Download Systems Dead Zones

Systems
Dead Zones
Dead Zones
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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.
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Examples: Lousiana coast, Hood Canal,
San Diego/Mexico area
Hood Canal
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Puget Sound Action Team
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
More Detail
juvenile perch (June 2003)
 numerous fish, octopi and sea cucumbers
(fall 2002 and 2003)
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Hood Canal’s dissolved oxygen (DO)
concentrations are at their lowest as
compared to data from the 1950s, 60s,
and 90s.
1950 – 2004 DO data
The Problem
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Many natural factors may contribute to the low
dissolved oxygen problem:
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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 Problem

People may be affecting the dissolved
oxygen concentration in several ways,
including
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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

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
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Wind over the Canal is an important driver of
surface currents.
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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.
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Upwelled water is also low in oxygen, wind-driven upwelling
is an important possible mechanism triggering fish kill events
Pale
orange =
crops
 Purple=
people
 Green=
forest

Land Use
Solving It

Using the information from Chapter 2 on
policy and economics what do you
suggest be done?
Solving It
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Will take time
Twenty-eight entities, including
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local, state and federal agencies,
tribal governments,
non–profit organizations and
universities,
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have come together to form the Hood Canal Low Dissolved Oxygen
Program (HCDOP).
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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
Hood Canal Dissolved Oxygen Program
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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.
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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.
Model
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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.
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Geologic Mapping
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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
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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
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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
Benthic Species with Resistance to
Hypoxia
Hood Canal Food Chains
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OPEN WATER SYSTEM
Tertiary Consumer - Orca
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INTERTIDAL SYSTEM
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Secondary Consumer –
harbor seal, sea lion, gulls
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Primary Consumer –
amphipods (eat detritus),
sea stars, urchin, mussel,
barnacle, perch
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Producer – Benthic
microalgae, eelgrass,
seaweed
Secondary Consumer Salmon (chinook high in
PCB) Seals, sea lions
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Primary Consumer –
forage fish (herring, surf
smelt)
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Producer - phytoplankton
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D
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P
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How Does excess Nitrogen cause
a dead zone?
1.
2.
3.
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5.
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.
Resources
Text Chapter 3
 http://www.psat.wa.gov/Publications/hoodc
anal_news/hc_news_online.htm
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