Selective feeding by benthic foraminifera on phytodetritus on the western Antarctic Peninsula shelf: evidence from fatty acid biomarker analysis

This study presents the first direct evidence, based on biochemical analysis of fresh material, that certain benthic foraminifera feed selectively on specific components of seasonally deposited phytodetritus in their natural environment. Three abundant species of benthic foraminifera, the calcareous species Globocassidulina subglobosa and Quinqueloculina seminula and the agglutinated species Thurammina albicans, collected after the deposition of phytoplankton bloom material at a shelf site (560 m water depth) west of the Antarctic Peninsula in March 2001, showed significant differences in their fatty acid profiles compared to the surrounding phytodetritus. Furthermore, the 2 calcareous species contained significantly higher amounts of polyunsaturated fatty acids (PUFAs) than were found in their presumptive phytodetrital food source, indicating that the foraminifera discriminate between, and selectively feed on, the different components of the deposited material. Possible implications for the benthic food web are discussed.