. MONTHS Fig. 31. Quantities of plankton at different times of year around South Georgia. Figures on the vertical scale represent numbers of hundreds of organisms. If we consider the charts of the four principal surveys in the order of the months in which they were taken, November 1930-1, December-January 1928-9, January- February 1929-30, and February-March 1927-8, we see that in the earliest (Fig. 29) the richest plankton was mostly grouped to the north of South Georgia, while in the latest (Fig. 24) it was concentrated to the south. In the January-February survey (Fig. 28) it was very
. MONTHS Fig. 31. Quantities of plankton at different times of year around South Georgia. Figures on the vertical scale represent numbers of hundreds of organisms. If we consider the charts of the four principal surveys in the order of the months in which they were taken, November 1930-1, December-January 1928-9, January- February 1929-30, and February-March 1927-8, we see that in the earliest (Fig. 29) the richest plankton was mostly grouped to the north of South Georgia, while in the latest (Fig. 24) it was concentrated to the south. In the January-February survey (Fig. 28) it was very rich almost everywhere, but in the December-January survey (Fig. 26) the only rich plankton was a patch to the south-east. It seems possible that there is a tendency for the concentrated plankton to occupy the northern part of the whaling area in the early part of the season, and later to shift down to the south side, and that in 1928-9 the shift for some reason took place unusually early, resulting in the reduction in the average number of organisms per haul in that survey. With the available data we cannot be certain that this shift takes place: it can only be said that there is some evidence for it. Drake Passage and Scotia Sea Figs. 32-9 are drawn on exactly the same principle as Fig. 23, but they show the amount of plankton taken at all stations in the Scotia Sea, and each chart shows the stations taken within a single short period. No certain conclusions can at present be drawn from the figures shown, but it will be seen that, while at all times there is a scarce plankton in the vicinity of the South Orkney and South Shetland Islands, the quantity of plankton varies greatly in other places.
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