BAN Syuhei




Research Fields, Keywords

Aquatic Ecology

Mail Address

E-mail address

Graduate School 【 display / non-display

  • Hokkaido University  Graduate School, Division of Fisheries  Doctor's Course  1991.02

Campus Career 【 display / non-display

  • University of Shiga Prefecture  School of Environmental Science  Department of Ecosystemus Studies  Professor   2008.02 - Now

  • University of Shiga Prefecture  School of Environmental Science  Department of Ecosystemus Studies  Associate Professor   2007.04 - 2008.01

  • University of Shiga Prefecture  School of Environmental Science  Department of Ecosystemus Studies  Associate Professor (as old post name)   2001.05 - 2007.03

Academic Society Affiliations 【 display / non-display

  • Association for the Sciences of Limnology and Oceanography

  • Japan Society on Water Environment

  • JpGU

Field of expertise (Grants-in-aid for Scientific Research classification) 【 display / non-display

  • Ecology/Environment

  • Aquatic bioproduction science

  • Environmental dynamic analysis


Research theme 【 display / non-display

  • Biodiversity-driven nutrient cycling and human-wellbeing in socio-ecological systems (lake ecosystem)

  • Sustainable management in lake ecosystem using macrophyte biomass

    macrophyte biomass, conservation in lake ecosystem, freshwater environments, methane fermentation, microalgal culture

  • Diversity and function of Chytrid fungi in lakes and oceans

    Chytrid fungi, diversity, phytoplankton, lakes

  • Long-term study on zooplankton biomass in Lake Biwa

    Lake Biwa, zooplankton, biomass, long-term analysis

  • Effects of internal wave on phytoplankton production in Lake Biwa

    internal wave, material flux, phytoplankton production, wind direction and speed

Papers 【 display / non-display

  • Are egg production and respiration of the marine pelagic copepod Acartia steueri influenced by crowding?

    Takayama Y., Hirahara M., Liu X., Ban S., Toda T.

    Aquaculture Research  Aquaculture Research  51 (9)   3741 - 3750  2020.09

    10.1111/are.14723  Joint Work  


    © 2020 John Wiley & Sons Ltd The understanding of the biological responses of copepods under crowding conditions contributes to establish their stable cultures at high densities for aquaculture industry, which are preferred live feeds for fish larvae. The present study investigated survivorship, fecundity, hatching success and respiration rate, of Acartia steueri raised under five densities, from 100 to 2,000 ind. L−1, to clarify the biological responses of the copepod under dense culture. There were no significant differences in survival, fecundity and hatching success among all density conditions, whereas the respiration rate at 2,000 ind. L−1 decreased by 80% as compared with a condition at 100 ind. L−1. The female copepods raised under a copepod density of >500 ind. L−1 probably invested a larger proportion of energy in reproduction in relation to total assimilated energy as compared with females under lower copepod densities. This change of energy allocation may allow A. steueri under high densities to maintain high fecundity. Acartia steueri might be a promising species for dense culture because its mortality and fecundity were independent of the effect of crowding, and the density-dependent reduction in the metabolic rate might increase reproductive investment to maintain a constant rate of reproduction even under high densities.

  • Novel wet-solid states serial anaerobic digestion process for enhancing methane recovery of aquatic plant biomass

    Iweh N.S., Koyama M., Akizuki S., Ban S., Toda T.

    Science of the Total Environment  Science of the Total Environment  730    2020.08

    10.1016/j.scitotenv.2020.138993  Joint Work  


    © 2020 Elsevier B.V. Aquatic plant biomass is characterised by high moisture content and a lignocellulose structure. To apply the anaerobic digestion (AD) treatment to aquatic plants, the simultaneous achievement of high methane (CH4) recovery per biomass volume and high biodegradability have been a challenge owing to these characteristics. Herein, we propose a novel two-stage serial wet- and solid-state AD (SS-AD) system that quickly digests the labile cytoplasm fraction in the first wet AD reactor in a short retention time while slowly digesting the lignocellulosic fraction in the later SS-AD with long retention time. In this study, the effect of this serial AD on CH4 recovery and chemical oxygen demand (COD) balance from aquatic plant biomass was examined in a semi-continuous operation. Elodea nuttallii, which grows excessively in the southern basin of Lake Biwa, Japan, was used as the substrate. For comparison, single-stage AD with different hydraulic retention times (HRTs) (30 d and 15 d) was performed. The CH4 conversion efficiency in single-stage AD deteriorated from 47.6 to 33.1% COD with shortened HRT, probably owing to the low degradability of slowly degrading fraction (i.e. lignocellulose) in the short retention time. In contrast, the serial AD under the same HRT (15 d) as a single-stage AD exhibited higher CH4 conversion efficiency of 65.1% COD, mainly owing to the enhanced degradation of slowly degrading fraction because of the prolonged solid retention time (52.2 d) of the entire system. The CH4 recovery from the wet AD alone in the serial AD system surpassed that from the 30 d-HRT of the single-stage AD, possibly due to the appropriate HRT for labile fraction and/or the microbial recirculation. The serial wet and SS-AD was suggested as a suitable technology for the treatment of aquatic plant biomass with recalcitrant cell walls and a labile cytoplasm.

  • Conditions for continuous cultivation of Chlorella sorokiniana and nutrient removal from anaerobic digestion effluent of aquatic macrophytes

    Liu X., Fujiwara M., Kodera T., Watanabe K., Akizuki S., Kishi M., Koyama M., Toda T., Ban S.

    International Biodeterioration and Biodegradation  International Biodeterioration and Biodegradation  149    2020.04

    10.1016/j.ibiod.2020.104923  Joint Work  


    © 2020 Elsevier Ltd Continuous cultivations of the microalga Chlorella sorokiniana using 10-L flat-panel bioreactors were conducted at different pH levels and hydraulic retention times (HRT) under natural light conditions to accomplish the maximum algal yields and high nutrient removal from anaerobic digestion effluent (ADE) of aquatic macrophytes, which contained high concentrations of ammonium-nitrogen and phosphate-phosphorus, but less available magnesium (Mg). In subsequent experiments, Mg was enriched directly or indirectly by lowering the pH in the original ADE as source medium of a flow-through system to increase the amount of available Mg for algal growth. In the Mg-enrichment experiment, a constant maximum algal yield, 0.7 g dry-weight L−1, was obtained at HRT of 5 days, and removal efficiencies in both ammonium-nitrogen and phosphate-phosphorus were >94%. The pH-controlled experiment was conducted at HRTs of 5 and 10 days at two different pH levels (5.0 and 6.5) of the source ADE. Finally, similar algal yields and nutrient removals were obtained using source ADE at pH 6.5 and 10 days HRT as those in the Mg-enrichment experiment. We demonstrated that pH control in the source ADE through continuous cultivation at the relatively longer HRT can help to maximize algal yield and improve nutrient removal without Mg enrichment.

  • pH treatments in continuous cultivation to maximize microalgal production and nutrient removal from anaerobic digestion effluent of aquatic macrophytes

    Qian J., Liu X., Ban S., Fujiwara M., Kodera T., Akizuki S., Toda T.

    Journal of Applied Phycology  Journal of Applied Phycology    2020.01

    10.1007/s10811-020-02196-z  Joint Work  


    © 2020, Springer Nature B.V. Green algae have great potential for removing inorganic nutrients from anaerobic digestion effluent (ADE), but there is insufficient available magnesium (Mg) in the ADE from aquatic macrophytes for effective algal growth. In this study, we determined suitable pH and hydraulic retention time (HRT) for maximizing growth of the alga Chlorella sorokiniana and nutrient removal efficiency with a flow-through continuous cultivation system. This used ADE from aquatic macrophytes, adjusted to pH 5.0, 6.0, 6.5 and 7.0 at two HRTs of 6 and 8 days. The highest C. sorokiniana biomass concentration was obtained in the pH 6.5 treatment, being 0.50 and 0.67 g L−1 at 6 and 8 days of HRT, respectively, without Mg enrichment. Both were equivalent to 83.6 mg L−1 day−1 of biomass productivity. Removal rates of both ammonium nitrogen and phosphate phosphorus were almost 100% in pH 6.5 and 7.0 treatments and declined to below 60% in pH 5.0 and 6.0 treatments during the study period. The results demonstrated that a source medium pH of 6.5 using a continuous cultivation system (irrespective of the two HRTs), and increasing available Mg, was suitable for maximizing C. sorokiniana biomass productivity and nutrient removal from the ADE.

  • Resting eggs of the perennial copepod Eodiaptomus japonicus in Lake Biwa (Japan)

    Liu X., Ban S., Beyrend D., Dur G., Kuwae M., Makino W., Urabe J.

    Inland Waters  Inland Waters    2020.01

    10.1080/20442041.2019.1671766  Joint Work  


    © 2019, © 2020 International Society of Limnology (SIL). Egg dormancy is a key life history strategy in copepods to temporarily escape catastrophic or repetitive detrimental events and ensure permanent colonization. In Lake Biwa, although the copepod Eodiaptomus japonicus dominates the zooplankton community year-round, it has been known to produce resting eggs, yet little is known about its dormancy. To clarify the nature of dormancy in E. japonicus, we collected a sediment core from Lake Biwa, isolated resting eggs, and conducted hatching experiments to determine the life-cycle traits of the hatched individuals. We isolated 242 eggs (maximum age, 60 years) from the upper 17 cm depth sediments, and although no strict catastrophic event such as seasonal drying up was found, the findings implied that E. japonicus might have a “bet-hedging” strategy. Accumulated egg density above 17 cm was 2.5 × 104 m−2, and mean annual egg flux was 103 m−2 per year. Over the first 10 cm sediments, average egg hatching success was 17%. No egg hatchings were confirmed below 10 cm depth. Embryonic development times of the resting eggs were longer than those of subitaneous eggs, indicating that a lag phase existed until development resumed; 33% of hatched nauplii molted to adulthood, and 80% of females produced offspring. These results suggest potential recruitment from resting eggs in the bottom sediments, which partly serve as an egg bank in this copepod.

  • Nutrient removal from anaerobic digestion effluents of aquatic macrophytes with the green alga, Chlorella sorokiniana

    Kimura S., Yamada T., Ban S., Koyama M., Toda T.

    Biochemical Engineering Journal  Biochemical Engineering Journal  142   170 - 177  2019.02

    10.1016/j.bej.2018.12.001  Joint Work  


    © 2018 Elsevier B.V. Green microalgae have great potential for removing inorganic nutrients from wastewater and anaerobic digestion effluent (ADE). We investigated the cultivation conditions for maximum algal yield and nutrient (ammonium and phosphate) removal rates. The green microalga, Chlorella sorokiniana, was cultured using ADE from anaerobic digestion by two dominant macrophytes, Elodea nuttallii and Egeria densa, which cause environmental problems in Lake Biwa, Japan, because of excessive growth. Available magnesium (Mg) in the ADEs from both macrophytes was not sufficient for maximum algal growth and nutrient removal. We demonstrated that Mg-enrichment was essential for enhancing algal yield in, and nutrient removal rate from, ADEs.

  • Determining suitable submerged macrophyte biomass in terms of dissolved oxygen concentration and biodiversity in the South Basin of Lake Biwa, Japan

    Ishikawa, K., H. Haga, E. Inoue and S. Ban

     Limnology    2019.01

    Joint Work  Joint(The vice charge)

  • Planktivorous fish predation masks anthropogenic disturbances on decadal trends in zooplankton biomass and body size structure in Lake Biwa, Japan

    Liu X., Dur G., Ban S., Sakai Y., Ohmae S., Morita T.

    Limnology and Oceanography  Limnology and Oceanography    2019.01

    10.1002/lno.11336  Joint Work  


    © 2019 Association for the Sciences of Limnology and Oceanography Pelagic zooplankton samples from Lake Biwa, Japan, collected monthly since 1971, were analyzed for biomass and body size structure. Our aim was to clarify the relative effects of food availability and global warming vs. top-down control by fish predation on long-term trends. Annual mean biomass and density-weighted body size were calculated and compared with water temperature, total phosphorus (TP), as a proxy of food amount, and catch per unit effort (CPUE) of Ayu (Plecoglossus altivelis altivelis), as a proxy of planktivorous fish predation pressure. Mean water temperature above 20 m increased by 0.94°C. TP increased until 1974 and then decreased until 1985, becoming stable after that. Ayu CPUE increased until 1987 and then declined. The study period can be divided into two nutritional phases: a high TP phase (1971–1985) and a low-stable TP phase (1986–2010). Five zooplankton taxa, Eodiaptomus japonicus, Cyclopoida spp., Daphnia spp., Bosmina longirostris, and Diaphanosoma orientalis, were continuously dominant. Annual mean total crustacean biomass varied from 0.3 to 3.6 g dry weight m−2, slightly decreasing until 1993 but increasing thereafter. Generalized linear models showed that annual mean body sizes were affected by temperature and CPUE, whereas annual mean biomass was affected by TP and CPUE. These had no effect during the high TP phase, whereas only CPUE affected both traits during the low-stable TP phase. We concluded that zooplankton biomass and body size long-term trends were mostly influenced by fish predation and that eutrophication and global warming impacts might be affected by top-down control.

  • Differences in dissolved phosphate in shallow-lake waters as determined by spectrophotometry and ion chromatography

    Yi R., Song P., Liu X., Maruo M., Ban S.

    Limnology  Limnology    2019.01

    10.1007/s10201-019-00574-2  Joint Work  


    © 2019, The Japanese Society of Limnology. Phosphorus (P) plays important roles in aquatic ecosystems, but accurately determining phosphorus species (particularly bioavailable phosphate) is difficult. When phosphate concentrations are spectrophotometrically measured as soluble reactive P (SRP), the actual values are often overestimated. Ion chromatography is one method for accurately measuring orthophosphate concentrations. To clarify how the spectrophotometrical measurement overestimates actual phosphate concentrations, we compared estimates of phosphate concentrations in lake waters using both methods. SRP and orthophosphate concentrations in water samples collected from four shallow lakes around Lake Biwa, Japan, were determined monthly for 1 year by spectrophotometry and ion chromatography, respectively. SRP concentrations were frequently higher than those for orthophosphate in all lakes throughout the study period, suggesting that SRP and orthophosphate are not equivalent, although a significant relationship was found between them. Orthophosphate/SRP (ortho/SRP) ratios varied spatiotemporally in all lakes (range 0.11–1.04; mean 0.56), being well predicted by biological-mediated relevant parameters using a stepwise multiple logistic regression analysis (R 2 = 0.76). The results implied that organic matter associated with biological activity contributes to the variability in ortho/SRP ratios. Such large variability in ortho/SRP ratios emphasizes the importance of accurate orthophosphate estimates for understanding P dynamics in aquatic ecosystems.

  • Validation of a high-resolution acoustic imaging sonar method by estimating the biomass of submerged plants in shallow water

    Mizuno K., Asada A., Ban S., Uehara Y., Ishida T., Okuda N.

    Ecological Informatics  Ecological Informatics  46   179 - 184  2018.07

    10.1016/j.ecoinf.2018.07.002  Joint Work  


    © 2018 Acoustic sensing is often used for mapping and monitoring aquatic plants in shallow waters. Recently, high-resolution imaging sonar was applied to study a variety of aquatic organisms. This method can provide high-resolution, three-dimensional (3D) acoustic data on the spatial distribution of submerged plants. However, no commercial software packages are available to digitalize the images of submerged plants generated from imaging sonar data, and the high-resolution imaging sonar method has not been standardized because of a lack of empirical data. In this study, we measured the biomass of submerged plants in the north basin of Lake Biwa using high-resolution acoustic imaging sonar and compared the results to directly measured biomass values to validate the utility of high-resolution acoustic imaging sonar as a quantitative method. Biomass was calculated in 10 randomly selected quadrats (1 × 1 m) in Lake Biwa. The analysis of the resulting data indicated a strong correlation between the number of pixels in the digital images of submerged plants and their directly calculated biomass (R2= 0.91, p <.0001). The results suggest that the high-resolution imaging sonar method is a promising tool for estimating the biomass of submerged plants. Thus, this method is expected to contribute to a better understanding of aquatic ecology.

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Review Papers 【 display / non-display