Antarctic scallop (Adamussium colbecki) spatial population variability along the Victoria Land Coast, Antarctica

Along the Victoria Land Coast, the population structure of the Antarctic sc allop (Adamussium colbecki) was studied in McMurdo Sound (New Harbor), Terr a Nova Bay, and Wood Bay, on a latitudinal spall of 3 degrees. At a large s patial scale, most relevant differences between the scallop populations are linked to their depth distributions. The McMurdo and Wood Bay populations show a shallower bathymetric distribution with maximum abundance between 5 and 15 m depth. In contrast, inside Terra Nova Bay, at sites with similar n ear-shore bathymetric profiles, the maximum biomass is found between 40 and 70 m. This difference can be related to the different ice-cover persistenc y characterising these two areas, bring less at Terra Nova Bay than in the other localities. Differences arise also in the reproductive period: at McM urdo, it seems to occur early in the austral spring, while at Terra Nova Ba y, mature females are observed at the beginning of February. Also at a smal l scale, in sites only a few miles from each other. the population structur es inside Terra Nova Bay and Wood Bay vary in terms of abundance and size f requency distribution, suggesting various environmental and biological cons traints. Among environmental factors, bottom features (slope, sediment grai n size, organic content) and water-column food supply during the summer mon ths may be considered. In addition, as Adamussium is preyed upon by starfis hes and fishes, its abundance and population structure may be affected by p redators and their abundance.