This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The goal of this project is designed to reduce uncertainties about the causes of variability in N. pachyderma (s) ä18O using a series of sediment traps and real-time hydrographic observations to better understand: 1) the seasonal production and isotopic chemistry of N. pachyderma (s) in the Arctic, 2) the relationship of the presence of this taxon to the amount of sea ice cover, and 3) the degree to which the smaller N. pachyderma (s) shells may be affected by lateral transport processes from the wide Arctic shelves into the deep basins of the Arctic Ocean.
The sediment traps are located in the Beaufort Gyre and have been deployed as part of the Beaufort Gyre Observing System. An initial sediment trap deployment sampled the 2004- 2005 annual cycle and four others sampled the 2007-2008 annual cycle. The sediment trap samples are complemented by a complete set of standard hydrographic measurements (temperature, salinity, depth, and current velocity), taken approximately once a day and spanning the water column from 50 to 2000 m below the surface. The moorings include upward-looking echo sounders to provide a record of sea ice concentration and thickness above each site. Ice Tethered Profiling Systems also transited the study area during the sediment trap deployments, providing quality records of sea ice thickness and hydrographic properties from the surface down to about 800 m during the winter periods of complete ice cover. These sediment trap samples and complementary hydrographic data will be used to evaluate the relationship of N. pachyderma (s) to changes in sea ice and low salinity.
