PHYTOPLANKTON OF EAST CUMBERLAND BAY 201 



There is no appreciable extent of low-lying land draining into the bay, and as all 

 considerable vegetation ceases at a height of about 500 ft., even on the most sheltered 

 slopes, it will be seen that the land drainage is, for the most part, very poor in nutrient 

 materials such as could be utilized by the phytoplankton. Further, even the blackest 

 pieces of morainic ice were found to be poorer in phosphate than the surface water. The 

 results of phosphate analyses also indicate that pollution from the whaling station at 

 Grytviken does not extend far beyond King Edward Cove. It may be mentioned here 

 that the mean phosphate value for the upper 20 m. of water at the routine station 

 throughout the season was 82-6 mg. per m.^, as against an average of about 85 mg. in 

 the open sea off South Georgia. 



The climate at Grytviken is typically sub-Antarctic. Features of the summer season 

 are strong variable winds, often deflected by the surrounding mountains, occasional 

 heavy falls of rain and snow, and periods of dense fog, the whole interspersed with a 

 few fine, calm, bright sunny days. The season 1930-1 was an unusually cold one, more 

 particularly towards the end of December and throughout the month of January. The 

 effect of this was to prolong the thawing of the snow on the lower slopes for over a month 

 after its usual date. 



The minimum salinity for the year normally coincides with maximum sea and air 

 temperature in January, according to Clowes' (unpublished) investigations of shore 

 water at Hope Point. At the station out in the bay, one would naturally expect a more 

 considerable lag after maximum air temperature before this point was reached ; but the 

 above-mentioned abnormalities in the weather during the season in question were 

 probably responsible for the fact that the mean salinity fell, while the temperature 

 remained high until the middle of March : indications of the recommencing of the cycle 

 were not apparent until the very last station. This retardation was augmented by heavy 

 falls of rain and snow in February and March. 



It is improbable that the main spring diatom increase was much affected by these 

 conditions, as it appeared to be in full swing when observations were begun on 

 November 12 and probably always takes place before thawing is nearly complete in the 

 locality under consideration. 



Thanks are due to Messrs H. F. P. Herdman, A. J. Clowes and G. E. R. Deacon 

 for advice on chemical points, and to the two last-named for the opportunity of con- 

 sulting their hitherto unpublished results. The attempted explanation of the relation 

 between hydrological and meteorological features owes much to discussion with Mr 

 Deacon. Throughout the season Mr A. H. Laurie rendered invaluable help with the 

 boat work. 



THE NATURE AND SEASONAL ABUNDANCE 

 OF THE PHYTOPLANKTON 



The analyses of the plankton samples taken at the various stations are shown in 

 Tables LI II and LIV. It will be seen that they were not only very poor in bulk and 



numbers but in species also. In all only fourteen species of diatoms were recorded. 



26 



DVIII 



