2 0 0 0 OA バフンウニ生殖腺の苦味の発現頻度
1 0 0 0 OA ニジマスの成長および塩分耐性に及ぼす飼料中塩化ナトリウム含量の影響
- 著者
- 朴 光植 竹内 俊郎 横山 雅仁 佐藤 秀一
- 出版者
- 公益社団法人 日本水産学会
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.64, no.3, pp.469-474, 1998 (Released:2008-02-29)
- 参考文献数
- 17
- 被引用文献数
- 1 1
Two feeding experiments were conducted to investigate the effect of dietary sodium chloride (NaCl) levels (0, 2.5, 5.0, 7.5, 10.0, 15.0%) on the growth of young and juvenile rainbow treout Oncorhynchus mykiss. After the feeding experiment, fish were acclimated to sea water (33‰) to check the sea water tolerance.Young rainbow trout (BW, 59g) fed diets containing 10 and 15% NaC1 for 4 weeks showed lower weight gain than the trout fed diets containing less than 5% NaCl. However, no mortality was observed in any group of fish after 7 days of sea water acclimation. On the other hand, juvenile trout (BW, 1.7g) fed the 2.5% NaC1 diet showed significantly better (p〈0.05) weight gain and protein efficiency ratio than those fed the 0, 5.0, 7.5, and 10.0% NaC1 diets during the 7 week feeding trial. Moreover, the mortality of fish fed the 2.5% NaC1 diet during the sea water tolerance test was the lowest. Therefore, the influence of NaCl levels in diet on growth and tolerance to sea water depends on the fish size. It is shown that the excess amount of NaCl level in diet is more than 7.5% (1.4g/kg fish/day) and 11.2% (1.4g/kg fish/day) for juvenile and young rainbow trout, respectively. The excess and minimum amounts of NaCl in diet for juveniles should be considered.
1 0 0 0 OA 海水培地中での生糸の生分解
- 著者
- 中山 昭彦 井上 喜洋 田原 陽三 小林 正三 横山 雅仁
- 出版者
- 公益社団法人 日本水産学会
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.64, no.4, pp.636-644, 1998-07-15 (Released:2008-02-29)
- 参考文献数
- 6
It is said that lines could be still made with silk as used to be done in Japan as a countermeasure against pollution by nylon fishing lines. However, it is not clear whether or not silk fishing lines would be decomposed biologically in marine environments. To answer this question, seawater was collected at six stations at the entrance of Tokyo Bay and sterile raw silk threads (27-denier) were added to these seawaters. The final concentrations of raw silk threads in the seawaters were 0.5%. The six seawaters with raw silk threads [silk-decomposing seawater media (SDS media)] were incubated for 2 months at 20°C. The tensile strengths of the raw silk threads in the three SDS media were clearly decreased at least after 2-month incubation. The degree of decomposition of the raw silk threads, which were observed visually, correlated approximately with the ammonia contents of the SDS media. When the incubated raw silk threads were examined microscopically, it was shown that the raw silk threads were split into more and finer filaments after 1-and 2-month incubation. These results suggest the possibility of decomposition of raw silk threads in marine environments.