I 

 t- 



ID 2000 



Figure 24. — Salinity cross section from cruise 16, R/V Geronlmo , in the Gulf of Mexico, 



August to October 1967, 



67 hydrographic stations in the southeastern 

 Gulf- Yucatan Strait area (Hurricane Gladys 

 prevented completion of the cruise). The data 

 from this cruise were analyzed, and although 

 few stations were occupied, the information 

 will be useful in supplementing the data from 

 the R/V Geronimo cruises. 



Hydrographic data for the upper 1,200 m. 

 (3,960 feet) from various cruises of the R/V 

 Alaminos (Texas A&tM University) in the Gulf 

 during 1965-68 were processed to supplement 

 the R/V Geronimo data. This information will 

 provide more detail on time variations of the 

 circulation. 



Reed S. Armstrong, Project Leader 



Biological Applications 



We collected sannples of zooplankton at most 

 hydrographic stations occupied during the 

 all-Gulf cruises of the R/V Geronimo and 

 cruise 3 of the R/V Oregon 11 . We obtained 

 these samples by making vertical hauls in the 



upper 100 m. (330 ft.) of water with a metered 

 NV-70 net. We counted the 12 most abundant 

 taxa (including fish larvae) and prepared some 

 frequency tables and contour maps to illustrate 

 distributions. We are now studying how the 

 seasonal abundance and distribution of these 

 taxa are related to the water nnasses, con- 

 vergences, and areas of upwelling. 



The preparation of all data has not been 

 completed, but preliminary plots of the distri- 

 bution of zooplankton indicate that the highest 

 catch was over the Continental Shelf in the 

 summer of 1967 near the mouth of the Sabine 

 River. More extensive concentrations of or- 

 ganisms, however, were found over the Conti- 

 nental Shelf of the northern Gulf in the winter of 

 1967. These areas were apparently at and 

 near local sites of upwelling and convergences. 



Concentrations of zooplankton were large 

 over the Continental Shelves and slopes of 

 eastern Yucatan and southwestern Florida. 

 Although the abundance of zooplankters was 

 generally similar during all cruises, catches 

 were somewhat greater in the winter. Also, 

 the population of zooplankters was dense in 



35 



