BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
291 
An interesting condition, which shows on practically all cruises, is the one along 
the line J, I, K just below the mouth of the Potomac River. The most saline bottom 
water is found at area J, located on the deep channel near the western shore, while 
the most saline surface water lies on the eastern side, usually at area K or at least 
at area I. The density profiles indicate that the condition mentioned is due to the 
pressure of the Potomac River water, which, coming from a westerly direction, crowds 
the more saline surface water overlying the deep channel toward the east. A similar 
but less marked condition occurs along the line P, L, L' . 
SALINITY OF WATER DURING WINTER 
It has been pointed out that there is a comparatively large decreasing range of 
salinities from the mouth of the bay to the head throughout the year. This range 
varies from time to time, but there is no evidence in our data to show that there is 
any uniform seasonal fluctuation in the amount of range. 
Inspection of the salinity values of the January cruises taken in 1916, 1920, and 
1922 shows that they were generally higher than those of the January, 1921, cruise. 
This condition is probably correlated with the fact that January, 1921, was an excep- 
tionally mild month. (Table 1.) (See section on salinity during the spring.) 
Table 1 . — Temperatures and salinities at surface, 20 meters, and 30 meters, during January, for various 
years and areas 
Areas 
January, 191G 
January, 1921 
January, 1922 
Tem- 
pera- 
ture, 
°C„ 
surface 
Sa- 
linity, 
surface 
Temperature, ° C. 
Salinity 
Temperature, ° C. 
Salinity 
Surface 
20 me- 
ters 
30 me- 
ters 
Surface 
20 me- 
ters 
30 me- 
teas 
Surface 
20 me- 
ters 
30 me- 
ters 
Surface 
20 me- 
ters 
30 me- 
ters 
G 
4. 1 
3.3 
1.4 
1.8 
1. 1 
1. 1 
1.0 
1.2 
.6 
23.40 
22.74 
15. 14 
14. 36 
13. 66 
12.77 
11. 13 
9.22 
6. 83 
5.9 
4.9 
3.9 
3. 1 
2.6 
2.7 
2.0 
1. 6 
1. 1 
6. 0 
4.9 
3.9 
3.0 
3.4 
19. 22 
28. 10 
— 
12.9 
4.4 
3.4 
2.6 
1. 4 
1.7 
.8 
5.9 
4.5 
3.2 
2.4 
2. 7 
________ 
2.7 
2.8 
2.5 
23. 91 
23. 96 
29. 15 
25.71 
\ 
4.8 
4.0 
3.7 
3.7 
25. 89 
J .. 
13. 12 
13. 64 
17.51 
13. 80 
18. 30 
16.80 
L 
15. 46 
15.81 
13. 17 
13. 26 
20.31 
19. 54 
20. 46 
19. 86 
R 
s 
x 
2. 1 
1 3.8 
12. 14 
10.88 
6.44 
12. 36 
1 14. 46 
3. 2 
18. 95 
Y 
u 
1 At 20.13 meters. 
Throughout the year the salinity usually increases with the depth (Katohalin). 
This might be expected in a body of water where there is fresh water from rivers flow- 
ing over tidal saline water entering from the ocean, even though currents, river floods, 
low air temperatures, and winds tend at times to alter that condition. A disconti- 
nuity in salinity was frequently seen during the winter cruises and, although the water 
was at times almost homohaline from the surface to the discontinuity layer, it was 
seldom that even an approach to complete homohalinity along the deep-water chan- 
nel was observed. The salinities for January, 1916, are typical: Area U, surface 
6.83, 4 meters 8.44, 9 meters 12.92, 15 meters 14.31; area L, surface 14.36, 5 meters 
14.92, 10 meters 15.72, 17 meters 16.87, 25 meters 19.27, 31 meters 19.87; area G , 
surface 23.40, 8 meters 27.20, 17 meters 32.54, 22 meters 32.57. Occasionally, how- 
ever, as on January 25, 1921, at area L, an approach toward an homohaline and homo- 
thermous condition was observed. The salinities were as follows at 7.35 p. m. : Sur- 
face 14.36, 10 meters 14.26, 20 meters 14.34, 30 meters 14.64, 33.9 meters 14.78. 
The temperatures were: Surface 3°, 10 meters 3°, 20 meters 2.9°, 30 meters 3°, 
1988—30 2 
