Ocean Acidification Risk to Food Webs and Fisheries

California Current Project


Tools for understanding risks of ocean acidification to the ecosystem and fisheries

The California Current is fueled by upwelling that drives high productivity but also leads to lower pH (ocean acidification). Ongoing increases in atmospheric CO2 will further drive declines in ocean pH, with negative impacts on shelled organisms and other species.

We developed an Atlantis ecosystem model to project impacts of acidification on lower trophic levels, harvested and protected species, and fishery catches in the California Current (Fig. 1). Fifty-year projections of Atlantis were forced by a Regional Ocean Modeling System (ROMS), coupled to a GFDL Earth System Model including IPCC CO2 scenario RCP 8.5. We conducted an extensive literature review to develop scenarios for the biological response of calcifying organisms to pH.

The most dramatic direct effects of ocean acidification were expected on epibenthic invertebrates such as crabs, shrimps, some sea urchins, and bivalves (Fig. 2). Strong indirect effects were predicted on some demersal fish such as rockfish, sharks, and Dungeness crab because they consume species known to be sensitive to changing pH. In the management context, scale mattered: model results suggest the strongest effects of acidification on nearshore state-managed invertebrate fisheries, and on northern fishing communities.

Along with other risk assessment tools and forecasting efforts, the results have been presented to the Pacific Fishery Management Council to support a Fishery Ecosystem Plan climate initiative, as well as to other partners such as the Washington Ocean Acidification Center and California Current Acidification Network.

Collaborator Team:

Isaac C. Kaplan a, Kristin N. Marshall a, Emma E. Hodgson b, Jerry Leonard a, Timothy E. Essington b, Shallin D. Busch a,c, Elizabeth A. Fulton d, Chris J. Harvey a, Albert Hermann e,f, and Paul McElhany a


  • Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA

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  • School of Aquatic and Fishery Sciences, University of Washington

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  • Ocean Acidification Program, NOAA

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  • CSIRO Oceans and Atmosphere, Australia

    CSIRO logo
  • NOAA Pacific Marine Environmental Laboratory

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  • Joint Institute for the Study of the Atmosphere and Ocean, University of Washington

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    1. Marshall et al. 2017;


    1. 1. Busch, D. Shallin, and Paul McElhany. 2016. “Estimates of the Direct Effect of Seawater pH on the Survival Rate of Species Groups in the California Current Ecosystem.” PloS One 11 (8): e0160669.

    2. 2. Fulton, Elizabeth A., Jason S. Link, Isaac C. Kaplan, Marie Savina-Rolland, Penelope Johnson, Cameron Ainsworth, Peter Horne, et al. 2011. “Lessons in Modelling and Management of Marine Ecosystems: The Atlantis Experience.” Fish and Fisheries 12 (2). Blackwell Publishing Ltd: 171–88.

    3. 3. Hodgson, Emma E., Timothy E. Essington, and Isaac C. Kaplan. 2016. “Extending Vulnerability Assessment to Include Life Stages Considerations.” PloS One 11 (7): e0158917.

    4. 4. Hodgson, Emma E., Isaac C. Kaplan, Kristin N. Marshall, Jerry Leonard, Timothy E. Essington, Shallin D. Busch, Elizabeth A. Fulton, Chris J. Harvey, Albert Hermann, and Paul McElhany. n.d. “Consequences of Spatially Variable Ocean Acidification in the California Current: Lower pH Drives Strongest Declines in Benthic Species in Southern Regions While Greatest Economic Impacts Occur in Northern Regions.” In Review.

    5. 5. Kaplan, Isaac C., Laura E. Koehn, Emma E. Hodgson, Kristin N. Marshall, and Timothy E. Essington. 2017. “Modeling Food Web Effects of Low Sardine and Anchovy Abundance in the California Current.” Ecological Modelling 359 (September): 1–24.

    6. 6. Marshall, Kristin N., Isaac C. Kaplan, Emma E. Hodgson, Albert Hermann, D. Shallin Busch, Paul McElhany, Timothy E. Essington, Chris J. Harvey, and Elizabeth A. Fulton. 2017. “Risks of Ocean Acidification in the California Current Food Web and Fisheries: Ecosystem Model Projections.” Global Change Biology 23 (4): 1525–39.

    7. 7. Siedlecki, Samantha A., Isaac C. Kaplan, Albert J. Hermann, Thanh Tam Nguyen, Nicholas A. Bond, Jan A. Newton, Gregory D. Williams, William T. Peterson, Simone R. Alin, and Richard A. Feely. 2016. “Experiments with Seasonal Forecasts of Ocean Conditions for the Northern Region of the California Current Upwelling System.” Scientific Reports 6 (June): 27203.


Figure 1 Graphic showing linked Oceanographic Model, Literature review of pH sensitivity, and Atlantis Model

Fig. 1. Graphic showing linked Oceanographic Model, Literature review of pH sensitivity, and Atlantis Model

Figure 2 Graphic showing effect of OA on food web and fisheries revenue by sectors

Fig. 2. Graphic showing effect of OA on food web and fisheries revenue by sectors

California Current