It is significant that fishes of the second trophic layer, the 

 herbivores, are commonly the most abundant fishes in a reef 

 community. Odum and Odtmi (1955) found a striking predominance 

 Con a weight basis) of herbivorous parrotfishes, surgepnf ishes, 

 damself ishes , and butterf lyfishes in comparison to wrasses, groupers, 

 and other carnivores. Hiatt and Strasburg C1960) found herbivores 

 to dominate reefs in the Marshall Islands, and Bardach (1959) found 

 that omnivores (said to be mostly herbivorous) far outnumbered 

 carnivores on a large Bermuda reef (but not on a smaller, isolated 

 reef) . 



Randall (1963) surveyed the fishes to two natural reef areas at 

 St. John, Virgin Islands, one a 600 m2 part of a fringing reef in 

 Lameshur Bay, averaging 3 m depth, the other 297 m^ of fringing reef 

 in about the same depth at Ram Head Bay. The two sites yielded 

 (by weight) 24.3% herbivores (Scaridae, Acanthuridae , and Blennidae) , 

 15.8% omnivores (Pomocentridae, Chaetodontidae, and Monocanthidae) 

 and 59.9% carnivores (the remaining families). Randall emphasized 

 that many fishes that live on coral reefs depend on food that does 

 not come from the reef proper. He cited certain grunts, snappers, 

 and certain plankton feeders, but in Lameshur Bay, this would 

 certainly apply as well to many species that graze throughout the day 

 on the adjacent algal plain, notably parrotfishes and surgeonf ishes . 



The parrotfishes were found to be the largest family by weight, at 

 both reef sites studied by Randall, and dominance of this family as 

 a rule throughout the West Indies was suggested. 



It has been established that plant-eating fishes influence the kind 

 and niimber of marine plants on and near coral reefs. But some 

 significant questions presently are unanswered. To what extent do 

 carnivores influence the kind and number of plant-eating fishes; i.e . , 

 what influence do carnivores have on plant distribution? Bardach (1959) 

 concluded that (in Bermuda) "carnivorous fish rarely feed upon 

 omnivorous ones; no angelflsh or surgeonf Ish were found in the 

 stomachs of carnivores, and young parrotfish were only partially 

 ingested." He attributed most herbivorous activity, and most food 

 for carnivorous fishes, to invertebrates. 



Randall's evidence (1963, 1967) contradicts Bardach's conclusions, 

 at least in part, as parrotfishes and surgeonf ishes were found to 

 comprise a significant percentage of the food of carnivores in the 

 West Indies. Parrotfishes are regarded by Randall (1963) as perhaps 

 the principal family of West Indian fishes eaten by predators except 

 on isolated patch reefs. 



VI-171 



