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Volume 35, Issue 1
Displaying 1-11 of 11 articles from this issue
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Jun-ichi NARIHARA1987 Volume 35 Issue 1 Pages 1-6
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESS -
Kenji KATO, Kazuhiko KASAI, Yuji AOKI, Kazuto ANDO, Mamoru MURAI1987 Volume 35 Issue 1 Pages 7-10
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe growth of reared one-year-old striped jack Caranx delicatissimus, during winter from December 1985 to April 1986, was compared between in Chichi-jima, one of the Ogasawara Islands, and in Izu-Oshima Island.
In case of Chichi-jima, daily amount of diet expressed as percentage to body weight and daily increment of specific growth in body weight showed 1.5 and 2 times in Izu-Oshima, respectively. Through the rearing period, water temperature was fluctuated between 18.0 and 22.5°C (average 20.4°C) in Chichi-jima, while was from 13.5 to 16.7°C (average 15.4°C) in Izu-Oshima. The rapid growth shown in Chichi-jima may be associated with higher water temperature up to about 5°C than that in Izu-Oshima.View full abstractDownload PDF (420K) -
Katsuhisa SHITANDA, Hiroshi SHUZUKI, Hiroshi NAKAYAMA, Kiyoshi MIZUTAN ...1987 Volume 35 Issue 1 Pages 11-18
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
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Kouichi KOSHO, Taku SASAKI, Fumio TAKASHIMA1987 Volume 35 Issue 1 Pages 19-20
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSOral administration of methyltestosterone between 25 and 100 μg/g⋅diet evoked sex reversal in carp Cyprinus carpio, when supplied from 1 month after hatching for 2 months.View full abstractDownload PDF (184K) -
Makoto NONAKA, Yoshito IWAHASHI1987 Volume 35 Issue 1 Pages 21-26
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
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Hachiro HIRATA, Shusaku KADOWAKI, Tsurayuki NAKAZONO, Teruo KASEDO, Sh ...1987 Volume 35 Issue 1 Pages 27-31
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSAccumulation of biodeposits at the bottom of rearing tanks poses a serious problem during the culture period. A movable aerator was then deviced to prevent biodeposits at the bottom of the tank. The system was based on principles of cultivation physiology and ecosystem in the rearing water.
A movable air suppliers were made by vinyl pipes (13mm in diameter) and were set on the bottom of 600m3 concrete tank (4×10×15m) . The suppliers were connected by elbows at four corners to form a rectangle. One-millimeter holes were drilled in a row in each of the suppliers. The holes were set facing the bottom area of the tank such that when air was suppolied by the blower, “water jets” are affected downward. The whole structure is a allowed to move back and forth in the tank by a reduction motor at a uniform speed of about 1m/min. As the movable aerator reaches the opposite end of the tank, the motor was stopped usually 30 min after which the structure was moved to the opposite direction. This procedure was repeated in the same manner throught the culture period.
The number of mysis larvae initially stocked in both tanks totaled approximately 600, 000 individuals each. Estimated final number of postlarvae in experimental tank and control tank were 555, 000 and 433, 000 individuals, respectively, thus resulting in survival rates of 92.5% in experimental tank employing the moveable aerator and 72.3% in control tank using fixed aeration. Such a result may be due to promotion of energy flow conducted by the moveable aerator in experimental tank. Relationship between growth rates of larvae and energy flow in each tank is also discussed in this paper.View full abstractDownload PDF (510K) -
Yasuki OGAWA, Shunpei KAKUDA, Fujio WAKASHITA1987 Volume 35 Issue 1 Pages 33-41
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSAn ecological study of the freshwater shrimp Necaridina denticulata inhabiting the Ashida river, eastern region of the Hiroshima Prefecture, was carried out. A total of 1, 776 shrimps including 49 ovigerous females was collected in the midstream of the Ashida river, through nine samplings in the period of eight months from May to December, 1985.
1) The spawning season of the present species in the Ashida river lasts five months from May to September, in which there exists two ovigerous peaks in July and September corresponding to the occurrences of the early hatching group and the late hatching group respectively.
2) The early hatching group occurring in July is produced through spawning activity of the early and the late hatching groups spawned in the spawning season of the preceding year. However, the late hatching group occurring in September is produced by some shrimps which belong to the early hatching group and attain sexual maturity in September of that (occurring) year.
3) For the population life span of both male and female shrimps, 14 months are estimated for the early hatching group while 11 months are for the late hatching group, and both groups will perish in August. Consequently, many shrimps of the early hatching group and all of the late hatching group can take spawning activity in the only one spawning season, namely in that of the following year, in each life span. On the other hand, some shrimps belonging to the early hatching group can take spawning activity in two spawning seasons of the occurring and the following years in their life span.
4) As to the mean growth of the early hatching group, male and female will attain 12.5 mm in body length : 35 mg in body weigt and 13 mm : 39 mg respectively at 3 months after hatching out, 17 mm : 86 mg and 19 mm : 128 mg at 6 months, 20 mm : 139 mg and 23 mm : 233 mg at 10 months, 21 mm : 161 mg and 24 mm : 267 mg in the perishing August (at 14 months) .
5) For the late hatching group, male and female will grow to 12 mm : 30 mg together at 3 months, 17.5 mm : 94 mg and 19 mm : 128 mg respectively at 7 months, and will almost reach respectively to the mean growths of perishing male and female of the early hatching group at 10 months (July) .
6) Of the present shrimp specimens, the female biological minimum size is 16.6 mm in body length, and sex identification is possible to those of 7.0 mm and larger in body length.View full abstractDownload PDF (1029K) -
Kazuhiko KASAI, Takakazu ARIMA, Minoru SAITHO1987 Volume 35 Issue 1 Pages 43-46
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
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Kazuhiko KASAI, Takakazu ARIMA, Fumio TAKASHIMA1987 Volume 35 Issue 1 Pages 47-51
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
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Distribution of Proteolytic Bacteria in a Goldfish Culture PondHaruo SUGITA, Masataka SUZUKI, Yoshiaki DEGUCHI1987 Volume 35 Issue 1 Pages 53-59
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSVertical distribution of proteolytic bacteria in the water and mud columns of a goldfish-culture pond was studied in the period of May to October 1984. In addition to several bacterial populations, proteolytic activity index (PAI) which was obtained from the summation of areas of digested protein around colonies of proteolytic bacteria, was also measured.
High density of each bacterial population was observed at the bottom layer of water and the surface layer of mud in the goldfish pond. High values of PAI were also observed at the mud-water interface. Suspended solids were mainly composed of bluegreen alga Microcystis and contained 16 to 29% of protein. This fact suggested that Microcystis is an important supplier of protein to the culture pond, and almost all of which are decomposed at the mud-water interface after death by bacteria including aerobes and anaerobes.View full abstractDownload PDF (577K) -
Ren KUWABARA1987 Volume 35 Issue 1 Pages 61-67
Published: June 30, 1987
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSIgnition loss, the simplest method for determination of organic content has also been applied to marine sediments. As shallow-water sediments obtained from Okinawa Islands showed considerably high values of ignition loss, because of driving off carbon dioxide from carbonate included as coral fragment in the materials, it was doubted that ignition temperature and time in established methods were not appropriate for them. To confirm the extent of this interference, the following two methods were examined : 1) Cumulative ignition of 1 hour at every increased 100°C stepwise from 300°C to 900°C ; 2) Ignition only for 2 hours at each increased 100°C stepwise from 300°C to 700°C. The increasing tendency of ignition loss to temperature and time was compared between these two methods by using of three kinds of sediments of different grain stze from Okinawa shallow-waters, two counter materials i, e. crushed coral and CaCO3 reagent, and a control material from Kasai tidal flat in Tokyo Bay.
Results of the cumulative ignition revealed mostly two parts of straight line in semilog grid between 300°C and 500°C, and 600°C and 900°C. The former range conducted incineration of organic matter, because it was confirmed by depletion of COD determined at the same time. The latter range showed abrupt increasing of ignition loss and it was due to decomposition of included carbonate because of the similar featured curve of counter materials. Hence, ignition temperature over 600°C must be avoided for accurate determination of organic matter. Results of 2 hours ignition exhibited higher values at every hundred temperatures than that of the cumulative ignition. At least, the Ionger ignition time than 2 hours might be required for complete incineration. Conclusively, ignition loss should be determined at 500°C for 2 hours whenever in using as an index of organic matter.View full abstractDownload PDF (737K)
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