EFFECT OF CRUDE OIL POLLUTION ON OYSTERS 
163 
5 tall hatching jars of 5 liter capacity, in each of which 4 adult oysters were elevated 
above the bottom by a 3-incli layer of clean oyster shell. An additional jar containing 
an automatic siphon arrangement was connected with each hatching jar by glass and 
rubber tubing so as to bring about the filling and emptying of these jars at regular 
intervals. One control and 4 experimental jars were used in each series of experiments, 
each of the latter containing a heavy surface layer (50 cc) of the following: Barre oil 
grade A, Barre oil grade B, Pelto oil (composite sample), and Barre sludge. After the 
experiments had been in progress for approximately 3 weeks, 50 cc of each of the above 
oils and sludge were added to each experimental jar, respectively. 
Four separate and complete series of experiments were conducted during the period 
from September 20, 1933, to January 3, 1934, in which a total of 64 oysters were com- 
pletely immersed in oil at intervals of 1 and 2 hours over a period of 6 to 8 weeks. The 
results of these studies are given in table 3. In the first series (1 hour interval), 
which was conducted in the early fall at fairly high water temperatures, there was a 
loss of 31.25 percent of the oysters exposed to oil and 50 percent of the control oysters. 
In the second series the losses in the control and experimental jars were the same 
amounting to 25 percent. In the third and fourth series (2 hours exposure interval) 
not a single specimen died in either the control or experimental jars or during the 
subsequent period of 3 months when they were returned to natural conditions in the 
harbor. During the course of the experiments it was frequently observed that the 
oysters kept the shell open when covered with oil and that the formation of new shell 
was much greater in the experimental oysters than in the controls. 
In order to test further the toxicity of water contaminated with oil and sludge, 
the overflow from all jars used in series 1 and 2 was passed into a tank containing 22 
seed oysters, 22 clams (3 species), 4 gastropods (2 species), and 6 anemones, none of 
which died during the course of the experiments. In the third and fourth series the 
overflow water was passed into a tank containing approximately the same number and 
ki nd of marine organisms as the former and in addition 6 small fish (Fundulus, Hypso- 
blennius), all of which survived and appeared to be in a healthy condition. 
Table 3. — Survival of oysters after immersion in oil and sludge at regular intervals of 1 and 2 hours 
over periods of 6 to 8 weeks 
Conditions 
Series no. 1 (Sept. 
20 to Oct. 31) 
Series no. 2 (Sept. 
20 to Oct. 31) 
Series nos. 3 and 4 
(Nov. 2 to Jan. 3) 
Total results (Sept. 
20 to Jan. 3) 
Control 
Experi- 
mental 
Control 
Experi- 
mental 
Control 
Experi- 
mental 
Control 
Experi- 
mental 
Number of oysters used... 
4 
16 
4 
16 
8 
32 
16 
64 
Number of times ovsters immersed in oil 
0 
1,008 
0 
1,008 
0 
720 
0 
720-1,008 
Number oysters alive at end of experiment-. 
2 
11 
3 
12 
8 
32 
13 
55 
Percent survival by jar: 
50 
75 
100 
81. 2 
75 
75 
100 
87. 5 
75 
50 
100 
81. 2 
50 
75 
100 
81. 2 
75 
100 
100 
93.7 
Percent survival, total 
50 
68.7 
75 
75 
100 
100 
81.2 
85.9 
EFFECT OF OIL ON GLYCOGEN CONTENT OF OYSTERS 
This series of experiments was conducted to determine the effect of 3 different 
grades of crude petroleum on the glycogen content of oysters over a period of 4 weeks 
(Dec. 6, 1933, to Jan. 4, 1934). Two hundred and ten oysters of uniform age and size 
were used, of which a representative sample of 10 oysters was taken for glycogen 
