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Volume 20, Issue 2
Displaying 1-6 of 6 articles from this issue
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On the “Mizukawari” phenomenon accompanied with the explosive occurrence of Brachionus quadridentatusTakashi ITO, Toshio IWAI1959 Volume 20 Issue 2 Pages 49-55
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSIn an eel-culture pond of mesohaline brackish water (area 1.9a, depth 30cm, Cl 5.15.5%) in the southern vicinity of Tsu City, Mie Prefecture, there was observed a marked surfacing phenomenon of cultured eels during the period from 16th to 20th of May, 1957.
At that time, a freshwater rotifer, Brachionus quadridentatus var. cluniorbicularis increased explosively (Figs.12), while the micron-algae which were the dominant species of phytoplankton quite disappeared (Figs.1 and 3). The colour of pond-water gradually changed from green to yellowish brown, and then quite discoloured; and the transparency suddenly became higher, and the dissolved oxygen and the pH-values diminished (Fig.1).
This so-called “Mizukawari” phenomenon seems to be due to an explosive increase of Br. quadridentatus which may devour micron-algae.View full abstractDownload PDF (1345K) -
On the “Mizukawari” phenomena accompanied with the considerable growths of Brachionus and ParameciumTakashi ITO, Toshio IWAI1959 Volume 20 Issue 2 Pages 56-63
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSIn an eel-culture pond of α-mesohaline brackish water (area 6.4a, depth 75cm, Cl 2.42. 8‰) in the south of Tsu City, Mie Prefecture, the surfacings of cultured eels were observed_three times during the period from the 1st to the 22th of May, 1957.
At the first and second surfacings, Brachionus angularis and Paramecium sp. increased considerably (Figs.12). On the contrary, Phormidium tenue, the dominant phytoplankter, diminished strikingly, but not perished (Figs.1 and 3). Then the oxygen dissolved in the pond-water decreased to a minimum amount of 0.4 cc/L, and the pH also fell down to 7.0 at least, while the transparency did not rise (Fig.1).
At the third surfacing, however, no great increase of rotifers and ciliates was observed, but the phytoplankton were entirely perished, the transparency suddenly becoming higher and the dissolved oxygen and the pH diminished.
It is considered that the most probable cause of the first and second surfacings was referable to a great increase of Brachionus and Paramecium, while in the third surfacing it may be due to a large quantity of natural water poured into the pond.View full abstractDownload PDF (1467K) -
Takashi ITO, Toshio IWAI1959 Volume 20 Issue 2 Pages 64-74
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSAcid eel-culture ponds with pH lower than 5 are very rare, but the authors favourably found one of such a kind of pond near the seashore in the southern vicinity of Tsu City, Mie prefecture, Middle Japan. It hasα-mesohaline brackishwater and the pH-value of 4.2, (area 25 a, depth 90 cm, Cl 2.12.4‰). Its acidity is possibly due to sulphuric acid which was derived from sulphide in the bottom mud.
1) The biological and chemical features of the acid eel-culture pond
The pond-water is of the pH4.24.6. Although a green alga Chlamydomonas acidophila enormously increased, the transparency about 30 cm, and the oxygen dissolved in the water was not so rich (4.5 cc/L, 61%). The diurnal changes of dissolved oxygen and pH are extremely slight ; and are rich in both NH4- and NO3N, but a little in PO4-P. The plankton is quite monotonous, being composed of Chlamydomonas acidophila and an oligochaeta, Nais pardalis, though their quantities are large. The fry of Mugil cephalus L. transplanted there from the sea were killed entirely. No feeding activity of eels in culture was observed at all.
2) The effect of liming
To neutralize the acid pond-water, 160kg of lime in total were sprinkled there on April 19th, 20th, and 23rd. After this operation, the feeding activity of eels became remarkably buoyant, but the green alga Chlamydomonas acidophila, as it was expected, suddenly diminished and the transparency accordingly rose, while the dissolved oxygen decreased. It is worthy of notice that an aquatic plant Potamogeton pectinalis began to grow over the bottom of the pond. Then the feeding activity of eels became dull day by day.
3) The effect of fertilization
To increase the phytoplankton and to control Potamogeton in the pond, fertilization was planned. It was carried out three times according to the following program :
1st fertilization May 17 phosphate of lime 14 kg
2nd fertilization May 22 phosphate of lime 28 kg dry poultry manure 150 kg
3rd fertilization July 16 phosphate of lime 35 kg urea 34 kg
The effects of the first and the second fertilization were not satisfactory, Potamogeton grow thicker, no “water-bloom” being observed (Figs.13). However, the third fertilization was quite effective after Potamogeton was removed as much as possible (Figs.13); a striking “water-bloom” occurred and the feeding activity of eels was rapidly improved. The quality of the pond-water, the zooplankton and phytoplankton have been restored as in a pond of normal conditions. Thus, the acid pond has been almost perfectly improved through the liming and three times of fertilization.View full abstractDownload PDF (1681K) -
Mikio NAGASAWA1959 Volume 20 Issue 2 Pages 75-79
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESS1. In Lake Sayama, during the summer stagnation period when the epilimnion and the hypolimnion forms the independent water systems, there appears a dichotomous microstratification of pH in the epilimnioil.
2. This dichotomous microstratification changes regularly every day, and the change is most noticeable at about noon.
3. An investigation made on August 29, 1597 showed that 36-41/cc of Volvox glabator L. existed in the layer 1.75m deep directly beneath the dichotomous microstratification of pH. Another investigation made on August 5 disclosed that there existed a large quantity (46705480/cc) of Ceratium hirundinella (O. F. M.) SOHRANK in the layer 2.8 m deep where the dissolved oxygen and pH markedly decreased.View full abstractDownload PDF (396K) -
Hiroshi KAWABATA1959 Volume 20 Issue 2 Pages 80-85
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSThe mineral water of the Ogoto spring is originated in its western mountain area, and receives on its way underground water with fluorine ion, etc, which flows down eastwards. A good content of total carbonic acid in this spring may originate from the fault of the western side of Lake Biwa-ko. This mineral water may have no outlet to Lake Biwa-ko, that is, it seems to be reserved between the clay strata. It will be explained that : the secular change of chemical contents of this spring is caused by the permeation of underground water in the high land of a higher hydropressure. The reservoir area of the Ogoto spring seems to be restricted to a narrow zone.View full abstractDownload PDF (615K) -
Matsunae TSUDA1959 Volume 20 Issue 2 Pages 86-93
Published: April 30, 1959
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSSome problems on the standing crop of Japanese streams are discussed.
(1) Except the extreme examples, which may have the weight of 20 gr to 30 gr, the quadrate (50 cm × 50 cm) samples of more than 5 gr in weight show very rich fauna.
(2) In general the standing crop of “Hayase” -rapids is more than that of “Hirase” -rapids, and the standing crop of rapids is more than that of pools.
(3) Among the life forms, such as crawling form, net-spinning form, casebearing form, swimming form, etc. (TSUDA et al., 1953), the net-spinning form is, with a few exceptions, the dominant life form, when the samples are of more than 5 gr.
(4) When the weight of quadrate samples is more than 5 gr, the rate of netspinners to the total benthic animals (net-spinner's percentage, or net-spinner's coefficient) is, with only a few exceptions, more than 80 %. And, when the weight of quadrate samples is less than 5 gr, the net-spinner's percentage is diverse.
(5) When the weight of quadrate samples is more then 5 gr, the rate of the second consumers to the total benthic animals (second consumer's percentage, or second consumer's coefficient) is usually less than 20%. And, when the weight of samples is less than 5 gr, the second consumer's percentage is diverse, though less than 40% in most cases.
(6) As for the insect production of Japanese streams, the net-spinners, especially the Stenopsychid-larvae, appear to play a very important role.View full abstractDownload PDF (1259K)
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