distribution of biocenoses is created, with a definite orientation 

 regarding the flow of solar energy, protection from destruction by wave 

 action, tectonic downwarping, etc. Given the relative constancy of the 

 temperature in the tropics, the conditions of life in the reef community 

 Are regulated primarily by the influence of the intensive vital activity 

 of its organisms. This is particularly true of the processes related to 

 the cycle of nutrients, which Are practically completely controlled in 

 the reef by the community itself. The regulating influence of the 

 community on environmental conditions makes them largely predictable, 

 which, in turn, allows specialization of a significant portion of the 

 flora and fauna (Grassle, 1973; Golikov et al . , 1972). 



These same properties of coral biogeocenoses apparently explain 

 their unusually high productivity largely counteracting the limiting 

 effect of the shortage of nutrients which limits the productivity of the 

 aquatic ecosystems of the tropical zone. The primary portion of 

 photosynthetic production of the reef is created under conditions of a 

 semiclosed cycle of nutrients. These conditions exist in the host 

 organisms of symbionts and in communities of periphyton organisms, where 

 the producers and reducers are joined into a single structure. We must 

 assume that this semiclosed cycle of biogens is characteristic to some 

 extent for colonies of calcareous algae as well. These colonies have a 

 porous surface, overgrown with microflora (DiSalvo, 1973), which can 

 mineralize the organic phosphates liberated by the algae. 



Another factor in the high productivity of the coral biogeocenosis 

 is, apparently, the existence of extremely effective mechanisms for 

 extraction and utilization of organic forms of nutrients from the ocean 

 water passing over the reef. The mean content of organic forms of 

 nutrients in the surface waters of the tropical zone of the ocean is 

 0.2-0.4 pg-atom/Jl of phosphorus and about 1 p-atom/Ji of nitrogen, as 

 great as the content in the water of the temperate zones (Sapozhnikov , 

 1971). Most of this matter is found in the composition of relatively 

 stable dissolved organic matter which is utilized by the periphyton 

 microflora of the reef in large quantities. Possibly, it is the 

 presence of this external source of organic matter and nutrients which 

 represents one of the main factors in the unusually rich development of 

 periphyton on all solid surfaces and in the large-grained sediment of 

 the reef. 



The richness of the microflora of the bottom sediments depends 

 directly on the degree of development of living corals in the biotope, 

 whereas the development of the periphyton, microflora and algoflora do 

 not depend on this factor (Sorokin, 1975b). The periphyton grows even 

 in places where the corals have been completely smashed by a typhoon. 

 The periphyton community of the reef, particularly in the frontal zone 

 and on the surface of the reef flat, exists by utilization of nutrients 

 and, to some extent, of the organic matter from the ocean waters passing 

 over the reef. 



Another portion of the organically bonded nutrients in the ocean 

 water passing over the reef is present in the form of suspended organic 

 matter, pseudoplankton, and plankton. The reef community actually is a 

 powerful biological filter, capable of utilizing this source almost 



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