SUB-ANTARCTIC WATER 57 



95 mg. southwards in the third week of June 1932, whilst a week later on the return 

 section (11) between the ice-edge in 6i° 05' S, 158 26' E, south of the Tasman Sea, 

 and North Cape, New Zealand (Sts. 921-924, Plate XVI), the southernmost sub- 

 Antarctic station had a surface value of 73 mg., a value which decreased to 38 mg. at 

 the northern end of the zone. 



In the South Pacific Ocean it is only in the western part that we can give any data 

 for the whole width of the sub-Antarctic zone. This is due to the fact that except near 

 New Zealand we have no exact knowledge at present of the position of the subtropical 

 convergence which in mid-South Pacific lies north of 35 S. In early September 1932 

 between Wellington, New Zealand, and the ice-edge north of the Ross Sea (Sts. 942- 

 949, section 12, Plate XVII), the surface value increased southwards across the zone 

 from 51 to 106 mg. In the third week of January 1934 section 13 was made from the 

 ice-edge at the eastern entrance to the Ross Sea to Auckland, New Zealand (Sts. 1276- 

 1280, Plate XIX). This latter section will serve to contrast with that of late winter in 

 September 1932 from Wellington, New Zealand. In January the main phytoplankton 

 outburst is finished in this zone, whilst in early September it has not yet begun. The 

 phosphate results in the January section showed that the surface value fell from 82 mg. 

 in the south of the zone to 14 mg. in the north, although the presence of some subtropical 

 surface water of low phosphate content is probably responsible for the very low value 

 of 14 mg. 



In the course of a W-shaped cruise (sections 12, 14, 15 and 16) across the South 

 Pacific Ocean in mid-September to early October 1932 a number of observations were 

 made in sub-Antarctic water at Sts. 962-967, 967-970 and 976-978 (Plates XVII, XXI, 

 XXIII and XXV). The subtropical convergence was not crossed in any of these sections, 

 and consequently no values for the northern boundary of the sub-Antarctic water can 

 be given. The surface content varied between 114 mg. at the most southerly stations 

 and 38 mg. at the most northerly one in 41 03-1' S, 126 03-9' W. 



In the eastern part of the South Pacific Ocean in 8o° W we have data from four sets 

 of observations in March, September, late October and late November; the data are 

 mostly restricted to the southern end of the zone. In March (Sts. 13 17-1320), the surface 

 phosphate content varied from 90 to 67 mg. between 6o° and 55!° S ; in mid-September 

 (Sts. 1417-1421), surface values varied between 97 mg. in 6i° S and 71 mg. in 55 22' S ; 

 in late October the most southerly station gave a value of 86 mg. in 61 \° S, whilst 

 values of 76 mg. were recorded farther north ; in late November there was only one 

 observation of 100 mg. at St. 1476 in 6o° 20' S, a somewhat high value for the time 

 of the year. 



As a summary of our present knowledge we can say that the surface phosphate 

 content at the southern end of the sub- Antarctic zone is of the order of 100-110 mg. 

 in winter and of about 70 mg. after the main phytoplankton outburst which in this 

 zone probably starts in October. At the northern boundary winter values of 60-70 mg. 

 are found in the South Atlantic and South Indian Oceans, but south of Australia and 

 the Tasman Sea values in June were found to be as low as 37-43 mg. Immediately 



