sheepshead, triggerfish, blennies and small reef fishes; sheepshead and 

 triggerflsh were principal predators on large cryptic species. 



The biomass dynamics of the blofouling community by depth and 

 biological season with respect to characteristic water column conditions 

 offshore of Galveston in summer and winter were described by Gallaway et 

 al. (1980). During all seasons, biomass levels near the bottom (<2 

 kg/m ) were markedly lower than biomass levels in the upper water column 

 ("20 kg/m 2 ). The depth of this biomass discontinuity appeared to 

 coincide with the distribution of the year-round bottom nepheloid layer, 

 and was mainly attributable to the absence of barnacles. Biomass levels 

 in winter ("28 kg/m 2 ) were significantly higher than summer levels (~20 

 kg/m 2 ) . Most of the observed seasonal change was attributable to the 

 blooms of the mat community. High dissolved nutrient levels and 

 phytoplankton blooms were also characteristic of the early winter 

 season, and may have contributed to the increased blofouling levels. 



The structure-associated fish fauna of the platforms offshore of 

 Galveston was classified by Gallaway et al. (1980) as either seasonal 

 transients or residents. The most important seasonal transients, at 

 least from a fisheries standpoint, were the warm-season pelagic 

 predators and their plankton- particulate feeding prey. The predatory 

 species representing this group in the field included king mackerel, 

 cobia, bluefish, little tuny, dolphin, sharks, blue runner, sharksuckers 

 and jack crevalle. Prey species included Spanish sardine, scaled 

 sardine, and rough scad. The attraction of the seasonal- transient 

 assemblage of fishes appeared to be the structures per se , but 

 residence times at the structures for most of the species were believed 

 to have been short. 



According to Gallaway et al. (1980) the resident species in the 

 field included (1) fishes which were directly dependent upon the 

 blofouling community for both food and cover, and (2) those which 

 apparently were attracted to the structures for cover alone; they 

 exhibited little or no trophic dependency on the blofouling community. 

 Category one included sheepshead (biomass dominant), blennies (numerical 

 dominant), triggerfish, and amber jacks ( Seriola sp.); as well as small 

 pelagic (damsel fishes, butterfly fishes, angelfishes, small sea basses) 

 and demersal (cubbyu, wrasses) "reef fish. Category two included 

 pelagic reef forms such as spadefish (usually the numerical and biomass 

 dominant of the entire .fish community) and tomtate, as well as benthic 

 reef species such as red snapper and groupers. In contrast to fishes 

 around platforms offshore of Louisiana, lookdowns and moonfish were 

 seldom observed in the Texas field and were never seen in huge schools. 



■Outer £h£lf. ZaiAJial Assemblage 



Soft bottom onminiinit.iBH. Levels of primary production and biomass 

 of primary producers are lower on the outer shelf than in inshore areas. 



41 



