PHYTOPLANKTON OF THE WEDDELL SEA AREA 95 



slight effect on the water passing out through the northern half of the strait ; during 

 the seasons studied this water appeared to invest Elephant and Clarence Islands with 

 a practically unchanged flora typical of Bransfield Strait. This was characterized by 

 the very pronounced dominance of Corethron valdiviae, such as was encountered at the 

 station here considered. 



After the completion of the line from South Georgia to Elephant Island, the 

 'Discovery II ' proceeded on a plankton survey of Bransfield Strait and the next piece 

 of work in the Weddell Sea proper was a very valuable series of observations obtained 

 by the 'William Scoresby' working south-east from South Georgia in January- 

 February and returning upon very nearly the same course. The positions of the stations 

 worked during this cruise are shown in Fig. 46. The full analyses of the phytoplankton 

 hauls are given in Tables XXVIII-XXXI, in which the stations have been grouped to- 

 gether in four areas arbitrarily chosen for the sake of convenience. As the numbers of 

 species and individuals recorded was large, the relative proportions of the leading forms 

 at each station have been calculated and tabulated separately so as to render the descrip- 

 tion more easy to follow. 



The first group of stations comprises those worked between 54 and 57° S, 25 and 

 36° W. From Fig. 46 it will be seen that they include the three worked between South 

 Georgia and the northern end of the South Sandwich Islands on the outward voyage, 

 and two stations worked to the west of this track on the return some eighteen days 

 later, and also St. WS 537, to the east of Zavodovski Island. As indicated on the 

 chart Visokoi Island was found to be surrounded by pack-ice on the outward voyage, 

 and this last station was worked while skirting the pack to the east. On returning a 

 fortnight later all this pack had disappeared. From the hydrological data given in 

 Table XXVIII, it will be seen that while the conditions at these stations varied con- 

 siderably, as would be expected from the wide range in space and time covered by them, 

 the sahnities were uniformly low for water of eastern Weddell Sea origin. The tempera- 

 tures at the surface were also somewhat low for the latitude and time of year, and the 

 probable reason for both these facts was the melting of the pack-ice mentioned above. 

 The quantity of the phytoplankton at these stations varied enormously, and though at 

 all but one of them Chaetoceros criophilum was the most numerous form, the quality also 

 varied considerably, as Table 16, giving the numbers and percentages of the more im- 

 portant forms, clearly shows. 



Taking these stations individually, it will be seen that at the first, worked off the 

 north-east coast of South Georgia, the phytoplankton was exceedingly poor, the bulk 

 of the sample being due to numbers of large Copepoda, as may be seen from Table 

 XXVIII : the following station, St. WS 535, on the contrary, furnished one of the richest 

 hauls in our experience. Here Chaetoceros criophilum was the dominant form, and 

 Nitzschia seriato, Rhizosolenia styliformis and Fragilaria antarctica were also present in 

 very large numbers. The immense haul was obtained almost exactly midway between 

 South Georgia and the northernmost of the South Sandwich Islands. Evidently there 

 was still a rich production in the moderately old water of eastern Weddell Sea type 



