HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 335 



of the larvae must be still (p. 321) mainly in the Calyptopis stages or at most (p. 330) in the early 

 Furcilia state. 



The West Wind drift, otherwise barren, is again seen to be affected in two localities by cold East 

 Wind tongues, one in the neighbourhood of the Balleny Islands, the other near Peter I Island. In 

 both localities, although the vertical gatherings are very small, our stramin nets (p. 363, Fig. 112) 

 show a moderately substantial late Furcilia population was present, and in both the advanced 

 developmental condition of the swarms recorded (p. 326, Fig. 87), relative to the probable cor- 

 responding condition (p. 327) of their contemporaries in higher latitudes, is again to be noted. We 

 have no May-June observations south-east of Kerguelen. The developmental condition of the swarms 

 recorded there in April, however (p. 325, Figs. 86 and 87), suggests that there too a moderately sub- 

 stantial population of late Furcilias would now be found. 



July-December. The distribution of the late Furcilias in winter (July-September) and spring 

 (October-December) is shown in Figs. 93 and 94. The low sampling power of the vertical net is 

 now becoming increasingly evident, especially during the last three months of the larval existence, 

 when, as Fig. 94 shows, the scatter of the positive occurrences is wide and the occurrences them- 

 selves only of small or very small numbers. It must, therefore, again be emphasised that during 

 the final phases of the larval life our vertical samples provide primarily a picture of the distribution 

 and its dynamics and only an inadequate conception of the relative abundance of the young krill before 

 they finally outgrow their larval state. The facts of the distribution themselves it will be seen are now 

 much obscured by the vast extent of the winter pack, for now, even in the Weddell drift, formerly wide 

 open, they can only be determined with certainty for a relatively narrow ice-free zone in the north. In 

 fact beyond this northerly strip, all that is left open of a vast area of larval abundance, of the other formerly 

 accessible krill-rich waters, the South Georgia whaling grounds alone remain ice-free and open to 

 investigation, the Bransfield Strait being closed until November and the East Wind drift until January. 



The periodic covering and uncovering of such an enormous area of the circumpolar sea by ice must 

 raise many questions in Antarctic oceanography to which the answers may for long remain obscure, 

 and perhaps the answer to the overriding question as to what in fact does happen to the vast population 

 of larval krill which now apparently exists, much of it in semi- or near-total darkness, below the sea 

 ice, may in the end only be provided by the establishment of elaborately equipped winter stations on 

 the pack itself. Both America and Russia have already done this in the Arctic by air (Tolstikov, 1957; 

 Armstrong, 1958), but on the highly mobile Antarctic floes^ it might prove (Debenham, 19306) a more 

 hazardous and difficult undertaking. It might, however, be done by freezing in powerful vessels of 

 the ice-breaker type. In any event, as Robin (1959) has said, a wide unexplored field now beckons to 

 Antarctic oceanographers, for as yet we know virtually nothing about life below the polar pack during 

 the southern winter. In the meantime there must inevitably be much speculation and much, and 

 perhaps wrongful, assumption. In so far, however, as the East Wind zone is concerned it now seems 

 likely that wintering vessels, perhaps of the amphibious landing-craft type, could do useful work in 

 the extensive areas of open water that from time to time it seems (p. 318, note i) appear in the coastal 

 waters there. 



^ They are particularly active in the Weddell Sea. I quote from Hurley (1925). 'Though sailing west during the day the 

 currents had carried the ice-floes on which we had rested during the night swiftly to the east. Not only had we lost all the 

 distance sailed but the drift had actually gained thirty miles on our efforts! ' Worsley (1931), again, refers to the embarrassing 

 situations that can arise through the movements of bergs travelling faster through the pack than the pack itself is moving, 

 'ploughing' he says through the floes as though they were so much tissue paper. Or to quote John (1934) on a mile long berg 

 I once watched driving through the pack many years ago, 'in doing so it was closing up and "pressuring" the pack in a wide 

 arc before it, and charging through it, leaving a broad wake behind'. It was travelling at about i\ knots. In the Arctic basin 

 on the other hand the ice is probably not moving faster than from i to i\ sea miles per day (Dunbar, 19556). 



