A reassessment of the distribution of the common Antarctic scallop Adamussium colbecki (Smith, 1902)

The bivalve Adamussium colbecki is an endemic Antarctic pectinid that can be locally abundant in nearshore habitats, sometimes as the dominant species. However, its distribution around the Antarctic continent is rather puzzling, because it has a disjunct distribution, only occurring at some shallow, nearshore sites. Furthermore, there are some records of living specimens from the deeper shelf. In order to understand the biogeography of this circum-Antarctic species, we critically reviewed literature data on its distribution, comparing the available habitat information for those sites that have the most conspicuous populations of A. colbecki. We identified some major types of environments suitable for this species; these environments, notwithstanding an apparent dissimilarity (e.g., in the trophic conditions), all share a good level of environmental “stability”. In shallow, nearshore areas, these environments are represented by calm hydrographical settings with permanent or persistent sea-ice coverage, while on the shelf, by areas with infrequent iceberg scouring without structured communities of suspension feeders.