The quantity of deep-water plankton may be influenced not only 

 by the production in the euphotic zone, but also by the balance of life 

 cycles of the surface communities, which determines the degree of utili- 

 zation of this production within the communities of the euphotic zone 

 itself (Banse, 1964). The lack of experimental determinations of the 

 ecologic and physiologic characteristics of deep-water plankton prevents 

 us as yet from testing this statement. If the structure of the deep-water 

 communities differs beneath water areas with differing balanced cycles 

 of surface plankton, this dependence may not arise at all (Vinogradov, 

 1958). 



At the ^ery least, in the temperate and cold water regions of 

 the ocean the flux of organic matter from the surface layers into the 

 depths undergoes seasonal cyclic variations. The seasonal unevenness 

 of delivery of food, obviously, must cause seasonal variation in the life 

 cycles of deep water fauna. Actually, even at ultra-abyssal depths 

 (below 6000 m) in the waters of the Kuril -Kamchatka trench, seasonal 

 variations in the age population structure of certain pelagic animals 

 have been detected (Vinogradov, 1970a). 



We should not forget that as depths increase, not only the quantity 

 of food, but also its nature, changes. As a result, the type of nutrition 

 of the main mass of plankton changes, and there is a change in the 

 dominant trophic groups with depth. All of this significantly influences 

 the species and spatial structure of deep-water communities. 



Tendency to decrease energy expenditures . In the highly productive 

 boreal regions of the Pacific Ocean, phytoplankton fixes approximately 110 c 

 of carbon for each square meter of surface each year, while in the oligo- 

 trophic central waters of the tropical zone, carbon fixation is only 

 28 g, i.e., some 4400 and 1100 g of wet organic matter is produced 

 beneath each square meter each year (Koblents-Mishke, 1965). If we know 

 the distribution of biomass of zooplankton in the world ocean and assume 

 that its production in the subpolar waters is 1.5 times greater (Yashnov, 

 1939), and in the tropical waters is 7 times greater (Steemann Nielsen, 

 Jensen, 1957) than the maximum biomass, we can calculate that for the upper 

 200 meter layer in both regions the ratio of primary production to pro- 

 duction of zooplankton (Pp/Pz) is approximately 45-50, i.e., 1 gram of 

 production of zooplankton requires 45-50 g of production as wet organic 

 matter in the phytoplankton. Riley (1951) believes that only 10% 

 of the organic matter produced in the surface zone ever gets below the 

 200 m level. Considering this information and assuming that the annual 

 production of the deep-water plankton is approximately equal to the biomass 

 or somewhat less, it is easy to see that at depths of 200-1000 m, the ratio 

 of Pp/Pz in the subpolar regions is 3-5*, in the tropics--ignoring 



*The biomass of plankton in the 200-1000 m layer includes the upper 

 interzonal species. Excluding these, the Pp/Pz ratio will be approximately 

 doubled. 



126 



