CGRG Bibliography of Canadian Geomorphology
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Author : Finney, B.; Sweetman, J.; Gregory-Eaves, I.; Barto, D.; Beesley, A.; Smol, J.P.; and Douglas, M.S.V.
Date : 2000.
Title : Paleolimnology of Pacific Salmon lakes: relationships between climate change, salmon abundance, and lake ecosystem dynamics
Publication : 8th International Paleolimnology Symposium, August 20 to August 24, 2000. Queen's University, Kingston, Ontario
Issue :
Page(s) :
Abstract
When Pacific Salmon return to freshwater to spawn, and subsequently die, they release significant quantities of nutrients into freshwater and terrestrial ecosystems. Sockeye salmon require lakes for freshwater habitat, and thus the sediment records from such systems are ideal for studies of lake ecosystem dynamics, salmon population variability, and North Pacific climate change. Historically, sockeye populations have fluctuated significantly on interannual and interdecadal time scales. We are using isotopic (d15N) and biological (diatom) proxies to track past changes in salmon-derived nutrients, and hence sockeye populations. Because salmon are highly enriched in 15N relative to terrestrial N sources, sediment d15N analysis is a powerful tool for reconstructing changes in salmon-derived nutrients. Lakes have been cored in Alaska, British Columbia, and the Pacific Northwest to reconstruct past changes in sockeye populations, and test hypotheses regarding temporal and spatial controls on abundance. Records from Alaskan sites generally show similar trends, consistent with large-scale climatic control. High-resolution records show significant variability on interdecadal timescales (~50 years) over the past 500 years, similar to the time frame of variability in the historic record. Significant long-term trends suggest response to lower frequency climate change during the Neoglacial. Pacific Northwest systems show different trends relative to Alaskan systems. Out of phase responses of northern and southern lakes to North Pacific climate change have been observed during the 20th century. The response of lake ecosystems to changes in climate and nutrient loading has been examined using a suite of proxies of primary and secondary (zooplankton) production. In general, both primary and secondary productivity are positively related to salmon-derived nutrients. Among lakes, the magnitude of responses varies as a function of the relative importance of salmon-derived nutrients to the overall nutrient budget. The data suggest a positive feedback, in which higher adult salmon abundance leads to increased lake productivity, and thus greater carrying capacity for juvenile salmon, which results in increased adult salmon abundance. Therefore, the effects of climate change on limnologica
Bibliography of Canadian Geomorphology