22 DISCOVERY REPORTS 



as opposed to a content of 75-82 mg. at the end of December 1933 at Sts. 1234 and 1235. 

 It is obvious that the April figure is showing the effect of regeneration, whilst the 

 December results were obtained after the maximum concentration of phytoplankton in 

 the northern region, and are correspondingly low. 



In the Scotia Sea between South Georgia and the Falklands a surface value of 99 mg. 

 was observed in the second week of October 1934; the main outburst of phytoplankton 

 had not yet occurred in this position. Just south of the convergence between the 

 Falklands and Elephant Island the surface had a phosphate content of 98 mg. in late 

 September 1934 (St. 1425), whereas earlier in March 1934 a surface value of no mg. 

 was recorded at St. 1326 in the same position. Very poor catches of phytoplankton were 

 taken at both stations ; the value of 98 mg. in September would appear to be low. 

 As evidence of an annual variation we have a surface value of only 85 mg. in early 

 March 193 1 at St. 634 (in a position very close to that of St. 1425) as opposed to 1 10 mg. 

 in March 1934. 



Immediately south of the Antarctic convergence to the north of the South Orkneys 

 we have data for late January, early April and early October. The surface contents are 

 respectively 76, 113 and 113 mg. ; these figures probably approach the limits of the 

 annual range of surface phosphate throughout the year in this position. If this is correct 

 the withdrawal from the surface during the phytoplankton season at the Antarctic con- 

 vergence is of the order of 37 mg. out of an available 113 mg., about 33 per cent. 



In the Scotia Sea, excluding South Georgia which is dealt with later in this report, 

 we have no surface values for the winter months of May, June, July and August. 

 Phosphate is probably maximal in these months unless a southward movement of sub- 

 Antarctic water across the convergence considerably reduces the phosphate content. 

 Consequently in the absence of winter surface values the seasonal range of phosphate 

 just south of the convergence in the Scotia Sea must be given with some reserve. 

 However, it seems clear that a midsummer value of about 75-80 mg. is usual and an 

 autumnal value of 1 10-1 15 mg. is to be expected. The value for the winter months may 

 be in the neighbourhood of 1 15-120 mg. 



In the South Atlantic Ocean in 30 W a value of 105 mg. was recorded in early April 

 193 1 for the surface phosphate just south of the Antarctic convergence, whereas in 

 22 W in mid- August 1934 only 94 mg. were found in the surface. In mid-October 

 1930 at St. 452 in 49 50' S, 08 32^' E, which position lies to the north of the easterly 

 drift out of the Weddell Sea, only 79 mg. were found at a time when the main outburst 

 of phytoplankton had not begun. 



At the Antarctic convergence north of Enderby Land the surface phosphate was of 

 the order of 85-95 mg. in February and April, whilst in early May 1934 it had risen 

 to 122 mg. On a diagonal course between Enderby Land and Fremantle, Australia, 

 in late April 1932 the surface value was 100 mg. just south of the convergence. In late 

 May 1932 the value farther east, and south of Australia, was 116 mg., whilst south of 

 the Tasman Sea a month later 1 06-1 15 mg. were recorded. 



At the convergence north of the Ross Sea we have values for the surface phosphate 



