記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Great Lakes Research  

The seasonal cycle is an important feature of life, leading to the succession of different species and allowing them to share a common environment. Disruption in the seasonal cycle of many species has been reported, but the source of disruption varies from species to species. Lacustrine zooplankton species are widely acknowledged to respond to climate-induced, thermal and trophic variations. Here, we discuss the case of a warm-adapted copepod in Lake Biwa (i.e., Eodiaptomus japonicus), which experienced changes in trophic status and thermal regime over four decades (1966–2010). We investigated the phenological response of E. japonicus to these changes over this period and aimed to identify the sources of the observed variations. The combined results of wavelet analysis and cluster analysis indicated that E. japonicus exhibited different seasonal cycles during the study period. The common unimodal seasonal cycle of the copepod was disrupted on several occasions during which it presented sometimes two or three modes. Wavelet coherence analysis revealed a strong stationary correlation with lake temperature for the total abundance, the clutch size, and the birth rate, but a transient correlation with the body size of females at the annual scale. No coherence was found with food proxies. Discriminant analysis between unimodal and plurimodal seasonal cycles highlighted the effect of low temperature and high predation in leading to plurimodal cycles. Our study emphasizes the need for considering the seasonality of both lower and higher trophic levels for understanding zooplankton phenology.

DOI： 10.1016/j.jglr.2022.06.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： https://doi.org/10.1093/plankt/fbac052

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： https://doi.org/10.1080/20442041.2022.2058861

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： https://doi.org/10.1002/rcm.9384

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Biochemical Engineering Journal  

Anaerobic digestion effluent (ADE) from aquatic macrophytes (Egeria densa, Elodea nuttallii, Ceratophyllum demersum and Potamogeton maackianus) contains insufficient available magnesium ions (Mg2+) to achieve maximum algal yield and nutrient removal, although Mg concentrations are not scarce at 6–10 mg L−1. Unavailable Mg2+ may be bound into complexes with dissolved organic matter (DOM). We determined the effects of ADE exposure to ultraviolet C (UVC), and degradation of DOM, on Mg availability for growth of Chlorella sorokiniana. Molecular sizes of DOM binding Mg2+ were identified with high-performance size-exclusion chromatography. The results demonstrated that 3 h exposure to UVC can decompose DOM, and release sufficient amounts of available Mg2+, i.e. 0.09 mg from 1 mg of dissolved organic carbon, thus enhancing algal yield and nutrient removal. Almost 50 % of Mg in the ADE was bound by DOM with a molecular size of 400–1170 Da as organic complexes, and the remaining Mg was bound by DOM of < 240 Da and/or Mg2+ and inorganic Mg complexes.

DOI： 10.1016/j.bej.2021.108065

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Climate Change  

Lake surfaces are warming worldwide, raising concerns about lake organism responses to thermal habitat changes. Species may cope with temperature increases by shifting their seasonality or their depth to track suitable thermal habitats, but these responses may be constrained by ecological interactions, life histories or limiting resources. Here we use 32 million temperature measurements from 139 lakes to quantify thermal habitat change (percentage of non-overlap) and assess how this change is exacerbated by potential habitat constraints. Long-term temperature change resulted in an average 6.2% non-overlap between thermal habitats in baseline (1978–1995) and recent (1996–2013) time periods, with non-overlap increasing to 19.4% on average when habitats were restricted by season and depth. Tropical lakes exhibited substantially higher thermal non-overlap compared with lakes at other latitudes. Lakes with high thermal habitat change coincided with those having numerous endemic species, suggesting that conservation actions should consider thermal habitat change to preserve lake biodiversity.

DOI： 10.1038/s41558-021-01060-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Limnology and Oceanography  

Copepods are important secondary producers that support higher trophic levels in aquatic food webs. Large-scale climate events such as climate oscillations and global warming force on physical and chemical conditions in aquatic ecosystems might regulate copepod production through physiological and biochemical processes. We evaluated how large climatic and anthropogenic events impacted secondary production of copepods in Lake Biwa, the largest lake in Japan. We determined demographic traits such as body size, growth rate, biomass and production of the dominant copepod Eodiaptomus japonicus in this lake over four decades (1971–2010). To evaluate in situ food conditions and estimate growth and production for this omnivorous species, we firstly defined a size-based food index (f), that is the ratio of in situ body size to ideal body size in adult females. Values of f were mostly < 1 even during eutrophication (1970s to the early 1980s), suggesting that this copepod continuously suffered from a food shortage in this lake. Quasi-decadal periodicities were detected in f, growth and production (but not biomass) for this copepod throughout the study period. These periodicities were correlated with the Arctic Oscillation, implying that long-term trends in climate could regulate copepod food availability and production. This correlation weakened after 1990, which might be due to a regime shift in lake water temperature, which increased abruptly in the mid-1980s. Global warming might now be disrupting historical quasi-decadal periodicity in growth and production of copepods in Lake Biwa.

DOI： 10.1002/lno.11918

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Aquatic Microbial Ecology  

Zoosporic fungi play an important role in aquatic environments, but their diversity, especially that of parasitic fungi of phytoplankton, has still not been fully revealed. We conducted monthly analyses of the community structure of zoosporic fungi at a pelagic site in Lake Biwa, Japan, from May to December 2016. Metabarcoding analysis, targeted to a large subunit region of ribosomal DNA in the nano-size fraction of particles (2-20 μm), was carried out on the samples. We also counted large phytoplankton and chytrid sporangia attached to the hosts. We detected 3 zoosporic fungal phyla (Blastocladiomycota, Chytridiomycota and Cryptomycota) within 107 operational taxonomic units (OTUs), in which Chytridiomycota was the most diverse and abundant phylum. Few fungal OTUs overlapped between months, and specific communities were detected in each month. These results showed that diverse zoosporic fungi with high temporal variability inhabited the lake. Five large phytoplankton species were found to be infected by chytrids: Staurastrum dorsidentiferum, S. rotula, Closterium aciculare, Asterionella formosa and Aulacoseira granulata. Some chytrids were detected by metabarcoding analysis: Zygophlyctis asterionellae infecting A. formosa, Staurastromyces oculus infecting S. dorsidentiferum and Pendulichytrium sphaericum infecting A. granulata. One OTU detected in association with infected C. aciculare by microscopic counting might have been an obligate parasitic chytrid of C. aciculare. The results indicated that a combination of metabarcoding and microscopic analysis revealed more information on zoosporic fungi, including those that are parasitic.

DOI： 10.3354/AME01970

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Plankton Research  

Egg size has numerous ecological implications for zooplankton, and can influence hatching duration and female fecundity. In this study, temperature functions of embryonic development time (EDT) were determined in the copepod Eodiaptomus japonicus from Lake Biwa, in the cold and warm seasons, to clarify synergistic effects of egg size and temperature on EDT. EDT was longer for cold season eggs than warm ones, but both seasons were well fitted by Bělehrádek's function. Egg size was significantly correlated with female body size within seasons, but the relationship did not differ significantly between seasons. These results suggest that seasonal variation in EDT, which was associated with egg size, may result from temperature-mediated variation of female body size, because larger females produced larger eggs as temperature decreased. Larger eggs may enhance fitness under severe food conditions in winter due to high hatchability and naupliar survival.

DOI： 10.1093/plankt/fbaa045

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Aquaculture Research  

© 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.

DOI： 10.1111/are.14723

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Science of the Total Environment  

© 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.

DOI： 10.1016/j.scitotenv.2020.138993

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Biodeterioration and Biodegradation  

© 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.

DOI： 10.1016/j.ibiod.2020.104923

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inland Waters  

© 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.

DOI： 10.1080/20442041.2019.1671766

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Applied Phycology  

© 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.

DOI： 10.1007/s10811-020-02196-z

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Biochemical Engineering Journal  

© 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.

DOI： 10.1016/j.bej.2018.12.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Limnology  

© 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.

DOI： 10.1007/s10201-019-00574-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Limnology and Oceanography  

© 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.

DOI： 10.1002/lno.11336

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Ecological Informatics  

© 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.

DOI： 10.1016/j.ecoinf.2018.07.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1007/s10201-017-0537-8

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（主担当）  

DOI： 10.1007/s10201-018-0557-z

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Plankton and Benthos Research  

© 2018, Plankton Society of Japan. All rights reserved. The freshwater calanoid copepod Mongolodiaptomus malaindosinensis is an endemic species of the lower Mekong basin, including Malaysia. The relationships between environmental factors and life history traits have been reported for many copepods, while they have never been assessed in this tropical species. Post-embryonic development time (post-EDT), body size and survival rate of M. malaindosinensis were determined under different algal concentrations of Chlamydomonas reinhardtii and Cryptomonas tetrapyrenoidosa at 25°C, to clarify the effects of algal species and carbon supply on their somatic growth and survival. Post-EDT until adult in M. malaindosinensis decreased with increasing food carbon supply regardless of the algal species tested. Although naupliar developments were the shortest at 10 4 cells mL −1 of C. reinhardtii, food shortage delayed the development time and also induced high mortality during the copepodid stages. The highest survival rate of 93% was obtained in the copepods fed on C. tetrapyrenoidosa at 5×10 4 cells mL −1 , whereas the survival rates in the remaining lower carbon supply were <23%. The most sensitive stages were the 1st copepodid stage, as indicated by high stage-specific mortalities, because of large morphological and physiological changes in this transitional stage. Prosome length of adult M. malaindosinensis positively correlated with food carbon supplies, though females were larger than males. Somatic growth rate exponentially increased with increasing food carbon supplies with a threshold at around 4.0 mgC L −1 . These results suggest that tropical copepods may be adapted to higher food quantities due to their high metabolic rates under high temperature conditions.

DOI： 10.3800/pbr.13.163

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記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1093/plankt/fbw084

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1016/j.biortech.2017.04.046

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1093/jcbiol/rux089

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（主担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1007/s00436-015-4829-9

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley   参加形態：共同（副担当）  

DOI： 10.1111/fwb.12626

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1007/s00436-015-4783-6

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

DOI： 10.1007/s10201-013-0417-9

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本陸水学会   参加形態：共同（副担当）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer   参加形態：共同（主担当）  

DOI： 10.1007/s10201-012-0387-3

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：水産増殖   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Biogeosicences   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：National Research Council Canada   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ASLO   参加形態：共同（副担当）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本プランクトン学会   参加形態：共同（主担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Biocontrol Science   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Microbiology   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Hydrological Research Letter   参加形態：共同（副担当）  

DOI： 10.3178/HRL.3.45

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The company of biologist Ltd.   参加形態：共同（主担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier   参加形態：共同（主担当）  

DOI： 10.1016/j.polar.2009.08.002

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer   参加形態：共同（主担当）  

DOI： 10.1007/s10201-007-0230-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本陸水学会   参加形態：共同（副担当）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：－   参加形態：共同（副担当）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本海洋学会   参加形態：共同（副担当）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：/  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：/   参加形態：共同（主担当）  

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記述言語：英語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：Hokkaido University   参加形態：共同（副担当）  

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記述言語：英語   掲載種別：研究論文（大学，研究機関等紀要）   出版者・発行元：Hokkaido University   参加形態：共同（主担当）  

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記述言語：英語  

The densities and growth rates of dominant phytoplankton in Lake Oshima-Ohnuma were determined during May to July 1996 to clarify the mechanism of change from spring-dominant to summer-dominant phytoplankton species, examining the influence of zooplankton grazing and nutrient limitation. The dominant phytoplankton in April and May were Asterionella gracillima and Nitzschia spp. Their growth rates were low in May and their densities fell thereafter. The bottle experiment suggests that the main reason for decreases in dominant species has been nutrient deficiency, and zooplankton (sized from 30 to 160μm) have supported the growth of A. gracillima to recycle nutrients in May. The maximum growth rate was shown by Melosira (Aulacoseira) ambigua living at 2m in May and June. Although the growth rate of the summer-dominant species Melosira (Aulacoseira) granulata was not as high as that of M. ambigua in May and June, the ambient density increased from late June. Survival in the lower zone of the unstratified euphotic layer might have contributed to the abundance of M. granulata, since the growth rate of this species was not so low as that of M. ambigua at 6m in June and July. The bottle experiment suggests that the growth of M. granulata was also nutrient limited in June and July and that zooplankton grazing was partially responsible for repressing the biomass of M. granulata before it began growing rapidly in late June.

DOI： 10.1007/s102010170013

Scopus

DOI： 10.1016/S0924-7963(97)00073-0

DOI： 10.5928/kaiyou.7.21

DOI： 10.3354/meps157287

記述言語：英語   出版者・発行元：KLUWER ACADEMIC PUBL  

Diel vertical migration (DVM) and diel feeding rhythm of two cladocerans, Daphnia longispina and Bosmina coregoni were investigated at the pelagic area of Lake Toya (Hokkaido, Japan) in May, August and October 1992. Both species performed 'nocturnal' DVM. The amplitude of DVM, however, became smaller from May to October. Such seasonal variations in DVM could not be explained by light penetration and/or water temperature. The two species had a clear feeding rhythm; they fed at night in May and October but also after sunrise in August. These feeding rhythms appeared to be related to the light-dark cycle, but were not necessarily associated with their DVM. We suggest that the diel feeding rhythm and DVM are regulated independently by light cues.

Web of Science