166 
BULLETIN OF THE BUREAU OF FISHERIES 
added and that this reaction can be correlated with the amount of brine present and 
salt content of the water. The three control specimens were open an average of 
7.26 hours daily as compared with daily open periods ranging from 8.5 to 11.8 hours 
in experimental specimens subjected to brine in amounts varying from 12.5 to 100 
parts per thousand. 
In many instances the brine was added when the oysters were open and had been 
feeding for a short period, which caused one or two partial contractions of the adduc- 
tor muscle but did not produce closure of the shell or appear to have any noticeable 
effect upon its subsequent movements. With the exception of specimen no. 7 all 
of the experimental oysters showed normal records as to the number of shell move- 
ments or muscular contractions per hour as compared with their respective records 
prior to the first addition of brine, and those of the control specimens. In the case 
of specimen no. 7 there were frequent, nearly complete, contractions of the muscle 
which might be attributed not only to the higher concentration of brine but also to 
the high salinity of the water which was considerably greater than that found in the 
natural environment of the oyster. In spite of such abnormal muscular activity 
this oyster was able to maintain shell closure for periods ranging from 24 to over 96 
hours toward the end of the experiment and subsequently recovered completely in 
running water. 
Table 6. — Comparison of length of time oysters remained open in normal sea water and brine-sea 
water mixture 
Specimen 
Medium 
Average 
salinity 
Total 
hours 
open 
Average 
number 
of hours 
per day 
Percent of 
time open 
CONTROL 
No. 1 
Normal sea water 
32. 17 
648 
7.2 
30.0 
No. 2 
do 
32. 17 
806 
8.9 
37.0 
No. 3 
do 
32. 17 
513 
5.7 
23.7 
EXPERIMENTAL 
BARRE BRINE 
12.5 parts per thousand-. 
33.30 
927 
10.3 
42.9 
25 parts per thousand 
34. 44 
1,026 
1,053 
11.4 
47.5 
50 parts per thousand 
36.71 
11.7 
48.7 
No. 7 - 
100 parts per thousand 
41.25 
1,062 
11.8 
49.1 
PELTO BRINE 
25 parts per thousand. 
33. 81 
765 
8.5 
35.4 
50 parts per thousand 
35. 46 
819 
9.1 
37.9 
One purpose of the experiments with brine was to determine its effect upon the 
holding power of the oyster muscle, since loss of this function was apparently the 
immediate cause of the oyster mortality in Terrebonne Parish. Consequently all of 
the specimens were kept in air for a period of 96 hours, at an average temperature of 
19° C., after completion of the experiments during which time they were able to keep 
the shells tightly closed and later showed no serious effects of such treatment when 
returned to running water. This test was again repeated 10 days later with the same 
result. 
The previous experiments indicate that the brine waters from the Lake Barre 
and Lake Pelto oil wells do not affect the muscular mechanism of the oysters in 
relatively high concentrations provided the quantity present does not increase the 
salinity beyond the limits favorable for the growth of tiffs shellfish. Since these 
effluents are greatly diluted before reaching the oyster beds, and since no significant 
