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Systems. Dead Zones. Dead Zones. Dead Zones – low concentrations of dissolved oxygen = hypoxia below 5 ppm movement slows, below 2 ppm organisms that can will leave, below 0.2 ppm black sediments with anerobic bacteria. Examples: Lousiana coast, Hood Canal, San Diego/Mexico area.

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Dead Zones

dead zones
Dead Zones
  • Dead Zones – low concentrations of dissolved oxygen = hypoxia
    • below 5 ppm movement slows,
    • below 2 ppm organisms that can will leave,
    • below 0.2 ppm black sediments with anerobic bacteria.
  • Examples: Lousiana coast, Hood Canal, San Diego/Mexico area
hood canal
Hood Canal
  • Spring of 2002 and again in the fall of 2003, thousands of dead fish and other marine life washed up on Hood Canal beaches, having basically suffocated

Puget Sound Action Team

more detail
More Detail
  • juvenile perch (June 2003)
  • numerous fish, octopi and sea cucumbers (fall 2002 and 2003)
  • Hood Canal’s dissolved oxygen (DO) concentrations are at their lowest as compared to data from the 1950s, 60s, and 90s.
the problem
The Problem
  • Many natural factors may contribute to the low dissolved oxygen problem:
    • slow water circulation and mixing,
    • the incoming ocean water quality,
    • changes in the weather,
    • high growth of algae,
    • loadings of carbon and nitrogen, and
    • changes in the native marine life composition.
the problem7
The Problem
  • People may be affecting the dissolved oxygen concentration in several ways, including
    • altering the river flows, landscapes,
    • and altering the marine life,
    • adding excess nutrients to the waters that can fuel extra algae growth, adding extra carbon to the ecosystem,
    • and influencing climate change. 
overgrowth due to increased nutrients
Overgrowth due to increased nutrients
  • July 14th 2005, people started noticing red streaks on the waters of the western shore of Hood Canal. By the weekend, it had grown to extensive patches between Potlatch and Hoodsport, north to Lilliwaup. It looked like tomato soup floating on top of the water.The cause of this coloration is an organism called Noctiluca (single cell algae) CAN CAUSE OXYGEN DEPLETION
marine systems wind driven fish kills
Marine Systems – Wind Driven Fish Kills
  • Wind over the Canal is an important driver of surface currents.
    • On average, the surface layer of the Canal is moving northward and outward carrying fresh water from rivers towards the ocean.
    • A northerly wind can cause a temporary reversal the surface current, while a southerly wind accelerates the northward current.
    • Such movements can cause the surface layer to evacuate certain parts of the canal, and its place is filled by water upwelling from the depth.
      • Upwelled water is also low in oxygen, wind-driven upwelling is an important possible mechanism triggering fish kill events
land use
Land Use
  • Pale orange = crops
  • Purple= people
  • Green=


solving it
Solving It
  • Using the information from Chapter 2 on policy and economics what do you suggest be done?
solving it12
Solving It
  • Will take time
  • Twenty-eight entities, including
    • local, state and federal agencies,
    • tribal governments,
    • non–profit organizations and
    • universities,
  • have come together to form the Hood Canal Low Dissolved Oxygen Program (HCDOP). 
  • The goal of the HCDOP is to determine the sources of the low dissolved oxygen in Hood Canal, the effect on marine life, and to work with local, state, federal, and tribal government policy makers to develop potential corrective actions that will help restore and maintain a level of dissolved oxygen that will not stress the marine life. 
systems organizational
Corrective Action and Education group focuses on preliminary assessment, corrective actions and demonstration projects that will help to improve levels of dissolved oxygen in Hood Canal.  This group educates and involves residents in ways they can help improve the quality of water the Canal. 

IAM is a three-year study to use marine, freshwater and biota monitoring data and a computer model to quantify the role the various natural processes and human actions are playing to control the concentrations of dissolved oxygen in Hood Canal and test corrective action scenarios.

Systems - Organizational

Hood Canal Dissolved Oxygen Program

  • Model will evaluate the effects of changes in inputs into the Canal,
    • such as different ocean conditions,
    • elimination of septic inputs,
    • changes in the Skokomish River flow,
    • or replacement of riparian alder trees with cedar, on the system.

Evaluate potential corrective actions for the low dissolved oxygen condition.

geologic mapping
Geologic Mapping
  • Mapping in this area is to address growing social issues associated with rapid suburban development.
  • The unconsolidated sediments in the area are a source for aquifers that provide drinking water to many residents.
  • Nature and extent of deposits in the area, to assess the long-term availability and potential contamination problems with the local groundwater resources.
marine life
Marine Life
  • Study effects on benthic organisms (critters living on and within the sea bed).
  • assess the effects of hypoxia on these benthic communities
  • Benthic organisms don’t move around a great deal - immobile
    • STUDY
    • how community structure varies in space and time in Hood Canal
    • which species are most important in determining benthic community variation
    • the relative importance of dissolved oxygen concentration in overlying water, water depth, sediment organic-carbon concentration, and other potentially important environmental variables in determining variation on benthic community structure
    • the statistical significance (by random permutation analysis) of observed relationships between oxygen concentration and benthic community structure
hood canal food chains

Tertiary Consumer - Orca

Secondary Consumer - Salmon (chinook high in PCB) Seals, sea lions

Primary Consumer – forage fish (herring, surf smelt)

Producer - phytoplankton


Hood Canal Food Chains
  • Secondary Consumer – harbor seal, sea lion, gulls
  • Primary Consumer – amphipods (eat detritus), sea stars, urchin, mussel, barnacle, perch
  • Producer – Benthic microalgae, eelgrass, seaweed
how does excess nitrogen cause a dead zone
How Does excess Nitrogen cause a dead zone?
  • Coastal waters are swamped with nutrients, particularly nitrogen, from sewage or fertilizer.
  • Excess nitrogen allows algae populations to grow very large.
  • Dead algae in turn feed bacteria and their populations grow.
  • Bacteria use up most of the oxygen in the water.
  • Shellfish suffocate, and fish must swim for more healthful waters.
  • Text Chapter 3