Letter | Published:

Upwelling-driven nearshore hypoxia signals ecosystem and oceanographic changes in the northeast Pacific

Nature volume 429, pages 749754 (17 June 2004) | Download Citation



Seasonal development of dissolved-oxygen deficits (hypoxia) represents an acute system-level perturbation to ecological dynamics and fishery sustainability in coastal ecosystems around the globe1,2,3. Whereas anthropogenic nutrient loading has increased the frequency and severity of hypoxia in estuaries and semi-enclosed seas3,4, the occurrence of hypoxia in open-coast upwelling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves1. Upwelling systems support a large proportion of the world's fisheries5, therefore understanding the links between changes in ocean climate, upwelling-driven hypoxia and ecological perturbations is critical. Here we report on the unprecedented development of severe inner-shelf (<70 m) hypoxia and resultant mass die-offs of fish and invertebrates within the California Current System. In 2002, cross-shelf transects revealed the development of abnormally low dissolved-oxygen levels as a response to anomalously strong flow of subarctic water into the California Current System. Our findings highlight the sensitivity of inner-shelf ecosystems to variation in ocean conditions, and the potential impacts of climate change on marine communities.

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We thank A. Kirincich for ADCP analyses, S. Oda and A. Walters for assistance and A. Pazar for crab fishery data. The Partnership for Interdisciplinary Studies of Coastal Oceans, funded by the David and Lucile Packard Foundation, and the US GLOBEC program, jointly funded by NSF and NOAA, both contributed to this work. J.A.B. acknowledges additional funding from NSF. ODFW ROV survey work was funded in part by the Oregon Department of Land Conservation and Development through NOAA.

Author information

Author notes

    • Brian A. Grantham
    • , Francis Chan
    •  & Karina J. Nielsen

    These authors contributed equally to this work


  1. Washington State Department of Ecology, Coastal and Estuarine Assessment Unit, Olympia, Washington 98504, USA

    • Brian A. Grantham
  2. Oregon State University, Department of Zoology, Corvallis, Oregon 97331, USA

    • Francis Chan
    • , Jane Lubchenco
    •  & Bruce A. Menge
  3. College of Oceanic and Atmospheric Sciences, Corvallis, Oregon 97331, USA

    • John A. Barth
    •  & Adriana Huyer
  4. Sonoma State University, Department of Biology, Rohnert Park, California 94928, USA

    • Karina J. Nielsen
  5. Oregon Department of Fish and Wildlife, Marine Resources Program, Newport, Oregon 97365, USA

    • David S. Fox


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Competing interests

The authors declare that they have no competing financial interests.

Corresponding author

Correspondence to Francis Chan.

Supplementary information

Word documents

  1. 1.

    Supplementary Table S1

    Average, minimum and maximum DO and chl-a concentrations along the SH hydroline.

  2. 2.

    Supplementary Figure S1

    Dissolved oxygen source properties and depletion patterns across the shelf.

  3. 3.

    Supplementary Figure S2

    Composite cross-shelf profiles of temperature, salinity, density, nitrate+nitrite, chlorophyll-a, and dissolved oxygen, SH line, 11-12 August, 2002.

  4. 4.

    Supplementary Figure S3

    Chl-a concentration (mg l-1) at 5 meters depth over Heceta Bank from 9-11 August 2002.

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