Coral-characterized benthic assemblages of the deep Northeast Atlantic: defining “Coral Gardens” to support future habitat mapping efforts

Providing statistically robust maps of habitat distributions on which to base spatial planning and management of the marine area is reliant upon established and agreed descriptions and definitions of habitats. “Coral Gardens” is an Oslo–Paris Convention (OSPAR) listed habitat, which currently cannot be reliably mapped as a result of poorly developed deep-sea habitat classification systems and habitat definitions. The aim of this study is to assess and inform development of the current definition of this habitat to support future mapping efforts. This study uses multivariate community analysis of video data to identify deep-sea benthic assemblages characterized by coral taxa and thus constituting a potential “coral gardens” habitat. Assemblages are assessed against a set of qualifying criteria, derived from current definitions of “coral gardens”, first at the assemblage level then sample by sample. The current definition of “coral gardens” captures a range of benthic assemblages, thus “Coral Gardens” cannot be considered a single “habitat”. While 19 assemblages are identified as being characterized by one or more coral garden taxa, only 8 meet the qualifying criteria. It is suggested that the current definition incorporates descriptions of the different “Coral Gardens” assemblages together with guidance on threshold densities for coral species specific to each assemblage type.