Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Discrete water samples were collected with Niskin bottles. Depths for discrete samples were chosen to characterize the shape of the vertical profile at each station, as determined by the CTD (see CTD data for full profiles). In some cases carbonate chemistry parameters and dissolved oxygen were not measured at the same depth. Temperature and salinity measurements are from the CTD; total dissolved inorganic carbon (CT), total alkalinity (AT), and dissolved oxygen (DO) were measured; pH and pCO2 were calculated.

All carbonate chemistry samples were collected and analyzed according to Dickson et al. (2007). Total alkalinity was measured by open-cell potentiometric titration and total dissolved inorganic carbon was measured by acidification and quantification using a CO2 coulometer (UIC model CM5015) at the University of Washington’s School of Oceanography. Certified Reference Materials were analyzed as an independent verification of instrument calibrations (Dickson et al. 2007). pH and pCO2 were calculated from AT and CT using the R package seacarb and constants from Lueker et al. (2000) and the total pH scale.

Dissolved oxygen was measured by the modified Winkler titration method (Carpenter 1965).

BCO-DMO processing notes:

• Adjusted parameter names to comply with database requirements

Description from NSF award abstract:
Low dissolved oxygen (hypoxia) is one of the most pronounced, pervasive, and significant disturbances in marine ecosystems. Yet, our understanding of the ecological impacts of hypoxia on pelagic food webs is incomplete because of our limited knowledge of how organism responses to hypoxia affect critical ecosystem processes. In pelagic food webs, distribution shifts of mesozooplankton and their predators may affect predator-prey overlap and dictate energy flow up food webs. Similarly, hypoxia may induce shifts in zooplankton community composition towards species that impede energy flow to planktivorous fish. However, compensatory responses by species and communities might negate these effects, maintaining trophic coupling and sustaining productivity of upper trophic level species. The PIs propose to answer the question "Does hypoxia affect energy flow from mesozooplankton to pelagic fish?" They approach this question with a nested framework of hypotheses that considers two sets of processes alternatively responsible for either changes or maintenance of pelagic ecosystem energy flows. They will conduct their study in the Hood Canal, WA. Unlike most hypoxia-impacted estuaries, hypoxic regions of Hood Canal are in close proximity to sites that are not affected. This makes it logistically easier to conduct a comparative study and reduces the number of potential confounding factors when comparing areas that are far apart.

Improved understanding of how hypoxia impacts marine ecosystems will benefit the practical application of ecosystem-based management (EBM) in coastal and estuarine ecosystems. Effective application of EBM requires that the impacts of human activities are well understood and that ecological effects can be tracked using indicators. This project will contribute to both of these needs. The PIs will share their findings on local and national levels with Federal, State, Tribal, and County biologists. To increase exposure of science to underrepresented groups, the PIs also will provide Native American youth with opportunities to participate in field collections and laboratory processing through summer internships. The PIs will collaborate with the NSF-funded Pacific Northwest Louis Stokes Alliance for Minority Participation and tribes from the Hood Canal region to recruit and mentor students for potential careers in marine science. This project will support several undergraduate researchers, two Ph.D. students, a post-doc, and two early-career scientists.