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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



(1929) who reported results of analyses of two 

 samples of water collected at the Dry Tortugas 

 in July 1922: 1.00 and 4.80 parts phosphate per 

 million parts of water (10.5 and 50 microgram- 

 atoms phosphate-phosphorus per liter). 



Information on the vertical distribution of 

 phosphorus in the Gulf of Mexico is very limited. 

 Determinations of phosphate were made on the 

 16 samples (surface to 1,732 meters) collected at 

 Atlantis station 1606 in the middle of the Yucatdn 

 Channel in May 1933 (Bulletin Hydrographique, 

 1934, p. 103). Graphs of the vertical distribution 

 of phosphorus at this station were published by 

 Rakestraw (1936, p. 160, fig. 11) and Rakestraw 

 and Smith (1937, p. 9, fig. 7).^ The phosphate- 

 phosphorus" remained nearly constant at 0.15 

 /ig-atoms/L from the surface to 97 meters, then in- 

 creased to a maximum of 2.47 at 736 meters, then 

 decreased to 1.71 at 1,732 meters. These data for 

 Yucatan Channel water were used in the charts of 

 horizontal distribution of phosphate at various 

 depths (Rakestraw and Smith, 1937, figs. 10-12). 



Horizontal and vertical distribution of phos- 

 phate near the mouth of the Mississippi River 

 in March 1937 was reported in tables and a map 

 by Riley (1937, pp. 74, 63). He found about 

 0.58 ^g-atoms/L in the low salinity surface water 

 at the station at the mouth of the river. Phos- 

 phate decreased in all directions to an average of 

 0.14 /ig-atoms/L at the stations in the Gulf. 



Distribution of phosphate at the Dry Tortugas 

 and in the Florida Straits was reported by Riley 

 (1938, 1939) and Riley, Stommel, and Bumpus 

 (1949, p. 16). Near Loggerhead Key where the 

 depth was 3 meters, the phosphate ranged from 

 0.015 to 0.10 Mg-atoms/L from July 18 to August 2, 

 1938. At his station midway between Loggerhead 

 and Garden Keys where the depth was 19 meters 

 the phosphate at depths of 1, 5, 10, and 15 meters 

 varied quite differently with depth on 4 days in 

 July 1938 from 0.02 to 0.16 Mg-atoms/L. His 

 data from other stations are summarized in table 1 . 



Riley (1951) presented a detailed summary of 

 phosphorus distribution in the Atlantic Ocean 



but omitted the Gulf of Mexico, except for his 

 discussion (p. 15) of the tendency for the products 

 of regeneration (phosphate and nitrate) to ac- 

 ciunulate in the deep water of the Caribbean-Gulf 

 of Mexico basins because the outflow through the 

 Straits of Florida is shallower than the maximum 

 depth of the inflowing water. 



» There appears to be some confusion regarding units in the three publica- 

 tions dealing with this phosphorus data. The raw data in the Bulletin 

 Hydrographique are reported in milligrams phosphate per cubic meter. 

 When these figures are divided by 95, the corresponding unit is milligram- 

 atoms per cubic meter or microgram-atoms per liter. The scale for fig. 11, 

 p. 160 of Rakestraw (1936) indicates phosphate from to 1.5 microgram-atoms 

 per liter, but the scale for fig. 7, p. 9 of Rakestraw and Smith (1937) indicates 

 phosphate from to 3 milligram-atoms per liter. It is believed that the 

 units in the last paper should be either microgram-atoms per liter or milli- 

 gram-atoms per cubic meter, which are numerically equal. Later papers 

 report this same data in microgram-btoms per liter (Sverdrup, Johnson, and 

 Fleming, 1942, p. 241) or milligram-atoms per cubic meter (Riley, Stommel, 

 and Bumpus, 1949; Riley, 1951). 



' Phosphate data reported in this section have been corrected lor salt error 

 by multiplying any uncorrected values by 1.15 (Cooper 1938, p. 177; Robinson 

 and Thompson 1948, p. 36). 



Results of phosphate analyses at various in- 

 shore stations in the Tampa Bay area and near 

 the southern tip of the Florida peninsula in 1946, 

 reported by Williams (1947) and Smith (1949), 

 are summarized in table 2. 



Table 2. — Phosphate {ng-aloms/ L) along Gulf coast of 

 Florida in 1946 



In connection with studies of the red tide along 

 the Gulf coast of Florida in 1947 made during and' 



