著者

Takashi Yada Fuminari Ito

出版者

The Japanese Society of Fisheries Science

雑誌

Fisheries science (ISSN:09199268)

巻号頁・発行日

vol.64, no.5, pp.694-699, 1998 (Released:2008-06-30)

参考文献数

34

被引用文献数

6 6

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Sexual differences in survival and changes in plasma ion levels after transfer from neutral water to acid water prepared with sulfuric acid were examined in medaka Oryzias latipes. In acid water at pH 3.5 and 3.8, survival of female fish was better than male. During exposure to acid water at pH 4.1, there was no mortality in either sex. Male fish showed a transient decrease in the plasma sodium level 24 h after transfer to pH 4.1, whereas there was no change in the female. The plasma level of sulfate was not affected in the female, but a significantly high level was consistently observed during the exposure in the male. In both sexes, the activity of gill Na+, K+-ATPase increased within 24 h after transfer to pH 4.1, and this high level was maintained for 1 month. Treatment with short day-photoperiod (8L:16D) caused a cessation of spawning due to inactivation of the testis and ovary. Transfer to acid water caused a decline in plasma sodium only in male fish, but not in female even under a short photoperiod. These results indicate that female medaka are more tolerant to acidic environment, possibly with a greater osmoregulatory ability than male fish.