Ocean Acidification & Harmful Algal Blooms: Defining a Research Agenda

A virtual workshop August 11-13th, 2020

Hosted by NOAA's National Centers for Coastal Ocean Science and Ocean Acidification Program

During June and July a webinar series set the foundation for the workshop - a recording of all of the presentations can be found below!

Contact elizabeth.turner@noaa.gov with any questions about the workshop or webinars!


This workshop aimed to determine a few tractable OA-HAB research priorities for potential  inclusion in an upcoming RFP during our time together by identifying:  

  • gaps in OA-HAB research; and
  • potential useful research products that incorporate OA-HAB interactions

  • view AGENDA 



    June 17th                          2pmET

                               June 24th  1:30pmET     

    June 26th    1:00pmET


    June 29th  1:00pmET


      July 8th           1:00pmET

                                            July 10th   1::30pmET

                                    July 13th    2:00pmET

      July 15th    2:00pmET


    Chris Gobler, Stonybrook University

    Raphe Kudela, University of California Santa Cruz

    Hans Paerl, University of North Carolina

    Clarissa Anderson, University of California San Diego; Samantha Siedlecki, University of Connecticut; Jan Newton University of Washington

    Beth Stauffer, University of Louisiana

    Regan Errera, Great Lakes Environmental Research Laboratory

    Melissa McCutcheon, Texas A&M Corpus Christi\

    Kris Holderied, NOAA National Centers for Coastal Ocean Science


    HABs and ocean acidification: Additive, synergistic, antagonistic, or otherwise?

    Synergies Between OAH and HAB Networks: California as a Case Study

    Acidification, eutrophication and HABs in estuarine waters:  What do long-term data tell us?

    Modeling and Forecasting OA and HABs to meet stakeholders needs – Regional Perspectives                                                                                                                                                                                                                                                                                                                                                                    

    A marginal sea of variability in ocean acidification and harmful algal blooms in the Gulf of Mexico

    Acidification and Harmful Algal Blooms in the Great Lakes                                                                  

                                                                                                 Effects of Ocean Acidification on HABs: A review of what we do and don't know

    Alaska Acidification and HABs: Networking and coastal variability


    Acidification, eutrophication and HABs in estuarine waters: What do long-term data tell us?

    Friday, June 26, 2020

    Estuaries receive and process nutrient loads generated in coastal watersheds and often exhibit accelerated rates of primary production (eutrophication), phytoplankton blooms, hypoxia and associated water quality and habitat declines.  As such, they are highly dynamic with respect CO2 fixation and mineralization of autochthonous organic matter (OM), which modulate pH.  Watershed-derived (allochthonous) OM plays an additional role in mediating carbon fluxes and pH.  Increasing anthropogenic activities as well as climatic changes (more extreme episodic rainfall events and increasingly variable wet/dry cycles) impact nutrient and inorganic/organic carbon loading to estuaries.  Long-term monitoring of these parameters in North Carolina’s Neuse River Estuary and downstream Pamlico Sound, NC, as well as Chesapeake Bay’s main stem reveals dynamic responses in primary production, phytoplankton biomass (as chlorophyll a), organic and inorganic nutrients, dissolved inorganic carbon (DIC) and pH, reflecting the effects of variable nutrient-and OM-enriched freshwater discharge.  Data from >20 year monitoring of these estuaries show only marginal trends in pH. In both systems, pH has risen slightly at upstream, nutrient-enriched locations, while downstream there is either no change or slight negative trends. Acidification is controlled by multiple interacting factors, including rates of primary production (CO2 fixation), which in some estuaries have increased due to eutrophication, tending to drive pH up, and mineralization of autochthonous and allochthonous organic matter, driving pH down. Large storm events, including increasingly high rainfall tropical cyclones, cause episodic drops in pH through “freshening” accompanied by large OM loads. With regard to potential linkages of autochthonous (within system) OM production due to algal blooms and effects on pH, we note that the estuary cannot mineralize more organic matter (driving pH down) than what is produced by algae and higher plants (driving pH up), Therefore, unless every CO2 molecule that is fixed is remineralized, which is unlikely if we assume that some fixed C is buried or exported, one would expect no significant net acidification.  In conclusion, estuarine pH trends driven by atmospheric- and ultimately estuarine enrichment of CO2 are masked by the combined effects of allochthonous OM and nutrient loading, and resultant eutrophication.       

    View the recording and complete this questionnaire after viewing.

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