Sedberry and Cuellar Planktonic and benthic feeding by Rhomboplites aurorubens 



707 



former two species feed primarily on sand bottom 

 benthos (Sedberry, 1985, 1988). Although H. auro- 

 lineatum and S. chrysops feed heavily on sand infauna 

 and are not completely dependent on reef habitat, ver- 

 milion snapper is more restricted to reef habitat and 

 does not range far from a home reef (Fable, 1980). 

 Wenner (1983) collected only 2 specimens in 11 trawl- 

 ing tows in sand bottom habitat on the southeastern 

 continental shelf, whereas S. chrysops and H. auro- 

 lineatum are dominant species in sand habitats 

 (Wenner, 1983; Sedberry-). Vermilion snapper did not, 

 however, feed directly on reef fauna, and its attraction 

 to reefs may be behavioral rather than trophic. 



Although vermilion snapper feeds extensively on de- 

 mersal zooplankton, many individuals also feed oppor- 

 tunistically on concentrations of holoplankton that oc- 

 cur on the southeastern shelf. Copepods, such as 

 Undinula vulgaris and especially Temora turbinata, 

 that were frequent food items for vermilion snapper 

 are epipelagic oceanic species that are transported land- 

 ward across the continental shelf (Hopkins et al., 1981 ). 

 Off the southeastern United States, upwelling at the 

 shelf edge and cross-shelf transport of deep, highly 

 productive oceanic water provide mechanisms for shore- 

 ward movement of shelf-edge biota, including copep- 

 ods (U. vulgaris, T. turbinata, Oncaea spp.), doliolids, 

 sergestid decapods (e.g., Lucifer faxoni), and other 

 abundant oceanic zooplankters (Yoder et al., 1983; 

 Paffenhbfer et al., 1984). Vermilion snapper, one of the 

 most abundant fishes at shelf edge depths ( Sedberry 

 and Van Dolah, 1984), apparently takes advantage of 

 this abundant resource and performs the function of 

 transferring some of this oceanic productivity to bot- 

 tom habitats on the continental shelf. 



In conclusion, vermilion snapper feeds on a variety 

 of prey above the substrate, much of which is demer- 

 sal zooplankton. Although it is unknown how much of 

 the biomass of the daytime benthos is composed of 

 nocturnally emerging demersal zooplankton, it is ap- 

 parent that these organisms are an important food 

 source for vermilion snapper and other reef fishes. De- 

 mersal zooplankton, such as mysids, cumaceans, 

 ampeliscid amphipods, and certain decapods, composed 

 at least eight percent of the total volume of food for 

 vermilion snapper in the present study and are more 

 important in the diet of smaller size classes. While a 

 small contribution, these benthic species provide a feed- 

 ing opportunity for vermilion snapper and may be more 

 important in the diet during periods of low productiv- 

 ity of holoplankton. Nektonic fishes and cephalopods 

 provide the greatest volume of food for larger vermil- 

 ion snapper. Because it is prey for other reef preda- 

 tors, vermilion snapper is an important trophic link 

 among several habitats on the southeastern continen- 

 tal shelf. 



Acknowledgments 



For their help in identification and confirmation of prey 

 items, we thank the following; D. M. Knott, amphi- 

 pods and copepods; C. B. O'Rourke and E. R. Hens, 

 polychaetes; and E. L. Wenner, decapods. D. M. Knott, 

 R. F. Van Dolah, P. H. Wendt, and E. L. Wenner pro- 

 vided the data on invertebrate distribution and abun- 

 dance for the electivity analyses. D. M. Knott, M. R. 

 Collins, W. D. Anderson Jr., and anonymous reviewers 

 provided helpful comments that improved the manu- 

 script. This work was supported with funds provided 

 by the Bureau of Land Management (Contract No. 

 AA551-CT9-27) and the Minerals Management Ser- 

 vice (Contract Nos. AA551-CT1-18 and 14-12-0001- 

 29185), U.S. Dept. of the Interior; and the National 

 Marine Fisheries Service (South Carolina MARMAP 

 contract No 50WCNF006002). Submersible time was 

 provided through the NOAA Undersea Research Cen- 

 ter at the University of North Carolina at Wilmington. 



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