Document Detail

Biotic control of stream fluxes: spawning salmon drive nutrient and matter export.
MedLine Citation:
PMID:  17536413     Owner:  NLM     Status:  MEDLINE    
Organisms can control movements of nutrients and matter by physically modifying habitat. We examined how an ecosystem engineer, sockeye salmon (Oncorhynchus nerka), influences seasonal fluxes of sediments, nitrogen (N), and phosphorus (P) in streams of southwestern Alaska. The purpose of this study was to investigate whether salmon act as net importers or net exporters of matter and nutrients from streams and how these roles change as a function of salmon population density. We measured discharge and concentrations of suspended sediments and total N and P every 7-14 days for up to four summers in 10 streams spanning a gradient in salmon densities. We statistically allocated whole-season fluxes to salmon activities, such as excretion and bioturbation, and to export by hydrologic discharge. In addition, we used counts of spawning salmon to estimate nutrient and matter imports by salmon to streams. Large seasonal pulses of suspended sediments, P, and N were associated with salmon spawning activities, often increasing export an order of magnitude higher than during pre-salmon levels. Years and streams with more salmon had significantly higher levels of export of sediments and nutrients. In addition, years with higher precipitation had higher background export of P and N. Salmon exported an average of the equivalent of 189%, 60%, and 55% of total matter, P, and N that salmon imported in their bodies. The relative magnitude of export varied; salmon exported more than their bodies imported in 80%, 20%, and 16% across all streams and years for sediments, P, and N, respectively. A bioassay experiment indicated that the P exported by salmon is directly available for use by primary producers in the downstream lake. These results demonstrate that salmon not only move nutrients upstream on large spatial scales via their migration from the ocean and subsequent death, but also redistribute matter and nutrients on finer spatial scales through their spawning activities.
Jonathan W Moore; Daniel E Schindler; Jackie L Carter; Justin Fox; Jennifer Griffiths; Gordon W Holtgrieve
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ecology     Volume:  88     ISSN:  0012-9658     ISO Abbreviation:  Ecology     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-05-31     Completed Date:  2007-07-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043541     Medline TA:  Ecology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1278-91     Citation Subset:  IM    
Biology Department, Box 351800, University of Washington, Seattle, Washington 98195, USA.
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MeSH Terms
Biological Transport
Environmental Monitoring
Fresh Water / analysis,  chemistry*
Geologic Sediments / analysis,  chemistry
Nitrogen / analysis,  metabolism*
Phosphorus / analysis,  metabolism*
Population Density
Salmon / metabolism,  physiology*
Reg. No./Substance:
7723-14-0/Phosphorus; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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