368 



[chap. 17 



summarized on a seasonal basis for three arbitrarily denned subdivisions of lati- 

 tude between the Antarctic Convergence and the continent. The data, expressed 

 as Harvey pigment units, were obtained from plankton-net hauls, which nor- 

 mally give much lower values than are obtained by modern ultra-filtration 

 techniques. Thus Hart's results cannot be compared with more recent studies of 

 plankton-pigment distribution. However, he has shown the comparison between 

 his data and those obtained by comparable methods in the English Channel, 

 indicating that the quantities of phytoplankton which develop in both regions 



150° West 180° East 



Fig. 10. The Antarctic Ocean showing regions referred to in Fig. 9. (After Hart, 1942.) 



are nearly the same. Note that plant growth in the whole Antarctic is restricted 

 to a single midsummer flowering, in contrast to the English Channel, and is 

 probably typical of productivity at high latitudes where radiation is the primary 

 controlling factor (page 356). 



As a rough approximation, based on Cooper's (1938) estimates for the 

 English Channel, an annual production of the order of 100 g carbon/m 2 seems 

 reasonable for the Antarctic Ocean as a whole. Certain locations of exceptionally 

 high fertility, such as the South Georgia area and the Scotia Sea, probably 

 exceed this figure by several-fold. 



