64. 



factor could be the abrasive effect of suspended inorganic 

 particulate matter, which would be expected to be substan- 

 tial in areas of high current activity (Grigg, 1965) . Grigg 

 found that colonies of Antipatharia grandis were very 

 susceptible to the deleterious effect of suspended particulate 

 matter in areas of high currents. Thus, increases in the 

 amount of suspended inorganic particulate matter could be 

 harmful to corals as a result of abrasion in areas of strong 

 currents, as well as sediment loading in tranquil areas. 



This conclusion should not be surprising if viewed in 

 terms of the biology of these organisms. Their simple morph- 

 ological structure results in direct exposure of tissue to the 

 surrounding environment. Thus, the rubbing against or the 

 accumulation of material on corals kills the tissue beneath 

 it. Another mechanism by which sediment load can have deleter- 

 ious effects on corals is by stimulating mucous production. 

 Experiments with shallow water corals show that stressed 

 corals increase mucous production in an attempt to remove 

 fouling material (Lewis and Price, 1976). Soft corals ar3 

 particularly sensitive to sediment loading if currents are 

 different from what they are usually exposed to or if an 

 increased amount of particulate matter is added to their 

 environment (Bayer, personal communication) . The corals 

 initially contract and then increase their mucous production 

 to rid themselves of the fouling material. After several 



