338 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
It will be noticed that in the densities taken in December the water at the bottom 
was a trifle fresher than that at the surface. By an inspection of the densities 
shown on the chart it will be seen that this occurs in a number of instances. In our 
observations it was of frequent occurrence (especially at low-water stage), showing 
the prevalence of fresh water springs in various parts of the bay. Whether this 
has anything to do with the distribution or the well-being of the oysters in this 
locality can hardly be determined from the limited number of our observations, and is 
here only pointed out as a possible field for investigation. Below is given a statement 
from the field notes showing that the phenomenon (fresher water at the bottom) was 
not due to an accidental reading of the hydrometer. 
Dauphin Island Bay (middle) abreast Marshall’s Store. 
Date. 
Time. 
Temper- 
ature 
of air. 
Temperature of 
water. 
Observed density. 
Depth. 
Remarks. 
Densities reduced 
to standard 
temperature, 15° C. 
Surface. 
Bottom. 
Surface. 
Bottom. 
Surface. 
Bottom . 
1894. 
Defc. 1 
8. 30 a. m 
c 
21.0 
O 
16.5 
o 
16.5 
1.0176 
1. 0176 
Feet. 
4.5 
Water clear. . . 
1.0179 
1. 0179 
4 
4. 50 p. m 
17.0 
17.0 
17.0 
1.0178 
1. 0176 
5.0 
W ater clear, 
1. 0182 
1. 0180 
5 
7. 30 a. m 
15.0 
16.0 
16.0 
1.0182 
1. 0180 
4.5 
tide west. 
do 
1.0184 
1.0182 
5 
8. 30 a. m 
14.0 
16.0 
15.5 
1. 0182 
1.0180 
5.0 
do 
1. 0184 
1.0181 
5 
9. 00 a. m 
16. 0 
16.0 
16.0 
1. 0180 
1.0180 
5.0 
do 
1.0182 
1. 0182 
5 
10. 10 a. m . . . 
15.5 
16. 0 
16.0 
1.0178 
1. 0181 
5.0 
do 
1. 0180 
1. 0183 
Natural oyster reefs in Mobile Bay, Alabama. 
Locality. 
Area in 
acres. 
Density of water 
during freshet, 
March, 1894. 
Density of water, 
end of drought, 
December, 1894. 
Depth of 
water. 
Character of bottom. 
Surface. 
Bottom . 
Surface. 
Bottom. 
Great Point Clear Reef. . . 
53 
83 
1; 0009 
1. 0036 
1. 0032 
1.0043 
1. 0160 
1.0187 
1.0160 
1.0187 
Feet. 
8Jt(f 10J 
7" 10 
Soft and hard mud ; sand. 
Soft and sticky mud. 
Soft and sticky mud; shelly. 
Do. 
68 
1.0063 
1. 0075 
1. 0189 
1.0187 
4 
9 
38 
1. 0043 
1. 0046 
1. 0189 
1.0189 
4 
7b 
10“ 
188 
1. 0054 
1. 0062 
1. 0192 
1. 0205 
4 
Do. 
Mobile Bay Light to Fowl 
100 
1. 0000 
1.0000 
1. 0118 
1. 0182 
5 
14 
Do. 
881 
1. 0007 
1.0035 
1.0120 
1.0120 
lb 
12 
Do. 
267 
1. 0018 
1.0065 
1.0152 
1. 0173 
6* 
124 
Do. 
Cedar Point NE. £ mile. . . 
Cedar Point E. 300 yards. . 
Cedar Point to Pass Drury 
139 
1. 0005 
1. 0005 
2| 
4£ 
9“ 
Do. 
45 
1. 0067 
1. 0071 
7b 
Do. 
813 
400 
1 * 1. 0005 
) 1 1.0056 
* 1. 0029 
1 1. 0074 
* 1. 0173 
1 1. 0189 
* 1. 01741 
1 1. 02273 
2 b 
2 
14 
9b 
Hard, shelly, and sand. 
Hard, shelly, sand, and mud. 
Do. 
Dauphin Island Bay and 
30 
1. 0051 
1. 0093 
1. 0182 
1. 0181 
3 
Total 
3,105 
* West. ' t East. 
Note. — The above densities have been reduced to the standard temperature of 15° C. Fresh water = 1.0000; 
standard sea water = 1.0260. 
