. ~i 1 1 1 1 1 1 1 r n m r? v vi th vjh MONTH IX x xi xn Fig. 9. Seasonal variation in the mean total volume of zooplankton in the whole water column sampled*( 1000-0 m.) in the sub-Antarctic and Antarctic. Numbers on each curve as in Fig. 8. It will be remembered that in calculating the monthly mean volumes for each depth interval the actual measurements had to be corrected to give the volume for a standard haul of 50 m. In this way variations in concentration at different levels in the whole water column can be assessed. When, however, the individual measurements at each depth are added
. ~i 1 1 1 1 1 1 1 r n m r? v vi th vjh MONTH IX x xi xn Fig. 9. Seasonal variation in the mean total volume of zooplankton in the whole water column sampled*( 1000-0 m.) in the sub-Antarctic and Antarctic. Numbers on each curve as in Fig. 8. It will be remembered that in calculating the monthly mean volumes for each depth interval the actual measurements had to be corrected to give the volume for a standard haul of 50 m. In this way variations in concentration at different levels in the whole water column can be assessed. When, however, the individual measurements at each depth are added together the resultant volume is a measure of the total standing crop of plankton in the whole water column sampled. Table 4 gives the mean monthly total volumes together with the number of observations in each month in the sub- Antarctic and Antarctic zones. It is compiled from all stations with a complete series of measurements from 1000 to o m., and the results are shown in Fig. 9. The monthly mean volumes show that, compared to the surface waters, there is relatively little
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