THE FORAMINIFERAL RECORD OF LARSEN C ICE SHELF EDGE IN NORTHWESTERN WEDDELL SEA, ANTARCTIC PENINSULA

This study provides baseline information on the distribution of benthic and planktonic foraminifera from a 238 cm marine sediment core recovered from near the Larsen C ice shelf (LSIC) edge in the northwestern Weddell Sea during oceanographic expedition ARA 2013 led by the Korean Polar Research Institute (KOPRI). These data are correlated with absolute diatom abundance data collected from the same core, in an effort to understand the processes that sustain foraminiferal communities in sub-ice shelf settings. The upper 20 cm of the core contains abundant benthic (predominantly calcareous forms) and planktonic foraminifera, with a high plankton-to-benthos ratio. The dominant benthic foraminiferal taxa occurring in this upper section of the core are Angulogerina spp. and Globocassidulina spp., both previously associated with productive ice shelf edge environments. Below 20 cm however, the core is marked by a sharp decline in the abundance of both benthic and planktonic forms. Despite the abundant foraminiferal fauna in the upper 20 cm, the absolute diatom abundance is extremely low, suggesting limited local food source. This observation raises the question of what processes sustain the foraminiferal fauna. Two possible causes for this mismatch are considered: one scenario involves the transport of advected food supply from the open Weddell Sea, while another scenario involves the possibility that the foraminiferal fauna might have adapted to less productive organic matter supply. Assessment of the processes that facilitate sustaining the foraminiferal fauna requires a better understanding of how the fauna responds to different types of organic matter supply.