The deficiency of knowledge on the distribution of planktonic foraminifers and their stable-isotopic compositions in the western Arctic Ocean constitutes a significant shortcoming in our capabilities to reconstruct its paleoclimatic history. This proposal aims at an in-depth investigation of planktonic foraminifers and stable isotopes in the water column and seafloor surface sediments in the Chukchi/Alaskan region of the Arctic Ocean. This area is characterized by a dynamic hydrographic system affected by the interaction of Arctic and Pacific waters and ice marginal processes. The need for understanding the evolution of this system is caused by dramatic modern reduction in ice cover that affects many aspects of marine and coastal environments in and far beyond the region. Planktonic foraminifers will be investigated in depth-specific plankton tow. The investigation will include (1) identification and counts of live foraminifers and empty tests in several size fractions starting at 63 m, (2) measurements of stable isotopes of carbon and oxygen in foraminiferal calcite from respective subsamples, and (3) stable-isotopic measurements in ambient water. This study will be supplemented by the similar investigation of planktonic foraminifers and their stable-isotopic compositions in seafloor surface sediment samples collected by the NSF Shelf-Basin Interaction (SBI) Program in 2002-2004. Interpretation of results will be facilitated by the extensive hydrographic, hydrochemical, biological, and ice data collected and/or compiled by the SBI. Results of this study will enable the use of planktonic foraminifers and their stableisotopic signatures as paleoceanographic proxies for hydrographic and ice conditions in the western Arctic Ocean. Specific objectives of this research will focus on understanding hydrographic and hydrochemical controls on the distribution of foraminifers and stable isotopes in the water column as well as respective spatial patterns in seafloor sediments across the Chukchi/Alaskan region. In addition to the importance of these results for paleoclimatic research in the western Arctic, they will also improve our fundamental knowledge of biologically-mediated calcification processes in low-temperature marine environments. The societal significance of this research stems from the need for a comprehensive evaluation of the potential effects of modern climatic change on the Chukchi/Alaskan region that has many socio-economical aspects. Work on the project will involve training of graduate and several undergraduate students in two universities.
