Contact Information
Graduate Program in Marine Science and Limnology335 Alaska Sealife Center
P.O. Box 757220
University of Alaska Fairbanks
Fairbanks, AK 99775-7220
Phone: (907) 474-7899
molly@sfos.uaf.edu
Molly BoughanM.S. Student
Thesis Title
Paleoceanographic Shifts in the Gulf of Alaska Over the Past 2000 Years: A Multi-Proxy Perspective
Research Overview
The Gulf of Alaska (GOA) is a dynamic region influenced by climate variability on time scales ranging from days to millennia. Recent documented regime shifts suggest that GOA primary productivity patterns may oscillate on interdecadal time scales, yet it is unclear whether such fluctuations extend beyond the instrumental record. This thesis examined the nature of prevalent climatic and oceanographic patterns before the twentieth century using several marine sediment core proxies for paleoproductivity and paleoceanography. Sediment cores were extracted from two locations: Bay of Pillars, Kuiu Island, in southeast Alaska (56.63[degrees]N, 134.35[degrees]W), and a central midshelf location (GAK4) along the Global Ecosystem Dynamics (GLOBEC) Seward Line (59.25[degrees]N, 148.82[degrees]W). Proxy data from these cores include: percentages of organic carbon, nitrogen and biogenic opal; organic carbon-to-nitrogen ratios; stable isotope ratios from sediment ([delta]13C and [delta]15N) and foraminifera tests ([delta]13C and [delta]18O); and foraminifera species density. Bay of Pillars proxy data suggests that the onset of the Little Ice Age (LIA) ca. 1200 AD coincides with pulses of fresher water and generally increased productivity. GAK4 proxy data indicates an increasing productivity trend over the past century and a trend towards fresher water during the LIA and positive Pacific Decadal Oscillation (PDO) phases.