Figure 22. — Bottom topography of the principal shrimping area In the vicinity of the Dry Tortugas, Fla., 1968-69. Relief 



Is contoured at 1-m. (3.3-ft.) intervals on a Mercator projection. 



Other mound and basin features at greater 

 depths mark old strandlines and indicate a 

 stillstand of the ancient prograding sea. Pro- 

 files that show topographic relief across the 

 area were prepared fronri echo- sounding traces 

 made during cruises of the R/V Geronimo . 



Waters in the southeastern Gulf . - - During 

 the cruise of the R/V Oregon II in October, we 

 collected 342 water samples from the south- 

 eastern Gulf. Dissolved oxygen content of the 

 water was determined aboard ship; concentra- 

 tions of phosphate-phosphorus and silicate- 

 silicon were determined in the laboratory. 



We completed the analysis of dissolved 

 oxygen and nutrient contents of samples col- 



lected during cruises 12, 16, and 20 of the 

 R/V Geronimo in the Gulf and Yucatan Strait. 

 We analyzed 6,742 samples. We are now 

 plotting these data and examining their quality 

 by several methods. Particular emphasis is 

 being placed on a study of dissolved oxygen 

 and temperature in the areas of strong and 

 persistent upwelling in the Straits of Florida 

 and the Yucatan Strait. Populations of plankton 

 are dense in each area. 



John R. Grady, Project Leader 



Circulation Dynamics 



The amount of data and extensive coverage 

 of the Gulf of Mexico accomplished during the 



33 



