Boring Sponges as Controlling Factors 

 in the Formation and Maintenance 

 of Coral Reefs 



THOMAS F. GOREAU, Department of Physiology, University of the 

 West Indies, Kingston, Jamaica 



WILLARD D. HARTMAN, Peabody Museum of Natural History and 

 Department of Biology, Yale University, New Haven, Connecticut 



TROPICAL reef communities harbor a diverse biota of indwelling 

 plants and animals which destroy corals, shells, and limestone 

 (Otter, 1937). Verrill and Smith (1873) suggested that the break- 

 down of insoluble skeletal carbonates by marine borers is a signifi- 

 cant factor in the calcium balance of the seas. Gardiner (1903, 

 1931 ) stated that boring algae, mollusks, and worms play important 

 roles in the breakdown and erosion of atoll reefs, whereas Yonge 

 (1930) believed the most obvious agents of reef destruction to be 

 the bivalve mollusks, Ginsbin-g (1957) affirmed that the weakening 

 of reefs by organic action makes them more susceptible to wave 

 erosion, and cited boring sponges as examples. 



Until the present, the destruction of reefs by burrowing organisms 

 has been studied only in extreme shallow-water environments where 

 the effects of boring are masked by rapid biological calcification 

 and energetic wave attrition. However, a series of recent investiga- 

 tions carried out in Jamaica on the coral communities of the steep 



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