yonemoto, Futoshi Nakamura
    LANDSCAPE AND ECOLOGICAL ENGINEERING 15 (2) 143 - 154 1860-1871 2019/04 [Refereed]
     
    Our understanding of ecosystem responses to exceedingly large rare flood events is currently limited. We report the resilience of aquatic community to a 100-year record-high flood, and how it varies depending on levels of water pollution, in a fourth-order gravel-bed river in northern Japan. We used data on riparian landscape structure, channel morphology, and community structure of aquatic fauna, which were collected in sites with and without effluent before (1 month-3 years) and after (10 months) the flood. Carbon and nitrogen stable isotope ratios of consumers and basal resources were measured only before (1 year) the flood. We observed aquatic food web with introduced rainbow trout (Oncorhynchus mykiss) as the top predator, with variable relative contributions of basal resources and their pathways to the rainbow trout, under the effects of water pollution. Biofilm-originating dietary carbon became the more dominant resource, with a slightly shorter food-chain length in the polluted sites. The flood led to a loss of riparian forest and a substantial increase in the proportion of exposed gravel bars (5-24%). While the average river-bed elevation changed a little, the localized scours of river bed down to > 2 m were observed with lateral shifts of channel thalweg. Despite the landscape-level physical and structural changes of ecosystem, aquatic community showed a remarkably high resilience exhibiting negligible changes in abundance, except in the polluted site where only fish abundance showed a slight decrease. This study suggests that the abundance of aquatic organisms in gravel-bed rivers is resilient to a flood of unprecedented magnitude in recent history.
  • Junko Morimoto, Junjiro Negishi
    Landscape and Ecological Engineering 15 (2) 131 - 132 1860-1871 2019/04 [Refereed][Not invited]
  • Noé Ferreira-Rodríguez, Yoshihiro B. Akiyama, Olga V. Aksenova, Rafael Araujo, M. Christopher Barnhart, Yulia V. Bespalaya, Arthur E. Bogan, Ivan N. Bolotov, Prem B. Budha, Cristhian Clavijo, Susan J. Clearwater, Gustavo Darrigran, Van Tu Do, Karel Douda, Elsa Froufe, Clemens Gumpinger, Lennart Henrikson, Chris L. Humphrey, Nathan A. Johnson, Olga Klishko, Michael W. Klunzinger, Satit Kovitvadhi, Uthaiwan Kovitvadhi, Jasna Lajtner, Manuel Lopes-Lima, Evelyn A. Moorkens, Shigeya Nagayama, Karl-Otto Nagel, Mitsunori Nakano, Junjiro N. Negishi, Paz Ondina, Panu Oulasvirta, Vincent Prié, Nicoletta Riccardi, Mudīte Rudzīte, Fran Sheldon, Ronaldo Sousa, David L. Strayer, Motoi Takeuchi, Jouni Taskinen, Amilcar Teixeira, Jeremy S. Tiemann, Maria Urbańska, Simone Varandas, Maxim V. Vinarski, Barry J. Wicklow, Tadeusz Zając, Caryn C. Vaughn
    Biological Conservation 231 77 - 87 0006-3207 2019/03 [Refereed]
  • 北海道における希少淡水二枚貝カワシンジュガイ属2 種（Margaritifera laevis, Margaritifera togakushiensis）の河川区間での生息の重複
    三浦 一輝, 石山 信雄, 川尻 啓太, 渥美 圭佑, 長坂 有, 折戸 聖, 町田 善康, 臼井 平, Gao Yiyang, 能瀬 晴菜, 根岸 淳二郎, 中村 太士
    保全生態学研究 24 (1) 39 - 48 2019/02 [Refereed]
  • Scott D. Tiegs, David M. Costello, Mark W. Isken, Guy Woodward, Peter B. McIntyre, Mark O. Gessner, Eric Chauvet, Natalie A. Griffiths, Alex S. Flecker, Vicenc Acuna, Ricardo Albarino, Daniel C. Allen, Cecilia Alonso, Patricio Andino, Clay Arango, Jukka Aroviita, Marcus V. M. Barbosa, Leon A. Barmuta, Colden V. Baxter, Thomas D. C. Bell, Brent Bellinger, Luz Boyero, Lee E. Brown, Andreas Bruder, Denise A. Bruesewitz, Francis J. Burdon, Marcos Callisto, Cristina Canhoto, Krista A. Capps, Maria M. Castillo, Joanne Clapcott, Fanny Colas, Checo Colon-Gaud, Julien Cornut, Veronica Crespo-Perez, Wyatt F. Cross, Joseph M. Culp, Michael Danger, Olivier Dangles, Elvira de Eyto, Alison M. Derry, Veronica Diaz Villanueva, Michael M. Douglas, Arturo Elosegi, Andrea C. Encalada, Sally Entrekin, Rodrigo Espinosa, Diana Ethaiya, Veronica Ferreira, Carmen Ferriol, Kyla M. Flanagan, Tadeusz Fleituch, Jennifer J. Follstad Shah, Andre Frainer, Nikolai Friberg, Paul C. Frost, Erica A. Garcia, Liliana Garcia Lago, Pavel Ernesto Garcia Soto, Sudeep Ghate, Darren P. Giling, Alan Gilmer, Jose Francisco Goncalves, Rosario Karina Gonzales, Manuel A. S. Graca, Mike Grace, Hans-Peter Grossart, Francois Guerold, Vlad Gulis, Luiz U. Hepp, Scott Higgins, Takuo Hishi, Joseph Huddart, John Hudson, Samantha Imberger, Carlos Iniguez-Armijos, Tomoya Iwata, David J. Janetski, Eleanor Jennings, Andrea E. Kirkwood, Aaron A. Koning, Sarian Kosten, Kevin A. Kuehn, Hjalmar Laudon, Peter R. Leavitt, Aurea L. Lemes da Silva, Shawn J. Leroux, Carri J. Leroy, Peter J. Lisi, Richard MacKenzie, Amy M. Marcarelli, Frank O. Masese, Brendan G. Mckie, Adriana Oliveira Medeiros, Kristian Meissner, Marko Milisa, Shailendra Mishra, Yo Miyake, Ashley Moerke, Shorok Mombrikotb, Rob Mooney, Tim Moulton, Timo Muotka, Junjiro N. Negishi, Vinicius Neres-Lima, Mika L. Nieminen, Jorge Nimptsch, Jakub Ondruch, Riku Paavola, Isabel Pardo, Christopher J. Patrick, Edwin T. H. M. Peeters, Jesus Pozo, Catherine Pringle, Aaron Prussian, Estefania Quenta, Antonio Quesada, Brian Reid, John S. Richardson, Anna Rigosi, Jose Rincon, Geta Risnoveanu, Christopher T. Robinson, Lorena Rodriguez-Gallego, Todd V. Royer, James A. Rusak, Anna C. Santamans, Geza B. Selmeczy, Gelas Simiyu, Agnija Skuja, Jerzy Smykla, Kandikere R. Sridhar, Ryan Sponseller, Aaron Stoler, Christopher M. Swan, David Szlag, Franco Teixeira-de Mello, Jonathan D. Tonkin, Sari Uusheimo, Allison M. Veach, Sirje Vilbaste, Lena B. M. Vought, Chiao-Ping Wang, Jackson R. Webster, Paul B. Wilson, Stefan Woelfl, Marguerite A. Xenopoulos, Adam G. Yates, Chihiro Yoshimura, Catherine M. Yule, Yixin X. Zhang, Jacob A. Zwart
    SCIENCE ADVANCES 5 (1) eaav0486  2375-2548 2019/01 [Refereed]
     
    River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
  • Junjiro N. Negishi, Kazuki Miura, Hokuto Izumi, Yutaka Negishi
    Limnology 19 (3) 343 - 354 1439-8621 2018/08 [Refereed]
  • 岩井尚人, 山中康裕, 根岸淳二郎, 山田朋人
    水利科学 364 (5) 59 - 80 0039-4858 2018/08 [Refereed][Not invited]
     
    地下水の持続可能な利用は，その保全にとって必要である。地下水を保全す る態度を育むために，小学校教育の中で地下水について学ぶ機会を作ることは，重要なことである。本研究では，小学校高学年生が地下水涵養に関する森 林の機能などの地下水に関する基本的知識を学べる教材を，タンクモデルを参 考にして開発した。教材は，3 段タンクで構成され，森林領域の下にある帯水 層に設置したスポンジが水を貯留し，その水は装置外へゆっくりと流出するよ うになっている。教材で表現したのは，森林は主要な地下水の涵養域であるこ と，地下水は地表水に比べて滞留時間が長いことの 2 つである。教材を用いた 散水実験では，3 段のタンクそれぞれからの流出ピークのタイムラグや滞留時 間の違いなど，上記 2 点を定量的に確認した。小学校等の教員13名を対象に実 施した教材の実演と，彼らに対する聞き取り調査では，多くの教員は，小学校 児童にとって，上記 2 点が分かりやすいと判断した。
  • Beverley C. Wemple, Trevor Browning, Alan D. Ziegler, Jorge Celi, Kwok Pan Sun Chun, Fernando Jaramillo, Nei K. Leite, Sorain J. Ramchunder, Junjiro N. Negishi, Ximena Palomeque, Derek Sawyer
    Ecohydrology 11 (3) 1936-0592 2018/04/01 [Refereed][Not invited]
     
    Roads are a pervasive form of disturbance with potential to negatively affect ecohydrological processes. Some of the most rapid growth in road networks is occurring in developing countries, particularly in the tropics, where political agendas are often focused on strengthening the economy, improving infrastructure, bolstering national security, achieving self-sufficiency, and increasing citizen well-being, often at the expense of the environment. We review what is known about road impacts on ecohydrological processes, focusing on aquatic systems, both temperate and tropical. We present seven cases that represent the broader trends of road development and impacts in tropical settings. Many of these process dynamics and impacts are not different from those experienced in temperate settings, although the magnitude of impacts in the tropics may be amplified with intense rainfall and lack of best management practices applied to road construction/maintenance. Impacts of roads in tropical settings may also be unique because of particular organisms or ecosystems affected. We outline a set of best practices to improve road network management and provide recommendations for adopting an agenda of research and road management in tropical settings. Importantly, we call for incorporation of transdisciplinary approaches to further study the effects of roads on ecohydrological processes in the tropics. Specific emphasis should also be placed on collaboration with governments and developers that are championing road development to help identify the drivers of road expansion and thresholds of negative impact, as well as methods of sustainable road construction and maintenance.
  • M. E. Haque, T. Gomi, M. Sakai, J. N. Negishi
    Landscape and Ecological Engineering 14 (1) 45 - 53 1860-1871 2018/01 [Refereed]
  • Kazuki Miura, Hokuto Izumi, Yuya Saito, Kaito Asato, Junjiro N. Negishi, Kazuo Ito, Akio Oomori
    Landscape and Ecological Engineering 14 (1) 157 - 164 1860-1871 2018/01 [Refereed]
  • Shoji Noguchi, Junjiro N. Negishi, Zulkifli Yusop, Yoshiko Kosugi, Siti Aisah Shamsuddin, Makoto Tani
    JARQ-JAPAN AGRICULTURAL RESEARCH QUARTERLY 52 (1) 63 - 75 0021-3551 2018 [Refereed]
     
    Knowledge of throughfall at abandoned skid trails in tropical forests is extremely scarce. Thus, throughfall was measured using 120 storage rain gauges set on a skid trail left abandoned 41 years after forest harvesting in the Bukit Tarek Experimental Watershed (BTEW) in Peninsular Malaysia. All trees of >= 1 m height in the plot were identified to the species level, and their diameter at breast height (DBH) and height were measured. Vegetation along the skid trail comprises trees with smaller DBH (0.2-31.0 cm, with a mean of 2.0 cm) and shorter height (1.0-20.0 m, with a mean of 2.8 m) than those in the regenerated secondary forests of BTEW. The diversity (i.e. 43 families, 131 species) at the skid trail was similar to that in an old tropical forest at BTEW. The ratio of throughfall to gross rainfall (Th/Rg) for 84 rain events ranged from 27.4% to 204.7% with a mean and standard deviation of 98.1% and 33.2%, respectively. We found that a considerable amount of rainwater dropped under bertam (i.e. Eugeissona tristis) and rattan (i.e. Daemonorops callicarpa, Calamus insignis) vegetation. The Th/Rg ratio weakly correlated with canopy openness. The mean Th/Rg ratio is the largest mean ratio ever reported for forests in Malaysia.
  • J. N. Negishi, M. Sakai, K. Okada, A. Iwamoto, T. Gomi, K. Miura, M. Nunokawa, M. Ohhira
    Landscape and Ecological Engineering 14 (1) 55 - 66 1860-188X 2018/01/01 [Refereed][Not invited]
     
    We examined the cesium-137 (137Cs) contamination of river food webs in a gradient of initial fallout deposition (net density estimates 2.5–3.5 months after the Fukushima Daiichi Nuclear Power Plant accident in March 2011), in Fukushima Prefecture, Japan. Litter, aquatic insects, and salmonid fish were collected in five headwater stream reaches (watershed-average fallout density, 368.1–1398.4 kBq/m2) for the measurement of 137Cs concentration and stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in June 2014. The stable isotope ratios suggested that the detrital food chain was a dominant energy pathway in rivers originating from a basal resource (litter) to primary (aquatic insects) and secondary (fish) consumers. The 137Cs concentration decreased with an increase in the trophic level, with the highest value for litter (10930 ± 5381 Bq/kg, mean ± SD), the lowest for fish (2825 ± 2451 Bq/kg), and the intermediate one for dominant (numerically and biomass-wise) detritivorous insect, Ephemera japonica McLachlan (4605 ± 1970 Bq/kg). 137Cs concentrations of three trophic levels were linearly predicted by the initial fallout amount of 137Cs. The evacuation of the gut contents of E. japonica during field experiments led to a reduction in their 137Cs concentration by approximately 50% within 1–2 day(s) without loss of body weight. This suggested that a substantial portion of 137Cs contamination of E. japonica was derived from highly contaminated fine solids deposited in depositional habitats at a disproportionately high density. Overall, the initial fallout amount of 137Cs was helpful in roughly predicting the contamination levels of headwater river-riparian ecosystems with the detrital food chain as a dominant energy pathway. Long-term monitoring of the dynamics and fates of 137Cs associated with fine organic and inorganic particulates appears important for better prediction of 137Cs contamination of food webs in forested headwater streams.
  • Terui, A, Negishi, J. N, Watanabe, N, Nakamura, F
    Ecosystems 21 (4) 772 - 781 1432-9840 2017/09 [Refereed][Not invited]
     
    Decades of research have revealed the crucial roles of cross-system energy flows (spatial subsidies) in mediating trophic interactions in recipient systems. Food web theory predicts that the responses of subsidized consumers are a key to understanding the net impacts of spatial subsidies on in situ prey/resources of recipient systems. However, less is known about the factors triggering the cascading biotic interactions across coupled ecosystems. Here, we quantify how riverine productivity (donor system) mediates terrestrial food web interactions through spatial subsidies to simplified gravel bar communities. Our comparative study in Japan indicated that higher algal biomass in aquatic systems led to increased supplies of emerging aquatic insects, which were associated with greater densities of terrestrial consumers (Carabid beetles) and enhanced consumption rates of supplemental in situ prey on gravel bars. Our results highlight the potential of donor productivity to drive cascading biotic interactions across coupled ecosystems. Because cross-system energy flows should originate, at least in part, from primary producers of donor systems, our fundamental finding may form the basis of future studies exploring the driving factors of cross-system trophic interactions.
  • Md Enamul Haque, Takashi Gomi, Masaru Sakai, Junjiro N Negishi
    Journal of environmental radioactivity 172 191 - 200 2017/06 [Refereed]
     
    We developed a food web-based transfer factor (TFweb) to study contaminant movements from multiple prey items to a predator based on the dietary contributions of prey items with their respective contamination levels. TFweb was used to evaluate the transfer of 137Cs into whitespotted char (Salvelinus leucomaenis) from the trophic structure of a stream-riparian ecosystem in headwater streams draining a Japanese cedar forest. We also examined the applicability of this method by comparing sites with different contamination levels but similar surrounding environments in Fukushima and Gunma. All samples were collected from August 2012 to May 2013. The dietary contributions from both aquatic and terrestrial prey items to whitespotted char were analyzed using stable carbon and nitrogen isotope ratios. 137Cs activity concentrations in char ranged from 704 to 6082 Bq kg-1-dry in Fukushima and from 193 to 618 Bq kg-1-dry in Gunma. Dominant prey taxa such as mayflies (Ephemera japonica), spider crickets (Rhaphidosphoridae gen. spp.), and freshwater crabs (Geothelphusa dehaani), each of them accounted for 3-12% of the fish diet, based on lower and upper estimates, respectively. TFweb ranged from 1.12 to 3.79 in Fukushima and from 1.30 to 4.30 in Gunma, which suggested bioaccumulation from prey items to predator. Widely used ecological parameters TFs by media-char and TTF by single prey-char showed high variability with both dilution and accumulation. TFweb is applicable for 137Cs transfer in predator-prey systems with complex food web structures of stream-riparian ecosystems.
  • Kazuki Miura, Nozomi Watanabe, Junjiro N. Negishi
    Limnology Springer Japan 18 (1) 9 - 16 1439-8621 2017/01 [Refereed]
  • Akira Terui, Takumi Akasaka, Junjiro N. Negishi, Fumihiko Uemura, Futoshi Nakamura
    ECOLOGICAL RESEARCH 32 (1) 27 - 35 0912-3814 2017/01 [Refereed]
     
    A variety of organisms mediate river-terrestrial linkages through spatial subsidies. However, most empirical studies have classified organisms rather broadly (e.g., by functional group or taxonomic family) and have dismissed species-level linkages at the interface of ecosystems. Here, we show how allochthonous resource use varies among taxonomically similar species of ground beetles (family Carabidae) across seasons (June-September). We investigated seasonal shifts in the distribution of five beetle species and their dietary responses to spatial subsidies (emerging aquatic insects) in a Japanese braided river. Despite their taxonomic closeness, the ground beetles showed species-specific responses to spatial subsidies, and beetle distribution patterns tended to coincide with their diets. Overall, 1-56% of ground beetle diets were derived from aquatic prey. One genus (Bembidion spp.) mainly consumed aquatic prey, while three species fed primarily on terrestrial prey across all seasons. However, one species (Lithochlaenius noguchii) showed shifts in its diet from aquatic to terrestrial prey according to subsidy availability. The observed variation in allochthonous resource use was likely related to species-specific foraging modes, physiological tolerance to dry conditions, and interspecific competition. Our findings suggest that considering species-specific interactions is necessary to fully understand cross-system interactions and recipient food-web dynamics.
  • Masaru Sakai, Takashi Gomi, Junjiro N. Negishi
    JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 164 169 - 173 0265-931X 2016/11 [Refereed]
     
    It is important to understand the changes in the Cs-137 concentration in litter through leaching when considering that Cs-137 is transferred from basal food resources to animals in forested streams. We found that the difference of Cs-137 activity concentration in litter between forest and stream was associated with both litter type and Cs-137 fallout volume around Fukushima, Japan. The Cs-137 activity concentrations in the litter of evergreen conifers tended to be greater than those in the litter of broad-leaved deciduous trees because of the absence of deciduous leaves during the fallout period in March 2011. Moreover, Cs-137 activity concentrations in forest litter were greater with respect to the Cs-137 fallout volume. The Cs-137 activity concentrations in stream litter were much lower than those in forest litter when those in forest litter were higher. The Cs-137 leaching patterns indicated that the differences in Cs-137 activity concentration between forest and stream litter could change with changes in both fallout volume and litter type. Because litter is an important basal food resource in the food webs of both forests and streams, the Cs-137 concentration gradient reflects to possible Cs-137 transfer from lower to higher trophic animals. Our findings will improve our understanding of the spatial heterogeneity and variability of Cs-137 concentrations in animals resident to the contaminated landscape. (C) 2016 Elsevier Ltd. All rights reserved.
  • Kousuke Ikeda, Hideyuki Doi, Kazunori Tanaka, Tadashi Kawai, Junjiro N. Negishi
    Conservation Genetics Resources 8 (3) 231 - 234 1877-7252 2016/09 [Refereed]
  • Masaru Sakai, Takashi Gomi, Junjiro N. Negishi, Aimu Iwamoto, Kengo Okada
    ENVIRONMENTAL POLLUTION 209 46 - 52 0269-7491 2016/02 [Refereed]
     
    Understanding the mechanisms of Cs-137 movement across different ecosystems is crucial for projecting the environmental impact and management of nuclear contamination events. Here, we report differential movement of Cs-137 in adjacent forest and stream ecosystems. The food webs of the forest and stream ecosystems in our study were similar, in that they were both dominated by detrital -based food webs and the basal energy source was terrestrial litter. However, the concentration of Cs-137 in stream litter was significantly lower than in forest litter, the result of Cs-137 leaching from litter in stream water. The difference in Cs-137 concentrations between the two types of litter was reflected in the Cs-137 concentrations in the animal community. While the importance of Cs-137 fallout and the associated transfer to food webs has been well studied, research has been primarily limited to cases in a single ecosystem. Our results indicate that there are differences in the flow of Cs-137 through terrestrial and aquatic ecosystems, and that Cs-137 concentrations are reduced in both basal food resources and higher trophic animals in aquatic systems, where primary production is subsidized by a neighboring terrestrial ecosystem. (C) 2015 Elsevier Ltd. All rights reserved.
  • Masaru Sakai, Takashi Gomi, Risa S Naito, Junjiro N Negishi, Michiko Sasaki, Hiroto Toda, Masanori Nunokawa, Kaori Murase
    Journal of environmental radioactivity 144 15 - 20 0265-931X 2015/06 [Refereed]
     
    In Japanese forests suffering from the Fukushima Daiichi Nuclear Power Plant accident, litter fall provides a large amount of radiocesium from forests to streams. Submerged litter is processed to become a vital food resource for various stream organisms through initial leaching and subsequent decomposition. Although leaching from litter can detach radiocesium similarly to potassium, radiocesium leaching and its migration are poorly understood. We examined both radiocesium and potassium leaching to the water column and radiocesium allocation to minerals (glass beads, silica sand, and vermiculite) in the laboratory using soaked litter with and without minerals on a water column. The mineral types did not affect radiocesium leaching from litter, but soaking in water for 1, 7, and 30 days decreased the radiocesium concentration in litter by ×0.71, ×0.66, and ×0.56, respectively. Meanwhile, the 1-, 7-, and 30-day experiments decreased potassium concentration in litter by ×0.17, ×0.11, and ×0.09, respectively. Leached radiocesium remained in a dissolved form when there was no mineral phases present in the water, whereas there was sorption onto the minerals when they were present. In particular, vermiculite adsorbed radiocesium by two to three orders of magnitude more effectively than the other minerals. Because radiocesium forms (such as that dissolved or adsorbed to organic matter or minerals) can further mobilize to ecosystems, our findings will increase our understanding regarding the dynamics of radiocesium in stream ecosystems.
  • J. N. Negishi, H. Tamaoki, N. Watanabe, S. Nagayama, M. Kume, Y. Kayaba, M. Kawase
    Limnology Springer 15 (3) 237 - 247 1439-8621 2014/08 [Refereed]
     
    Identification of landscape structures that predict the distribution of aquatic organisms has the potential to provide a practical management tool for species conservation in agricultural drainage channels. We tested the hypothesis that sites with imperiled freshwater mussels have distinct rural landscape structures and are characterized by the presence of diverse fish communities. In central Japan, the proportion of developed land use in surrounding areas was compared among sites with mussel populations (mussel sites) and randomly chosen sites (random sites) across multiple spatial scales (with a radius ranging from 100 to 3,000 m). Mussel sites were characterized by a much lower proportion of developed land (mean 5-18 %) compared with random sites (mean 32-35 %) at a scale of a parts per thousand currency sign300 m. The areas that met the landscape criteria for mussel sites across multiple scales constituted only 0.23 % of the area that was presumed to have suitable slope and elevation as a mussel habitat. Landscape metrics derived from mussel sites to locate unknown populations had a low predictability (16.7 %). Sites with mussels were located close to each other and had fish communities with higher taxonomic diversity than in sites without mussels. In addition, mussel taxonomic richness was a good predictor of fish community diversity. The quantitative measures of landscape structure may serve as a useful tool when prioritizing or identifying areas for conservation of mussels and fish if spatially autocorrelated distribution of habitat and other critical environmental factors such as habitat connectivity are also considered.
  • Nisikawa Usio, Junjiro N. Negishi
    LIMNOLOGY 15 (3) 199 - 200 1439-8621 2014/08 [Refereed]
  • Futoshi Nakamura, Nobuo Ishiyama, Masanao Sueyoshi, Junjiro N. Negishi, Takumi Akasaka
    Restoration Ecology 22 (4) 544 - 554 1061-2971 2014/07 [Refereed]
     
    The meanders and floodplains of the Kushiro River were restored in March 2011. A 1.6-km stretch of the straightened main channel was remeandered by reconnecting the cutoff former channel and backfilling the straightened reach, and a 2.4-km meander channel was restored. Additionally, flood levees were removed to promote river-floodplain interactions. There were four objectives of this restoration project: to restore the in-stream habitat for native fish and invertebrates; to restore floodplain vegetation by increasing flooding frequency and raising the groundwater table; to reduce sediment and nutrient loads in the core wetland areas; to restore a river-floodplain landscape typical to naturally meandering rivers. In this project, not only the natural landscape of a meandering river but also its function was successfully restored. The monitoring results indicated that these goals were likely achieved in the short term after the restoration. The abundance and species richness of fish and invertebrate species increased, most likely because the lentic species that formerly inhabited the cutoff channel remained in the backwater and deep pools created in the restored reach. In addition, lotic species immigrated from neighboring reaches. The removal of flood levees and backfilling of the formerly straightened reach were very effective in increasing the frequency of flooding over the floodplains and raising the water table. The wetland vegetation recovered rapidly 1 year after the completion of the meander restoration. Sediment-laden floodwater spread over the floodplain, and approximately 80-90% of the fine sediment carried by the water was filtered out by the wetland vegetation. © 2014 Society for Ecological Restoration.
  • Junjiro N. Negishi, Kotaro Katsuki, Manabu Kume, Shigeya Nagayama, Yuichi Kayaba
    Freshwater Biology 59 (5) 1026 - 1038 0046-5070 2014/05 [Refereed]
  • Junjiro N. Negishi, Masashi Soga, Nobuo Ishiyama, Noriyasu Suzuki, Teruaki Yuta, Masanao Sueyoshi, Chitose Yamazaki, Itsuro Koizumi, Shigeru Mizugaki, Kazufumi Hayashida, Masanori Nunokawa, Nobuhiko Yoshimura
    Freshwater Biology 59 (5) 942 - 954 0046-5070 2014/05 [Refereed]
     
    Degradation of floodplains continues with an increasing number of floodplain lakes disconnected from the fluvial dynamics of rivers. Limited understanding is available as to how historical geomorphic formation processes (i.e. geomorphic legacy) determine contemporary ecosystem structure and function. We tested the hypothesis that geomorphic legacy mediates morphometry and results in heterogeneity of macrophyte distributions in disconnected floodplain lakes.The distribution of macrophyte cover was examined in relation to environmental factors, including water nutrient level, morphometry of lakes and patch shelter level across and among three types of lakes along the Ishikari River, Japan. Artificial lakes (isolated by channelisation), natural oxbow lakes and marsh lakes have been disconnected for more than 40years from natural flood pulses because of dyke construction.The presence of macrophytes (in 5x5m areas) was predicted well by a combination of local water depth and bed slope. Lake average depth, higher values indicating lakes that are more deeply incised with a steeper-sloped littoral zone, had the strongest and most negative influence on total macrophyte cover across lakes. Cover was least in artificial lakes because of greater average depth.Predicted area of macrophyte cover was significantly less than occupied by actual cover in artificial lakes compared with other lake types. Macrophyte cover in artificial lakes was particularly vulnerable to external factors such as waves and wind.This study underscored the significance of geomorphic legacy in explaining a large proportion of heterogeneity of total macrophyte cover in the study lakes. Artificial lakes did not have the macrophyte habitat quality of natural lakes. When lake morphometry needs to be altered, local conditions as well as patch-scale properties should be carefully examined in the light of the geomorphic legacy left by dynamic river-floodplain interactions.
  • Manabu Kume, Junjiro N. Negishi, Shiro Sagawa, Tetsuya Miyashita, Shigeyuki Aoki, Tetsuji Ohmori, Seiji Sanada, Yuichi Kayaba
    Limnology Springer Japan 15 (2) 109 - 115 1439-8621 2014/04 [Refereed]
  • Shigeya NAGAYAMA, Morihiro HARADA, Yuichi KAYABA, Junjiro N. NEGISHI
    Ecology and Civil Engineering 17 (1) 29 - 40 1344-3755 2014 [Refereed]
  • Masashi Soga, Nobuo Ishiyama, Masanao Sueyoshi, Yuichi Yamaura, Kazufumi Hayashida, Itsuro Koizumi, Junjiro N. Negishi
    LANDSCAPE AND ECOLOGICAL ENGINEERING 10 (1) 55 - 64 1860-1871 2014/01 [Refereed]
     
    Although both patch area and shape are key factors driving biodiversity in fragmented terrestrial landscapes, researchers have had limited and mixed success in documenting the effects of these two factors on aquatic ecosystems. Here we examined the effects of lake area and shape on macrophyte species richness in a lowland floodplain by considering the differences in lake types (i.e. marsh, oxbow, man-made lakes). We surveyed species richness of native macrophytes in 35 lakes including 11 marshes, 11 oxbows and 13 man-made lakes with various complex shapes covering from 0.25 to 46.3 ha. Model selection clearly supported the existence of interaction between area and shape effects: large-circular and small-complex lakes supported a higher macrophyte species richness, while it was lower in large-complex and small-circular lakes. Among the three lake types, marsh lakes were more circular and man-made lakes had more complex shapes, while oxbow lakes were intermediate between these two. Also, marsh lakes had positive species-area relationships, while man-made lakes had negative relationships. Our results suggest the opposing shape complexity and species-area relationships of these two contrasting lake types are the result of the interactions between lake area and shape. These results indicate that different lake types result in variations in their conservation value for preserving macrophyte diversity. We suggest that small complex-shaped patches (especially oxbow lakes), which are often given the lowest conservation priority in terrestrial ecosystems, cannot be disregarded when conserving macrophyte biodiversity in aquatic ecosystems.
  • Hideyuki Doi, Izumi Katano, Junjiro N. Negishi, Seiji Sanada, Yuichi Kayaba
    Ecosphere 4 (8) art102 - art102 2150-8925 2013/08 [Refereed]
     
    Anthropogenic impacts on biodiversity and habitat conditions can lead to loss of ecosystem services. Cultural services of ecosystems are one of the major categories of ecosystem services, but the relationships between ecosystem conditions and human uses of their cultural services are still largely unknown. To estimate the effects of biodiversity, habitat structure, and environmental pollution on recreational uses of ecosystems, existing data sets for 109 rivers across Japan were used to analyze the relationships among recreational uses of these rivers (fishing, playing in the river, walking, and engaging in sports near the river) and their biodiversity, habitat structure, and water quality. Fish diversity, habitat structure, and water quality had significant effects on the number of people fishing and playing in the rivers. The number of people walking and engaging in sports, which typically takes place on floodplains and dikes, was significantly positively related to the size of the surrounding population rather than to biodiversity or habitat structure. However, water quality had significant effects on such uses of river ecosystems, even though these activities did not involve direct contact with river water. Overall, a decline in biodiversity and ecosystem health was related to a decrease in recreational use.
  • Sohei Kobayashi, Takashi Gomi, Roy C. Sidle, Junjiro N. Negishi
    Ecohydrology 6 (1) 117 - 124 1936-0584 2013/02 [Refereed]
  • J.N. Negishi, S. Nagayama, M. Kume, S. Sagawa, Y. Kayaba, Y. Yamanaka
    Ecological Indicators Elsevier 24 127 - 137 1470-160X 2013/01 [Refereed]
     
    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 km2). 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.
  • JUNJIRO N. NEGISHI, SHIRO SAGAWA, YUICHI KAYABA, SEIJI SANADA, MANABU KUME, TETSUYA MIYASHITA
    Freshwater Biology 57 (7) 1500 - 1511 0046-5070 2012/07 [Refereed]
  • J. N. Negishi, S. Sagawa, S. Sanada, M. Kume, T. Ohmori, T. Miyashita, Y. Kayaba
    River Research and Applications 28 (2) 258 - 267 1535-1459 2012/02 [Refereed]
  • Junjiro N. NEGISHI
    Ecology and Civil Engineering 応用生態工学会 15 (2) 235 - 242 1344-3755 2012 [Refereed]
  • Feeding damage by exotic species, nutria (Myocastor coypus), to unionid mussels in a floodplain water-body of the Kiso River, Japan
    Kume Manabu, Onoda Yukio, Negishi N Junjiro, Sagawa Shiro, Nagayama Shigeya, Kayaba Yuichi
    Biology of Inland Waters 27 41 - 47 2012 [Refereed][Not invited]
  • NAGAYAMA Shigeya, NEGISHI Junjiro, KUME Manabu, SAGAWA Shiro, TSUKAHARA Koji, MIWA Yoshiaki, KAYABA Yuichi
    ECE Ecology and Civil Engineering Society 15 (2) 147 - 160 1344-3755 2012 [Refereed][Not invited]
     
    We examined use of small perennial agricultural canals by fish according to seasons and life stages and habitat characteristics in 4 regions, southern Gifu, central Japan, in irrigation (June and August) and non-irrigation (September and February) periods. Seasonal changes in the number and size composition of six dominant fish species showed that the canals function as habitat for growing and overwintering. Total abundance of all fish species was higher in earth canals, which had natural bed materials, than in concrete canals in all study periods other than August. Fish diversity was higher in earth canals than in concrete canals only in winter (February) . Abundance of each of most dominant fish species was positively related to the bed materials, such as silt, sand, or gravel, in warmer seasons (from June to September) . In winter, that was primarily explained by cover ratio or water depth. In addition, we found close positive relationship between bitterling and mussel abundance in three study periods including spawning and other seasons. These habitat characteristics according to the study periods were satisfied in earth canals. Our findings suggest that a set of natural bed materials and covers, such as bank vegetation and undercut bank, is important when canals are considered as fish habitat throughout irrigation and nonirrigation periods including winter. Therefore, the bank-lined canal with natural bed should be adopted for canal construction and modification, although unlined earth canal is ideal. If the canal bed is necessarily lined, the hydrological conditions that allow sediment deposition should be ensured.
  • 山下 慎吾, 根岸 淳二郎, 河口 洋一, 赤坂 卓美, 中村 知美, 島谷 幸宏, 中村 太士
    流域圏学会誌 流域圏学会 1 (1) 19 - 24 2186-9065 2012 [Refereed][Invited]
  • Junjiro N. Negishi, Hideyuki Doi, Izumi Katano, Yuichi Kayaba
    Aquatic Conservation: Marine and Freshwater Ecosystems 21 (1) 49 - 56 1052-7613 2011/01 [Refereed]
     
    1. The vertical and horizontal distribution of unionoid mussels (Pronodularia japanensis) were examined in spring, late summer and winter for different size classes, including juveniles (<20 mm) and large adults (>50 mm), in an agricultural drainage channel in Central Japan.2. A large number of small-sized juveniles were found at the surface (0-3 cm depth) in spring, whereas approximately half of the adults remained in the deep layer (3-8 cm depth). Most individuals were found in the surface layer irrespective of size classes in summer, and approximately 70% of all individuals descended to the deep layer in winter.3. Horizontal distribution did not substantially change across seasons and high density patches were consistently found in the areas where substrate appeared to be stable or hydraulically sheltered. Spatial distribution of small juveniles was relatively well predicted by the abundance of adults.4. The size-frequency distribution was multi-modal in three seasons and estimated numbers of newly recruited juveniles were highly variable in recent years, suggesting that juveniles were rarely found owing to irregular reproduction and/or recruitment not the overlooked habitat preferred by small-sized juveniles.5. As P. japanensis is characterized by the behaviour of burrowing down to a depth of similar to 10 cm, maintaining the processes of sediment deposition appears to be one of the critical criteria for the conservation of mussel habitats in agricultural drainage channel systems, which are commonly lined with smooth concrete materials. Copyright (C) 2010 John Wiley & Sons, Ltd.
  • Takashi Gomi, Sohei Kobayashi, Junjiro N. Negishi, Fumitoshi Imaizumi
    Landscape and Ecological Engineering 6 (2) 257 - 270 1860-1871 2010/07 [Refereed]
  • Junjiro N. Negishi, Yuichi Kayaba
    Ecological Research Springer Japan 25 (2) 403 - 411 0912-3814 2010/03 [Refereed]
  • Junjiro N. Negishi, Yuichi Kayaba
    Journal of the North American Benthological Society 28 (4) 821 - 831 0887-3593 2009/12 [Refereed]
  • Jyun-ichi Kitamura, Junjiro N. Negishi, Masaki Nishio, Shiro Sagawa, Jyun-ichi Akino, Shigeyuki Aoki
    Ichthyological Research 56 (3) 296 - 300 1341-8998 2009/07 [Refereed]
  • Fumitoshi Imaizumi, Takashi Gomi, Sohei Kobayashi, Junjiro N. Negishi
    CATENA 77 (3) 207 - 215 0341-8162 2009/06 [Refereed]
  • Izumi Katano, Junjiro N. Negishi, Tomoko Minagawa, Hideyuki Doi, Yôichi Kawaguchi, Yuichi Kayaba
    Journal of the North American Benthological Society 28 (2) 331 - 351 0887-3593 2009/06 [Refereed]
     
    Macroinvertebrate organization along a river was examined to relate biological responses to environmental changes observed across 2 discontinuities (a dam and a tributary). Benthic macroinvertebrates and a range of environmental variables were sampled from 4 study segments (above the dam, below the dam, below the tributary confluence, and in the tributary). Substrate was significantly coarser below than above the dam. In contrast, water-quality variables, such as water temperature and dissolved O-2, changed little below the dam. The most striking discontinuity was substrate coarseness at the tributary confluence. Substrate below the confluence was finer than substrate below the dam and similar to the substrate above the dam. Macroinvertebrate organization differed across the 2 discontinuities. Assemblage composition above the dam was more similar to composition below the confluence than to composition below the dam. The longitudinal organization of the macroinvertebrates could be explained largely by changes in substrate characteristics and habitat preferences of the indicator species. The densities of drifting zooplankton and phytoplankton were higher below than above the dam and were higher below the dam than below the confluence. However, the density of drifting plankton did not differ between the reach immediately above the confluence and the reaches below the confluence. This result suggests that the decrease of zooplankton and phytoplankton occurred above the tributary, probably because of biological entrapment or passive deposition rather than the contribution of the tributary inflow. The dam and tributary caused contrasting discontinuities in macroinvertebrate organization. The tributary generally reversed the dam-related changes to the main stem habitat and the macroinvertebrate community. A key management implication of our study is that efforts to restore dam-related environmental impacts would be facilitated by understanding the role of tributaries downstream of the dam.
  • Alan D. Ziegler, Thomas W. Giambelluca, Mike A. Nullet, Ross A. Sutherland, Chatchai Tantasarin, John B. Vogler, Junjiro N. Negishi
    AGRICULTURAL AND FOREST METEOROLOGY 149 (2) 373 - 384 0168-1923 2009/02 [Refereed]
     
    Throughfall determined by stationary and mobile methods in a disturbed evergreen-dominated forest stand in northern Thailand was 82% of rainfall (1134 mm) during a 4-month study period in the monsoon rain season of 2002. Associated coefficients of variation and standard errors were <= 10% and 2%, respectively, for both methods. Agreement between four stationary trough collectors and 20 mobile standard gauge collectors was achieved only after 35 sampling occasions, having a total rainfall depth >700 mm, and included one storm event >100 mm. Several canopy trees contributed to points with throughfall > rainfall by channeling stemflow to common drip points on the trunk and large limbs. However, no significant correlation was observed between throughfall point measurements and corresponding canopy cover. Although 180-point measurements of throughfall provided a realistic representation of the spatial variability within the 500-m(2) forest stand, it is questionable that they duplicated the basin-scale variability, which would be affected both by tree gaps and variable topographically related rain shadow effects. (C) 2008 Elsevier B.V. All rights reserved.
  • Masanori Nunokawa, Takashi Gomi, Junjiro N. Negishi, Osamu Nakahara
    LANDSCAPE AND ECOLOGICAL ENGINEERING 4 (2) 125 - 131 1860-1871 2008/11 [Refereed]
     
    We developed a method for estimating the substrate coherent strength of a net-spinning caddis larva, Stenopsyche marmorata, in the field. Plastic experimental cages (prefabricated containers with 5-mm mesh; 0.1 m high, 0.12 m wide, 0.2 m long) that enclosed gravel substrate and an objective stone (5-6 cm in diameter) were prepared. We expected the caddisflies to build a retreat(s) between the objective stone and cage substrate when submerged in a riffle channel reach for 6 days. Ten final-instar larvae (4-5 cm long) were placed in the cage and allowed to form retreats. Two treatments (cages with and without larvae) with 15 replicates each were used in two experimental trials. The vertical lift-force of objective stones associated with a retreat (coherent strength) was measured using a spring weighing scale. In 87% of 30 cages of with-larvae treatment, retreats were formed between the objective stone and cage substrate. Coherent strength ranged from 0.0 to 1.6 kg. Our approach can be used under varying flow velocities, substrate conditions, and larval biomass, all of which are normally difficult to test in flume experiments. Findings based on our field method provide unique physical properties of the caddisfly retreats in stream ecosystems.
  • Ecological studies on Unionoida: current status and future challenges
    根岸 淳二郎, 萱場 祐一, 塚原 幸治, 三輪 芳明
    2008/10 [Refereed]
  • J. N. Negishi, R. C. Sidle, A. D. Ziegler, S. Noguchi, N. Abdul Rahim
    Earth Surface Processes and Landforms 33 (8) 1174 - 1191 0197-9337 2008/07 [Refereed]
  • Junjiro N. NEGISHI, Yuichi KAYABA, Koji TSUKAHARA, Yoshiaki MIWA
    Ecology and Civil Engineering 11 (2) 195 - 211 2008 [Refereed]
  • Alan D. Ziegler, Junjiro N. Negishi, Roy C. Sidle, Takashi Gomi, Shoji Noguchi, Abdul Rahim Nik
    EARTH SURFACE PROCESSES AND LANDFORMS 32 (13) 1947 - 1970 0197-9337 2007/11 [Refereed]
     
    Measurements of saturated hydraulic conductivity (K-s) and diagnostic model simulations show that all types of logging road/trail in the 14.4 ha Bukit Tarek Experimental Catchment 3 (BTEC3) generate substantial Horton overland flow (HOF) during most storms, regardless of design and level of trafficking. Near-surface K-s(0-0.05 m) on the main logging road, skid trails and newly constructed logging terraces was less than 1, 2 and 34 mm h(-1), respectively. Near-surface K-s on an abandoned skid trail in an adjacent basin was higher (62 nun h(-1)), owing to the development of a thin organic-rich layer on the running surface over the past 40 years. Saturated hydraulic conductivity measured at 0.25 m below the surface of all roads was not different (all <6 mm h(-1)) and corresponded to the K-s of the adjacent hillslope subsoil, as most roads were excavated into the regolith more than 0.5-1 m. After 40 years, only limited recovery in near-surface K-s occurred on the abandoned skid trail. This road generated HOF after the storage capacity of the upper near-surface layer was exceeded during events larger than about 20 mm. Thus, excavation into low-K-s substrate had a greater influence on the persistence of surface runoff production than did surface compaction by machinery during construction and subsequent use during logging operations. Overland flow on BTEC3 roads was also augmented by the interception of shallow subsurface flow traveling along the soilsaprolite/bedrock interface and return flow emerging from the cutbank through shallow biogenic pipes. The most feasible strategy for reducing long-term road-related impacts in BTEC3 is limiting the depth of excavation and designing a more efficient road network, including minimizing the length and connectivity of roads and skid trails. Copyright (c) 2007 John Wiley & Sons, Ltd.
  • J. N. Negishi, S. Noguchi, R. C. Sidle, A. D. Ziegler, Abdul Rahim Nik
    Hydrological Processes 21 (6) 789 - 806 0885-6087 2007/03/15 [Refereed]
  • Alan D. Ziegler, Junjiro N. Negishi, Roy C. Sidle, Shoji Noguchi, Abdul Rahim Nik
    CATENA 67 (2) 89 - 104 0341-8162 2006/10 [Refereed]
     
    Using a constant-head permeameter we found an abrupt natural decrease in saturated hydraulic conductivity (K-s) within the upper 1.0-m soil profile of an Orthoxic Tropudult at the Bukit Tarek Experimental Catchments research area in tropical, Peninsular Malaysia. The depth at which low K-s could cause a perched water table in response to high-intensity rainfall, however, was too great to generate saturation overland flow on planar hillslopes in the study area. The effects of logging activity on K-s at five subsurface depths (0.1, 0.25, 0.5, 0.75, and 1.0 m) on the non-roaded portion of the harvest area were examined at the three following sites, which differed in the degree of disturbance and recovery since timber harvesting: (1) selective logging conducted in the 1960s; (2) mechanized selective tree removal conducted 4 years ago; and (3) high-impact clear-cutting just prior to measurement. This recent logging greatly disturbed the soil surface (via compaction, topsoil/subsoil mixing, burning) and produced comparatively high variability in near-surface K-s. Changes in K-s at or below 0.25-m, however, were not detected with certainty at any sites. In terms of hillslope hydrologic response, the connectivity of zones of low K-s in the harvest area with dense networks of skid trails and terraces was identified as one of the most important consequences of timber harvesting, although this phenomenon was not quantified. We estimate the recovery time for near-surface K-s on the non-roaded hillslope to be less than 40 years. (c) 2006 Elsevier B.V. All rights reserved.
  • Akira Takao, Junjiro N. Negishi, Masanori Nunokawa, Takashi Gomi, Osamu Nakahara
    JOURNAL OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY 25 (3) 545 - 555 0887-3593 2006/09 [Refereed]
     
    The influence of the net-spinning caddisfly larva Stenopsyche marmorata on streambed substratum stability was examined in 14 riffles of 5 rivers in northern Hokkaido, Japan. In each riffle, 6 representative stones were measured and 7 variables were quantified for each stone: 1) ambient flow velocity, 2) ambient depth, 3) extent of embeddedness, 4) force required to initiate shifting of the stone parallel to the flow direction, 5) biomass of S. marmorata living on and under the stone, 6) wet mass of the stone, and 7) size of the stone. Regression analyses were used to examine which of the variables best predicted the coherent strength of a particle with the stream bed (F-C). Riffle-scale patterns derived from the means of 6 stones showed significant influences of biomass of S. marmoratalstone and embeddedness on F-C; however, the collinearity of these 2 variables hindered evaluation of their relative importance. At the stone scale, biomass of S. marmorata/stone was positively related to F-C when standardized for the degree of stone embeddedness. F-C of stones inhabited by S. marmorata at the maximum range of their biomass is predicted to be 50 to 260% greater than F-C of stones without S. marmorata. The effects of biological consolidation of substratum particles by S. marmorata probably are substantial, even in inherently heterogeneous natural environments.
  • Takashi Gomi, Roy C. Sidle, Shoji Noguchi, Junjiro N. Negishi, Abdul Rahim Nik, Shozo Sasaki
    Forest Ecology and Management 224 (1-2) 166 - 175 0378-1127 2006/03 [Refereed]
  • J.N. Negishi, R.C. Sidle, S. Noguchi, Abdul Rahim Nik, R. Stanforth
    Forest Ecology and Management 224 (1-2) 176 - 186 0378-1127 2006/03 [Refereed]
  • RC Sidle, AD Ziegler, JN Negishi, AR Nik, R Siew, F Turkelboom
    FOREST ECOLOGY AND MANAGEMENT 224 (1-2) 199 - 225 0378-1127 2006/03 [Refereed]
     
    To assess the effects of forest management on soil erosion in Southeast Asia, clear distinctions must be made between surface erosion and landslide processes. Although surface erosion is a natural process, it is exacerbated by surface disturbance and compaction that reduce the soil hydraulic conductivity and break down soil aggregates. Management practices and attributes such as roads and trails, agricultural cultivation, fire, land clearing, and recreation all accelerate surface erosion processes due to their disturbance, compaction, and connectivity along hillslopes. Agroforestry practices in Southeast Asia that incorporate cover crops with trees reduce surface erosion by more than an order of magnitude compared to monoculture plantations with no ground cover. Cleared fields tilled up and down steep slopes are highly erodible; passive conservation practices (e.g., contour tillage, strip cropping, reduced tillage; maintaining adequate ground cover) are effective in reducing surface erosion if properly implemented. Poorly designed and managed terraces are not effective in controlling surface erosion and may actually increase mass wasting if they concentrate water.In contrast to surface erosion, shallow, rapid landslides are episodic processes triggered by individual rainfall events or artificial inputs of water; slower, deep-seated landslides initiate or activate after a longer-term accumulation of water. Thus, landslide assessment must be based on long-term observations. Deep rooted trees and shrubs impart a significant cohesive strength into shallow soil mantles and facilitate preferential drainage, thereby reducing the probability of shallow landslides. Conversion of mountain forests to cropland or plantations permanently reduces rooting strength, thus increasing landslide potential, while timber harvesting with subsequent regeneration of secondary forests reduces rooting strength for up to two decades after initial cutting.Roads contribute the largest surface erosion and landslide losses (per unit area disturbed) compared to other land uses. Both landslide and surface erosion fluxes along roads are typically one to more than two orders of magnitude higher compared to undisturbed steepland forests. High storm runoff from roads is caused by the generation of infiltration-excess overland flow on compacted surfaces and the interception of subsurface flow at road cuts; these altered pathways increase surface erosion and accelerate the delivery of storm runoff to streams. Discharge nodes from roads facilitate the connectivity of water and sediment to headwater streams. Trails, although narrower than roads, can contribute significantly to soil loss and storm runoff and are important sediment conduits if directly linked to channels. Thus, the location of roads and paths with respect to the hydrologic network is a critical factor governing the spatial-temporal movement of sediment and water in the tropics. (c) 2005 Elsevier B.V. All rights reserved.
  • Alan D. Ziegler, Junjiro Negishi, Roy C. Sidle, Pornchai Preechapanya, Ross A. Sutherland, Thomas W. Giambelluca, Sathaporn Jaiaree
    Journal of Environmental Quality 35 (1) 151 - 162 0047-2425 2006/01 [Refereed]
  • Junjiro N Negishi, John S Richardson
    The Journal of animal ecology 75 (1) 118 - 29 0021-8790 2006/01 [Refereed]
     
    1. The passive or active movement of organisms between habitat patches plays important roles in achieving ecosystem resilience to disturbance and long-term control of population levels. However, causal mechanisms of disturbance-induced movements of mobile biota across heterogeneous habitat patches at a relatively short time-scale are little understood. 2. We experimentally tested the effects of food resource values on macroinvertebrate colonization of hydraulic refugia from spates in a second-order creek. Experimental cages were colonized by macroinvertebrates with combinations of resource types (natural or polyester leaves), and extent of exposure to stream flow (exposed to or sheltered from current); one half of each set was collected before and after a spate. This experiment was repeated over three spates of varying magnitude and seasonal contexts. 3. Pre-spate colonization was consistently greater for the cages with natural leaves relative to artificial leaves regardless of the extent of flow exposure. Two autumn spates with relatively low and stable antecedent flow conditions caused large movements of organic matter and macroinvertebrates across the stream, showing community-level accumulations into hydraulically sheltered patches independent of food treatment. The smallest spate with high and variable antecedent flows during winter resulted in negligible responses, which we interpret to be a result of depletion of easily transportable organic matter and organisms. 4. Two detritivorous taxa, the mayfly Paraleptophlebia spp. and stonefly Despaxia augusta (Banks) were the most responsive to autumn spates, and had disproportionately higher colonization rates of cages when provided with natural leaves during the largest autumn spate. Preferential settlement in food-enriched hydraulic refugia was attributable to taxon-specific mobility related to efficient acquisition of detritus resource, whose availability varies spatially and temporally. 5. Our findings suggest (1) detritivorous macroinvertebrate colonization of hydraulic refugia can be influenced by hydraulic controls as well as food resource value, and (2) pre-spate environmental conditions in terms of resource distribution and availability may pre-condition organisms' susceptibility to spates and also affect refugium usage, at least in food-limited, detritus-based stream systems.
  • YX Zhang, JS Richardson, JN Negishi
    JOURNAL OF ANIMAL ECOLOGY 73 (4) 756 - 766 0021-8790 2004/07 [Refereed]
     
    1. Interference between species from different functional groups may influence ecosystem functioning and biological diversity. This study tested whether interactions between predacious cutthroat trout and an omnivorous signal crayfish modified the crayfish's trophic and engineering effects within a detrital-based, stream benthic community.2. We show in a trough experiment that omnivorous crayfish through their trophic and engineering roles enhance detritus decomposition, reduce particulate organic matter (POM) accumulation, and diminish diversity in leaf packs.3. In crayfish troughs by day 30, leaf dry weight loss was 1.8-fold greater, whereas POM trapped in leaf packs was 80% less, than of those in controls, and the abundance, biomass and taxon richness of benthos in leaf packs were lower than those in controls. Predatory cutthroat trout did not affect those variables and did not interfere with the crayfish.4. Crayfish and cutthroat trout both decreased fine material sedimentation in the troughs.5. Thus, with no interference from cutthroat trout, the signal crayfish acted as ecosystem processors and engineers, and strongly influenced detrital processing, benthic diversity, and the accumulation of POM and fine sediments.
  • Yixin Zhang, Junjiro N Negishi, John S Richardson, Renata Kolodziejczyk
    Proceedings. Biological sciences 270 (1529) 2117 - 23 0962-8452 2003/10/22 [Refereed]
     
    Energy and nutrient subsidies transported across ecosystem boundaries are increasingly appreciated as key drivers of consumer-resource dynamics. As purveyors of pulsed marine-derived nutrients (MDN), spawning salmon are one such cross-ecosystem subsidy to freshwaters connected to the north Pacific. We examined how salmon carcasses influenced detrital processing in an oligotrophic stream. Experimental manipulations of MDN inputs revealed that salmon carcasses indirectly reduced detrital processing in streams through temporarily decoupling the detrital resource-consumer relationship, in which detrital consumers shifted their diet to the high-nutrient resource, i.e. salmon carcasses. The average decomposition rate of alder leaves with salmon carcass addition was significantly lower than that without the carcass, which was associated with lower abundance and biomass of detritivorous Trichoptera on the carcass-treated leaves. There were generally larger in size Trichopteran detritivores on the carcasses than on leaves. These results imply that cross-boundary MDN subsidies indirectly retard the ecosystem processing of leaf litter within the short term, but may enhance those food-limited detritivorous consumers. Because unproductive freshwaters in the Pacific northwest are highly dependent upon the organic matter inputs from surrounding forests, this novel finding has implications for determining conservation and management strategies of salmon-related aquatic ecosystems, in terms of salmon habitat protection and fisheries exploitation.
  • Junjiro N Negishi, John S Richardson
    Canadian Journal of Fisheries and Aquatic Sciences 60 (3) 247 - 258 0706-652X 2003/03/01 [Refereed]
     
    Diversity and productivity of stream food webs are related to habitat heterogeneity and efficiency of energy retention. We tested the hypothesis that experimental boulder placements in a second-order stream would increase diversity and abundance of macroinvertebrates by restoring detrital retention and habitat heterogeneity. Two relatively natural, upstream, reference reaches and a downstream treatment reach with a relatively straight channel and less woody debris were studied for 3 months before and 1.2 years after the placement of six boulder clusters in the treatment reach. Mean velocity and its coefficient of variation increased in the treatment reach (140 and 115%, respectively), whereas the reference reaches remained relatively unchanged after the placements. Enhanced particulate organic matter storage (550%) was accompanied by increased total macroinvertebrate abundance (280%) in the treatment reach, converging with those of the reference reaches almost 1 year after the treatment. Detritivorous taxa numerically dominated the macroinvertebrate community, the total densities of which were best predicted by the fine fraction of organic matter biomass at microhabitat scale. However, the effect of boulder clusters on taxonomic richness was negligible. Our findings suggest that boulder clusters can be used at least as a short-term means to restore macroinvertebrate productivity in detritus-based stream systems.
  • J. N. NEGISHI, M. INOUE, M. NUNOKAWA
    Freshwater Biology 47 (8) 1515 - 1529 0046-5070 2002/08 [Refereed]

MISC

Research Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2025/03 
    Author : 根岸 淳二郎, 三浦 彩, 早川 裕弌, 渡辺 幸三, 三宅 洋
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2021/04 -2024/03 
    Author : 小林 憲生, 大原 昌宏, 根岸 淳二郎
     
    海浜性昆虫は、海浜という限られた環境にのみ生息する。特に飛翔力を欠く種が多く知られる海浜性甲虫は、海浜環境への適応を考える上で格好の材料である。さらに、この海浜性甲虫群集は、波打ち際（微環境a）、湿った砂（微環境b）、乾燥した砂（微環境c）と、僅か20-30mの範囲内で種構成が変化していく。その上、種によっては生息微環境と餌の場所が異なり、微環境a-bを行き来する種、微環境b-cを移動する種など、複数の微環境を利用する場合も有る。その結果、防潮堤建設によって、上記のいずれかの環境が消失する、或いはこれら微環境a-b-cが分断され、様々な海浜性生物の存否に影響を及ぼす可能性がある。その一方、消滅を免れた種においては、餌資源を変更するなどが生じている可能性もある。 本研究では、海浜性昆虫（主として甲虫類）の詳細な生息場所の調査、及び食性に関する実験等を行い、海浜性昆虫が生息可能な条件を探索すると共に、食物網（Food-Web）を拡張させた、生息場所から餌までの資源利用に関する多次元的な「資源利用-Web」を作成し、防潮堤がもたらすWeb構造の“変化”の解明を目的とする。 初年度は東北地方太平洋側の中でも宮城県中心（宮城県荒浜、蒲生、由比ガ浜、北浜、野蒜）に調査・採集を行い、海浜性昆虫の生息状況を確認した。 また、現在は、餌資源利用の実態を明らかにするため、ハマヒョウタンゴミムシダマシ、ヒョウタンゴミムシ等を用い、食性選好性、生息微環境の選好性に関する室内実験を行っている最中である。
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2019/04 -2023/03 
    Author : 松島 肇, 島田 直明, 平吹 喜彦, 岡 浩平, 根岸 淳二郎
     
    本年度は初年度に設置した防潮堤への覆砂試験のモニタリング調査の継続、および防潮堤の海側・陸側における植生調査とともに、防潮堤の生態系への影響把握指標として徘徊性昆虫の食物網への影響に着目し調査をおこなった。また、宮城県や岩手県における学校カリキュラムと連動した海浜植物群落の保全・再生への取り組みを宮城県気仙沼市立大谷小学校、北海道石狩市立浜益小学校、浜益中学校でも実施し、合わせてアンケート調査による環境意識の変化の定量化をおこなった。 防潮堤への覆砂試験では、植物群落の定着が促進されている様子が確認されたものの、防潮堤の上部については、季節風の影響で砂の移動が顕著に確認され、特に内陸側の堤体法面では冬から春にかけて上部の砂が植生ごとなくなり、その後夏から秋にかけて再び砂と植生に覆われる様子が確認された。これが安定化するかについては引き続き継続した調査が求められる。防潮堤より海側の植生については大きな変化は見られないが、陸側ではニセアカシアなどの外来木本が顕著に侵入している様子が確認できた。徘徊性昆虫としてオオハサミムシに着目し、体の安定同位体比を計測して防潮堤の海側と陸側で比較した結果、汀線から陸に向かっていくについれて海由来の同位体の寄与率が低下していく様子が確認できた。しかし、防潮堤の影響で大きく変化する様子はみられなかった。小中学生との海浜植物群落の保全・再生活動は継続することで知識・関心が高まることが確認された。６年目となる仙台市立岡田小学校では、児童が家族とともに自主的に海浜植物の種子を採取するなど、大きな進展が見られた。植物種の判別だけでなく、多くの児童が種子からどの海浜植物種の種子かを同定できるようになっていり、自主的に図鑑を作成するなど、関心の高まりが伺えた。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Negishi Junjiro
     
    In order to elucidate the ecological function of saturated interstitial zone underneath the riverbed (hyporheic zone) in transferring resource to river-riparian food web, the following four major findings were obtained. First, the food web in the hyporheic zone was visualized with the identification of aquatic insect species adapted to hyporheic habitat (hyporheic species). Second, the amount of resource provided from the hyporheic zone to the riparian zone was estimated by focusing on hyporheic species. Third, the responses of macroinvertebrate community including hyporheic species to floods and nutrient pollution in surface water were measured. Overall, this research project comprehensively provided techniques and a conceptual scheme useful in the assessment of river-riparian environmental heath based on hyporheic species in particular by focusing on their adults that are easier to catch in comparison with their aquatic larvae in physically concealed hyporheic zone.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : 中村 太士, 萱場 祐一, 山浦 悠一, 根岸 淳二郎
     
    国土交通省が管理する109水系の管理区間を対象として樹林化の進行と河道内に形成された樹林地がどのような地被から転換されているかを分析した。具体的には、1㎞毎の地被状態を水面＋裸地、草地、樹林地、人工地に分類し、Ⅲ期（1990～1995年度）からⅤ期（2001年～2005年度）の2時期において1）河道面積が大きく変化せず、2）樹林地が5％以上増加した区間を抽出した。この結果、樹林化が進行した区間には、人工地の増大によって説明できる区間も多く、人為的な利用圧の低下（例、耕作放棄地）も樹林化に寄与していることが示唆された。 札内川中流域を対象に、水生昆虫羽化成虫による河畔域の森林植生利用と河川堤防に付随した多年草植生帯がその利用に及ぼす影響を定量化した。横断方向への飛翔距離や群集構造で評価した河畔域利用の程度は目レベルで明瞭に異なり、特に河床間隙域由来のカワゲラ目昆虫において森林植生の利用度が高かった。一方で、堤防の植生帯は、河川からの距離が水生昆虫の飛翔距離に対して十分に小さい場合に、生息場として利用されていた。河畔域の植生帯が、水生昆虫の成虫期の生息場として重要であることが示唆された。 火山性地質においては湧水成分が多くなり、非火山岩地質と比べると夏季においても低温が維持されることから、温暖化の影響を予測するために地質を加味した水温の分布を予測できるモデルを完成させた。 土地利用の変化が鳥類群集に与えた影響を北海道の石狩平野で推定した。各種資料から最近100年間の土地利用を再構築した。土地利用と鳥類各種の個体数の関係を統計モデルで記述し、過去の土地利用に当てはめた。その結果、この時期土地利用は森林が激減した一方で、畑は一時期増加したが水田に置き換わり減少していた。これに伴い、裸地性鳥類以外の湿地性、草地性、森林性鳥類は長期的に大きく個体数を減らしていたと推定された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/05 -2015/03 
    Author : GOMI Takashi, TODA Hiroto, KIMURA Sonoko DOROTEA, WATANABE Hirozumi, ASANO Yuko, MIZUGAKI Shigeru, NUNOKAWA Masanori, NEGISHI Junjiro
     
    Fukushima Dai-ichi Nuclear Power Plants accident caused radiocaesium contamination in forested areas. We analyzed transport and concentration of radiocaesium in aquatic and terrestrial ecosystems in watersheds with forest and agriculture transitions. Cs-137 distribution varied depending on topography, forest types, and landscape position. Cs-137 concentrations on streams tended to be lower than that on forest floor by leaching Cs-137 in aquatic environment. Level of radiocesium concentration in consumers depends on the level of contamination of primary producers available in consumers' habitat ranges. For fish species such as char, radiocaesium concentrations appeared to be greater in the individuals with greater body sizes. Findings of this study showed that the dynamics of radiocaesium via litter decomposition and transport in streams is a primal factor for understanding biological transfer of radiocaesium in terrestrial and aquatic environment of watershed ecosystems.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/04 -2015/03 
    Author : NEGISHI Junjiro
     
    Fist, endangered unionoid mussels were found more in the drainage channel that had a high connectivity to the downstream rivers, and fish community with high taxonomic diversity co-occurred. Also, landscape surrounded by low levels of urbanization characterized their habitat. Second, macrophyte diversity in floodplain lakes were positively correlated with their cover area, and the quality of macrophyte habitat was the lowest in the artificially created oxbow lakes. Third, spring-fed rivers harbored unique sets of species of aquatic insects, thereby contributing to the taxonomic diversity at the watershed scale. These suggest that systematic classifications of habitat across landscapes based on landform and groundwater would facilitate efficient conservation of aquatic biodiversity.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011/04 -2015/03 
    Author : NAKAMURA Futoshi, SUZUKI Toru, YAMAURA Yuichi, MORIMOTO Junko, NAGAYAMA Shigeya, NEGISHI Junjiro, AKASAKA Takumi
     
    This project focused on connectivity between various ecosystems, and examined the effects of restoration project. Among fish and aquatic insects, only high mobility groups could enhance species richness as spatial and hydrologic connectivity increased. Pond connectivity significantly affected the spatial variation of both population abundance and genetic diversity of the ninespine stickleback. We revealed millennium-scale dietary shifts of brown bears on the Hokkaido islands, Japan, using carbon, nitrogen, and sulfur stable isotope analysis, and found that human activities have caused an alteration in the trophic structure of brown bears. The meander and floodplains restoration project successfully increased the frequency of flooding over the floodplains and raised the water table, resulting in an increase of abundance and species richness of fish and invertebrate species and wetland vegetation areas.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2011 
    Author : NEGISHI Junjiro
     
    The dominant riverbed material in the mid segment of Kiso River has changed over time from sands and gravels to peat outcrops. In places, substantial riverbed incisions having> 20m water depth occurred probably because the loss of peat outcrop(few meters think) resulted in acute erosions of sandy deposits below. Furthermore, peat outcrop appeared to provide a suitable habitat for mayfly(Ephoron shigae), which is often considered as a pest, serving as a main source of huge swarms of adults in the area.

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