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Volume 58, Issue 1
Displaying 1-8 of 8 articles from this issue
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Shuji HINO1997 Volume 58 Issue 1 Pages 1-14
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSVariations in the physiological state of planktonic assemblages were studied twice in hypertrophic and shallow Lake Barato. The adenylate energy charge (AEC) and adenylate concentration were applied as indicators of the physiological state of a plankton community. AEC value and adenylate concentration in three fractions (> 100μm, 100 to 2μm, 2 to 0.2μm) fluctuated markedly, but the variations did not synchronize. AEC values significantly varied during the observation over 24 hr. AEC varied from 0.51 to 0.65 for the large fraction, > 100μm, from 0.30 to 0.71 for the medium fraction, 100 to 2μm, and from 0.31 to 0.74 for the small fraction, 2 to 0.2μm, in June 1986. In August 1986, they ranged from 0.47 to 0.72 for > 100μm, 0.55 to 0.75 for 100 to 2μm, and 0.43 to 0.77 for 2 to 0.2μm. These values ranged from " in a high active state " to " in a low active state " (CHAPMAN, 1977). Other factors detected in the lake water might influence variations in the physiological state of planktonic assemblages in L. Barato. A relatively high correlation was found between the AEC values of planktonic assemblages of the 100 to 2μm and 2 to 0.2μm fractions and concentration of dissolved proteins (D-Pro) and dissolved sugars (D-Su). It is suggested that a microbial community of the 2 to 0.2μm fraction is affected through the excretion of D-Pro and D-Su which increased with the activity of plankton of 100 to 2μm. This indicates that the physiological state of microorganisms in the 2 to 0.2μm fraction may depend on that of planktonic organisms larger than 2μm, probably through the release of organic matter.View full abstractDownload PDF (683K) -
Naoshi C. WATANABE, Shin-ichi ISHIWATA1997 Volume 58 Issue 1 Pages 15-25
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe geographic distribution of Ephoron shigae in Japan was surveyed based on questionnaires and selected information from publications as well as collections. This species is distributed in rivers on Honshu, Shikoku and Kyushu from ca. 39°N to ca. 33°N in latitude. Temperature regimes from autumn to spring seem likely to be the main factor limiting distribution to this area. No or few males were found in some populations (unisexual populations), whereas many males as well as females were collected in some other populations (bisexual populations). The distributions of both populations broadly overlapped. The unisexual populations evidently reproduce parthenogenetically.View full abstractDownload PDF (624K) -
Kunihiko SAGI, Shuichi ENDOH, Munetsugu KAWASHIMA, Yasuaki OKUMURA, Ta ...1997 Volume 58 Issue 1 Pages 27-44
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSSeasonal variation and characteristics of the benthic nepheloid layer (BNL) were investigated in Lake Biwa. During the last four years, vertical and horizontal distributions of water temperature, turbidity and electric conductivity have been obtained both in the South Basin and the southern part of the North Basin of Lake Biwa. The BNL developed in the seasons of thermal stratification, and is not detectable in the non-stratification period (winter). Turbidity in the BNL was much affected by the turbid water from rivers after heavy rainfall. In this case, the major component of the suspended substance (SS) in the BNL was inorganic soil. The particulate P concentration in the BNL, which originated from phytoplankton, also increased after a rainfall. This suggests that phytoplankton in the surface layer sinks with clay and silt entering via the rivers. The particulate Al concentration (soil origin) also increased after every heavy rainfall, but decreased soon thereafter. However, the concentration of particulate P increased consistently after heavy rain. These results show that inorganic matter sinks quickly due to its high density, and that the turbidity in the BNL is mainly maintained by organic matter such as phytoplankton under decomposition. From summer to the end of the stratification period, another kind of turbidity appeared in the bottom layer. This is caused by the chemical reaction of Mn under anoxic conditions. Resuspension of bottom sediment by strong currents also occurred, but it was not a major process for maintaining the BNL.View full abstractDownload PDF (1033K) -
Shinichi ONODERA, Masaki KATO1997 Volume 58 Issue 1 Pages 45-59
Published: March 01, 1997
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSIn order to clarify the effect of cold and hot summers on solute transport in forest soil, we conducted a hydrochemical investigation into forest soil in the Inashiki upland near Tsukuba from 1992 to 1994. The N03--N concentration in the surface soil was high in the hot summers of 1992 and 1994, whereas it was low in the cold summer of 1993. The nitrogen amount produced was small in the cold summer of 1993, as compared with the summers of 1992 or 1994. This trend agreed with the results of incubation experiment. The N03--N loss in 1992 under wet conditions was more than the input by throughfall and stemflow, whereas in 1994 under drought conditions it was less than in unusually wet 1993 because of little water flux. The SO42--S concentration in soil solution increased from 1993. Since SO42--S was the main exchangeable anion in this forest soil, the 5O42--S loss decreased with an increase in the total ion amount and a decrease of pH in the soil solution. These results establish that more SO42--S and less NO3--N is lost in cold summers, whereas less 5O42--S and more NO3--N is lost in hot summers.View full abstractDownload PDF (722K) -
Michiro MATSUYAMA, Sang-Wook MOON1997 Volume 58 Issue 1 Pages 61-67
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSA freely swimming hypotrichous ciliate was found in all samples from different depths of the H;2;S layer in Lake Kaiike on 24 May 1996 (<10 cells ml-1). Growth of these ciliates was tested by adding living cells of Chromatium sp., a phtotrophic bacterium blooming at an upper boundary of the H2S layer (bacterial plate). The bacterium was found to be an effective food for the ciliates in the lake. If the ciliate growth rate, estimated as a maximum 0.6 day-1, was assumed to be determined solely by bacterial cell density, a single ciliate cell would soon grow to 2500 cells (a number sufficient to consume the entire bacterial population). However, results suggest that growth of the ciliates in the lake was greatly controlled by other environmental factors such as predation by larger zooplankton or by the occurrence of a high concentration of H2S at and around the bacterial plate. The ciliates found in the H2S layer appeared to be those expelled from their original habitat.View full abstractDownload PDF (1374K) -
Yatsuka SAIJO, Osamu MITAMURA, Kozo HINO, Isao IKUSIMA, José Ga ...1997 Volume 58 Issue 1 Pages 69-82
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe Pantanal is one of the largest wetland in the world, and its located almost in the central part of South America. Preliminary studies on the chemical features of waters were carried out in July, 1983 in Rio Paraguai and its tributaries in southern Pantanal, and in January, 1986 for some lakes near Porto Jofre and a river in northern Pantanal. The former showed an extremely oligotrophic character and the latter a eutrophic character, while the nitrogen seemed to be the limiting nutrient rather than phosphorus in both waters. The oxygen deficiency in water seemed rather common throughout the area studied in spite of the difference in water temperature and the organic matter contents.View full abstractDownload PDF (723K) -
1997 Volume 58 Issue 1 Pages 83-104
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (1277K) -
1997 Volume 58 Issue 1 Pages 105-124
Published: March 01, 1997
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (1111K)
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