アサリの成長と酸素消費量におよぼす高温の影響 Upper Temperature Effect on Rates of Growth and Oxygen Consumption of the Japanese Littleneck Clam, Ruditapes philippinarum
The rates of growth and oxygen consumption <i>in vitro</i> of <i>Ruditapes philippinarum</i> were examined in relation to their high temperature tolerance. Two groups of the clam (16.7 and 11.4mm mean shell length) were fed cultured algae <i>Pavlova lutheri</i> for 4 weeks under various constant temperatures between 10 and 34°C. Cumulative mortality in each group during the experiment was 0 to 3% except at 34°C. All clams reared at 34°C died within 10 days. The growth rate (daily percent increase in shell length) was maximum at about 25°C. A condition index (dry weight ratio of shell to soft body) declined at 30°C. The oxygen consumption rate was determined volumetrically at intervals of 5°C from 5 to 50°C using specimens of 31.1mm mean shell length. The oxygen consumption rate decreased markedly above 40°C. Q<sub>10</sub> for the oxygen consumption rate between 5 and 25°C remained close to 2.0, but decreased from the value above 25°C. The temperature considered to be optimum for the oxygen consumption was coincident with the maximum growth temperature. These results suggest that <i>Ruditapes philippinarum</i> probably suffers from thermal stress over 25°C, and has significant mortality at around 34°C within a few days and no heat resistance over 40°C.
日本水産学会誌 64(3), 373-376, 1998-05-15