abundances for noncopepod categories differed at 6 m from those at either 15 m 

 or 24 m. These data indicate differences between shallow and deeper reef sites 

 which should be investigated further. They also indicate that caution should 

 be used when extrapolating data from shallow reefs to other reef sites. 



Robichaux, et al. (1981) and Youngbluth (1982) discuss the effect of 

 differing collection methodology on zooplankton species composition. In light 

 of the many confounding variables, comparisons between this study and others 

 will be brief and restricted to shallow reef sites. The data from the 6 m site 

 in this study compare most closely with those from 3 m in the Philippines 

 (Walter, et a! . , 1982). The relative abundance of most plankton groups and the 

 absolute abundance of certain groups are comparable. Lucifer , for example, is 

 an important component of the fauna in both shallow reef collections; however, 

 amphipods are more important in their study than in this study. Although the 

 abundant taxa from this study are not the same as those from the sealed traps 

 of Hobson and Chess (1979) and Robichaux, et al . (1981), the values for certain 

 of the taxa are comparable. Robichaux, et al . (1981) , for example, collecting 

 over a Thalassia bed (3 m), recovered an average of 56 tanaids and 54 amphipods/m^, 

 while this study produced an average of 53 tanaids and 78 amphipods/m? at the 6 m 

 reef site. 



CONCLUSIONS 



This study indicates that reef-associated zooplankton can only be of minor 

 caloric value to sessile reef organisms. While there is a negative correlation 

 between abundance of zooplankton and depth of the reef site, local abundance is 

 highly unpredictable. It would appear difficult for planktivores to choose 

 areas of maximum food potential and unlikely that local zooplankton abundance 

 has any causal effect upon patterns of species diversity. The polytrophic 

 habit of many of the reef dwelling invertebrates (Trench, 1974) may reflect the 

 unpredictability of this food source. 



It should be noted that the significance of zooplankton may lie not in 

 their role as a major caloric source, but in their critical role in the cycling 

 of nutrients in the reef environment. Zooplankton are able to feed on the very 

 abundant mucus and organic particles in the water (Johannes, 1967; Gerber and 

 Marshall, 1979; Richman, et al . , 1975; Gerber and Gerber, 1979), much of which 

 is generated by reef organisms themselves (Lewis, 1973; Coles and Strathmann, 

 1973). Zooplankton also feed on the bacteria on these organic aggregates 

 (Sorokin, 1973) and on the phytoplankton. Thus, the zooplankton prevent the 

 nutrients from all of these sources from being lost from the reef ecosystem. 

 Not only do these nutrients pass along the food chain through predation upon 

 zooplankton, but the production of fecal pellets, often composed of only 

 partially digested material, provides an important food source for certain 

 benthic invertebrates (Frankenberg and Smith, 1967; Turner and Ferrante, 1979) 

 and also serves to keep the important nutrients within the reef ecosystem. 



ACKNOWLEDGMENTS 



I would like to thank J. B. C. Jackson, N. Knowlton, W. D. Liddell, and M. 

 Youngbluth for their very helpful criticism of this manuscript. K. G. and J. 



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