Transcript Chapter 12

Chapter 12
Lecture
Slides
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Chapter 12
Estuaries
Do Now
• Review/Thinking Ahead
• 1) What is the difference between an osmoregulator and an
osmoconformer? (look up the definition for osmoregulation in the
back of the book if you need a hint)
• 2) what is the difference between euryhaline and
stenohaline organisms?
Objective
• SWBAT- Describe the four different types
of estuaries
• Describe how and why a salt wedge forms
What is an Estuary?
• Where freshwater meets the sea
• Partially enclosed coastal regions where
fresh river water meets ocean water
• They are amoung the most productive
environments on earth
Life in Estuaries
Make predictions
• Make a list of 5 animals
that you think would live
in this environment
Life in Estuaries
Plant Life
• Salt marsh grasses
• Mangroves
• Seaweeds
• Cyanobacteria
Animal life
• Worms
• Clams
• Shrimps
• Fishes
• Plankton
Copy this graphic organizer into
your notes
Type of Estuary
How its formed
Example
Different types of Estuaries
• 1) Drowned river valleys
• 2) Bar-built estuary
• 3)Tectonic estuary
• 4) Fjords
Types of Estuaries
• Drowned river valleys
– Most common type of estuary
– They were formed by the “drowning” of low land
around the mouths of rivers when sea level rose after
the last ice age
– Ex: Chesapeake Bay
– Video Real world NASA and the Chesapeake Bay
– NASA uses satellites
– http://www.youtube.com/watch?v=htggO_QOIEc
NASA Questions
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T1: What states does the CB stretch across
How many L of water does it hold
T2: Why is NASA apart of estuaries
Where does the water come from
T3: Where do most pollutants come from
How is marsh/forest areas good for estuaries
T4: What is eutrophication
What does N do when it enters an estuary
T5: What is Hypoxic water
What is the grading scale of an estuary
T6: What score did CB score
How can the score be improved
Types of Estuaries
• Bar built estuary– Built by the
accumulation of
sediments into sand
bars or barrier islands
– Ex: North Carolina
(seen in lower part of
the photo to the right
near Cape Hatteras)
Types of Estuaries
• Tectonic estuaries –
– Formed as a result of land sinking due
to movements of the Earth’s crust
– Ex: San Francisco Bay
Types of Estuaries
• Fjords –
– Deep channels
cut in the coastal
zone as a result
of retreating
glaciers
– Ex: Alaska,
Norway
Development of Estuaries
• Estuaries are the best developed in areas
where the coastal plain is flat and the
continental shelf is wide.
• The opposite is true in areas with steep,
narrow continental shelves and coastal
plains
• **What type of margin is best for estuary
development?** (hint active or passive)
Physical Characteristics of Estuaries
• Salinity-
– Can vary from 5 – 30
ppt
– Salinity varies
according to distance
from saltwater (tides)
or freshwater (river)
input
– Can also vary as a
result of storms
– Depth also contributes
to salinity
– The diagram to the
right illustrates that
the salinity is not
uniform (saltwater is
heavier and sinks
below freshwater) –
this is known as a salt
wedge
Dealing with Salinity Changes
• Organisms in the estuaries are normally
euryhaline (can tolerate a wide variety of
salinities)
• Some are osmoregulators that have
mechanisms for keeping their internal
concentration stable
• Others are osmoconformers with internal
concentrations that vary with their
surroundings
Dealing with Salinity Changes
• Flowering plants in the estuarine
community must either expel excess
solutes (such as Spartina and margrove
trees using salt glands) or concentrating
solutes in specific tissues (such as in
Salicornia, a.k.a. “pickleweed” or
glasswort
Substrate
• Mostly composed of sand or mud
• Mud is difficult to move through
• Mud or sand can also shift unlike hard
substrate which is a challenge for
organisms as well
• Particle sizes are so small that most areas
are devoid of oxygen
• *what is that called?*
Water Temperature
• Like in the intertidal community (and
some areas of estuaries are intertidal),
temperature can vary greatly.
• Temperatures can vary especially at times
when water levels are low.
Water Clarity
• Water clarity is very poor in estuaries
• This is due to suspended sediments and
particles from rivers in the water
• This reduced clarity makes it more difficult
for photoautotrophs in the water
• Most primary production is the result of
flowering plants in the salt marsh as
opposed to algae or plankton
Do Now
• 1) How is the water Quality in estuaries?
• 2) What are the 4 types of estuaries?
Communities within an Estuary
• Open water in bays
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and tidal creeks
Predominant organisms
include plankton,
floating algae, fish and
many larval forms
(crabs, shrimp, molluscs,
fish, etc)
At the right, this
diagram shows the
EXTREME IMPORTANCE
of estuaries as a
“nursery” area for larval
species
Many marine species
spend at least a portion
of their life in an
estuary, mainly as
larvae.
Communities within an Estuary
• Saltmarsh
• The vegetated
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area of an estuary
Spartina species
predominate near
the water in most
estuaries (Juncus
or needlerush can
be found near the
water in low
salinity estuaries <
10 ppt)
Representative Inhabitants in a
Mudflat of an Estuary
Communities within an Estuary
• Mangroves or mangals
• Found in tropical and subtropical coastal areas
• Replace saltmarshes in these areas normally
• http://www.youtube.com/watch?v=ijwsrEqF6-U
Communities within an Estuary
• Seagrass beds can be found in some estuaries)
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if the water clarity permits
Water clarity must be better than the average
estuary to support this growth
Worldwide Distribution of
Saltmarshes and Mangrove
Forests
Generalized Food Webs in
Estuarine Ecosystems
Aerial View of a Mangrove
Communities within an Estuary
• Some mangrove tree
species possess
pneumatophores, or
vertical root
extensions, that assist
the plant with the
exchange of gases
(pictured at right)
Communities within an Estuary
• “Oyster reefs” are
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found in many estuaries
These congregations of
oysters are the platform
on which dozens of
other species grow and
thrive
The oysters provide the
only hard substrate in
many estuaries
Article
• What are some functions of estuaries biologists are
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interested in studying
What percent of the world’s population lives along
estuaries and the coast
Name 4 factors that are causing estuaries to suffer
Why are estuaries so productive?
What are the zones seen in an estuary?
What type of animal makes an estuary as rich in
biodiversity as a rainforest
Make a list of threats to estuaries