Estuary Definition and Orientation

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Estuary Definition and Orientation
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What is an estuary?

• An estuary is formed where rivers meet the sea.
• An estuary is a semi-enclosed river mouth or bay
  where salty seawater is diluted by freshwater
  from rivers and creeks.
• An estuary is made up of tidal marshes, tidal
  flats, and open water channels.
• An estuary is flooded by the tides.

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What does an estuary look like from the air?
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What is South Slough National Estuarine Research
Reserve?

• a 4,771 acre protected natural area
• A place to investigate and conduct studies
  (research)
• A place for people to learn about estuaries and
  their watersheds (education)
• A place to restore and protect estuaries and
  their watersheds (stewardship)

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Is this still the estuary?
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Is this still the estuary?
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Is this still the estuary?
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The Physical Estuary
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The flooding and ebbing of the tides is one of
the most important forces shaping and influencing
the estuary.
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The flooding and ebbing of the tides is one of
the most important forces shaping and influencing
the estuary.
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High tides and low tides can make the same place
look very different.
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High tides and low tides can make the same place
look very different.
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The gravitational forces of the moon and the sun
drive the tides.
Spring tide
Neap tide
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Water quality in the estuary is determined by the
combination of temperature, salinity, turbidity,
pH, dissolved oxygen, and other factors.
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Sediment and other particles are common in the
estuarys waters, yet too much sediment can cause
damage to habitat and the flora and fauna.
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Estuaries are flooded by the tides twice daily.
Winter rains increase the depth of the flooding
waters expanding the reach of the floodplain.
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Upwelling occurs during the late spring and
summer when strong, continuous winds from the
north bring cold, nutrient rich ocean water to
the surface.
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The Life Zones of the Estuary
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Estuary zones upper estuary
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Estuary zones upper estuary
Tidal marsh
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Estuary zones upper estuary
Tidal marsh
Tidal flat
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Estuary zones upper estuary
Tidal marsh
Tidal flat
Open water channel
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Estuary zones lower estuary
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Estuary zones lower estuary
Open water channel
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Estuary zones lower estuary
Open water channel
Tidal flat
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Estuary zones lower estuary
Open water channel
Tidal flat
Tidal marsh
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Salt marshes and tidal fresh marshes are some of
the most productive environments on earth!
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Tidal flats of the estuary are usually made of
sand, mud, or cobble.
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Tidal flats may be made of exposed bedrock where
strong currents prevent sediment from
accumulating.
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Low tide exposes the flats to predators such as
herons, shorebirds, and raccoons.
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Life of the Estuary
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The producers of the estuary are the plants.
They capture the suns energy and convert it to a
food source for millions of animals.
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Salmon and many other kinds of fish use the
estuary as a zone of transition, a place where
young fish grow, safe from predators they will
face in the ocean.
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Many forms of life in the estuary live beneath
the surface of the mud or sand.
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Migratory birds depend on the wetlands of the
estuary for resting and feeding as they travel
between nesting and wintering grounds.
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Crabs live in many different types of habitat in
the estuary.
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Many animals begin their lives in the protective
waters of the estuary.
A larval crab
A juvenile English sole
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Estuary Functions and Impacts
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Healthy estuaries can provide many different
values and perform many important functions.

• Flood control
• Nursery areas
• Migratory stopovers
• Recreation
• Production of biomass
• Safe harbor
• Feeding grounds

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Timber harvest is a regulated activity in the
watershed that must be properly conducted to
reduce impacts to streams, rivers, and estuaries.
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Waste that is not properly treated pollutes the
waters of the estuary with excess nutrients.
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Research has improved our understanding of what
is necessary to restore estuary functions and
habitat.
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Welcome to the Estuary!