PHYTOPLANKTON OF SOUTH GEORGIA 



6i 



Rhizosolenia styliformis. This species was widely distributed and present in all three 

 types of surface water, but its abundant occurrence closely coincided with the limits of 

 the Weddell Sea influence (Fig. 29), and it was particularly abundant in the cold tongue 

 of eastern Weddell Sea water off the east coast, the position of which could be clearly 

 demonstrated from the distribution of this species alone. 



Dactyliosolen laevis (Fig. 30) was an example of yet another species which attained its 



1 



'/? zh 



1 7a 





V2 



^^,>^ 





21 



5 





20 M^_- 9/a 



5% 



22 



15 



6^ 



B'k. 



17 



9/2 

 3'A 



Fig. 30. The distribution of Dactyliosolen laevis. South Georgia survey, November 1930. i = one hundred 



thousand. 



maximum development for this survey in the western Weddell Sea water to the south 

 and south-west of the island. Many more might be cited from the less numerous forms, 

 for example Nitzschia sp. A, a minute colonial form closely resembling the N . rigida 

 of northern waters. 



On this second survey two series of water samples for examination by means of the 

 centrifuge were taken. The first of these was at St. 483, where analysis of the net haul 

 had shown the phytoplankton to be poorer than anywhere else on the survey, with 

 Corethron valdiviae completely dominant. From the centrifuged samples it was esti- 



