SPATIAL VARIATION IN HARD-BOTTOM EPIFAUNA IN THE SANTA-MARIA BASIN, CALIFORNIA - THE IMPORTANCE OF PHYSICAL FACTORS

Hard-bottom epifauna were photographically sampled at 11 locations in the Santa Maria Basin near Platform Hidalgo. The sampling locations ra nged in depth from 105 to 212 m, and were categorized as either low-re lief (0.2-0.5 m) or high-relief (>1.0 m) habitat. Sampling was conduct ed on seven occasions between October 1986 and October 1990. Analysis of variance indicated that the 22 most common taxa varied according to depth and habitat relief, with many taxa exhibiting highest abundance s in deeper high-relief locations. Some of the deep high-relief taxa a lso varied according to orientation on high-relief rocks, and most oft en faced into stronger currents. Conversely, several taxa which were m ost abundant in low-relief habitat often faced into weaker currents. T here was a strong negative correlation (r = -0.988) between the combin ed abundances of the deep high-relief taxa and the flux of suspended s ediments measured with near-bottom sediment traps at each location. We suggest that the rich epifaunal assemblages that characterize deep hi gh-relief habitat in the Santa Maria Basin are associated with a balan ce between the positive effects of high current speeds and the negativ e effects of suspended sediments.