RECRUITMENT OF YOUNG CORAL REEF FISHES FROM THE PLANKTON 



William N. McFarland 



Section of Ecology and Systematics 



Cornell University 



Ithaca, New York 14853 



John C. Ogden 



West Indies Laboratory 



Fairleigh Dickinson University 



Teague Bay 



St. Croix, U.S. Virgin Islands 00820 



ABSTRACT 



This paper examines the widely held view that the planktonic eggs and/or 

 larvae of most coral reef fishes represent mechanisms that reduce predation 

 and/or serve for dispersal of the young. Data on spawning, the pelagic phase, 

 and recruitment of coral reef fishes are examined. Recruitment represents the 

 successful end product of a complex suite of adult and larval behaviors and 

 physical conditions that directly affect survival of offspring. Although 

 considerable data are available, in no single species has the cycle from spawning 

 to recruitment been clearly documented. As a result, assessing the various 

 hypotheses that attempt to explain the almost universal presence of a pelagic 

 larval phase in coral reef fishes remains tenuous. 



Predation on young and ultimate dispersal are both potent selective factors. 

 The high degree of variation in reproduction, larval characteristics, and 

 recruitment amongst coral reef species implies, however, that these two selective 

 factors undoubtedly vary in importance among species. 



INTRODUCTION 



Virtually all coral reef fishes produce numerous offspring and release 

 either their eggs or larvae into the offshore plankton (Breder and Rosen, 1966; 

 Ehrlich, 1975; Goldman and Talbot, 1976; Sale, 1977, 1978a_; Johannes, 1978; 

 Barlow, 1981). There is one known exception, the pomacentrid Acanthochromis 

 polyacanthus ; members of this species brood their young and disperse them 

 directly onto the reef (Robertson, 1973). Also, some apogonids (mouth brooders) 

 and some brotulids (live bearers) have completely eliminated the planktonic 

 larval phase. 



Considering the high diversity of reef fishes (Connell, 1978; Sale, 1980) 

 and their numerous ecological roles (Hobson, 1974; Sale, 1978b; Smith, 1978), 

 it is astonishing that so many species use the same reproductive strategy. 

 Indeed, the central position of a larval pelagic existence in coral reef fishes 

 led Helfman (1978) to wonder whether answers to the high species diversity of 

 coral reef fish assemblages "lie in the plankton." One major hypothesis favors 

 the view that community composition is dependent on the chance recruitment of 

 each species from the plankton when space becomes available (Russell, et al . , 



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