PHYTOPLANKTON OF THE WEDDELL SEA AREA 



103 



of phytoplankton was encountered, with Chaetoceros criophilum very strongly dominant 

 in moderate hauls. 



Having rounded the pack-ice to the east an entirely different association was en- 

 countered when proceeding on a more southerly course. Rhizosolenia styliformis became 



GO 



30° 



20° 



65 



Chaetoceros 



criophilum 



' Chaetoceros \ 

 crlophlliim. 



Rhizosolenia 

 styliformis 



-i--corethr.on valdiviae 

 0_Rhizosolenia styliformis 

 A-Chaetdceros criophilum 

 □ -Chaetoceros neglectus 

 >|( -Chaetoceros socialis 



^.FraGILARIA ANTARCTICA 



^-Nitzschia closterium 

 q_nltzschia seriata 

 riiirmirii Pack-ice i 



o ^ 



Nitzschia 

 seriata. 



Small Chdctocerids 

 Nitzschia seriata & 

 N. closterium 



A on 

 A*bo 



60 



65 



30 



20° 



Fig. 48. Distribution of the principal phytoplankton species in the eastern Weddell Sea, 



January-February 1931. 



by far the most abundant species in an exceedingly rich phytoplankton. This in its turn 

 gave way to a series of moderate hauls with the minute form Nitzschia seriata pre- 

 dominating in about 63° S, and finally in the region of the Antarctic circle small Chaeto- 

 cerids became dominant in hauls in which Nitzschia seriata was still prominent, 

 accompanied by the Antarctic-littoral and ice-form N. closterium. 



