QJ 

 10 

 fD 

 CD 



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 U 



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COMPARISON OF RESULTS FROM DIFFERENT REGIONS 



that the values in the oceanic region are 

 nearly as high as those in the neritic 

 area in the northern hemisphere in 

 nearly corresponding latitudes, thus 

 leaving little doubt of the greater rich- 

 ness of Antarctic surface w^aters over 

 north temperate seas, which vvrould be 

 expected from their greater nutrient 

 salt content. Another interesting 

 feature clearly brought out by this 

 figure is the relative lateness of the 

 main increase in Antarctic as compared 

 with north temperate seas. Possible 

 reasons for this have already been 

 discussed (Hart, 1934, pp. 189-90). 



The great differences in climate and 

 hydrological conditions which account 

 for such a contrast between the two 

 hemispheres, described in the earlier 

 work quoted, are all bound up with the 

 extension of polar conditions so much 

 farther towards the equator in the 

 southern hemisphere. For this reason 

 it may appear that the comparison 

 given in Fig. 18 is obviously too remote 

 to be of direct significance, but I find it 

 very helpful to be able to visualize our 

 results against those obtained by similar 

 methods under conditions which, while 

 vastly different from those obtained in 

 the southern hemisphere, have been 

 studied intensively for half a century. 



Some idea of the relative density of 

 standing crop in the several areas with 

 which we have been chiefly concerned 

 may be gained from Fig. 19. This 

 shows the average quantities of plant 

 pigments per 50-0 m. haul over the 

 period of the main increase, and below, 

 on a necessarily smaller scale, the 

 highest individual value recorded in 

 each region or area. For this com- 



331 



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od_ 



0) 



to 

 ro 



(_ 



QJ 

 > 

 < 



tn 

 c 

 o 



1.000 



60.000- 



> E 50.000 



QJ I- 

 l/l QJ 



O in 40.000 



c 



QJ 



3) r 



-5 §)3Q000 



S ^20.000 -h 



-CO. 



=c 10.000 



1933 o 



1934 • 



Fig. 19. Comparisons of the average quantities of plant 

 pigments per m.', over the period of the main increase 

 in different areas. The highest individual observations 

 are shown on a smaller scale below. 



