number of individual populations during the course of the year may be very 

 significant. It is particularly great for plankters with nonoverlapping 

 generations, including all of the interzonal copepods. The numbers of 

 the new generation are maximal after hatching. Subsequently, their number 

 decreases due to consumption and natural death. At the same time, as 

 the juveniles develop, the relative fraction of older individuals 

 increases. On the average, during the time of the development of the 

 population from the stage of domination of early copepodites to domination 

 of the fourth or fifth stage, the number of crustaceans beneath each 

 square meter decreases by a factor of three or four, then still more 

 sharply over the next winter. It follows from this that, in addition to 

 the regional aspects of distribution, any survey reflects the seasonal 

 aspects, the differences resulting from disagreement in phases of the 

 cycle overlapping with local differences. This is important to consider 

 in any comparative evaluation of the abundance of a given species in 

 various latitudinal zones or areas with different ice regimes. A comparison 

 of areas with identical age composition of individual mass species shows 

 that the number of crustaceans may vary by a factor of more than 20, 

 creating a rather variegated picture. It is based upon factors deter- 

 mining their distribution. The former include the number of organisms 

 in the spawning pool and the feeding conditions during the period of 

 breeding and growth. The distribution of the spawning pool of inter- 

 zonal animals depends on the abundance of individuals of the previous 

 year's generation, descending from the surface waters, and on their 

 subsequent transport by deep water currents. Since the rate of transport 

 by deep water currents is slow, it usually results in no significant 

 changes. Data on the distribution of Calanoides acutus (Andrews, 1966) 

 and the total biomass of zooplankton (Foxton, 1956) shows that the 

 character of distribution remains practically unchanged during the course 

 of the winter months. Only in the central Atlantic sector, where the 

 deep waters, compensating for the great efflux of bottom water, have 

 an elevated southern component in their velocity vector (Arsen'yev et al., 

 1975), is significant southward shift of the wintering pool of plankters, 

 as well as penetration of subtropical species far into the Subantarctic, 

 and of Subantarctic species into the Antarctic, possible (Andriyashev 

 et al . , 1973; Voronina, 1975). In addition to this, some changes in 

 the deep water plankton occur in the zones of divergence, to which the 

 meridional components of the currents "carry" the animals from the 

 nearby water areas. Although these currents are weak, over the course 

 of the long winter, the concentration may increase significantly in 

 comparison with neighboring sections (Voronina, 1966b). In general, 

 the abundance of the wintering pool varies less than the abundance of 

 summer population (Voronina, 1975). 



The amount of food available for the ascending plankters depends 

 on the coincidence between the time when the main mass of the population 

 rises to the surface and the beginning of phytoplankton bloom which, as 

 was shown above, varies over rather broad limits. Therefore, in early 

 spring, in some localities we may find older copepodites which have 

 already risen, but because of food absence, cannot moult and begin 

 breeding, whereas in neighboring areas, where the bloom has occurred, many 

 juveniles are already present. Since the regional differences in the 



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