Pacific salmon (Oncohrynchus) abundance has declined significantly over the last century. The lack of a long-term context of salmon abundance hinders restoration efforts. A ca. 6000-year record of coho salmon abundance in the Oregon Coast Range was developed using paleolimnological techniques (δ15N and complimentary proxies) at Woahink Lake and compared to a control lake (Triangle Lake) that is inaccessible to salmon. Proxies of salmon abundance declined over the record, consistent with a reduction in coastal upwelling and marine forage caused by increasing Pacific sea-surface temperatures. The record suggests that salmon abundance was anomalously high at the time of early Euro-American settlement. The resolution of this study is limited by low sedimentation rates and additional factors influencing δ 15N concentrations. Visual stratigraphy, magnetic susceptibility, loss-on-ignition, organic carbon and nitrogen, bulk density, biogenic silica, δ 15N, δ13C, and pollen were used to reconstruct vegetation, earthquake disturbances, and the dune-barrage origin of the lake.
|Advisor:||Gavin, Daniel G.|
|Commitee:||Ford, Jesse, Marcus, Andrew|
|School:||University of Oregon|
|Department:||Department of Geography|
|School Location:||United States -- Oregon|
|Source:||MAI 51/02M(E), Masters Abstracts International|
|Subjects:||Geography, Environmental science, Geochemistry|
|Keywords:||Coho salmon, Dunal activity, Lake sediments, Oncorhynchus kisutch, Oregon, Pacific, Stable isotopes|
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