Subphotic contours were surveyed between 350 and 500 m at six deep-sea coral beds in Hawaii. The density and mean height for the deep-sea corals Corallium secundum Dana, 1846, Corallium lauuense Bayer, 1956, and Gerardia sp. at each bed were recorded relative to temperature, substrate, and bottom relief. Species composition and density at the six sites varied; however, the mean size of the coral colonies did not vary except at sites where there was a history of coral harvesting. The Corallium species had the highest densities and, at some sites, were found in mono-specific patches. The three coral taxa overlapped in their depth range. Water temperature varied as much as 3-4°C across the six stations. Multi-year monitoring at two of the sites indicated that temperature differences persisted year-round and exhibited monthly and seasonal fluctuations. All three coral taxa colonized both carbonate and basalt/manganese substrates. The largest patches of C. secundum were found on flat exposed bottom, whereas C. lauuense encrusted uneven rocky bottom. Corallium lauuense was often intermixed with Gerardia sp., which colonized cliffs, pinnacles, and the tops of walls. Of the habitat variables, bottom relief best explained the distribution of the three coral taxa. It is hypothesized that the corals favor areas where bottom relief enhances or modifies flow characteristics perhaps improving the colony's feeding success.
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