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Volume 54, Issue 2
Displaying 1-9 of 9 articles from this issue
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Shigeyuki TOMITA1993 Volume 54 Issue 2 Pages 97-108
Published: April 30, 1993
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSHumic substances are the dominant dissolved organic matter in natural fresh waters, and have much chelating ability with dissolved metals such as iron ions. These chelated metals are speculated to promote the growth of phytoplankton. Humic substances in natural water were concentrated using an anionexchange resin, diethylamino-ethyl-cellulose, and were determined by photometric analysis.
Concentrations of humic substances in the waters of the Seta River ranged from 0.3 to 0.73 μg⋅ml-1 from May till December in 1990. The ratios of humic to fulvic fractions in the waters were from 0.25 to 1.7. The average rate of discharge of humic substances from the lake was 56 g⋅sec-1, and the maximum rate with heavy rain was over 380 g⋅sec-1.
Lake water in the south basin of Lake Biwa contained humic substances in the concentration range of 0.20 to 0.91 μg⋅ml-1. High concentrations of humic substances were found in the water in eutrophic areas of the lake.View full abstractDownload PDF (815K) -
Misako URABE1993 Volume 54 Issue 2 Pages 109-116
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe genetic and morphological variations of a freshwater snail, Semisulcospira reiniana were studied in the Lake Biwa water system and its adjacent two localities. The two types distinguished genetically were distributed sympatrically at Hamaotsu, Uji, and Mino-tsuya. MPI-A type snails had relatively small, and smooth or ribbed embryonic shells. MPI-B type snails had large and ribbed embryonic shells. How-ever, these two types in the same locality could not be distinguished by adult shell morphology. Thus, the convergence of shell morphology with growth was suggested. These results clarified the confusion between these two types in past taxonomic studies of S. reiniana.View full abstractDownload PDF (392K) -
Masako TABATA, Youko TAKADA, Masaki SATO, Junzo SUZUKI, Shizuo SUZUKI1993 Volume 54 Issue 2 Pages 117-123
Published: April 30, 1993
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSThe number of DNA and RNA hydrolyzing bacteria in the water of six lakes was found to range from 102 to 104 N⋅ml-1. They accounted for 8% to 67% of heterotrophic bacteria in the lake water. While the number of DNA and RNA hydrolyzing bacteria in the sediment of six lakes was found to range from 104 to 106 N⋅ml-1 and from 103 to 106 N⋅ml-1, respectively. They accounted for 6% to 50% of heterotrophic bacteria in the sediment. The distribution of both bacteria was correlated with the amount of chlorophyll a. The vertical distribution of DNA and RNA hydrolyzing bacteria in Lake Shinseiko reached maxima at a depth of 2m during the circulation period, and a maximum at a depth of 2m and at the surface layer for DNA and RNA hydrolyzing bacteria, respectively, during the stagnation period.
The bacteria which could grow nourished solely by DNA or RNA were isolated from the sediment. They were identified as the genus Moraxella and Bacillus, respectively. When Moraxella sp. was incubated in synthetic medium containing DNA as the sole carbon source, extracellular DNase and alkaline phosphatase were detected in the medium, and DNA decomposion occurred, producing orthophosphate. In the case of Bacillus sp., extracellular RNase and alkaline phosphatase were detected, and the RNA decomposed to form orthophosphate.View full abstractDownload PDF (383K) -
Takayoshi TSUCHIYA, Seiichi NOHARA, Toshio IWAKUMA1993 Volume 54 Issue 2 Pages 125-130
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSZonal distribution of aquatic macrophytes was investigated in the littoral zone of Edosaki-iri Bay in Lake Kasumigaura. Muddy sediment with litter was deposited on the sandy bed near the shore line. In the emergent plant zone, Phragmites australis (Cav.) Trin. ex Steud. tended to dominate near the shore line, but was successively replaced by Zizania latifolia Turcz. and Typha angustifolia L. toward the deeper sites. The emergent plants were distributed on the shelf to a depth of 80 cm, while a floatingleaved plant, Nymphoides peltata (Gmel.) O. Kuntze, occupied lakewards on the steeper slope from depths of 60 to 200 cm. Distribution of each species along the water depth gradient overlapped. The zonation of emergent plants was more associated with depth to sandy sediment surface than that with water depth and that with the thickness of muddy sediment.View full abstractDownload PDF (366K) -
Keiichi KAWABATA1993 Volume 54 Issue 2 Pages 131-136
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSSeasonal and ontogenetic changes in mortality rate were studied for Eodiaptomus japonicus in Lake Biwa during May to November from 1984 to 1986. Mortality rate during each sampling interval was determined for individuals born within a certain time interval by comparing the actual individual number on the latter sampling date with the number that would be expected in the absence of mortality. The present method differs from existing methods in following changes in the number of individuals through their development instead of confining itself to a fixed age class. Adult E. japonicus showed large mortality rates throughout the study period, while juveniles showed large values during May to July of both 1984 and 1985.View full abstractDownload PDF (334K) -
Michiro MATSUYAMA1993 Volume 54 Issue 2 Pages 137-140
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSChromatium sp. blooming at an upper boundary of the H2S layer of Lake Kaiike was cultured in the medium of PFENNIG (1965) under a variety of light intensities. Specific growth rate of the bacterium (Y) could be approximated by frequency of the dividing cells (X) as follows:
Y=0.098e3.8X(r=0.609)
indicating that measurement of frequency of the dividing cells was very simplified method adequate to estimating the growth rate. In situ specific growth rate of the bacterium could be estimated as about 0.17-day-1, which is only about twice the maintenance rate constant obtained in the pure culture. Bacterial ability to depress growth capacity to such a low level in response to environmental limitations is considered one of the factors causing the bloom in Lake Kaiike.View full abstractDownload PDF (1435K) -
Tomiko ITO, Kazumi TANIDA, Takao NOZAKI1993 Volume 54 Issue 2 Pages 141-150
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThis is the first in a series of checklists which will review taxonomical, biogeographical and ecological publications on Japanese Trichoptera. This part deals with 10 species belonging to 4 genera of Hydroptilidae and 31 species belonging to 5 genera of Lepidostomatidae.
In Hydroptilidae we suggest four taxonomical problems: 1) Hydroptila itoi KOBAYASHI and Stactobia japonica IWATA should be compared with similar species from the adjacent country; 2) descriptions of Hydroptila usuguronis MATSUMURA and Oxyethira angustella MARTYNOV are insufficient for species identification; 3) many descriptions of larvae and cases are also insufficient for species identification; 4) four undescribed species are in the collections of the authors.
The Japanese Lepidostomatidae have been intensively studied in recent years. However, two taxonomical problems remain: 1) generic status of four species, Dinarthrodes albardanus (ULMER), D. albicorne (BANKS), D. elongatus MARTYNOV and D. kasugaensis TANI, has not been clarified; 2) nine undescribed species have been collected.View full abstractDownload PDF (666K) -
1993 Volume 54 Issue 2 Pages 151-154
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (280K) -
1993 Volume 54 Issue 2 Pages 155-159
Published: April 30, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (226K)
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