52 



OYSTER BOTTOMS OF MISSISSIPPI SOUND, ALA. 



The top of the bench mark accorded with readmg 3.65 on the 

 scale of the staff gauge. 



The tides in this region, as in general on the Gulf coast, are small, 

 averaging from 1 to 1 J feet in height, but reaching 2^ feet under cer- 

 tain conditions of wmd, etc. 



No special observations were made of the velocity of the currents, 

 but in general they are sufficient for the transport of food and water 

 to the oysters in all places covered by the survey. 



SALINITY OF THE WATER. 



As is well known, the quantity of salt in the water is an important 

 factor in determining the growth and character of oysters. Neither 

 fresh water nor that of full oceanic saltiness is suitable for the oyster 

 itself, and, moreover, the degree of saltness often determines the pres- 

 ence, absence, or relative abundance of such oyster enemies as the 

 drill or borer. During the survey upward of 300 specific-gravity 

 observations were made to determine the condition of the water in 

 respect to its content of salt. Three tests were made daily on the 

 Fish Hawk, and in addition observations were taken on the oyster 

 beds and in their immediate vicinity. The followiag table is a sum- 

 mary of all of the ship's observations, supplemented by some of those 

 taken on and near the important natural beds : 



Specific Gravity of Water at Various Places and Dates. 



Locality. 



Date. 



Average 

 temper- 

 ature. 



Average 

 si)ecific 

 gravity. 



Maximum 

 specific 

 gravity. 



Minimum 

 specific 

 gravity. 



Mobile Bay: 



Near Buoy Reef 



1910. 



Nov. 17-24 



Nov. 29-Dec.l. 



Nov. 23 



Nov. 24 



Dec. 7-9 



Dec. 29-Jan. 5. 

 Dec. 5-7 



60 

 56 

 57 

 63 

 48 

 50 

 51 



1. 0166 

 1. 0206 

 1. 0178 

 1. 0193 

 1. 0186 

 1. 0150 

 1. 0235 



1. 0206 

 1. 0215 

 1. 0191 



1.0122 



2 miles east of Grants Pass 



1. 0201 



Sand Reef 



1.0165 



Oyster beds, near Grants Pass 





Mississippi Sound, 1 to 2 miles oS Mid 

 Signal. 



1. 0210 

 1. 0200 

 1. 0247 



1. 0156 

 1. 0114 

 1.0223 



Dec. 12-16 



Dec. 20-22 



Dec. 29-Jan. 2. 

 Mar. 20-24 



54 

 51 

 57 

 66 



1.0209 

 1. 0213 

 1. 0191 

 1. 0198 



1. 0235 

 1. 0220 

 1. 0219 

 1. 0216 



1. 0173 

 1.0206 

 1. 0187 

 1. 0160 



Portersville Bay 



1911. 

 Jan. 10-11 



54 



1. 0137 



1. 0167 



1.0108 



Mississippi Sound, one-half mil© west of 

 Coffee Island. 



1910. 

 Dec. 9-11 



Dec. 17-20 



Dec. 22-24 



Dec. 27-28 



54 



55 

 50 

 56 



1. 0228 



1. 0219 

 1. 0205 

 1. 0205 



1. 0240 



1. 0236 

 1. 0210 

 1. 0213 



1.0223 



1. 0211 

 1. 0196 

 1. 0203 



Mississippi Bay, 2^ miles south of Grand 

 Bay. 



1911. 



Jan. 3-9 



Jan. 10-16 



Mar. 14-19 



Mar. 25-27 



Mar. 29-Apr. 1. 



Apr. 6-9 



Jan. 17-20 



49 

 59 

 64 

 63 

 65 

 74 

 61 



1. 0207 

 1. 0180 

 1. 0205 

 1. 0198 

 1. 0197 

 1. 0170 

 1. 0178 



1. 0227 

 1. 0214 

 1. 0222 

 1. 0216 

 1. 0206 

 1. 0203 

 1. 0194 



L0180 

 1. 0150 

 1. 0174 

 1. 0160 

 1. 0188 

 1. 0148 

 1. 0154 



Jan. 24-28 



62 



1. 0175 



1. 0206 



1. 0141 



