discussion section that spawning is a variable act within and between species 

 and an activity that involves considerable behavioral plasticity. If the 

 function of casting eggs into the plankton is to rapidly remove them from reef 

 predators, then doing so at dusk (as many fish do) would seem safest. The fact 

 that many fish do not spawn at dusk may relate to the presence of favorable 

 currents that flush the eggs rapidly offshore and out of the reach of abundant 

 small reef predators. Unfortunately, few papers deal simultaneously with 

 spawning and local currents (McFarland and Ogden, 1985). As a result, it is 

 rather difficult to resolve the differences that exist between species (see 

 Robertson, 1983, for spawning variation in several acanthurids). 



Although recruitment from the plankton occurs at the end of the larval 

 stage, knowing how and when potential propagules are introduced into the plankton 

 is essential for understanding recruitment because the spawning act initiates 

 the recruitment process. The difficulties identified above could be partly 

 resolved by an integrated study in a local area of the seasonal, monthly, and 

 diel spawnings of many different species of coral reef fishes. Evaluating the 

 function(s) of differential spawning amongst the various species will require 

 that the observations be tightly coupled with analysis of local currents (for 

 example, Robertson, 1983). If this is accomplished in several different areas, 

 it should be possible to sort out the trade-offs that different species invoke 

 in order to "safely" deliver young to the plankton. 



Once spawned, the eggs of coral reef fishes usually hatch within a day 

 (Thresher, 1984). Although most coral reef fish eggs and larvae are flushed 

 offshore, in some circumstances the eggs and larvae are entrained within lagoons 

 (apparently by local currents). Because eggs and very young larvae cannot swim 

 and orient actively (Leis and Rennis, 1983), it is generally assumed that, when 

 at sea, larvae are widely dispersed (through diffusional and other processes). 

 As pointed out by Lobel during the discussion, similarly sized larvae of the 

 same species often are taken in the same plankton hauls. In addition, newly 

 recruited fish larvae often appear on reef sites in small groups of 3 or more 

 fish (e.g., pempherids, high hats, grunts, etc.), but may also recruit as 

 individuals, as noted by McFarland at the discussion. The question arose, 

 therefore, as to how valid is the assumption of wide dispersion of individuals 

 at sea? There was general agreement that little is really known about the 

 distribution and dispersion of the eggs and larvae of individual species at sea 

 (but see Leis and Goldman, 1984, for a beginning). Shapiro's paper in volume 1 

 of these proceedings develops a model which suggests that the dispersion of 

 eggs resulting from a single spawning act will retain reasonable cohesiveness 

 (after 24 hours of drift in a current; this varies depending on assumed 

 conditions, but could yield as many as 1 post-hatchl i ng in each adjacent m^ of 

 water). If newly hatched larvae can swim actively and are mutually attracted, 

 it is at least possible that in the first few days they might form cohesive 

 aggregations. Shapiro's thesis specifically suggests the possibility that 

 young recruiting reef fishes may, in some instances, be kin. Tests of this 

 hypothesis can involve electrophoretic analysis of recent recruits that occur 

 in cohesive groups. A more immediate test involves the aging of all recruits 

 in a group by use of the otolith aging technique (Brothers and Thresher, 1985; 

 Victor, 1983). If spawned simultaneously and dispersed as a group, the 

 cohesiveness of which is retained by active behaviors by individuals in the 



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