INFLUENCES OF PREDATORS AND CONSPECIFICS ON RECRUITMENT OF A TROPICALAND A TEMPERATE REEF FISH

An active debate has focused on whether patterns in the abundance of r eef fishes are primarily determined by the supply of larvae or by subs equent interactions occurring on the reef. By manipulating the presenc e of predators and the density of older conspecifics on small standard ized reefs, we tested the influences of these 2 factors - and interact ions between them - on recruitment of reef fishes. To assess the gener ality of our findings, we conducted similar experiments on 2 closely r elated species in 2 different systems: 1 tropical and 1 temperate. At Santa Catalina Island (a temperate site in southern California, USA) w e worked with the blackeye qoby Coryphopterus nicholsii and at Lee Sto cking Island (a tropical site in the Bahamas) we studied the bridled g oby Coryphopterus glaucofraenum. Predators reduced recruitment of blac keye gobies, but in contrast, in one experiment, recruitment of bridle d gobies was positively affected by 1 class of predators (reef residen ts) and unaffected by transient predators. In another experiment, recr uitment of bridled gobies was unaffected by either class of predators; however, there was little statistical power to detect a similar posit ive effect of predators. Older conspecifics (adults and subadults) did not significantly influence recruitment of blackeye gobies, but recru itment of bridled gobies was negatively related to density of adult co nspecifics. For both species, the presence of predators did not influe nce the relationship between recruitment and the density of older cons pecifics. Our results suggest that patterns of abundance among local p opulations of reef fishes can be decoupled from patterns of larval sup ply by reef-based biotic processes (namely predation and intraspecific interactions). However, the influences of older conspecifics and pred ators varied widely between the 2 quite similar species that we studie d. This underscores the need to understand the specific reasons for su ch differences in order to make predictions regarding the relative imp ortance of these processes in novel circumstances.