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Freshwater inflows
from rivers and
bayous meet
saltwater from the
Gulf of Mexico
Fresh + Salt =
Brackish water
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List 1:
Dissolved Oxygen
Tides
Wind speed and
direction
Salinity
Water depth
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List 2:
Brown shrimp
Oysters
Chord grass
Dolphin
Blue crab
Red drum
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
Freshwater inflows
from rivers and
bayous meet
saltwater from the
Gulf of Mexico
Fresh + Salt =
Brackish water
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On your map, add
shading: more blue
near mouth of
rivers and bayous,
More yellow at
mouth of Bay
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Trinity River – 54%
inflow
San Jacinto River –
28% inflow
Add these numbers
to your map!
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Tides are caused by the moon.
Two high tides and two low tides each day.
Tides are most dramatic closer to the ocean.
On your map, mark a point where there
would be most dramatic tides (TIDES!!!) and
least dramatic tides (tides) and (no tides)
 Title:
Abiotic Factors in an
Estuary
 Date: check the board!
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Important abiotic factors in Galveston Bay
Dissolved Oxygen
Tides
Wind speed and direction
Salinity
Water depth
Nitrates/Phosphates
pH
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Where would you
expect to find
these? Add them to
your map!

Juvenile blue crab - 0.0 0.5 ppt salt
Oysters - 0.5 - 15.0 ppt
salt
Lady fish- 25.0 ppt salt
Nurse shark – 35 ppt salt
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Ocean 35 ppt
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All organisms have
a limit for each
abiotic factors in
their habitat. There
is an upper and
lower limit for how
much they can
tolerate.
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Blue water = salty
Colorless = fresh
What happens when
they mix?
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Natural
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Human caused
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Salts occur naturally in soil on the land.
Rainwater picks up salts in runoff.
Rivers bring salts to the ocean.
Evaporation in the ocean removes water,
leaving salt behind.
Over millions of years, oceans become salty.
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1. Which is more dense – salt water or fresh
water?
2. What river contributes the greatest amount
of fresh water in Galveston Bay?
3. Why couldn’t a juvenile crab live at the
mouth of Galveston Bay?
4. List three abiotic factors that affect
organisms in an estuary.
5. Why is the ocean salty?
 Title:
Barrier Islands
 Date: check the board!
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One white board
One marker
One playdough
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Draw what you built.
Include:
◦
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Ocean
Bay
Beach
Dune
Swale
Prairie
Wetland
◦ Fresh water
◦ Salt water
◦ Brackish water