Environmental Biology of Vol. 18, No. 4, pp. 303-308,1987 0 Dr W. Junk Publishers, Dordrecht. Benefits of heterospecific foraging by the Caribbean , garnoti (Pisces: Labridae)

Richard B. Aronsonr & S. Laurie Sanderson 1Department of Pure and Applied Zoology, University of Reading, Whiteknights, Reading RG6 2A J, England 2Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, U.S.A. 3 To whom reprint requests should be sent.

Keywords: Behavior, Fishes, Mixed- groups, Mullidae

Synopsis

Terminal-phase yellowhead , Halichoeres garnoti, foraged alone or in association with foraging , Pseudupeneus maculatus and Mulloides martinicus. Whereas H. garnoti did not dig for benthic infauna, the goatfish foraged almost exclusively on and in sand substrata. Wrassesin the company of goatfish made significantly more strikes on sand substrata than did solitary wrasses, although there were no significant differences in the frequency of strikes on sand and hard substrata combined. The frequencies of other behaviors (searches, scratches, flights, chases, rests, yawns, and cleanings) were not significantly different between solitary and associated wrasses. H. garnoti are attracted to foraging goatfish, which provide accessto an otherwise unavailable food resource.

Introduction Halichoeres bivittatus. While he quantified her- bivore foraging behavior and related it to group Mixed-species groups have been describedin birds, size and composition, he did not investigate the mammals, and fishes (e.g. Karplus 1978, Mont- behavior of the carnivorous wrasse and goatfish. gomery 1981,Dubin 1982,McNaughton 1984,Bar- Although there are numerous accounts of hetero- nard & Thompson 1985, Berner & Grubb 1985). specific foraging by carnivorous fishes, few quan- Morse (1977) reviewed the potential foraging and titative data are available on the costs and benefits predator-avoidance advantages of membership in to individuals. such groups. Mixed-species foraging in her- Wrasses (family Labridae) are among the most bivorous coral reef fishes has been related to avoid- abundant and diverse fishes on coral reefs world- ance of attacks from territorial damselfish that de- wide. Randall et al. (1978) commented that they fend an algal mat (e.g. Barlow 1974,Robertson et are also among the most opportunistic carnivores al. 1976,Foster 1985,Reinthal & Lewis 1986).Wolf in their exploitation of the activities of fishes that (1983, 1985) presented information regarding the forage by digging in the substratum. effects of social organization on diet in such school- (family Mullidae) possess a pair of highly devel- ing herbivores. oped chemosensory hyoid barbels that are used in In Jamaica, Itzkowitz (1977) examined the dy- foraging to excavate or dislodge prey (Gosline namics of mixed-speciesforaging groups composed 1984). We present a quantitative analysis of the of parrotfish, surgeonfish, butterflyfish, the goat- feeding behavior of the , Hali- Pseudupeneus maculatus, and the wrasse choeres garnoti, in association with the spotted 304 goatfish, Pseudupeneus maculatus, and the yellow strikes that the wrasses made at different substrata goatfish, Mulloides martinicus. (sand, rock, erect sponge, and branching gorgo- nian) while foraging alone and with goatfish. Due to the heterogeneity of the substratum, the wrasses Methods had accessto all substratum types. Each wrasse was observed for a maximum of 20min, or until lost Field work was conducted between 0830 and 1700 from view. hours during July, 1985 in Salt River Canyon, St. Maximum observation time for the Great Croix and during August,