SPAWNING AND SETTING OF OYSTERS 
67 
(1929) in Long Island Sound, where the entire season’s spawning takes place within 
less than one month and can be predicted on the basis of water temperature. In 
that place the oysters spawn completely within a short time, while in the Gulf 
waters the spawn is ejected slowly over long periods of time. About a month and 
a half was required for spawning to reach its maximum, while in Long Island Sound 
and similar waters the maximum is reached within a few days after the water 
reaches 20° C. 
Table 2. — Temperature in °C. of surface water, Galveston Bay, in summer, 1929 
The water temperature in the bayou fluctuated around 25° C. during April 
and May, and during June, July, and August seldom dropped below 30°. Tempera- 
tures between 30° and 33° C. are extremely high, as compared with the North 
Atlantic waters, but probably are not much above average during the summer for 
the bays on the Gulf coast. The high temperature of the water throughout a large 
part of the year is probably responsible for the rapid growth of oysters, which attain 
marketable size in two years. 
In the open bay the temperature did not rise quite as high as in the bayou. 
In Table 2 records of separate readings of the temperature of surface water in both 
East and West Bays are given. Because of the exposure of these waters to wind 
the temperature in general ranged slightly below 30° C. during the^summer. 
SALINITY AND HYDROGEN-ION CONCENTRATION 
Galveston Bay is subject to changes in salinity due to discharge from the San 
Jacinto and Trinity Rivers and innumerable small bayous which drain the main- 
land as well as to the direction and strength of the wind. Being a shallow bay it 
would be expected to exhibit marked changes in salinity, particularly as a result 
of swollen rivers. 
Samples of bayou water, from the surface 6 inches, were tested daily for salinity 
and pH. Frequent tests were also made with samples from the Deer Islands in 
West Bay and Hanna Reef in East Bay. A brief description of the changes taking 
place in the water during spring and summer is necessary to show what is perhaps 
a semitypical example of the variation in the bay waters of most of the Gulf coast. 
