PHYTOPLANKTON OF BRANSFIELD STRAIT 



129 



the stations in the old Bellingshausen Sea water, the proportion of Corethron will be as 

 large as that found on the autumn survey, and larger than on the spring survey. 



The estimated total phytoplankton was also lower than on the other two surveys, and 

 though it would be very much higher had it been possible to count the small colonial 

 forms at the three stations in the Weddell Sea eddy, it may be said that there was a 

 decrease over the strait as a whole, well shown by conditions on the two more westerly 

 lines (see Fig. 65). 



The distribution of the more important species serves to emphasize the points made 

 above. Chaetoceros sociolis and Ch. tortissimtis are not considered here, as they were 



Fig. 65. Phytoplankton distribution (totals per loo-o m. haul) in Bransfield Strait, December 1930. 



I = one million. 



confined to the three Weddell Sea stations, as the tables clearly show. Fig. 66 shows the 

 distribution of the dominant species Corethron valdkme. It will be seen that it reached 

 its maximum to the north-east at Sts. 538 and 539, suggesting that the eastward move- 

 ment of the phytoplankton association regenerated in the old Bellingshausen Sea water 

 within the strait, observed during the spring of the previous season, had on this occasion 

 advanced still farther. This view is strongly upheld by the distribution of Rhizosolenia 

 gracilUma (Fig. 67), whose maximum development here coincided with the Corethron 

 maximum. As we have previously tried to show, this form is apparently regenerated in 

 moderate abundance in the old Bellingshausen Sea surface water in the spring (see 

 p. 121). Comparison of Fig. 65, where the phytoplankton totals are given, with Fig. 66, 

 showing the distribution of Corethron, also shows the relatively small proportion of that 



nviir ^7 



