Estuaries and Salt Marshes
Essential Nursery Habitat
Estuaries & Salt Marshes
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Estuaries

Dynamic habitat where
two aquatic systems
meet
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Types of Estuaries
1. Drowned river valleys
or coastal plain
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2. Bar-built Estuary



Sand bars
Barrier islands
NC
Estuaries & Salt Marshes
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3. Tectonic Estuaries


Subsidence
San Francisco Bay
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4. Fjords


Retreating glaciers
Sill
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Physical Characteristics of
Estuaries: Salinity


Salt Wedge
Positive Estuary (high tide)
Isohalines
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Salt Wedge

Positive Estuary (low tide)
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Negative Estuary


Inverse estuary
High salinities


> 50‰
100‰ or more during dry
spells
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Factors that affect Salinity


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Tides
Topography
Wind
Evaporation
Precipitation
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Physical Characteristics of
Estuaries: Substrate



Substrate
Particle size and
current velocity
Oxygen concentration
in sediment
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Living in the Mud
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Other Physical Characteristics

Temperature

Wave action and currents

Turbidity

Oxygen in the water column
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Coping with Salinity
Fluctuations
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Fauna
Estuaries & Salt Marshes
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Flora


Macroflora is limited due
to unsuitable substrate
and increased turbidity
The dominant vegetation
is emergent plants


Occur in the upper intertidal
Succulent
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Types of Estuarine Communities
1. Open water
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2. Mud flats


Most animals are
infauna and are usually
feeding on detritus
Epifauna



Sessile
Deposit feeders
Suspension feeders
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3. Salt Marshes



Tidal marshes
Wetlands
Halophytes
Atlantic Beach, NC
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Salt Marsh
Flora & Fauna

Dominant plants


Spartina, Juncus,
Salicornia
Dominant animals

Fiddler crabs, mussels,
oysters, amphipods,
and juvenile fish
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4. Mangrove Forests



Tropical
equivalents of salt
marshes
Mangals
Red, black and
white
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