ZOOPLANKTON IN THE SOUTHERN OCEAN 205 



autumn and in deeper water during winter. The 8o° W September volumes were less at all depths 

 than those in the other meridians, and it may be either that in winter this area is generally poorer in 

 zooplankton or that the bulk of the plankton moves into water deeper than the range of the nets. As 

 in other areas the October observations show a reconcentration of plankton at the shallower depths, 

 though not quite at the high level of the greatest concentrations of November and December. 



DEGREES SOUTH g 



S 4* 5 b 58* 6 0° 6 2° 64 66 68 7 O 



DECEMBER 1933 



SEPTEMBER 1934 



CTN 1421 1430 1419 1416 1417 1416 1415 

 J— I 1 I I LA.C I I 



IOO 

 2SO 



soo 



7SO 

 IOOO 



OCTOBER 1934 



CTN 1441 1442 1443 1444 14451446 1447 1448 1449 I4S0 



III ) J ) 



7SO 



tooo 



2SO 

 SOO 



NOVEMBER 1934 



CTN 1476 1475 1474 1473 1472 



a — IAC J I I I 



O lO 2 O 3-0 CCS 



SCALE 



Fig. 3. Vertical distribution of the standing crop of zooplankton in 80° W. 



Observations in o°, 20 E and 8o° W in other years (Fig. 4) 

 The observations in o°, 20 E and 8o° W present a more or less complete series extending over a 

 12-month period from which it has been possible to gain some idea of the vertical distribution of the 

 standing crop in any one month. Conditions, however, may not be the same in different years, 

 particularly in Antarctic regions where the presence or absence of pack ice can influence the biology 

 of the whole area. In order to see what year to year differences are likely to occur, observations in 



