Chapter III includes contributed papers whose topics span those covered 

 in the four discussion groups. McFarland and Ogden provide a comprehensive 

 review of recruitment in coral reef fishes and evaluate the various hypotheses 

 advanced to account for the presence of planktonic larvae. They conclude that 

 both reduced predation on young and enhanced dispersal favor the development of 

 long-lived larvae which migrate offshore from local reefs. Due to the hetero- 

 geneity in patterns of larval development, however, these authors note that the 

 relative importance of these selective factors must vary among different species 

 of reef fishes. Brothers and Thresher evaluate the relationship between larval 

 durations and the extent of the geographic distributions in 115 species of reef 

 fishes. Their study yields the new and interesting result that, if larval 

 durations are < about 45 days, the size of the geographic range (usually an 

 indication of dispersal patterns) is not correlated with length of larval life. 

 Larvae which have pelagic phases longer than 45 days, however, all have broad 

 distributions and can transgress oceanic barriers at least occasionally. This 

 work, then, has important implications for patterns of colonization and biogeog- 

 raphy. Lobel and Neudecker analyze another aspect of reproductive biology of 

 reef fishes that can influence dispersal of larvae on reefs: the timing and 

 location of spawning. They describe and compare courtship in several species 

 of hamlets. These fishes spawn at dusk over specific high reef structures, 

 which may reduce predation and facilitate dispersal of eggs. The time and 

 duration of spawning is influenced by depth and/or lunar phase as well as 

 simulated attacks by predators. Emson, Mladenov, and Wilkie provide information 

 on a different aspect of reproductive biology in a reef invertebrate. Various 

 modes of asexual reproduction, including fission, are well known in a number of 

 relatively sessile invertebrate phyla. However, these authors demonstrate that 

 fission represents the major method of reproduction in many small species of 

 motile brittle stars associated with algae and sea grass in lagoonal habitats. 

 Many of these ophiuroids also apparently produce dispersing planktonic larvae, 

 an unexpected phenomenon because small size usually is associated with brooding. 

 These results again have implications for patterns of recruitment and maintenance 

 of local populations. 



Both meroplankton (the larvae of benthic reef organisms) and holoplankton 

 (organisms that spend their entire life in the plankton) exhibit diel vertical 

 migrations that are likely to influence their tendency to disperse in currents 

 and their susceptibility to predation. The long term study reported by Ohlhorst 

 also suggests that other factors, such as preceding rain and lunar effects, 

 can influence abundance of zooplankton above the reef. Ohlhorst further demon- 

 strates that numbers of zooplankton decline significantly with increased depth, 

 and that even in the shallow areas these plankton can provide relatively little 

 of the metabolic requirements for sessile reef organisms. Using frequent 

 collections throughout the day and night, Ohlhorst and Liddell provide the 

 first precise documentation of a predawn surge in abundance of plankton over 

 the reef that complements the postsunset peak of emergence known for these 

 organisms. A swarming holoplanktonic copepod usually was the most common 

 zooplankter in both Jamaica and St. Croix, although other taxa, including 

 meroplankters, became prominent during the hours around sunset. These papers 

 therefore are related to the topics of dispersal and reproductive biology 

 discussed above but also bear on community organization and energy flow among 

 different components of the reef community. 



