78 



DISCOVERY REPORTS 



From that list we give in Table VIII the phosphate and oxygen values from the upper 

 50 m. for stations taken off the north-east coast in late August and also for corresponding 

 stations in late December. We see an average phosphate content for August of 149 mg. 

 per cu.m. and for December 112 mg. per cu.m. ; that is a reduction of 37 mg. per cu.m. 

 in four months. Naturally, on account of the flow of currents, the water is not the same 

 as that sampled in August, but presumably it had the same origin and had originally 

 approximately the same phosphate content. In 1926 we saw a reduction of 15 mg. per 

 cu.m. in a little over three weeks between November and December, so it is likely that 

 the greater part of this 37 mg. reduction up to the end of December in 1928 would be 

 made during November and December as the light intensity increased. (We see that 

 the average content for December 1928 is 17 mg. per cu.m. higher than that for De- 

 cember 1926; we do not know whether this was due to less phytoplankton production 

 in 1928 or to a higher initial content at the beginning of the season.) 



Table VII 

 Comparison of phosphate content, expressed in mg. per cu.m., of the top 50 m. on a line of 

 five stations taken off the north-east coast of South Georgia in November 1926 and 

 again a month later 



If it can be assumed that at mid-winter the phosphates in the upper layers of a par- 

 ticular stretch of sea are approximately evenly distributed then it would be possible to 

 compare the amount of phytoplankton production that had taken place in different 

 sub-areas as the season advances by studying the differences in phosphate content of 

 these areas later in the season. This assumption is tentatively made by Gran (1931) when 

 he compared the phytoplankton production with phosphate consumption in respect to 

 the samples obtained by Ruud at his fourteen stations in the Weddell Sea. Kreps and 

 Verjbinskaya (1930), estimating phytoplankton by chlorophyll mg. per cu.m., have 

 recently shown from surveys in the Barents Sea how phytoplankton production along 

 a line of stations is accompanied by phosphate and nitrate reductions. The chlorophyll 



