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TERRESTRIAL AND MARINE SOURCES OF NUTRIENTS TO STREAMS IN THE OREGON COAST RANGE
Citation:
Compton, J E., M R. Church, AND S T. Larned. TERRESTRIAL AND MARINE SOURCES OF NUTRIENTS TO STREAMS IN THE OREGON COAST RANGE. Presented at Oregon Chapter American Fisheries Society, Eugene, OR, February 26-28, 2003.
Description:
Research on nutrient delivery to Pacific Northwest streams generally focuses on watershed processes and land use, but anadromous fish also can serve as a significant source of nutrients and energy to the streams where they return and die. To understand the relative importance of terrestrial and marine nutrients sources, we compared the watershed export of N, C and P with the delivery of these elements in returning chinook and coho salmon. We measured dissolved nutrient fluxes from the Salmon River in the Oregon Coast Range during the year 2000. Dissolved element export was 9.7 kg N ha-1 yr-1, 16 kg C ha-1 yr-1, and 0.19 kg P ha-1 yr-1. These data are compared with the flux of nutrients returning from the ocean as spawning salmon (0.03, 0.13 and <0.01% for N, C and P, respectively). The ratio of terrestrial to marine derived nutrients is very high, indicating that under present conditions, most of the C and N passing through the stream is derived from the watershed. Present-day salmon runs are approximately 1-5% of historic runs, however, indicating that marine-derived N, C and P were relatively more important before the decline of salmon runs. The forms and timing of nutrient supplies to streams, and their mode of entry into stream food webs, are important to consider in light of developing efforts for augmenting nutrient inputs to aid in salmon recovery.