como las variaciones en la salinidad de los estuarios afecta la vida de los organismos que viven en el

1. How does the change in
salinity due to tides in an
estuary effect living
organisms?
Presented by:
Natalie Brunelle
Diane Kowal
Bob Stringer

2. What is an Estuary?
 Native Americans once
called the estuary
"Between-Land", not quite
land and not quite water.
 Today, an estuary is defined
as a water passage where
the tide meets a river
current.

3. Salinity of Sea Water
 Salinity is the amount of salt found in one kilogram of
water. Salinity, or salt content, is expressed in parts per
thousand (ppt).
 The average ocean salinity is 35 ppt. This number does
vary, usually between 32 and 37 ppt. Rainfall, evaporation,
river runoff and ice formation cause the variations.
 Freshwater salinity is usually less than 0.5 ppt. Water
between 0.5 ppt and 17 ppt is called brackish. Estuaries
examples of brackish water. The salinity of an estuary
changes with the tides.

4. The Effect of Tides on an Estuary
In a typical estuary, there is a constant change in the
salinity of the water.
As the tide rises, water from the ocean begins to surge
into the mouth of a river, bringing with it higher levels
of salt. This results in an increase in the salinity of the
water in an estuary.
Several hours later, at low tide, the ocean water recedes
resulting in water with a lower salinity.

5. HIGH LOW
DATE
AM hgt PM hgt AM hgt PM hgt
1 Tue 3:34 2.6 4:01 3.2 8:50 0.5 9:56 0.5
2 Wed 4:33 2.9 4:58 3.5 10:06 0.3 11:00 0.2
3 Thu 5:27 3.3 5:51 3.7 11:16 0.1 11:55 -0.1
4 Fri 6:17 3.7 6:41 3.9 - - 12:16 -0.3
5 Sat 7:06 4.1 7:30 4.1 12:44 -0.4 1:10 -0.5
6 Sun 7:54 4.3 8:18 4.1 1:30 -0.6 2:02 -0.7
7 Mon 8:42 4.5 9:06 4.0 2:16 -0.7 2:52 -0.7
S A K O N N E T
41o28'N 071o12'W
Rhode Island Tide Chart - Oct. 2002

6. Changing Salinity in the Westport
River Estuary
Salinty of Westport River During One
Tide Cycle - 9/21/02
0.0
5.0
10.0
15.0
20.0
25.0
30.0
M
HW
2
hours
afterM
HW
4
hours
afterM
HW
M
LW
2
hours
afterM
LW
4
hours
afterM
LW
Tide Level
Salinity(ppt)
Series1
Series2

7. What Lives in an Estuary?
 Birds
 Fish
 Insects
 Mammals
 Plants
and ...

8. Orange Striped Jellyfish
Scallop
Stalked Jellyfish
Opalescent Nudibranch
Hooded Nudibranch
Brooding Sea Anemone
Skeleton Shrimp
Sunflower Star
Blood Star
Bubble Shell
Dungeness Crab
Hermit Crab
Native Littleneck Clam
Bent-nosed Clam
Mud Shrimp
Purple Shore Crab
Lugworm
Sea Creatures

9. How do the changing tides effect life in
an estuary?
One example of an organism that has adapted
to life in an estuary is the cord grass, Spartina.
Spartina can survive in salt water where many
plants would die. This is a result of an
adaptation. Spartina has little openings that
allow it to drain out the salt so it can survive.

10. Science is difficult to study in isolation. A study of
ocean chemistry naturally raises questions about its
relationship with living organisms. What kinds of
questions does this presentation raise for you?
There is lots of information on the web to pique
your curiosity. Take some time to surf the net.