to SUW also decreased on either side of the 

 main axis of the water (fig. 43). 



Even though there have been no other 

 "all-Gulf" cruises, analyses of data from 

 parts of the Gulf during February and March 



vicissitudes and biologic constituents is clear. 

 As the SUW spreads through the Gulf, 

 it is (1) mixed and (2) modified by reac- 

 tions between the sea and the atmosphere. 

 The salinity and temperature are changed-- 



DEPTH TO SUW IN HECTOMETERS 



96 94 



82 W. 



3tf 

 N. 



28' 



26- 



24- 



2 2' 



20" 



le 



Figure 43. — The depth to the SUW In the Gulf of Mexico in February and March 1962 in 

 hundreds of meters (hectometers). 



of other years are sufficient to indicate that 

 the distribution of SUW in the late winter of 

 1962 does not depict a "steady-state" condi- 

 tion. For example, no SUW was north of lat. 

 25° N. in the northwestern Gulf in 1964. 



Data from the central and eastern Gulf 

 taken in fall, spring, and summer are being 

 evaluated. It seems that the distribution of 

 SUW chcinges dramatically, both in position 

 and in time. Because this water mass is the 

 habitat for the major fish populations in the 

 Gulf of Mexico, the significance in learning its 



the manner and extent depending on which 

 of the two processes dominates during 

 the period under consideration. A further 

 change in the surface and near-surface 

 waters is in the nutrient content. Surface 

 waters entering the Gulf are notoriously 

 devoid of inorganic nutrients. Inorganic phos- 

 phate is a good indicator. Waters to depths of 

 lO's of meters frequently have none. The addi- 

 tion of this inorganic nutrient to the waters of 

 the Gulf in the late winter of 1962 was cin 

 evident change--easily noted (fig. 44), 



38 



