The Vertical Zonation of the Deep-Sea Antarctic Acorn Barnacle, Bathylasma corolliforme (Hoek): Experimental Transplants from the Shelf Into Shallow Water

Eight hypotheses potentially explaining the vertical zonation of Bathylasma corolliforme were tested by experimental transfer of barnacles from bathyal depths into shallow oligotrophic and eutrophic habitats of McMurdo Sound. Hypotheses predicated on physiological constraints, or general shallow-water habitat factors including substrata avialability, were negated by the successful transfers and by natural history observations. Also negated were hypotheses built on limits to dipersal as we observed nauplii larvae well adapted to planktonic existence and actual larval settlement in shallow McMurdo Sound. We also observed recruitment of complemental males of Bathylasma. Tentatively negated were hypotheses of predation on adult barnacles. Relative lipic contents of the barnacles provide evidence suggesting nutrient limitations in the McMurdo Sound region. Because of the passive feeding of Bathylasma, these limitations probably relate to the low velocity currents. It is predicted that Bathylasma will be found in the Sound where sufficent currents are found since it apparently occurred there in the past, when ice free and wind driven currents were greater.