Antarctic benthic foraminifera facilitate rapid cycling of phytoplankton-derived organic carbon

Fatty acid biomarker analyses of Cassidulina crassa, a dominant calcareous foraminieran at 55-m water depth in Arthur Harbor, Anvers Island (64°46′S, 64°04′W), Antarctica, revealed that this species responds rapidly to the deposition of fresh phytoplankton material from the overlying water column. During the sampling period in January/February 2002, a late summer phytoplankton bloom was clearly reflected in the fatty acid composition of C. crassa. This was apparent in the significant short-term increase of the relative content in polyunsaturated fatty acids, which more than doubled within the short period of one week from just over 14% on 28/29 January to 32% on 6 February. C. crassa feeds selectively on the high quality part of deposited organic matter, is highly abundant and widely distributed around the Antarctic, and has a wide bathymetric range. The present study shows that this species, like other, similar Antarctic benthic foraminiferal species such as Globocassidulina subglobosa, plays an important role in the rapid cycling of phytoplankton-derived organic carbon in Antarctic marine environments.