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

Abstract

For the first time, comatulid crinoid feeding behaviour is used to infer near-bottom current (NBC) directions on the Terre Adélie 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.