Distribution of deep-water corals along the North American continental margins: Relationships with environmental factors

Despite the increasing attention to assemblages of deep-water corals in the past decade, much of this research has been focused on documenting and enumerating associated fauna. However, an understanding of the distribution of most species of coral and the ecological processes associated with these assemblages is still lacking. In this study, we qualitatively and quantitatively described the habitats of two families of deep-water corals in relation to six oceanographic factors (depth, slope, temperature, current, chlorophyll a concentration and substrate) on the Pacific and Atlantic Continental Margins of North America (PCM and ACM study areas, respectively). This study focused primarily on the distributions of Primnoidae and Paragorgiidae because of the large number of documented occurrences. For each environmental factor, deep-water coral locations were compared to the surrounding environment using chi(2) tests. On both continental margins, coral locations were found to be not randomly distributed within the study areas, but were within specific ranges for most environmental factors. In the PCM study area, Paragorgiidae and Primnoidae locations were found in areas with slopes ranging from 0 degrees to 10.0 degrees, temperature from -2.0 to 11.0 degrees C and currents from 0 to 143 cm s(-1). In the ACM study area, Paragoragiidae and Primnoidae locations were found in areas with slopes ranging from 0 degrees to 1.4 degrees, temperature ranging from 0 to 11.0 degrees C and currents ranging from 0 to 207 cm s(-1). Although the patterns in habitat characteristics were similar, differences existed between families with respect to particular environmental factors. In both study areas, most environmental parameters in locations where corals occurred were significantly different from the average values of these parameters as determined with chi(2) tests (p < 0.05) except for substrate in Paragorgiidae locations and depth in Primnoidae locations on the PCM. This is the first study to show coral distributional patterns at the continental shelf/slope scale. (c) 2006 Elsevier Ltd. All rights reserved.