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Salmon-mediated nutrient flux in selected streams of the Columbia River basin, USA

February 26, 2013

Salmon provide an important resource subsidy and linkage between marine and land-based ecosystems. This flow of energy and nutrients is not uni-directional (i.e., upstream only); in addition to passive nutrient export via stream flow, juvenile emigrants actively export nutrients from freshwater environments. In some cases, nutrient export can exceed import. We evaluated nutrient fluxes in streams across central Idaho, USA using Chinook salmon (Oncorhynchus tshawytscha) adult escapement and juvenile production data from 1998 to 2008. We found in the majority of stream-years evaluated, adults imported more nutrients than progeny exported; however, in 3% of the years, juveniles exported more nutrients than their parents imported. On average, juvenile emigrants exported 22 ± 3% of the nitrogen and 30 ± 4% of the phosphorus their parents imported. This relationship was density dependent and nonlinear; during periods of low adult abundance juveniles were larger and exported up to 194% and 268% of parental nitrogen and phosphorus inputs, respectively. We highlight minimum escapement thresholds that appear to 1) maintain consistently positive net nutrient flux and 2) reduce the average proportional rate of export across study streams. Our results suggest a state-shift occurs when adult spawner abundance falls below a threshold to a point where the probability of juvenile nutrient exports exceeding adult imports becomes increasingly likely.

Citation Information

Publication Year 2013
Title Salmon-mediated nutrient flux in selected streams of the Columbia River basin, USA
DOI 10.1139/cjfas-2012-0347
Authors Andre E. Kohler, Paul C. Kusnierz, Timothy Copeland, David A. Venditti, Lytle Denny, Josh Gable, Bert Lewis, Ryan Kinzer, Bruce Barnett, Mark S. Wipfli
Publication Type Article
Publication Subtype Journal Article
Series Title Canadian Journal of Fisheries and Aquatic Sciences
Series Number
Index ID 70042646
Record Source USGS Publications Warehouse
USGS Organization Alaska Cooperative Fish and Wildlife Research Unit

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