OXYGEN CONSUMPTION OF OYSTERS 
497 
Nozawa (1929) studied the effect of oxygen tension on respiration of the oyster 
and found that the rate of oxygen consumption of Ostrea circumpicta is independent 
of oxygen tension until the latter is reduced to 1 cubic centimeter per liter. 
Several experiments to determine the effect of low oxygen tensions on the respir- 
atory exchange of the American oyster were undertaken during the present investiga- 
tion. The results of one of the experiments are as follows: At 10.30 a. m. six normal 
oysters were placed in a closed chamber and samples of water were removed at one- 
half hour intervals until 8.30 p. m. In spite of the fact that small amounts of fresh 
sea water were added each time the sample was removed, the concentration of oxygen 
in the water was reduced by the metabolism of the oysters themselves to a low level. 
The results of the experiment presented in Table 6 and Figure 4 indicate that the 
oxygen consumption was not affected until 0 2 tension reached the level of approxi- 
mately 1.50 cubic centimeter per liter. In order to determine whether the products 
of the metabolism that were allowed to accumulate in the water might conceivably 
influence the respiratory exchange, the oxygen in the chamber was replenished by 
bubbling air through the water for one-half hour (from 8.30 to 9 p. m.). In this 
way the oxygen was renewed and the pH rose from 7.5 to 7.9. 
Table 6. — Effect of oxygen tension on oxygen consumption and effect of products of metabolism on 
oxygen consumption 
Date 
Oyster 
Time 
pH 
O 2 ten- 
sion, c. c. 
per liter 
0° C.,760 
mm. 
Oj con- 
sump- 
tion, c. c. 
per hour 
per 10 g. 
dry 
weight 
Aug. 6 
52-57, inclusive.. 
10. 30 
8.0 
4.76 
11. 00 
4. 49 
7. 86 
11. 30 
4. 02 
9.20 
12.00 
3. 62 
8.95 
12.30 
3. 05 
9. 04 
1. 00 
2. 72 
10. 008 
2.00 
2. 07 
9. 81 
2.30 
1. 57 
10. 012 
3. 00 
1. 08 
7. 73 
4. 00 
1. 03 
2. 81 
4. 30 
0.90 
4. 36 
5.00 
0. 78 
4. 36 
5.30 
0.915 
1.895 
6. 00 
0. 468 
2.04 
6.30 
0.953 
2. 04 
Date 
Oyster 
Time 
pH 
O 2 ten- 
sion, c. c. 
per liter 
0° O., 760 
mm. 
O 2 con- 
sump- 
tion, c. c. 
per hour 
per 10 g. 
dry 
weight 
Aug. 6 
52-57, inclusive.. 
7. 00 
1. 005 
1. 918 
7. 30 
0. 982 
2. 452 
8.00 
<>) 
9.00 
7.5 
0.920 
3.362 
7.9 
2. 44 
9. 30 
2. 28 
2. 315 
10.00 
1. 64 
8. 950 
( ! ) 
12.20 
Aug. 7 
52-57, inclusive.. 
8.0 
4. 80 
1.20 
2. 20 
3.20 
4. 26 
3. 64 
2. 775 
6. 298 
7.580 
6. 33 
4. 20 
2. 06 
7. 04 
5.20 
2.281 
5.61 
1 From 8.30 to 9.00 p. m., water in metabolism chamber was aerated. 
2 At 10 p. m. oysters were removed from the chamber, placed in running sea water until the next morning. Water in the cham- 
ber was then aerated for 2 hours, the same oysters put back in it, their oxygen consumption measured. 
Table 7. — Control on experiment in Table 6 
[Same six oysters, put in running sea water overnight. Next day oxygen consumption in fresh sea water determined] 
Date 
Oyster 
Time 
pH 
O 2 ten- 
sion, c. c. 
per liter 
0° C.,760 
mm. 
O 2 con- 
sump- 
tion, c. c. 
per hour 
per 10 g. 
dry 
weight 
Date 
Oyster 
Time 
pH 
O 2 ten- 
sion, c c. 
per liter 
0° C.,760 
mm. 
Oj con- 
sump- 
tion, c. c. 
per hour 
per 10 g. 
dry 
weight 
Aug. 8 
52-57, inclusive.. 
9. 50 
8. 2 
4. 37 
Aug. 8 
52-57, inclusive.. 
12. 15 
2. 05 
7 16 
10. 20 
3. 70 
9. 85 
12. 45 
1. 865 
4 38 
10. 50 
3. 28 
6. 75 
1. 15 
1. 345 
9 70 
11. 10 
2. 86 
9. 70 
1. 45 
1. 189 
4. 55 
n. 45 
2. 51 
7.27 
