On the Relation of Calcification 

 to Primary Productivity in 

 Reef Building Organisms 



T. F. GOREAU 



Physiology Department, University College of the West Indies, Mona, Jamaieu, 

 W. I., and Department of Marine Biochemistry and Ecology, New York Zoological 

 Society. 



Coral reefs are tropical shallow water communities built up by 

 calcareous organisms attached to the sea bottom. Such ecosystems 

 may be regarded as biochemical factories which catalyse a large 

 scale transfer of dissolved calcium and carbonate ions from sea 

 water into the sediments as insoluble calcium carbonate. The result- 

 ing reef limestones are deposited in typical formations which may 

 in time become several thousand feet thick, as for example in some 

 of the Pacific atolls ( 9 ) . 



A unique characteristic of coral reefs, found in no other deposi- 

 tional system in the biosphere, is that maximum biological accre- 

 tion of calcareous matter takes place only in the turbulent surface 

 waters where the forces of mechanical and chemical erosion are 

 also at a maximum. Corals and algae which build reefs do so by 

 secreting hard calcareous masses that become aggregated into an 

 organised coherent structure adapted for maximum attenuation of 

 mechanical stresses set up by the constant battering of the seas, 

 yet so shaped as to expose a maximum surface area for efficient 

 matter-energy exchange with the environment. The papers of 

 Tracey ef al. (16) and Emery ct al. (1) should be consulted for 

 further aspects of this problem. 



In the West Indies, the interlocking reef framework is built up 

 by the larger Scleractinia and Milleporidae, their separate colon- 



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