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Volume 41, Issue 2
Displaying 1-5 of 5 articles from this issue
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Ryohei TSUDA1980 Volume 41 Issue 2 Pages 57-67
Published: April 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSBased on the data of Secchi disk depths, the beam attenuation coefficients and downward spectral irradiance, water colour and the optical characteristics of the natural light field were examined in Lake Biwa. The peaks of spectral distribution of downward irradiance in the deeper layer were found at about 560 nm in the south basin and about 540 nm in the southern part of the north basin. The colour of the lake was similar to that of the turbid coastal sea waters reported in the literature. In Lake Biwa, the value of Kv = ZSD is found to be 1.49 and the depth to which 1% of surface illumination penetrated is about 2.7 times as large as the Secchi disk depth.View full abstractDownload PDF (1214K) -
Ken'ichi SATAKE1980 Volume 41 Issue 2 Pages 68-74
Published: April 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSLake Katanuma (pH 2.0-2.1) was covered with a layer of snow and ice on 27 February, 1975. The layer consisted of a surface snow layer, five ice sheets and four water layers between them. Field observations and study of the chemical composition of the snow, ice and lake water revealed that the main component of the ice sheets was deposited snow, and in the case of the water layers, acid lake water had penetrated the snow layer. The snow and ice contained a considerable amount of ammonia (1.06-3.56 μg-at N/1), which, when they melt, is supplied into the lake water.View full abstractDownload PDF (3027K) -
Nobuhiko TANAKA, Masayuki ONIZAWA, Hajime KADOTA1980 Volume 41 Issue 2 Pages 75-83
Published: April 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe relations between growth rate (μ, h-1) and organic nutrient concentrations (S, mg/l) were examined by using natural bacterial populations and isolated strains in Lake Biwa. The kinetic parameters Ks (half-saturation constant) of three groups of natural populations counted with different agar media containing 0.5, 5 and 10 g peptone per liter were 1.15, 0.82 and 0.49 mg/l, respectively. The Ks of these three groups of bacteria isolated were <0.005-6.94, 0.04-313 and 0.156-4000 mg/l, respectively.
The relations between the colony number and the concentration of peptone in agar medium were also examined for different size fractions of suspended particles in the lake water.
According to the results obtained, the micro-habitat segregation of natural bacteria in the lake water was discussed.View full abstractDownload PDF (1139K) -
Michiro MATSUYAMA1980 Volume 41 Issue 2 Pages 84-94
Published: April 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe purpose of the present study is to consider the dense population of a purple sulfur bacterium, Chromatium sp., at the mid-depth of Lake Kaiike on Kamikoshiki Island. In summer (1979), the lake was well stratified and at the boundary (4.75 m) between upper O2, and deeper H2S layers a dense population (5 x 106 cells/ml) of Chromatium sp. was found. A hyperbolic relation between the bacterial growth and H2S concentration obtained in the laboratory experiment indicates that the in situ growth of Chromatium sp. is controlled by the supply of H2S from the reducing deeper water where it accumulated. The facts that further penetration of light beyond the mid-depth was greatly limited by self-shading of Chromatium sp. and that the carbon assimilation at this depth by the bacterium occupied a substantial part of the whole process in the lake suggest that the bacterium also has an important role in the formation and maintenance of the reducing condition of deeper water.View full abstractDownload PDF (1591K) -
Kazumi TANIDA1980 Volume 41 Issue 2 Pages 95-111
Published: April 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSDistribution and life history of net-spinning caddis larvae (Hydro psyche tsudai, H. gifuana, and H. selys) were studied from December 1970 to April 1973 in a mountain stream near Kyoto, Central Japan. H. tsudai, which is smaller than the other two species, was found at all the four stations studied, but H. selys at the upper two and H. gifuana at the lower three. H. gifuana was univoltine at the lower station, Jadani-bashi. H. tsudai was univoltine at the upper station, Azodan, but bivoltine at Jadani-bashi with long flight periods. Over wintering larvae of H. tsudai had larger head width than non-overwintering ones, and they were also heavier. At Jadani-bashi highly dense larval populations were destroyed by the flood in the summer of 1971 and thereafter the density of H. tsudai remained low. In the high density period, mean head width and growth were significantly smaller than the low density period in both species. This high density, especially in H. tsudai, seems to suppress the growth. The difference in the seasonal growth pattern between H. tsudai and H. selys at Azodan seems to be caused by interspecific competition. H. tsudai and H. gifuana at Jadani-bashi show high overlapping in habitat and life-cycle but slight overlapping in head widths, which determine the mesh-sizes of capture-nets and food-size. The probable partitioning of food-size seems to contribute much to their stable coexistence.View full abstractDownload PDF (2908K)
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