FISHERY BULLETIN: VOL. 74, NO. 2 



at night. Possibly this jack followed the Haren- 

 gula as they dispersed, to continue feeding 

 through the night. 



A large number of benthic reef species occupy 

 the bottom below the platform and also the area 

 immediately surrounding the stage, where much 

 litter has accumulated, apparently discarded by 

 workmen on the platform above. Other benthic 

 species were observed on the pilings and cross- 

 members of the platform structure, where en- 

 crusting invertebrates and algae provided food 

 and hiding places for smaller species. In addition, 

 habitat for benthic species may be provided by 

 accumulations of shell hash at the bases of the 

 pilings, probably broken loose from the pilings by 

 storms or by the grazing of fishes or predation by 

 other organisms. Some of the more important 

 benthic species at the stages are Gymnothorax 

 nigromarginatus, Opsanus pardus, Antennarius 

 ocellatus, Ogcocephalus radiatus, Centropristis 

 ocyurus, Diplectrum formosum, Serranus sub- 

 ligarius, Rypticus maculatus, Apogon pseudo- 

 maculatus, Equetus lanceolatus , E. umhrosus, 

 Chaetodon ocellatus, Pomacentrus variabilis, 

 Halichoeres caudalis, Blennius marmoreus, 

 and Hypleurochilus geminatus. A few of these, 

 such as S. subligarius, R. maculatus, and R 

 variabilis, seemed to be equally at home on the 

 pilings at all levels of the water column, while 

 others were found only near the bottom (G. nig- 

 romarginatus, Opsanus pardus, Antennarius 

 ocellatus, Ogcocephalus radiatus, Centropristis 

 ocyurus, D. formosum, Apogon pseudomaculatus, 

 E. lanceolatus, E. umbrosus, and Halichoeres 

 caudalis) or only on the pilings {Hypleurochilus 

 geminatus). 



An interesting contrast was noticed among 

 members of the families Pomacentridae and Lab- 

 ridae at Stage I. Those species which are charac- 

 teristic and permanent members of the northern 

 gulf reef fauna {Chromis enchrysurus, C. scotti,P. 

 variabilis, and Halichoeres caudalis) were most 

 numerous on the bottom in association with plat- 

 form supports and other objects. In contrast, 

 species which are not permanent residents of 

 reefs in this area, but are apparently tropical 

 species carried north by currents {Abudefduf 

 saxatilis, P. partitus, and Thalassoma bifas- 

 ciatum) were never observed near the bottom, but 

 were always associated with the pilings and 

 cross-members within about 10 m of the surface. 

 These are shallow-water species which appar- 



ently do not occur at the greater depths at Stage 

 I (32 m). 



At least two species, G. nigromarginatus and 

 Mystriophis intertinctus, were usually seen par- 

 tially buried in the substrate, often with only 

 their heads protruding. 



Several other species occurring on the bottom 

 were most numerous over the open sandy areas 

 surrounding the stages. Stenotomus caprinus, 

 Leiostomus xanthurus, Paralichthys albigutta, 

 and Lactophrys quadricornis are examples. 



This benthic group includes both diurnal and 

 nocturnal species. Species which are active and 

 apparently feed at night are R. maculatus, Apo- 

 gon pseudomaculatus , and E. umbrosus. Benthic 

 species which are diurnal and inactive at night 

 are Centropristis ocyurus, D. formosum, Serranus 

 subligarius, Chaetodon ocellatus, Pomacentrus 

 variabilis , and H. caudalis. The other species 

 were not observed enough to determine activity 

 patterns. 



Generally counts of the nocturnal species were 

 higher during the nocturnal observations. Ryp- 

 ticus maculatus was more numerous in Station 1 

 on the bottom under cross-members or other shel- 

 tering objects, but was counted in Station 2 near 

 the surface three times, during each of the noc- 

 turnal counts between about 1730 and 0215 CST 

 Hiding places on the pilings are rather limited 

 and can, in most cases, accommodate only small 

 individuals, so apparently these soapfish were 

 moving up the pilings at night to feed. Other ref- 

 erences also report noctural feeding in the 

 grammistids (Hobson 1965; Starck and Davis 

 1966). 



Apogon pseudomaculatus , when observed at 

 night, was active, swimming about in open areas 

 near the bottom, while those observed during the 

 day were always inactive, hiding among shells or 

 other debris or under the stage cross-members. 

 On one occasion a group of about 15 juvenile Apo- 

 gon was seen associated with a diadematid sea 

 urchin below a cross-member at Stage I. These 

 small cardinal fish remained motionless among 

 the long spines of the urchin. Cardinal fishes in 

 general are nocturnal predators (Hobson 1965; 

 Starck and Davis 1966; Livingston 1971). 



Species of Equetus (or the related Pareques) 

 have been reported to remain in small groups in 

 sheltered areas by day, and then feed individually 

 in the immediate vicinity at night (Hobson 1965; 

 Starck and Davis 1966). Similar observations 



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