^ Divergence (upwelling) 







Convergence 





too 



m-\ -» 



Fig. 1. Diagram of turnover 

 (DOM) in the succession of a 

 ocean. Top: 1, Ascent of nu 

 utilization in the cycle of p 

 community; 3, Loss of nutrien 

 organisms; 4, Turbulent risin 

 the lower maximum of phytopla 

 DOM rising from the lower max 

 surface community. Bottom: 

 of phytoplankton at various d 

 and bottom phytoplankton maxi 



of nutrients and dissolved organic matter 

 pelagic community in the tropic waters of the 

 trients and DOM in upwelling; 2, Repeated 

 roduction and destruction of the surface 

 ts with descending organic residue and migrating 

 g of nutrients and DOM and their retention at 

 nkton and bacteria; 5, Intake of nutrients and 

 imum layer into the productive cycle of the 

 Variation in distribution of relative quantity 

 istances from the upwelling zone (a, b, top 

 ma) (Vinogradov et al . , 1971). 



consumed by colonies of phytoplankton and bacteria formed in the layer 

 above the thermocline, which serves as the dividing line between the portion 

 of the community which lives above it and the source of nutrients below. 



The population of the layers above the underlying maximum exists 

 primarily on the nutrient salts transported by the flow of water from the 

 ascending zone to the descending zone. These nutrients, entering the cycle 

 of production and destruction of the community, are practically entirely 

 contained in the bodies of organisms, their concentration in the water 

 itself being close to analytic zero. The nutrient background of the surface 

 layer decreases as the water "ages," due to the constant loss of a portion 

 of the organic matter with the animals migrating into the depths and with 

 the descending dying phytoplankton and detritus. As the community matures, 

 it is carried with the water ever further from the location of the upwelling 

 and, therefore, the time picture of development of the community is unrolled 

 in space as well . 



Since the upwelling of water occurs almost steadily, near the zone of 

 water ascent the community is constantly in the initial stages of its 



14 



