養殖マダイにおける安静時代謝量の急激な水温低下に伴う変化とそれに及ぼす棲息水温の影響

概要

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The change of resting metabolism (RM) with rapid lowering of water temperature was studied in cultured red sea bream Pagrus major acclimatized at 25 and 15°C. The RM decreased with rapid lowering of water temperature from the habitat temperature to the range 10-9°C in the 15°C group (the group acclimatized to 15°C) and to the range 15-13°C in the 25°C group (the group acclimatized to 25°C). However, after RM reached the minimum level as the water temperature was lowered, the metabolism of both groups increased contrary to expectation. The inflection temperature of the 15°C group was lower than that of the 25°C group. However, the minimum level of RM showed no significant difference between the two groups. The temperature dependence of RM in the 15°C group was significantly larger than that in the 25°C group within the range from the habitat temperature to the inflection temperature. On the other hand, the reaction temperature dependence of Mf Mg2+-ATPase activity in the 15°C group was larger than that in the 25°C group within the same range of RM. This result of the reaction temperature dependence of Mf Mg2+-ATPase activity coincided with that of RM. We consider that the increase of metabolism in low temperature water might be caused by the increasing Ca2+ concentration around myofibrils.