Barlow suggests that postzygotic activity leads to a reduction in lifetime 

 fecundity in part because of the parental investment required. Most coral reef 

 fishes that spawn demersal eggs tend to be small, a circumstance that in itself 

 limits egg production. In addition, most coral reef species are strongly site- 

 attached and spend their adult lives in a relatively small local area (Sale, 

 1980). Pelagic dispersal thus can be considered a necessary consequence of 

 their restricted mobility. If, for example, specific reef habitats tend to be 

 unstable over time, a circumstance that recent events document (e.g., severe 

 hurricane damage of reef habitat at Jamaica, Woodley, et al . , 1981; Kaufman, 

 1983; storm effects at Lizard Island, Lassig, 1983; coral blight in the Caribbean 

 and Pacific, Lessios, et al . , 1983), then dispersal to colonize adjacent or 

 distant habitats is an essential element in each species' survival. 



RECRUITMENT--HOW DO FISHES SETTLE ON REEFS? 



In a review of coral reef fish ecology, Sale (1980) stated, "The mechanisms 

 whereby larval fishes make their return to the reef are totally unknown." In 

 addition, it is only over the last few years that more systematic observations 

 of recruitment in reef fish larvae have begun to appear in the literature. For 

 most of the observations, maximum recruitment occurs over a single season and 

 often is episodic; it may follow a lunar periodicity (Johannes, 1978); it may 

 be monthly but not coupled to a particular phase of the moon (mixed guilds of 

 pomacentrids; Williams, 1983), or a rhythm may not be conspicuous ( Thalassoma 

 bifasciatum ; Victor, 1982, 1983a_). 



Larval French grunts ( Haemulon f lavol ineatum ) settle from the offshore 

 plankton following a semi-lunar timetable. This periodicity is most closely 

 correlated with the quarter moons and/or daily intermediate tidal excursions 

 that fall between the spring and neap tides (McFarland, et al . , 1985; also see 

 McFarland, 1982). Furthermore, although seasonal, some recruitment continues 

 throughout the year. Larval life is short (ca. 15 days; Brothers and McFarland, 

 1981), which implies that spawning also must occur throughout the year; also 

 ripe eggs are present in adult French grunts at all times of the year (Munro, 

 et al_^, 1973). 



The extreme variations seen in the spawning periodicities of reef fishes 

 (see earlier section) are reflected in the variable periodicity in recruitment. 

 What do larvae select when they settle from the plankton to the reef? Here we 

 are almost totally in ignorance. Most larval (or postlarval) recruits are 

 first observed on substrate (coral patches, seagrass beds, sand, etc.). Usually, 

 it is not possible to state that they have just settled. In a study of recruiting 

 pomacentrids, Williams and Sale (1981) found that different species tended to 

 prefer different species of corals. Earlier Sale (1969) found that young 

 surgeonfish preferred reefs with shaded overhangs. It is generally understood 

 that each species has certain needs for settlement, but determination of these 

 needs has barely been initiated. In addition, settlement to a specific site 

 can be dramatically influenced by resident competitors (Shulman, et al . , 1983). 



Actual settlement has seldom been observed. During observations of the 

 acronurus larvae of Acanthurus triostegus in Hawaii, Randall (1961) concluded 



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