29 

 28 

 27 

 26 

 25 

 24 

 23 

 22 



21 

 20 

 19 

 18 

 « 17 



o 



bu 18 



ee 



i 15 



z 14 



UJ 



- 13 



12 



11 



10 



9 



8 



7 



8 



5 



35 



SALINITY (0/OOJ 

 38 



37 



T — r— I — I — I — I — I — I — I — I — I — I — I — I — I — I — >"> — ""T 



® 



® ^ ® 





® FLORIDA CURRENT 



• SOUTHWARD BAND 



® NORTHWARD BAND 

 (ANTILLES CURRENT) 



    I  I I I 1—1 I I I I I I 1 I — I 1 I I — L. 



FiGURE 5.-0bserved temperature (°C) - salinity ("/oo) points in 

 the northward and southward bands and the Florida Current 

 from six occupations of Standard Section A-7. 



the net northward transport of plankton would be 

 small, even in the area of higher current speeds 

 near the continental shelf. Instead, planktonic or- 

 ganisms may be caught up in eddies or slowly 

 moving water for long periods of time. Since the 

 waters east of the northern Bahama Islands con- 

 tain a relatively small plankton biomass and are 

 thought to yield low rates of primary and second- 

 ary production, pelagic fish larvae held in the 

 area for an extended period of time would have 

 little likelihood of growth and survival. 



A clearer resolution of quasi steady-state 

 currents should be realized when analysis of data 

 and geostrophic computations are complete for 

 two MARMAP cruises (July-August 1972 and 

 January-March 1973), which included the area east 

 of the Bahama Islands. However, the transport of 

 planktonic organisms in the surface layer may be 

 governed by local wind-driven currents which may 

 not be manifested as geostrophic currents com- 

 puted from the density field. Average monthly 

 wind roses (U.S. Naval Oceanographic Office 1963) 

 for the area off the northern Bahamas shows that 

 the winds from the east or northeast occur with 

 greater frequency than those from any other 

 quadrant every month, except June, July, and 

 August, when winds from the south and southeast 

 are more frequent. Such easterly and northeast- 

 erly winds would yield northward and north- 

 westward Ekman (wind-driven) transports in the 

 surface layer coinciding with the direction as- 

 sumed for the Antilles Current. The net Ekman 

 transport in the surface layer depends on the 

 frequency distribution of wind direction and speed 

 during the time period of interest, the subject of 

 further research. 



assumed to be moving steadily toward the north- 

 west along the path traditionally assigned to the 

 Antilles Current. Planktonic organisms located in 

 water just seaward of the continental shelf at this 

 latitude (28.5°N) are likely to have a northward 

 compoent of velocity of about 10-30 cm/s, while 

 those in deeper water 100-200 km farther offshore 

 are likely to have a southward component of about 

 the same magnitude. Seaward of that, plankton 

 are likely to move either northward or southward 

 at relatively slow speeds, in the range of 5-10 cm/s. 

 If the higher speeds in the northward and south- 

 ward bands are manifestations of a quasi-per- 

 manent eddy or transient eddies passing through. 



LITERATURE CITED 



BiGELOW, H. B. 



1917. Explorations of the United States Coast and Geodetic 

 Survey steamer "BACHE" in the Western Atlantic, 

 January-March, 1914, under the direction of the United 

 States Bureau of Fisheries. Oceanography. U.S. Bur. 

 Fish., Rep. U.S. Comm. Fish., 1915, append. V (Doc. 833), 

 62 p. 

 BOISVERT, W. E. 



1967. Major currents in the North and South Atlantic 

 Oceans between 64°N and 60°S. U.S. Nav. Oceanogr. 

 Off., Tech. Rep. TR-193, 92 p. 

 Day, C. G. 



1954. A note on the circulation in the region northeast of the 

 Bahama Islands. Woods Hole Oceanogr. Inst., Tech. Rep. 

 54-4, 6 p. 



631 



