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Riverine input of macronutrients, iron, and organic matter to the coastal ocean off Oregon, U.S.A., during the winter


Wetz, MS and Hales, B and Chase, Z and Wheeler, PA and Whitney, MM, Riverine input of macronutrients, iron, and organic matter to the coastal ocean off Oregon, U.S.A., during the winter, Limnology and Oceanography, 51, (5) pp. 2221-2231. ISSN 0024-3590 (2006) [Refereed Article]

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Copyright 2006 American Society of Limnology and Oceanography

DOI: doi:10.4319/lo.2006.51.5.2221


Three cross-shelf transects were conducted off northern Oregon in February, 2003, coincident with flooding of Coast Range rivers, to assess the riverine impact on coastal ocean biogeochemistry. During downwelling conditions, low salinity river-influenced water was located in a narrow band near the coast and contained elevated macronutrient, iron, and organic carbon concentrations. Wind relaxation allowed the river-influenced water to spread out at the surface across the shelf. Nutrients supplied by the rivers could result in winter carbon fixation equating to ,20% of the summer upwelling carbon fixation if conditions are suitable for phytoplankton growth, which is likely on the basis of recent studies. This implies that wintertime production may be significant and requires further study. Iron supplied by the rivers is sufficient to support the entire summer upwelling production and because downwelling conditions prevail during the winter and minimize cross-shelf transport, this iron may be retained on the shelf to support the summer phytoplankton blooms. Of the major eastern boundary current systems, the northern California Current (including Oregon) and Portugal Current (i.e., Iberian Peninsula) have the highest riverine discharge rates normalized to coastline length. In contrast, riverine inputs to the central California, Canary (i.e., northwest Africa), Benguela and Peruvian Current systems averaged only 3–35% of that in Oregon. This patchy riverine input (and narrower shelves) might explain why iron limitation is more widespread off California and Peru than Oregon. These results show that small coastal rivers, characteristic of the U.S. Pacific Northwest, can significantly alter coastal biogeochemical cycles and influence ecosystem structure.

Item Details

Item Type:Refereed Article
Keywords:iron nutrients Oregon winter rivers
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Chase, Z (Professor Zanna Chase)
ID Code:79536
Year Published:2006
Web of Science® Times Cited:44
Deposited By:IMAS Research and Education Centre
Deposited On:2012-09-18
Last Modified:2012-11-06

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