Shinichi Doi, Masahiko Ishihara, Toshiaki Esumi, H. Kamiya, M. Yamamuro
Although reductions in both the abundance of the zooplankton Chironomus plumosus and the fisheries yield of shrimps occurred immediately after the use of neonicotinoids began at Lake Shinji, Japan, there have been no studies on the actual concentration of neonicotinoids in the lake water. Thus, we performed a preliminary analysis of the concentration of neonicotinoids in the lake water and the water in the surrounding watershed. The concentration of neonicotinoids in the lake water at sampling sites influenced by the Hii River was under our detection limit, while lake water at sites influenced by the waste water from rice paddies contained neonicotinoids at concentrations more than the detection limit. The total concentration was below the chronic concentration. Because the concentration of neonicotinoids in the waste water from rice paddies was higher in June than in July, the concentration in Lake Shinji may become higher immediately after the planting of rice at this time.
{"title":"Preliminary report on the concentration of neonicotinoid pesticides in the water of Lake Shinji, Japan","authors":"Shinichi Doi, Masahiko Ishihara, Toshiaki Esumi, H. Kamiya, M. Yamamuro","doi":"10.3739/rikusui.79.179","DOIUrl":"https://doi.org/10.3739/rikusui.79.179","url":null,"abstract":"Although reductions in both the abundance of the zooplankton Chironomus plumosus and the fisheries yield of shrimps occurred immediately after the use of neonicotinoids began at Lake Shinji, Japan, there have been no studies on the actual concentration of neonicotinoids in the lake water. Thus, we performed a preliminary analysis of the concentration of neonicotinoids in the lake water and the water in the surrounding watershed. The concentration of neonicotinoids in the lake water at sampling sites influenced by the Hii River was under our detection limit, while lake water at sites influenced by the waste water from rice paddies contained neonicotinoids at concentrations more than the detection limit. The total concentration was below the chronic concentration. Because the concentration of neonicotinoids in the waste water from rice paddies was higher in June than in July, the concentration in Lake Shinji may become higher immediately after the planting of rice at this time.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47796952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The springs of brownish-colored water called “ moor hot springs ” are force-pumped to the surface in various regions in Hokkaido, northern Japan. The color is due to the presence of dissolved organic matter, mainly humus, in water. The carbon, nitrogen, and phosphorus contents of the dissolved organic matter and humus were determined for the brownish-colored spring waters collected from seven regions in Hokkaido. The DOC, DON, and DOP concentrations ranged from 0.31 － 6.2 mmol L -1 , 0.004 － 0.80 mmol L -1 , and 0.001 － 0.060 mmol L -1 , respectively. Humus was extracted as hydrophobic acid using Supelite DAX-8 resin. The concentrations of carbon, nitrogen and phosphorus in the hydrophobic acid ranged from 0.15 － 3.5 mmol L -1 , 0.004 － 0.24 mmol L -1 , and 0.001 － 0.021 mmol L -1 , respectively. The concentrations of hydrophobic acid carbon were higher than those of hydrophilic acid carbon at the six sites. This implied that hydrophobic acid was main component of dissolved organic matter in most springs. Compared to the surface waters, DOC concentrations showed a wider range and the proportions of hydrophobic acid carbon to DOC also showed a wider range. These findings suggest that DOC and hydrophobic acid concentrations have remarkable variation among brownish springs in Hokkaido. In addition, the C:N and C:P ratios of hydrophobic acid were distributed across a wider range than those of the surface waters. High C:N ratios in DOM and hydrophobic acid were found at sites where well depth was shallowest. Spring water from deeper layers had a longer retention time in the ground. This suggested that for shallow springs, hydrophobic acid was solubilized from the source of DOM, such as peat, recently. Spring water at one site had remarkably high C:P and N:P ratios in DOM and hydrophobic acid. Detection of dissolved inorganic phosphorus indicates that mineralization was activated from organic to inorganic phosphorus. The C:N:P ratios in DOM and hydrophobic acid varied among the sites, suggesting that this ratio may be used as an index to provide a unique profile for each of the brownish-colored springs.
{"title":"Contents of carbon, nitrogen and phosphorus in dissolved organic matter and humus in brownish spring waters in Hokkaido, Japan","authors":"Keishi Takano, E. Uchino, N. Aoyanagi","doi":"10.3739/rikusui.79.169","DOIUrl":"https://doi.org/10.3739/rikusui.79.169","url":null,"abstract":"The springs of brownish-colored water called “ moor hot springs ” are force-pumped to the surface in various regions in Hokkaido, northern Japan. The color is due to the presence of dissolved organic matter, mainly humus, in water. The carbon, nitrogen, and phosphorus contents of the dissolved organic matter and humus were determined for the brownish-colored spring waters collected from seven regions in Hokkaido. The DOC, DON, and DOP concentrations ranged from 0.31 － 6.2 mmol L -1 , 0.004 － 0.80 mmol L -1 , and 0.001 － 0.060 mmol L -1 , respectively. Humus was extracted as hydrophobic acid using Supelite DAX-8 resin. The concentrations of carbon, nitrogen and phosphorus in the hydrophobic acid ranged from 0.15 － 3.5 mmol L -1 , 0.004 － 0.24 mmol L -1 , and 0.001 － 0.021 mmol L -1 , respectively. The concentrations of hydrophobic acid carbon were higher than those of hydrophilic acid carbon at the six sites. This implied that hydrophobic acid was main component of dissolved organic matter in most springs. Compared to the surface waters, DOC concentrations showed a wider range and the proportions of hydrophobic acid carbon to DOC also showed a wider range. These findings suggest that DOC and hydrophobic acid concentrations have remarkable variation among brownish springs in Hokkaido. In addition, the C:N and C:P ratios of hydrophobic acid were distributed across a wider range than those of the surface waters. High C:N ratios in DOM and hydrophobic acid were found at sites where well depth was shallowest. Spring water from deeper layers had a longer retention time in the ground. This suggested that for shallow springs, hydrophobic acid was solubilized from the source of DOM, such as peat, recently. Spring water at one site had remarkably high C:P and N:P ratios in DOM and hydrophobic acid. Detection of dissolved inorganic phosphorus indicates that mineralization was activated from organic to inorganic phosphorus. The C:N:P ratios in DOM and hydrophobic acid varied among the sites, suggesting that this ratio may be used as an index to provide a unique profile for each of the brownish-colored springs.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49555423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Komuro, Y. Tabayashi, H. Kamiya, Y. Saga, Toshikuni Kato, M. Yamamuro
The organic carbon concentration of surface sediment influences bottom water hypoxia. To investigate whether the organic carbon concentration of surface sediment can be used to reconstruct temporal changes in organic carbon concentration, surface sediments from Lake Shinji, Shimane Prefecture, Japan were studied. Samples were analyzed using ignition loss. For comparison with earlier studies, the techniques used by these studies were also used herein, and a conversion formula developed to calculate equivalent organic carbon concentrations. The converted organic carbon concentrations at the same locations in 1982, 1997 and 2016 were compared, and found to be significantly lower in 1997. Since the organic carbon concentration decrease in the 1990s was not detected by an earlier study, it was thought that the decrease for around ten years may have been obscured during early diagenesis. In addition, the organic carbon concentration was significantly higher in sediments collected from the western part of Lake Shinji where a halocline exists. When monitoring hypoxia in brackish lakes, attention should be paid to areas with a halocline as well as the deeper areas.
{"title":"Temporal change in the organic carbon concentration of surface sediment at Lake Shinji during the past 30 years","authors":"T. Komuro, Y. Tabayashi, H. Kamiya, Y. Saga, Toshikuni Kato, M. Yamamuro","doi":"10.3739/rikusui.79.161","DOIUrl":"https://doi.org/10.3739/rikusui.79.161","url":null,"abstract":"The organic carbon concentration of surface sediment influences bottom water hypoxia. To investigate whether the organic carbon concentration of surface sediment can be used to reconstruct temporal changes in organic carbon concentration, surface sediments from Lake Shinji, Shimane Prefecture, Japan were studied. Samples were analyzed using ignition loss. For comparison with earlier studies, the techniques used by these studies were also used herein, and a conversion formula developed to calculate equivalent organic carbon concentrations. The converted organic carbon concentrations at the same locations in 1982, 1997 and 2016 were compared, and found to be significantly lower in 1997. Since the organic carbon concentration decrease in the 1990s was not detected by an earlier study, it was thought that the decrease for around ten years may have been obscured during early diagenesis. In addition, the organic carbon concentration was significantly higher in sediments collected from the western part of Lake Shinji where a halocline exists. When monitoring hypoxia in brackish lakes, attention should be paid to areas with a halocline as well as the deeper areas.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44062753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junki Kobayashi, Yasuhide Nakamura, Yo Miyashita, H. Daido, I. Imai
Harmful algal blooms of certain nuisance cyanobacteria are observed almost every year in Lake Oshima-ohnuma, located in Hokkaido, Japan. However, an unusual milky-white bloom was observed in September 2015. The causative organism of this milky white b loom was an algae-lysing protist, Asterocaelum sp., feeding on Dolichospermum planctonicum , which caused the cyanobacterial bloom. The bloom of the cyanobacterium D. planctonicum was recognized ( 8.6 × 10 3 cells mL -1 ) before the milky-white bloom and the number of Microcystis aeruginosa , a cyanobacterium, increased ( 1.2 × 10 4 cells mL -1 ) after the milky-white bloom. Microscopic observation revealed seasonal fluctuations in the cell numbers of the algae-lysing protist and cyanobacteria. Quantification in this study confirmed the hitherto-known information that members of the genus Asterocaelum feed on D. planctonicum and cause the milky-white bloom. The observation on the number of Asterocaelum sp. as well as that of cyanobacteria is newly proposed to understand the mechanism of harmful algal blooms in freshwater ecosystems better.
{"title":"Milky-white bloom in lake oshima-ohnuma caused by an algae-lysing protist, Asterocaelum sp.","authors":"Junki Kobayashi, Yasuhide Nakamura, Yo Miyashita, H. Daido, I. Imai","doi":"10.3739/RIKUSUI.79.109","DOIUrl":"https://doi.org/10.3739/RIKUSUI.79.109","url":null,"abstract":"Harmful algal blooms of certain nuisance cyanobacteria are observed almost every year in Lake Oshima-ohnuma, located in Hokkaido, Japan. However, an unusual milky-white bloom was observed in September 2015. The causative organism of this milky white b loom was an algae-lysing protist, Asterocaelum sp., feeding on Dolichospermum planctonicum , which caused the cyanobacterial bloom. The bloom of the cyanobacterium D. planctonicum was recognized ( 8.6 × 10 3 cells mL -1 ) before the milky-white bloom and the number of Microcystis aeruginosa , a cyanobacterium, increased ( 1.2 × 10 4 cells mL -1 ) after the milky-white bloom. Microscopic observation revealed seasonal fluctuations in the cell numbers of the algae-lysing protist and cyanobacteria. Quantification in this study confirmed the hitherto-known information that members of the genus Asterocaelum feed on D. planctonicum and cause the milky-white bloom. The observation on the number of Asterocaelum sp. as well as that of cyanobacteria is newly proposed to understand the mechanism of harmful algal blooms in freshwater ecosystems better.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"79 1","pages":"109-117"},"PeriodicalIF":0.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43970414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I investigated the life cycle and habitat of the larvae and pupae of Rhyacophila nigrocephala in middle reaches of the Kino-kawa River, Nara, Japan. Monthly occurrence of larvae, pupae, and adult suggested that this species was bivoltine: the wintering generation started in November 2014 and terminated in May and June 2015, whereas the non-wintering generation started in June and terminated in October 2015. The larvae of this species were predominately found in hyporheic habitat of the riverbed. However, a few of the first instar larvae, which hatched from eggs just before sampling, were collected from the surface of cobbles in June. The later stage of the fifth instar larvae and most pupae also were collected from the surface of cobbles. These results indicate that this burrowing caddis larvae used the surface of the riverbed temporally after hatching from eggs and before pupation.
{"title":"Life cycle and larval and pupal habitat of Rhyacophila nigrocephala in the midstream of the Kino-kawa River","authors":"A. Taira","doi":"10.3739/RIKUSUI.79.119","DOIUrl":"https://doi.org/10.3739/RIKUSUI.79.119","url":null,"abstract":"I investigated the life cycle and habitat of the larvae and pupae of Rhyacophila nigrocephala in middle reaches of the Kino-kawa River, Nara, Japan. Monthly occurrence of larvae, pupae, and adult suggested that this species was bivoltine: the wintering generation started in November 2014 and terminated in May and June 2015, whereas the non-wintering generation started in June and terminated in October 2015. The larvae of this species were predominately found in hyporheic habitat of the riverbed. However, a few of the first instar larvae, which hatched from eggs just before sampling, were collected from the surface of cobbles in June. The later stage of the fifth instar larvae and most pupae also were collected from the surface of cobbles. These results indicate that this burrowing caddis larvae used the surface of the riverbed temporally after hatching from eggs and before pupation.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"79 1","pages":"119-126"},"PeriodicalIF":0.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43013605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Masahiko Kuwata, Kazuaki Tanaka, Takeo Suzuki, T. Toda, N. Natori
{"title":"水凍結乾燥法を用いた淡水産微小生物のSEM試料作製と観察－1（藍藻類）","authors":"Masahiko Kuwata, Kazuaki Tanaka, Takeo Suzuki, T. Toda, N. Natori","doi":"10.3739/RIKUSUI.79.101","DOIUrl":"https://doi.org/10.3739/RIKUSUI.79.101","url":null,"abstract":"","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"79 1","pages":"101-108"},"PeriodicalIF":0.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46797372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Urabe, T. Ishikawa, Izumi Katano, Y. Ishida, K. Nozaki, T. Yoshitomi
{"title":"Water quality bioindicator programs as an educational tool: measuring effectiveness with a university student questionnaire","authors":"M. Urabe, T. Ishikawa, Izumi Katano, Y. Ishida, K. Nozaki, T. Yoshitomi","doi":"10.3739/RIKUSUI.79.1","DOIUrl":"https://doi.org/10.3739/RIKUSUI.79.1","url":null,"abstract":"","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"79 1","pages":"1-18"},"PeriodicalIF":0.0,"publicationDate":"2018-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42350667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ryouta Tsuchiya, Masaki Kihira, Y. Sakanoue, T. Araki
{"title":"Assessment of inhibition effect on growth of Microcystis aeruginosa by autoclaved water extracts from leaves of 104 woody plant species","authors":"Ryouta Tsuchiya, Masaki Kihira, Y. Sakanoue, T. Araki","doi":"10.3739/RIKUSUI.79.41","DOIUrl":"https://doi.org/10.3739/RIKUSUI.79.41","url":null,"abstract":"","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"79 1","pages":"41-48"},"PeriodicalIF":0.0,"publicationDate":"2018-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49024816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A combination of carbon stable isotopic compositions (δCDIC) and chemical compositions of the water in Lake Haruna (LH) was used to investigate origins and supply processes of dissolved inorganic carbon (DIC) during the summer stagnant period in LH, located in the central part of Gunma Prefecture. The temperature depth profile illustrated that the lake water could be divided into two main layers: an epilimnion and a hypolimnion, and the boundary was 7 to 8 m deep as thermocrine. Higher values of pH and dissolved oxygen (DO) were observed to be associated with lower values of DIC, partial CO2 pressure (logPCO2), and δ CDIC in the epilimnion than those in the hypolimnion. This can be attributed to photosynthesis occurring in the epilimnion, since it is the euphotic zone. A Rayleigh model with -16.6‰ as the isotopic enrichment factor (ε) demonstrated that a photosynthesis process, which consumed up to approximately 30% of DIC, sufficiently accounts for the decreases in the DIC concentrations and the increases in the δCDIC values, upon moving upwards from the hypolimnion to the epilimnion. Moreover, δC value for the CO2 gas, which initially equilibrated with DIC in LH, was calculated to be approximately -21‰ , which indicated that DIC in LH originated entirely from the decomposition of organic materials through a respiration process and was not likely to be derived from atmospheric CO2.
{"title":"Origins and supply processes of dissolved inorganic carbon during the summer stagnant period in Lake Haruna, Gunma Prefecture, Japan","authors":"M. Yamanaka","doi":"10.3739/RIKUSUI.78.217","DOIUrl":"https://doi.org/10.3739/RIKUSUI.78.217","url":null,"abstract":"A combination of carbon stable isotopic compositions (δCDIC) and chemical compositions of the water in Lake Haruna (LH) was used to investigate origins and supply processes of dissolved inorganic carbon (DIC) during the summer stagnant period in LH, located in the central part of Gunma Prefecture. The temperature depth profile illustrated that the lake water could be divided into two main layers: an epilimnion and a hypolimnion, and the boundary was 7 to 8 m deep as thermocrine. Higher values of pH and dissolved oxygen (DO) were observed to be associated with lower values of DIC, partial CO2 pressure (logPCO2), and δ CDIC in the epilimnion than those in the hypolimnion. This can be attributed to photosynthesis occurring in the epilimnion, since it is the euphotic zone. A Rayleigh model with -16.6‰ as the isotopic enrichment factor (ε) demonstrated that a photosynthesis process, which consumed up to approximately 30% of DIC, sufficiently accounts for the decreases in the DIC concentrations and the increases in the δCDIC values, upon moving upwards from the hypolimnion to the epilimnion. Moreover, δC value for the CO2 gas, which initially equilibrated with DIC in LH, was calculated to be approximately -21‰ , which indicated that DIC in LH originated entirely from the decomposition of organic materials through a respiration process and was not likely to be derived from atmospheric CO2.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"78 1","pages":"217-230"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49242946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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