SUMMARY AND CONCLUSIONS 361 



GENERAL SUMMARY AND CONCLUSIONS 



This report is intended to form an introduction to the pelagic ecology of the Antarctic 

 seas. The plankton community is considered in relation to its hydrological background, 

 and to the distribution of the Blue and Fin whales which feed upon the plankton and 

 form the object of such an important fishery in these seas. The particular area chosen 

 for this study, the whaling grounds of South Georgia, is situated geographically well 

 outside the Antarctic Circle, but hydrologically well within the Antarctic Zone. Whilst 

 intensive work was carried out in the immediate region of South Georgia, lines of 

 observation were made across the Antarctic Convergence into the sub-Antarctic Zone 

 in two directions. 



The horizontal and vertical distribution of the plankton has been studied in detail 

 with three main objects in view: 



(1) To find out which are the more important species in the plankton community and 

 their relative abundance. 



(2) To describe the actual distribution of these species at the time of the survey for 

 comparison with surveys in later years. 



(3) To obtain as far as possible a knowledge of the behaviour of the different 

 organisms and the factors, physical, chemical and biological, governing their lives. 



In fulfilling the first two of these objects much space in the report is necessarily 

 occupied with a description of the distribution and relative abundance of the different 

 species. It is evident that beyond satisfying the first of the objects a mere description of 

 the distribution in itself is of entirely latent value until it can be compared with a number 

 of future surveys. A few weeks earlier and a few weeks later the pattern of distribution 

 will have been, at least in part if not entirely, different from that at the time of the 

 survey; it will have been changed by the flow of ocean currents, the growth or decline 

 of the phytoplankton and a number of other factors. Nevertheless, the detailed study 

 of the component elements of the plankton community at any one phase of distribution, 

 no matter what pattern that distribution may have, and their correlation with various 

 environmental factors, is of immediate value in revealing to some extent the comparative 

 behaviour of different organisms, and in bringing to light general principles governing 

 planktonic life. The numerous charts illustrating the horizontal and vertical distribution 

 of the more important species show the type of distribution which the different species 

 may have, and considered together present the "anatomy" of the plankton community 

 at one particular period. This summary, in briefly describing the contents of the report 

 in order of their treatment, will pay particular attention to those points which may be of 

 general interest to the marine biologist, and form a guide to the parts of the report in 

 which they are dealt with. 



Part I, in addition to the introduction, deals with the geography and hydrology of 

 the area (pp. 3-16), the methods of collecting in the field (pp. 17-19), the cruises 

 undertaken (pp. 19-24), the laboratory methods and their degree of accuracy (pp. 25- 

 38). The degree of refinement in plankton analysis which may be warranted both by 



