. V V V V "V h Ai' -Vi Fig. 174. N /^ f I A ^ f ;"a w WIND I r V 'V ' I1 :; A/ Fig- 175- *» â />. '/, /, â /, /, NE / / 7. periphery of the curving current. In this manner an assembly of animals might be kept circulating in one area whilst the water masses were continually passing on. In actual practice an animal would rarely be brought back to exactly the same place, but with swirling current systems as we see round South Georgia in the meeting and mixing of the two streams of Bellingshausen Sea and Weddell Sea origin, varying slightly in salinity and temperature, we may often g
. V V V V "V h Ai' -Vi Fig. 174. N /^ f I A ^ f ;"a w WIND I r V 'V ' I1 :; A/ Fig- 175- *» â />. '/, /, â /, /, NE / / 7. periphery of the curving current. In this manner an assembly of animals might be kept circulating in one area whilst the water masses were continually passing on. In actual practice an animal would rarely be brought back to exactly the same place, but with swirling current systems as we see round South Georgia in the meeting and mixing of the two streams of Bellingshausen Sea and Weddell Sea origin, varying slightly in salinity and temperature, we may often get conditions which might hold assemblies of animals for considerable periods in one neighbourhood. The probable maintenance of patches of Euphausia superba in one place from one month to another has been demon- strated by the whale concentration charts shown in Figs. 155 and 156 on pp. 292 and 293. We may now consider the move- ments of vertically migrating animals in relation to surface waters moved by wind. In Fig. 175 let the main water massâfine broken linesâbe moving in a north-easterly direction. Now a west wind will have the effect1 of causing the surface stratum to move at 45° to the main water mass, to the north, shown by continuous fine lines. Thus an animal starting at A will be moved under the influence of this westerly wind, not in a more easterly direction as one might first of all imagine, but in a path to A'. In Fig. 176 an easterly wind is shown acting upon a similar water mass moving to the north-east; the surface stratum is again deflected at 450 from the main water mass, but this time to the south, and an animal would move from A to A'. 1 In the southern hemisphere. I am indebted to Mr G. E. R. Deacon for this information regarding the influence of wind in moving the surface stratum in relation to the lower mass. G A"" I i i â /! ' /. WIND 5 Fig. 176.
Size: 2157px × 2316px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
