巻号一覧
38 巻 (1977)
- 4 号 p. 109-
- 3 号 p. 75-
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38 巻, 1 号
選択された号の論文の4件中1～4を表示しています
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新井 正, 森 和紀, 高山 茂美1977 年 38 巻 1 号 p. 1-8
発行日: 1977/01/30
公開日: 2009/10/21
ジャーナル フリーGeneral characteristics of the inland water in Miyake Island were investigated as a part of the water conservation project of the island. Miyake Island, locating about 180 km south of Tokyo, is a volcanic island and covered with highly permeable volcanic ash or scoria that prevent the formation of surface water bodies except for two crater lakes.
The main groundwater system of the island is assumed to exist as a wedge of Ghyben-Herzberg's model. But, another form of groundwater also exists in the elevated regions as the under-ground compartment supposed by Ecker (1976).
Lake Tairo-ike is a crater lake created by the volcanic eruption about 2200 years B. P. The lake is considered as a part of main groundwater mentioned above. Salt intrusion is not observed in this lake, though the lake bottom reaches about 6 m below the sea surface.
Lake Shinmiyo was created by the eruption in 1763. The lake surface shows a clear tidal fluctuation, and its maximum amplitude reaches about 60 cm. The lake is a meromictic, i. e., its deep layer is occupied by salt water, the concentration of which increases gradually with the depth as expressed in Fig. 3 and Fig. 4. The vertical circulation is restricted to the layer shallower than about 10 m in depth. The residence time of the bottom water (30 m layer) was estimated as 29.7 years, based on concentration of tritium. The meromictic nature of the lake is explained by this low rate of water exchange. Salt water in the deep layer is considered to originate from the sea, as seen in the key-diagram of water quality (Fig. 5).抄録全体を表示PDF形式でダウンロード (1443K) -
松山 通郎1977 年 38 巻 1 号 p. 9-18
発行日: 1977/01/30
公開日: 2009/10/21
ジャーナル フリーLimnological surveys were undertaken on a small coastal lake on Kamikoshiki Island, Lake Kaiike (surface area : 0.15 km2; maximum depth : 11.6 m). The lake and adjacent Lake, Namakoike (surface area : 0.50 km2; maximum depth : 24.4 m), are separated from the sea by narrow gravel bars. Lake Namakoike has a considerable exchange of water with the sea, because a part of the gravel bar has been worn away by wave action and through it sea water seeps freely into the lake or lake water into sea following the tidal cycle of sea level. Usually, water flows through a small ditch from Lake Kaiike into Lake Namakoike. But an reverse flow occurs intermittently on a rare occasion when tidal action becomes great enough to raise the lake level of Namakoike higher than that of Kaiike. Chlorinity of lake water of Namakoike ranges between 13-17 ‰. Chlorinity of surface water of Lake Kaiike is 7-9 ‰, and it increases downwards and attains 18.64 ‰ near the bottom. The deeper high saline water of Lake Kaiike originates in sea water which seeps through the gravel bar between the lake and sea. Unusually high temperature and dissolved oxygen maxima are observed in the middle layer, where the vertical gradient of chlorinity is the highest (halocline). Dissolved oxygen has been depleted in the deeper water and hydrogen sulfide is present.抄録全体を表示PDF形式でダウンロード (1496K) -
カワチブナ, ハクレンおよびニゴロブナの発育に伴う消化吸収率の変化岩田 勝哉1977 年 38 巻 1 号 p. 19-32
発行日: 1977/01/30
公開日: 2009/10/21
ジャーナル フリーBy using unialgal culture of the two species of green algae (Closterium moniliferum : 300μ in length and Selenastrum sp. 10μ) which were labeled with 14C, the assimilation efficiency in terms of carbon of three cyprinids, Kawachibuna (Carassius auratus cuvieri), Nigorobuna (C. auratus grandoculis) and Silver carp (Hypophthalmichthys molitrix) was studied at the various life stages. In addition, radioactivities of different fractions (oligo-and poly-saccharides, organic acids, lipides, protein and residue) of the both species of 14C-algae and of the fecal algae egested by Kawachibuna and Silver carp were measured.
In Kawachibuna and Nigorobuna, the assimilation efficiency for Closterium increased with their growth until they attained to 20 mm in total length (B. L. 14-15 mm), and reached the maximum level of more than 20 mm length (57-63%) at the successive stage. In Silver carp of 20 mm total length, the assimilation efficiency for Closterium was lower than for Kawachibuna and Nigorobuna of the same length. In Silver carp of more than 33 mm total length (B. L. 26-27 mm), 54-64% of carbon was assimilated.
Kawachibuna and Silver carp are already known to change their food items from zooplankton to phytoplankton when they grow up more than 15 and 24 mm in body length respectively. The body length at which the maximum values of assimilation efficiency were obtained coincides approximately with the body length at which the change in diet occurs. It is suggested that the increase in the assimilation efficiency for Closterium with the growth of the fishes is not directly correlated with the increase in the length of their intestines but with a functional differentiation of their digestive systems.
The three cyprinids assimilated 12-16% of carbon of Selenastrum and the rate was fairly stable throughout their lives, in contrast with those for Closterium. No difference was found in photosynthetic activity between fecal algae of Selenastrum egested by young Kawachibuna and fresh ones, while the activity of fecal algae of Closterium was approximately one-fifth of the fresh ones. The difference in assimilation efficiency may be related partly to the physiology of digestion of the cyprinids and partly to differences in chemical nature and cell structure of the two species of algae.抄録全体を表示PDF形式でダウンロード (2606K) -
佐竹 研一1977 年 38 巻 1 号 p. 33-35
発行日: 1977/01/30
公開日: 2009/10/21
ジャーナル フリーPDF形式でダウンロード (354K)
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