(M. tricarinata , P_. ciliata ) , and others (particularly Gonodactylus sp. nov.) are 

 characteristic inhabitants of our deeper (35-50 m) control and experimental reef 

 sites. These opportunists reached higher densities in the new rubble habitat 

 (particularly in the absence of predation) than the populations that normally in- 

 habit rubble on the reef slope at this depth. There were no differences in the 

 species of stomatopods found in the A vs. C experimental reefs. Numbers of poly- 

 chaetes were significantly lower on the experimental reefs exposed to predation 

 (A) than in the control rubble from the reef wall, and intermediate numbers of 

 polychaetes were found in rubble from the C reefs. Ophiuroids also showed 

 relatively low recruitment to the new habitat on the experimental reefs, but were 

 equally abundant on A and C reefs (Table 1). 



DISCUSSION 



Does the presence of cryptic invertebrates in rubble influence colonization by 

 fishes ? 



Coral rubble harbors hundreds of invertebrates (Table 1), providing an abundant 

 food source for some fishes. Many authors have argued that living space is more 

 important than food in limiting (or structuring) populations of reef fishes (e.g., 

 Sale, 1978; Smith, 1978). Although evidence of the importance of space comes from 

 several sources (discussed in Sale, 1980), other studies show that space is not 

 always limiting (e.g., Talbot, et^ al_. , 1978; Robertson, et al., 1981). Evidence 

 that food directly influences numbers of fishes is limited TTsuda and Bryan, 1973). 

 In the present study, however, the timing of colonization suggests that fish re- 

 cruitment to reefs is related to the availability of benthic food. On those reefs 

 with rubble-dwelling invertebrate fauna (A, C), the number of invertebrate-eaters 

 peaked after 2-5 months, which coincides with the colonization rate of inverte- 

 brates in coral rubble at this depth (Reaka, 1981, 1983, and Reaka, et aj_. , in 

 prep.). In addition, cinderblock reefs with rubble had more invertebrate-eating 

 fishes than cinderblock reefs without rubble. Rubble around the base of the A 

 reefs gave the latter a slightly more complex structure than the B reefs, but 

 whether or not this contributed to the observed differences in fish populations is 

 unclear. Other variations in the structure of small artificial reefs (differences 

 in the sizes of available holes) have not been related to number of fishes present 

 or species composition (Molles, 1978; Talbot, et a]_. , 1978). Separation of the 

 effects of food vs. habitat complexity in the present study would require an 

 experiment comparing colonization of reefs with rubble initially containing a 

 natural complement of invertebrates to that of reefs with sun-dried (defaunated) 

 rubble. 

 Does the presence of fish predators influence invertebrate colonization ? 



Stomatopods appear to be strongly influenced by the presence of fish predators 

 in this habitat (Table 1). After 6 months, these mantis shrimps were more abundant 

 on the experimental reefs with fewer invertebrate-eaters (C) than on those with 

 more and larger fish predators (A). This could not have been due to differences 

 in location or habitat, since the positions of A and C reefs were alternated 

 regularly down the canyon at equal distances from the reef wall. Except for 

 octopuses (which in this habitat are very rare compared to the rubble fauna re- 

 ported here), stomatopods are the largest and most active of the mobile cryptic 

 fauna. Due to periodic movements on the surface of their rubble (Reaka, 1980b; 

 Dominguez and Reaka, in review), stomatopods may be more exposed to predators 

 than are many of the smaller, more secretive taxa. Ophiuroids had slow rates of 

 colonization, but appeared unaffected by the fishes. Although recruitment of 

 polychaetes to the new rubble also was slow, the effects of fish predators upon 

 polychaete population levels are enigmatic. Invertivorous and planktivorous fishes 

 possibly are responsible for decreased survivorship of settling polychaete larvae. 



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