Seasonal Ecological Analysis of Seafloor Organic Nutrient Supplies

Project Description
Seasonal Ecological Analysis of Seafloor Organic Nutrient Supplies (SEASONS) is an ongoing study to investigate the impact of seasonality on benthic foraminiferal communities of the western Antarctic Peninsula (WAP). The WAP, in particular the northern Gerlache-southern Bransfield Straits, displays strong seasonality in primary productivity due largely to seasonal sea ice conditions and light availability. These extremes in primary productivity result in significant differences in organic flux to the sea floor. Cruises SEASONS I and II were devoted to sampling surface and near surface sediments in mid-April and late June, 2008 for foraminiferal, sedimentological, pore water, and geochemical analyses. Samples were collected across a productivity gradient, and at shallow (~600 meters) and deep (~1200 meters) water depths in the northern Gerlache-southern Bransfield Straits. Foraminiferal samples were treated to identify specimens containing protoplasm (living) at the time of collection with a protein marker, CellTracker Green and biological stain, Rose Bengal. Foraminiferal samples will be used to determine the seasonal impact on the population dynamics of the foraminiferal communities, and to assess seasonal impact on the geochemical properties of the biogenic carbonate. Additional samples were collected for organic carbon and sedimentological analyses. Pore waters were collected from the sediments for geochemical analyses. Results of these analyses will further our understanding of the environmental controls on foraminiferal geochemistry and distributions, extensively used proxies for paleoceanographic/paleoclimatic interpretations.