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5/8/2018
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Prepared by Diana Wheat-LBCC
� Compare and contrast the various types of
estuaries, including their origin, size, shape,
and general location on earth.
� Distinguish and describe the different types of
habitats found in a typical estuary.
� Evaluate the different types of osmotic capabilities of estuarine species.
� Discuss threats to estuaries.
� Summarize uses by humans.
Where the Fresh water (rivers & streams) meets the Ocean.
Also known as bays if ship traffic occurs there.Salinity and currents fluctuates with the tides.Often an area rich in nutrients.Ecotone of possibly
high biodiversity.Also called:� Fjords� Sound� Tide/mud flats� Inlets� Salt Marshes
Estuaries are classified by:
> Mode of formation
e.g. glaciers, deposition, sea level rise
> Patterns of water circulation
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I. Coastal plain
Broad and shallow embayments
Continuously modified
by wave erosion
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II. Bar-built
Formed by a barrier island trapping water near the
coast that enters from a river or stream
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III. Coastal lagoon
� Large embayment with little freshwater input
IV. Delta
Estuary with a broad, poorly defined fan-shaped mouth
The Mississippi River Delta, showing the
sediment plumes from the Mississippi
and Atchafalaya Rivers, 2001.
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V. Tectonic
� Created when the underlying land sank because of
crustal movements of the Earth e.g. San Francisco
Bay
VI. FjordEstuary that is deeply entrenched into a landform—carved out by a glacier
Seen in:NorwayAlaskaCanadaChileIcelandNew Zealand
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Salt marshes
� Very wet grasslands
� Include many halophytes
▪ Pickleweed, marshgrass, cordgrass
A true plant – not a seaweed.
Contributes to GPP.
Habitat for many fish/invertz.
Reduce erosion from tides/storms
Food for many animals including sea turtles, & marsh herbivores.
An area the size of a football field is
lost every day on a world wide
average.
These are areas of refuge and
protection– including to human
interests.
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Mudflats
� Made of rich, thick mud exposed to air at low tide
� Include many diatoms, seaweeds, and seagrasses
Courtesy of James Sumich
Oyster plots on the mudflat in Netarts Bay. OSU research
Photo credit: Tiffany Woods, Oregon Sea Grant
Channels
� Always filled with
water
� Include many
planktonic, nektonic,
and benthic organisms
▪ Crabs, fish, oysters,
zooplankton, phytoplankton
(c) ollirg/Shutterstock
� Estuaries have frequent salinity changes.
� Animals and plants living in estuaries must have
special adaptations.
� Osmoconformers - body fluids fluctuate with
changing salinity e.g. soft bodied epifauna.
� Osmoregulators – animals that regulate to some
degree their body fluid composition e.g. crabs
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I.Stenohaline – Tolerance to limited salinity ranges -
most FW fish, can’t tolerate higher salinity and
Haddock, can’t tolerate lower salinity. “steno”
means “narrow.”
II. Euryhaline – Tolerance to a wide range of salinity.
e.g. sharks often rely on shallow inshore areas for
nurseries – including wetlands.
Migratory species like Salmon, Herring
" There has long been a belief that the sea, at least, was inviolate, beyond man's
ability to change and to despoil.
But this belief, unfortunately, has proved to be naive."
Rachel Carson
� Withdrawing water at unsustainable rates
- Surface and groundwater are being depleted
- One-third of the world’s people are affected by shortages.� Most water (FW) is used in agriculture� People also engineer waterways
- Dams, levees, diversion canals
- For supplies, transportation, and flood control� Dredging: Clearing waterways for commerce.� Pollution: including plastics, toxins, antibiotics,
thermal, organic matter e.g. sewage, oil spills, dioxins� Coastal development – loss of mangroves, eel grass
beds, salt marshes etc.� Overfishing
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� Shellfish & crab harvesting
� Fishing – especially dredging
� Mariculture – oysters/shrimp
� Boating sports e.g. kayaking, paddleboarding
� Cruises for tourists
� Commerce – shipping/bays� Bird watching
� Vacation spots e.g. tropical lagoons
NOAA education portal
https://oceanservice.noaa.gov/education/tutori
al_estuaries/welcome.html
Ocean Blue Projecthttps://www.oceanblueproject.org/
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