著者
後藤 敏一
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.5, pp.111-114, 1990

珪藻はひじょうに美しい形,模様をもっています.研究を離れて,自然の造形美にうっとりとすることもあります.どうしたらもっと美しい顕微鏡写真が撮れるだろうか?そんな思いをされている方も多いと思います.被写体がこれほど美しいわけですから,撮る側の工夫次第で美しい写真が必ず撮れると思います.<BR>私達が撮る写真(モノクロ)は研究用であり,撮影した珪藻の写真から種の同定に必要な形質を抽出したり,自己の資料としての記録用に,あるいは論文中の写真として利用します.このような目的から顕微鏡写真には高い再現性が要求されます.っまり,写真に表現される情報が高品質であり,同時に量が多いことが要求されるのです.高品質で多量の情報を含む写真とはどのようなものでしょうか.それは階調(濃度の最大から最小までの段階)の幡の広い写真といえます.純黒から純白までの間に何段階もの濃淡の差があってはじめて,珪藻の微細な部分の三次元構造が二次元の写真として正しく表現される訳です.それではどのような点に注意すればそのような顕微鏡写真が撮れるのでしょうか.顕微鏡写真ができ上がるまでには次のような過程があり,それぞれに美しい写真を撮るためのちょっとしたコッがあります.以下にその要点をあげてみたいと思います.
著者
小島 隆宏 齋藤 めぐみ 岡田 誠
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.32, pp.47-55, 2016-12-25 (Released:2016-12-28)
参考文献数
17

栃木県に分布する中期更新世の湖成堆積物である塩原層群宮島層から産出した新種化石珪藻Stephanodiscus akutsui sp. nov.を記載した。本種は殻面が円形で同心円状に波打ち,殻套は薄い。殻縁部の束線は2~3列の胞紋からなる。殻面有基突起は0~2つで2または3個の付随孔を伴い,唇状突起は1つである。また,しばしば刺を用いて鎖状に連結していることで特徴づけられる。これらの形態学的特徴の組み合わせは他種と一致しない。よって,著者らは本種を新種として提案する。
著者
佐藤 裕司 居平 昌士 松田 功 熊野 茂
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.13, pp.193-199, 1997

Diatom assemblages in sediments were analyzed to clarify sedimentary environments during the mid- to late-Holocene and to determine the upper limit of marine facies at the Mokoto site along the Okhotsk Sea in Hokkaido.<BR>There was a replacement of marine and brackish-water diatoms by freshwater ones at +1.80 m altitude. Marine and brackish-water diatoms occurred over 40 % at the horizons below +1.80 m altitude, where a marine diatom <I>Cocconeis scutellum</I> and brackish-water diatoms <I>Bacillaria paradoxa, Navicula peregrina</I> and <I>Synedra tabulata</I> occurred. This indicates that sedimentation took place under a lagoon-like environment. Peat accumulation and the dominance of freshwater epiphytic diatoms indicate peat moor environments at the horizons above +1.80 m altitude. At about 5,500 yrs BP, the Mokoto site changed from lagoon littoral to peat moor conditions. Based on the diatom assemblages in sediments, the upper limit of marine facies can be regarded to be +1.80 m altitude, indicating the mid-Holocene sea-level high stand at the Mokoto site.
著者
伊藤 良永 堀内 誠示
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.6, pp.23-44, 1991-01-31 (Released:2012-12-11)
参考文献数
20
被引用文献数
4 or 0

The distribution of living terrestrial diatom communities is examined at 9 stations. The communities on soil and mosses are similar to each other. In all 91 taxa are distinguished. These taxa can be divided into two distinct groups based on the tolerance for desiccation. The group A is composed of species with high tolerance for desiccation and it indicates dry habitats. The group B consists of species which accompanied by the group A and recognized in both terrestrial and aquatic conditions. It is very useful to apply these terrestrial diatoms for palaeoenvironmental reconstructions.
著者
吉澤 一家 中村 文雄
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.11, pp.9-15, 1995-12-31 (Released:2012-12-11)
参考文献数
25

The growth characteristics and extracellular organic matter of Synedra acus Kützing, which often causes problems to the public water supply, were investigated by using an artificial culture medium. Synedra acus was removed from the water of a reservoir; the cultivations were carried out between 10-25°C with continuous light illumination, under cool-white fluorescent lamps at 4,500 lx and 2,000 lx.Under these conditions, the higher the temperature and the brighter the light became, the more rapidly the diatoms grew. With the growth of the diatoms, extracellular organic matter, which included saccharides, increased at a 40% ratio. Following the Logarithmic phase, extracellular saccharides were yielded at a ratio of 11-12% to the dry algae.The composition of these saccharides was recorded as follows: Rib + Ara: Fuc: Xyl: Man: Gal: Glu = 4.3: 1.8: 7.1: 8.6: 9.4: 68. As a result, saccharides produced by Synedra acus were characterized by a high concentration of Glu and the absence of Rha.
著者
大塚 泰介 中村 優介 向井 康夫 岩渕 成紀
出版者
日本珪藻学会
雑誌
Diatom (ISSN:09119310)
巻号頁・発行日
vol.29, pp.42-47, 2013-12-31 (Released:2013-12-19)
参考文献数
26

Diatom assemblages in a rice paddy inundated by the 2011 Tohoku Earthquake tsunami were studied. We collected diatom samples from a rice paddy in Sabusawa Island in Miyagi Prefecture on 14 August 2011. The rice paddy was intruded by seawater during the high tide of the spring tide as a result of destruction of the coastal levee and the land subsidence after the earthquake. The salinity of the paddy was slightly higher than that of the coastal seawater, and naturally, rice was not cultivated at that time. In total 117 diatom taxa (including 22 unidentified ones) belonging to 50 genera were observed. The diatom assemblages consisted of fresh, brackish, and marine water species, and moreover, extinct Miocene marine diatoms. The dominant species was Tabularia parva on Zannichellia palustris and in a floating algal floc, and Navicula phylleptsoma on the surface soil. Halamphora luciae was subdominant in all samples. Judging from the past literature, these diatoms all tolerate changes in salinity.