RELATIONSHIPS BETWEEN FISHES AND MOBILE BENTHIC INVERTEBRATES ON CORAL REEFS 



Nancy G. Wolf 

 Section of Ecology and Systematics 

 Cornell University 

 Ithaca, NY 14853 



Eldredge B. Bermingham 

 Department of Molecular and Popular Genetics 

 University of Georgia 

 Athens, GA 30602 



Marjorie L. Reaka 



Department of Zoology 



University of Maryland 



College Park, MD 20742 



ABSTRACT 



Observations of 3 types of artificial reefs at 20 m depths show that fish preda- 

 tion alters the pattern of colonization of stomatopods, the largest and most mobile 

 members of the cryptic reef fauna. Recruitment by polychaetes probably is adverse- 

 ly affected by the presence of fish predation also. Possibly because of their 

 secretive habits, the densities of the remaining taxa of cryptic invertebrates were 

 unaffected by fish predators. The data also suggest that the presence of an in- 

 vertebrate biota influences the colonization and abundance of invertebrate-eating 

 fishes. 



INTRODUCTION 



The importance of predator-prey interactions in governing community structure 

 has been demonstrated for some marine systems (e.g., Paine, 1966; Dayton, 1975; 

 Menge and Sutherland, 1976; and many others), but their role in coral reef communi- 

 ties remains poorly understood. Coral-eating fishes can influence the structure of 

 coral reefs (Kaufman, 1977; Neudecker, 1979; Wellington, 1982), and herbivores 

 exert both direct and indirect effects upon coral reef communities (Ogden and Lobel, 

 1978; Hay, 1981; Hixon and Brostoff, 1983). In laboratory microcosm experiments, 

 Brock (1979) showed that parrotfish grazers influence the abundance and diversity 

 of the benthic flora and fauna, and that the presence of refuges (3-dimensional 

 surfaces) is an even more important determinant of benthic community structure than 

 the densities of consumers. Additionally, it has been suggested that a variety of 

 structural, behavioral, and chemical defense mechanisms found in benthic reef 

 organisms represent adaptations to strong predation pressures in reef environments 

 (e.g., Bakus, 1966, 1981; Vermeij, 1978; Reaka, 1980a, 1980b; Reaka and Manning, 

 1981). However, astonishingly little experimental and quantitative information is 

 available regarding the relationships between fish predators and the abundant in- 

 vertebrate fauna that inhabits the reef substrate in the field. Most of this 

 benthic biota lives in cryptic refuges under and within the coral substrate. 

 Jackson and Buss (1975) have suggested that the cryptic sessile fauna currently 

 does not experience strong predation. Many of these encrusting organisms grow in 

 inaccessible sites, and particularly the colonial organisms exhibit chemical 

 defenses that are used in competitive interactions (see also Buss and Jackson, 



1 Present address: Biology Department, Woods Hole Oceanographic Institution, Woods 

 Hole, MA 02543. 



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