Near-bottom current direction inferred from comatulid crinoid feeding postures on the Terre Adelie and George V shelf, East Antarctica

摘要

For the first time, comatulid crinoid feeding behaviour is used to infer near-bottom current (NBC) directions on the Terre Adelie and George V shelf, East Antarctica. We analysed 47 still-image and video transects sampled during the Collaborative East Antarctic Marine Census (CEAMARC) expedition in 2007-2008. We recorded the inferred current direction from 1537 comatulid observations and interpolated these data across the shelf using the Natural Neighbour Interpolation (NNI) method. Results revealed a mode current directionality at each station and a close local agreement between the observed and interpolated NBC directions. The interpolated NBC directions show a coherent counter-clockwise gyre in the deep George V Basin, with a northward and westward flow over the northern flank of the basin and eastward flow near the coast consistent with the distribution of bottom salinity. There also appears to be a clockwise gyre on the relatively shallow Adélie Bank, with an easterly or southeasterly flow along the outer-shelf, south and southwesterly on the east Adélie Bank, and westerly along the Terre Adélie coast.