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PALEOLIMNOLOGICAL RECORDS OF NUTRIENT DYNAMICS ASSOCIATED WITH SOCKEYE SALMON (ONCORHYNCHUS NERKA) PRODUCTION IN SUB-ARCTIC AND ALPINE NURSERY LAKE ENVIRONMENTS
SELBIE, DANIEL T Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen's University.
Finney, Bruce P Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska, Fairbanks.
Lewis, Bert Alaska Department of Fish and Game (ADFG), Commercial Fisheries Division, Ketchikan, Alaska .
Smol, John P Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen's University.
Pacific salmon (Oncorhynchus spp.) represent a keystone ecological resource in sensitive arctic and alpine environments throughout the coastal North Pacific. In many systems, returning spawners import critical nutrients to inland, nutrient-limited aquatic ecosystems and associated riparian areas. The past 150 years, however, have witnessed significant declines in salmon populations coast-wide, associated with anthropogenic stressors such as harvest pressures, habitat destruction, hydroelectric development and hatchery production. These changes have occurred in the broader context of climatic change, a large-scale forcing mechanism of Pacific salmon through time.
Recently, novel application of established methods in the field of paleolimnology, the study of lake histories, has provided a means to reconstruct long-term sockeye salmon productivity. By exploiting the “counter-current” nutrient flow created by sockeye moving inland to oligotrophic nursery lakes to spawn, we use information archived in lake sediment cores to track salmon-derived nutrients and infer records of salmon abundance through time.
We present paleolimnological records of salmon-derived nutrient (SDN) dynamics and related trophic changes using stable nitrogen isotope (δ15N) and biological (diatoms, zooplankton) proxies, from sockeye salmon (Oncorhynchus nerka) nursery lake sediment cores. Our data represent both natural variability and human-induced changes in a ~2000 yr record from Redfish Lake, ID, an alpine nursery environment, and a ~5000 yr record from Tahltan Lake, BC a remote sub-arctic nursery lake.
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