著者

今井 一気

出版者

早稲田大学社会科学学会

雑誌

早稲田社会科学総合研究. 別冊, 2018年度学生論文集 (ISSN:13457640)

巻号頁・発行日

pp.173-184, 2019-03-25

著者

佐藤 毅彦 前田 健悟 今井 一雅 戎崎 俊一 川井 和彦 坪田 幸政

出版者

独立行政法人宇宙航空研究開発機構

雑誌

特定領域研究

巻号頁・発行日

2005

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平成17年度に引き続き、星座カメラi-CANを米国ニューメキシコ州(アパッチポイント天文台)、スペイン・カナリー諸島(ブラッドフォード望遠鏡施設)、米国ハワイ州(国立天文台すばる望遠鏡)に設置した。これにより、海外6サイト、国内1サイトのネットワークが完成した。特にスペイン・サイトの設置は、日本の早朝に夜空の観察を可能とし、学校の授業での利用に対する制限を大幅に緩和した。また、ハワイ・サイトは、子どもたちが帰宅した後、自宅から星空を見るのに便利である。授業後の感想に大変多い「家へ帰ったら、早速見てみたい」という希望を叶えるものとなった。授業実践も、熊本市立龍田小学校、同清水小学校、同松尾西小学校、天草市立本町小学校、北海道教育大学附属小・中学校、石狩市立石狩小学校などにおいて、多数行った。また、科学技術館におけるサイエンス・ライブショー「ユニバース」での定期的な活用、熊本市博物館における特別講演会「ワンダー・プラネタリウム:南天の星空を見上げて」など、社会教育への展開も精力的に行った。これらを通じて、子どもたちの反応をアンケートにもとづき評価し、「興味・関心・意欲」といった情意面、「知識・理解」といった認知面の両方において有効な天体学習ツールに成長し得たことを確認できた。今後は授業での活用を継続するとともに、科学館・博物館における有効利用、さらに宇宙航空研究開発機構などで推進されている宇宙開発の啓蒙の一端を担うツールとしての発展が期待される。

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1985, no.17, pp.7-17, 1984-10-01 (Released:2010-02-22)

---

Shigeko Uriu, nee Masuda is one of the first Japanese girl students sent to the U.S. in 1871. When she arrived at Washington D.C., she was only ten years old. In 1872 she was placed in the care of Rev. Dr. John S.C. Abbott in Fair Haven, Conn., and his daughter Miss Nelly Abbott became her second mother and teacher. For seven years she was brought up by Miss Abbott till she entered the Vassar College in Poughkeepsie, N. Y..In 1881, on her graduation from the Vassar College she came back to Japan. Next year she became a music teacher at the request of the Ministry of Education, and at the end of this year she got married to Sotokichi Uriu, a naval officer who was the first Japanese graduate of Annapolis. Thereafter besides teaching music and English at many schools, such as Tokyo Higher Girls' School, Tokyo Music School, and Tokyo Women's Higher Normal School, she lived to be a good wife and wise mother.On the 3rd of November, 1928, suffering from cancer of the rectum, she died at the age of sixty-seven.Now her fourth son is alive and has many articles left by his parents. Among them I found two interesting pieces of writing.One is her diary written in a notebook when she was at thirteen and fourteen years of age and the other is a document under the title of‘My recollections of the Early Meidji days’.The former is written in fairly good English, though it was only a few years since she began to learn English. According to her diary she often made a trip around New England with Miss Abbott every summer vacation, and in July the 7th, 1875, after listening to Longfellow ricite his poems, she met him in Brunswick, Main. She also confessed the Christian faith in this diary of hers.The latter written in 1927, the year before she died, was printed in the Japan Advertiser on the 11th of September that year. In this article the observation of her childhood and the various amusing events which happened before and after her sending to America are described vividly, and it is concluded with the following:Our stay of three years in America was prolonged to ten years during which time we enjoyed perfect freedom as all American young girls of good families enjoy and the memory of our young lives in that dear country will nevelr fade.

著者

今井 一雅

出版者

高知工業高等専門学校

雑誌

基盤研究(C)

巻号頁・発行日

2016-04-01

---

2016年7月に木星に到達したNASAの木星極軌道探査機JUNOと、アメリカにある世界最高レベルの感度を持つ低周波電波望遠鏡LWAを使った木星電波観測により、木星電波の放射機構を解明する上で重要となる電波放射源の位置やそれに関連する電波放射ビーム特性を調べ、3次元的な木星電波放射ビーム構造を明らかにすることを目的としている。LWAの観測データについては、木星電波のダイナミックスペクトラム上に見られる斜めの縞状構造のモジュレーションレーンに着目し、偏波特性を考慮したモジュレーションレーンの傾きの解析を行った。このモジュレーションレーンの測定によって、木星電波源の位置が推定でき、従来から同定されている木星電波源の衛星イオの位置に関連するIo-CとIo-Bについて、起源の異なる電波源の領域があることがわかった。それらを新たにIo-C'とIo-B'を呼ぶことにし、その電波源の領域が、衛星イオを貫く磁力線の根元で最もオーロラ発光強度が高い経度と一致するという重要な情報が得られた。特にIo-Cの領域においては、木星の北磁極側と南磁極側の両側から同時に電波が放射されていることがわかり、複雑な木星電波放射源の様相を明らかにすることができた。また、JUNOで観測された木星電波観測データの解析から、従来の木星電波放射が木星の磁力線に対して角度を持ち磁力線に軸対称に放射されているとするコニカルシート状のビーム構造を支持する結果が出始めている。つまり、JUNOから見た木星電波の緯度方向のビーム構造は、コーン状の一部を見ていることを示しており、電波放射機構を解明する上で、非常に重要な情報を得ることができたことになる。今後、さらに多くのJUNOで観測された木星電波のデータ解析を行うことにより、コニカルシート状のビーム構造が一般的であるかの統計解析も行っていく予定である。

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1983, no.15, pp.15-32, 1982

---

On the 13th of February, 1860, the U. S. Steam Frigate Powhatan left Yokohama for the United States taking on board the members of the first Japanese Embassy to the U. S. Among them there were two men who had relation to the Kaga Clan. One is Kanae Sano and the other is Onojiro Tateishi. Sano had already been a professor of gunnery in Kaga then, but Tateishi, who was then a probationer interpreter, became an English teacher of Kanazawa School of English in Kaga ten years later.<BR>It is common knowledge that Tateishi was nicknamed &ldquo;Tommy&rdquo; and was a star among the American ladies.<BR>At sea some of the members learned English and Sano wrote this in a letter to a friend of his in Kaga. In it he mentioned that the chaplain, the Rev. Mr. Wood taught English to them through the assistance of Tommy.<BR>It goes without saying that Tommy was often reported in the American newspapers, but it is striking that Sano was also reported in the papers despite of his low position. The intellectual ability and culture which he exhibited impressed so many Americans.<BR>After he visited six countries in Europe joining the Takeuchi Mission to Europe in 1862, making good use of his experiences he devoted himself to the various fields of duties such as military affairs, diplomacy, education, etc. for the benefit of the Kaga Clan.<BR>After the Meiji Restoration he was appointed to an officer of the Ministry of Military Affairs by the new Japanese Government, and in 1871, in Tokyo he established the Kyoryu Gakko, a school in which the practical English was taught.<BR>He died of cholera on the 22nd of October, 1877 at the age of 47.<BR>Tommy was the second son of a retainer of the Tokugawas and born in 1843. His name was Keijiro Komeda, but as he could take part in the Japanese Embassy to the U. S. in the capacity of the adopted son of his uncle Tokujuro Tateishi, interpreter, his name was given as Onojiro Tateishi.<BR>After coming back to Japan he was appointed to the interpreter attached to the American legation in Yedo, and at the same time he kept an English school and taught many students.<BR>Through the period of the Meiji Restoration he engaged in battle against the new Government, and was injured in the leg. After the war he came back to Tokyo, but he changed his name into Keijiro Nagano so as not to be arrested.<BR>In 1872 he took part in the Iwakura Mission to America and Europe, visiting the U. S. and eleven European countries.<BR>After returning to Japan he successively held the posts of an officer of the Ministry of Industry and the Authorities of Hokkaido Development. From 1887 till 1889 he went to Hawaii as the superintendent of Japanese emigrants.<BR>Afterwards, for about eighteen years since 1891 he had been serving the Osaka High Court as an interpreter, and died on the 13th of January, 1917.

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1983, no.15, pp.15-32, 1982 (Released:2009-09-16)

参考文献数

16

---

On the 13th of February, 1860, the U. S. Steam Frigate Powhatan left Yokohama for the United States taking on board the members of the first Japanese Embassy to the U. S. Among them there were two men who had relation to the Kaga Clan. One is Kanae Sano and the other is Onojiro Tateishi. Sano had already been a professor of gunnery in Kaga then, but Tateishi, who was then a probationer interpreter, became an English teacher of Kanazawa School of English in Kaga ten years later.It is common knowledge that Tateishi was nicknamed “Tommy” and was a star among the American ladies.At sea some of the members learned English and Sano wrote this in a letter to a friend of his in Kaga. In it he mentioned that the chaplain, the Rev. Mr. Wood taught English to them through the assistance of Tommy.It goes without saying that Tommy was often reported in the American newspapers, but it is striking that Sano was also reported in the papers despite of his low position. The intellectual ability and culture which he exhibited impressed so many Americans.After he visited six countries in Europe joining the Takeuchi Mission to Europe in 1862, making good use of his experiences he devoted himself to the various fields of duties such as military affairs, diplomacy, education, etc. for the benefit of the Kaga Clan.After the Meiji Restoration he was appointed to an officer of the Ministry of Military Affairs by the new Japanese Government, and in 1871, in Tokyo he established the Kyoryu Gakko, a school in which the practical English was taught.He died of cholera on the 22nd of October, 1877 at the age of 47.Tommy was the second son of a retainer of the Tokugawas and born in 1843. His name was Keijiro Komeda, but as he could take part in the Japanese Embassy to the U. S. in the capacity of the adopted son of his uncle Tokujuro Tateishi, interpreter, his name was given as Onojiro Tateishi.After coming back to Japan he was appointed to the interpreter attached to the American legation in Yedo, and at the same time he kept an English school and taught many students.Through the period of the Meiji Restoration he engaged in battle against the new Government, and was injured in the leg. After the war he came back to Tokyo, but he changed his name into Keijiro Nagano so as not to be arrested.In 1872 he took part in the Iwakura Mission to America and Europe, visiting the U. S. and eleven European countries.After returning to Japan he successively held the posts of an officer of the Ministry of Industry and the Authorities of Hokkaido Development. From 1887 till 1889 he went to Hawaii as the superintendent of Japanese emigrants.Afterwards, for about eighteen years since 1891 he had been serving the Osaka High Court as an interpreter, and died on the 13th of January, 1917.

著者

仲村 康秀 松岡 數充 今井 一郎 石井 健一郎 桑田 晃 河地 正伸 木元 克典 鈴木 紀毅 佐野 雅美 José M. Landeira 宮本 洋臣 西川 淳 西田 周平

出版者

日本プランクトン学会

雑誌

日本プランクトン学会報 (ISSN:03878961)

巻号頁・発行日

vol.66, no.1, pp.22-40, 2019-02-25 (Released:2019-02-28)

参考文献数

137

---

Plankton are aquatic organisms unable to swim against the current, and they include diverse taxa of different phylogenetic origins. The taxonomy, phylogeny and ecology of nine plankton groups are reviewed in this paper, in order to comprehensively understand the latest information and current situation of plankton studies. The order-level classification of dinoflagellates was re-arranged, but the classification system is still not well organized at the family-level. The taxonomy of raphidophytes and dictyochophytes was partly confused, however, molecular studies provided clear categorization between these groups. The diatoms could be identified by observing some important morphological characteristics. Yet, these characteristics are sometimes not observable because of inappropriate specimen treatments, and furthermore, the morphological terms are not enough unified, resulting that the species-level identification is complicated and difficult. Recent studies revealed the cryptic diversity and high abundance of some microalgae, such as haptophytes and prasinophytes. The diversity and ecology of planktonic foraminifers have been clarified, but those of radiolarians and phaeodarians are still wrapped in mystery. The classification needs to be re-arranged especially for collodarians, phaeodarians and acantharians. The phylogeny of copepods has been elucidated, and this group was re-classified into 10 orders. Future studies should clarify their evolutionary process and create useful databases for easier identification. The methods to reveal the larva-adult correspondence are established for decapods, and further clarification of the correspondence is expected. The classification system of chaetognaths has been updated, and the intra-species diversity is also being studied. The species diversity of scyphozoans has not been well clarified especially for deep-sea species, and their classification still involves problems such as cryptic species. The dataset including DNA sequences and different types of images (taken in the field and under the microscope, etc.) should be accumulated for comparing the data from different methods (e.g., direct microscopy, optics-based survey and environmental DNA analysis).

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1985, no.17, pp.7-17, 1984

---

Shigeko Uriu, nee Masuda is one of the first Japanese girl students sent to the U.S. in 1871. When she arrived at Washington D.C., she was only ten years old. In 1872 she was placed in the care of Rev. Dr. John S.C. Abbott in Fair Haven, Conn., and his daughter Miss Nelly Abbott became her second mother and teacher. For seven years she was brought up by Miss Abbott till she entered the Vassar College in Poughkeepsie, N. Y..<BR>In 1881, on her graduation from the Vassar College she came back to Japan. Next year she became a music teacher at the request of the Ministry of Education, and at the end of this year she got married to Sotokichi Uriu, a naval officer who was the first Japanese graduate of Annapolis. Thereafter besides teaching music and English at many schools, such as Tokyo Higher Girls' School, Tokyo Music School, and Tokyo Women's Higher Normal School, she lived to be a good wife and wise mother.<BR>On the 3rd of November, 1928, suffering from cancer of the rectum, she died at the age of sixty-seven.<BR>Now her fourth son is alive and has many articles left by his parents. Among them I found two interesting pieces of writing.<BR>One is her diary written in a notebook when she was at thirteen and fourteen years of age and the other is a document under the title of&lsquo;My recollections of the Early Meidji days&rsquo;.<BR>The former is written in fairly good English, though it was only a few years since she began to learn English. According to her diary she often made a trip around New England with Miss Abbott every summer vacation, and in July the 7th, 1875, after listening to Longfellow ricite his poems, she met him in Brunswick, Main. She also confessed the Christian faith in this diary of hers.<BR>The latter written in 1927, the year before she died, was printed in the Japan Advertiser on the 11th of September that year. In this article the observation of her childhood and the various amusing events which happened before and after her sending to America are described vividly, and it is concluded with the following:<BR>Our stay of three years in America was prolonged to ten years during which time we enjoyed perfect freedom as all American young girls of good families enjoy and the memory of our young lives in that dear country will nevelr fade.

著者

今井 一気

出版者

早稲田大学社会科学学会

雑誌

早稲田社会科学総合研究. 別冊, 2018年度学生論文集 (ISSN:13457640)

巻号頁・発行日

pp.173-184, 2019-03-25

著者

今井 一雅 北村 健太郎 高田 拓 若林 誠 浅井 文男 平社 信人 梶村 好宏 村上 幸一 篠原 学 島田 一雄

出版者

日本航空宇宙学会

雑誌

宇宙科学技術連合講演会講演集 (ISSN:18841945)

巻号頁・発行日

vol.60, 2016-09-06

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1984, no.16, pp.51-62, 1983

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At the end of the second year of Meiji (1869 A. D.) an English <I>oyatoi</I> came to Nanao, a port town in Kaga, in order to teach English and French at a school there. <BR>The name of the school was Nanao Gogakusho i. e. Nanao Foreign Language School that was established by Kanazawa Clan as the branch school of Chienkan, English language school founded by the clan in Kanazawa.<BR>This Englishman's name has been known as Osborn, but it was not until seven years ago that his first name became known. His full name was Percival Osborn, and at the same time his Japanese wife's name and his career in Japan etc. were proved as the fruit of the late Mr. Tsukahara's and my many years' study.<BR>Percival was born in London on the 16th of September in 1842. His father John Jenks Osborn was an American army officer stationed at Aachen in Germany and he was given an education in Germany and Switzerland besides England. So he learned German and French in addition to English.<BR>In 1867 he landed in Japan via China. When he came to Nanao, his Japanese wife named Seto was pregnant and on the 15th of June in 1870 his son George was born there.<BR>The number of his pupils was about thirty and many among them grew up to make their names immortal. They contributed greatly to the modernization of Japan, and especially following six men are famous : Joji Sakurai ; a doctor of science, Jokichi Takamine; a doctor of pharmacy and science, Isoji Ishiguro; a doctor of engineering, Jintaro Takayama; ditto, Seijiro Hirai; ditto, and Sotokichi Uriu; an admiral.<BR>For about two years from 1871 he had been employed as a teacher of English and French at the school of Okayama Clan.<BR>In Novenber 1872 he was employed in the Kanagawa prefectural government and had filled the post of foreign secretary for nearly seventeen years. Japanese government decorated him with the third order for his sincere service to the local government.<BR>In 1890 he went back to England with his wife and two children. His daughter Agnes was born in Yokohama in 1876.<BR>After he returned to his native country, he lived in comfort and died at Vevey in Switzerland in 1905. Now his granddaughter Margaret is in good health and lives at Uckfield in East Sussex, England.

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1984, no.16, pp.51-62, 1983 (Released:2009-09-16)

参考文献数

17

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At the end of the second year of Meiji (1869 A. D.) an English oyatoi came to Nanao, a port town in Kaga, in order to teach English and French at a school there. The name of the school was Nanao Gogakusho i. e. Nanao Foreign Language School that was established by Kanazawa Clan as the branch school of Chienkan, English language school founded by the clan in Kanazawa.This Englishman's name has been known as Osborn, but it was not until seven years ago that his first name became known. His full name was Percival Osborn, and at the same time his Japanese wife's name and his career in Japan etc. were proved as the fruit of the late Mr. Tsukahara's and my many years' study.Percival was born in London on the 16th of September in 1842. His father John Jenks Osborn was an American army officer stationed at Aachen in Germany and he was given an education in Germany and Switzerland besides England. So he learned German and French in addition to English.In 1867 he landed in Japan via China. When he came to Nanao, his Japanese wife named Seto was pregnant and on the 15th of June in 1870 his son George was born there.The number of his pupils was about thirty and many among them grew up to make their names immortal. They contributed greatly to the modernization of Japan, and especially following six men are famous : Joji Sakurai ; a doctor of science, Jokichi Takamine; a doctor of pharmacy and science, Isoji Ishiguro; a doctor of engineering, Jintaro Takayama; ditto, Seijiro Hirai; ditto, and Sotokichi Uriu; an admiral.For about two years from 1871 he had been employed as a teacher of English and French at the school of Okayama Clan.In Novenber 1872 he was employed in the Kanagawa prefectural government and had filled the post of foreign secretary for nearly seventeen years. Japanese government decorated him with the third order for his sincere service to the local government.In 1890 he went back to England with his wife and two children. His daughter Agnes was born in Yokohama in 1876.After he returned to his native country, he lived in comfort and died at Vevey in Switzerland in 1905. Now his granddaughter Margaret is in good health and lives at Uckfield in East Sussex, England.

著者

今井 一郎

出版者

公益社団法人 日本マリンエンジニアリング学会

雑誌

日本舶用機関学会誌 (ISSN:03883051)

巻号頁・発行日

vol.10, no.2, pp.130-135, 1975-02-01 (Released:2010-05-31)

著者

今井 一良

出版者

日本英学史学会

雑誌

英学史研究 (ISSN:03869490)

巻号頁・発行日

vol.1990, no.22, pp.1-14, 1989 (Released:2010-01-25)

参考文献数

7

---

In 1888 Kyoka Izumi (born Kyotaro Izumi in 1873), who failed in the entrance examination of the Fourth Higher Middle School at Kanazawa, entered a private school kept by Tajiro Inami, and was soon left in charge of English lessons there, since he had attended a missonary school (the Hokuriku Eiwa Gakko) before and was very good at English.Tajiro Inami was also known as a compiler of an English-Japanese dictionary entitled 'the Shinsen Eiwa Jiten'. This dictionary was published in 1886 from the Unkondo's which had already issued a literary magazine, 'the kinjo Shishi'.Therefore, the advertisements of sale of Inami's dictionary were put in this magazine many times, and in addition so much information concerning English learning at Kanazawa or in Tokyo was reported.In this essay, I would like to give a full detail of the following items, amplifying the above-mentioned matter : 1. Biographical Sketch of Tajiro Inami.2. On 'the Kinjo Shinshi '.3. On 'the Shinsen Eiwa Jiten'.4. Situation of English learning at Kanazawa about the middle of 1880's based on the reports in the Kinjo Shinshi.

著者

笹岡 勇佑 須藤 洸基 清水 義彦 今井 一雅 河合 和久

出版者

一般社団法人電子情報通信学会

雑誌

電子情報通信学会技術研究報告. ET, 教育工学 (ISSN:09135685)

巻号頁・発行日

vol.113, no.482, pp.213-218, 2014-03-01

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英単語を習得する方法には,従来型の単語カードを使ったものから,Web上のオンライン教材,近年では携帯情報端末上で学習する方法などがある.報告者らは,携帯情報端末の利用場面(シーン)に着目し,いわゆる「すきま時間」にも英単語の学習から復習テストが行なえる,高専生を対象とした英単語学習支援システムを開発した.このシステムを高専専攻科の学生20名に授業の一部として17週間利用させ,その利用状況や習得度を分析し,学習支援効果の検討を行なった.利用前と利用後テスト,利用時間の状況,利用者アンケートの結果から,学習支援効果を認めた.

著者

今井一彦

雑誌

靴の医学

巻号頁・発行日

vol.6, pp.54-56, 1992

被引用文献数

3

著者

手代木 純 梛野 良明 山口 亜希子 今井 一隆 半田 真理子

出版者

日本緑化工学会

雑誌

日本緑化工学会誌 (ISSN:09167439)

巻号頁・発行日

vol.34, no.1, pp.291-294, 2008-08-31

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国営昭和記念公園みどりの文化ゾーンの「花みどり文化センター」の屋上庭園「浮游の庭」において,環境負荷低減効果として特殊空間緑化による温熱環境改善効果,および雨水流出遅延効果を解析した。その結果,2007年夏で最も暑い8月16目(最高気温37.6℃)では「浮游の庭」における潜熱フラックスは一日で9.7MJ/m^2あることが明らかとなり,温熱環境改善効果が検証された。またドレーンからの排水量,降水量等の計測結果から,雨水貯留および遅延について効果があること,年間の流出係数は0.76であることが明らかとなった。

著者

今井 一仁

出版者

公益社団法人日本数学教育学会

雑誌

数学教育論文発表会論文集

巻号頁・発行日

vol.39, pp.121-126, 2006-10-07

著者

原田 柚子 今井 一博 髙嶋 祉之具 中 麻衣子 松尾 翼 南谷 佳弘

出版者

特定非営利活動法人 日本呼吸器外科学会

雑誌

日本呼吸器外科学会雑誌 (ISSN:09190945)

巻号頁・発行日

vol.36, no.6, pp.621-626, 2022-09-15 (Released:2022-09-15)

参考文献数

16

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区域切除はIA期の非小細胞肺癌(NSCLC)に対する標準的治療の一つであるが,根治を目的として区域切除を行う際は適切なリンパ節転移の評価と,切除断端の確保が必須である.本研究の目的は,術中判断で区域切除から肺葉切除に移行した症例の頻度と理由,予後を検討することである.当院で2014年から2020年までに臨床病期IA期のNSCLCに対して区域切除が予定された121名の転帰を検討した.121例中8例が術中診断と術者の判断により区域切除から葉切除に変更されていた.4例が術中迅速診断でリンパ節転移陽性の診断,4例は手術手技に関する問題が変更の主な要因となっていた.リンパ節転移の評価には迅速免疫組織化学染色も併用した.区域切除を完遂した患者(n=113)と肺葉切除術に変更した患者(n=8)の間で,全生存期間に有意差はなかった(P=0.5828).適切な術中の判断がなされれば,術前に区域切除の適応と考えられた症例のうち,肺葉切除すべき症例を発見することができる.

著者

小林 淳希 宮下 洋平 大洞 裕貴 織田 さやか 田中 邦明 松野 孝平 山口 篤 今井 一郎

出版者

Faculty of Fisheries Sciences, Hokkaido University

雑誌

Memoirs of the Faculty of Fisheries Sciences, Hokkaido University (ISSN:24353361)

巻号頁・発行日

vol.60, pp.33-67, 2021-12

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Onuma and Konuma are belonging to the Onuma Quasi-National Park and are located in southern Hokkaido. The fisheries and tourism are important industries in this lake area. Eutrophication has progressed in these lakes since the 1980s, and nuisance blooms of cyanobacteria have occurred every summer to autumn. The outbreaks of cyanobacterial blooms substantially destroy the ecosystem due to the production of cyanobacterial toxins, and effective countermeasures are urgently needed. However, in the lakes of Oshima Onuma, there is a paucity of knowledge about the appearance trends of phytoplankton including cyanobacteria. Therefore, seasonal monitorings were carried out on the phytoplankton community in the water column and the relatioships were discussed between dynamics of phytoplankton communities and changes in environmental factors in the lakes of Oshima Onuma. The survey was conducted once a month as a rule at Stns. 1-5 (Stn. 1 is the northeastern end of Onuma, only Stn. 5 is in Konuma) and at Stn. OP and Stn. OC along the shore of the Lake Onuma during the period of May-November 2015 and April- October 2016. The parameters of hydraulic environments were measured about water temperature, pH, transparency, dissolved oxygen, nutrient concentrations (NO3-N, NO2-N, NH4-N, PO4-P, SiO2-Si), chlorophyll a concentration, and pheophytin. The chlorophyll a concentration of the surface water showed a single-peak type fluctuation with the maximum value (28.7 μg L-1 at Stn. 2) in August at all stations in 2015. In 2016, the largest single-peak type fluctuation was observed in September- October with the exception of Stn. 3. Concerning the seasonal variation of the phytoplankton species, the proportion of Uroglena volvox (Chrysophyceae) was high at Stn. 5 in May, but the pennate diatoms Fragilaria crotonensis and Asterionella formosa, and the centric diatoms Aulacoseira spp. at other stations other than Stn. 5. As for cyanobacteria in August 2015, Dolichospermum planctonicum, possessing an ability of nitrogen-fixation, dominated (maximum 4.4×104 cells mL-1) at all the stations under the severe nitrogen-deficient conditions (N/P &lt; 16). In the following year 2016, the cell densities of Dolichospermum spp. were low, and Microcystis spp. dominated at all the stations (up to 5.6×104 cells mL-1) with the enough nitrogen conditions. It is hence thought that the N / P ratio determined the dominant species of cyanobacteria in the summer season. In September and thereafter, the number of phytoplankton cells decreased on the whole in both years, and the centric diatoms Aulacoseira spp., Cyclotella spp. and the cryptophyte Cryptmonas spp. tended to increase. Considering the occurrence mechanisms of cyanobacterial blooms based on the fluctuation trends of cyanobacteria in the water columns, it is found that the supply of Microcystis aeruginosa from the lake bottom sediment to the water column (water temperature of 10-15ºC is required) is progressing at all stations in April-June. Since Onuma and Konuma are shallow with an average depth of 4.7 m, wind-inducing resuspension of bottom sediments probably contribute to the supply of cyanobacteria to water columns. In addition, since cyanobacterial cells tend to float and accumulate in surface water, it is needed to take physical factors such as wind and flow into consideration regarding the distribution of the blooms of cyanobacteria.