TEMPORAL CHANGES IN LIVING (STAINED) BENTHIC FORAMINIFERA FROM THE GERLACHE STRAIT, ANTARCTICA

Seasonal changes in surface productivity can have dramatic effects on the delivery of organic material to the deep seafloor. As a result, dramatic seasonal changes in Antarctic surface waters have the potential to influence deep-sea ecosystems. In an on-going effort to understand seafloor ecosystem responses to seasonal changes, living (Rose Bengal stained) benthic foraminifera were examined from five mega (multi-)cores taken at a 1200m water depth site in the Gerlache Strait. Samples were collected in April, 2008 shortly after a surface productivity bloom and again about 3 months later in late June during non-bloom times. Foraminiferal assemblages (>150 microns) were generally dominated by Bolivina pseudopunctada, with abundant Reophax dentaliniformis, Haplophragmoides parkerae, and Pullenia sp. Surprisingly, for the cores examined thus far at this site, total foraminiferal densities were greater in June compared to April, and the overall assemblages and vertical distribution patterns of both sampling times are similar. In all but one core infaunal densities are greater than those in the 0-1cm interval. However, Haplophragmoides parkerae and Pullenia subsphaerica have maximum densities in the 0-1 interval. These results will be compared with pore water chemistry data to assess any relationships between environmental changes and species distributions and assemblage characteristics.