1. INTERTIDAL ZONATION Robert Perry
WELCOME TO MY INTERTIDAL POWERPOINT SHOW. THIS SHOW EXPLORES THE QUESTION “HOW ARE SEA CREATURES ARRANGED OR DISTRIBUTED ALONG THE SHORELINE”?
Robert Perry

2. Copyrights:
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IMPORTANT LEGAL STUFF. DON’T COPY THE ORIGINAL PHOTOS AND USE THIS SHOW ONLY FOR NON PROFIT EDUCATIONAL PURPOSES. THANKS.
All Rights Reserved
© Robert Perry

3. PREVIEW OUTLINE: A. THE INTERTIDAL ZONE & ZONATION
B. FACTORS CONTROLLING ZONATION
1. Tides
a. Activity cycles & inter-specific competition
b. Desiccation
c. Temperature
d. Terrestrial & atmospheric forces
2. Waves
a. Wave shock
b. Increased submergence
3. Slope of the shore
4. Substrate type
a. Attachment of larvae
b. Porosity of substrate
c. Movement of substrate
SUGGESTION: PRINT OUT A COPY OF THIS OUTLINE AND FOLLOW ALONG DURING THIS SLIDESHOW, OR BETTER YET, USE IT TO TAKE NOTES.

4. High Tide Line Low Tide Line
THE INTERTIDAL ZONE
FIRST, A LITTLE INTRODUCTION. THE LIVING ORGANISMS WE SEE LIVING ALONG THE SHORE LIVE IN A VERY SPECIAL ZONE IN THE OCEAN KNOWN AS THE INTERTIDAL ZONE. THE TERM, INTERTIDAL, MEANS “BETWEEN THE TIDES.” SO THIS IS THE PLACE WHERE LIVING THINGS DWELL BETWEEN THE HIGHEST HIGH TIDE AND THE LOWEST LOW TIDE. IT IS A UNIQUE ENVIRONMENT FOR LIFE BECAUSE IT IS EXPOSED TO MANY IMPORTANT AND UNUSUAL ENVIRONMENTAL FORCES.
THE INTERTIDAL ZONE:
A zone of life between the high tide line and
the low tide line on any beach.

5. Distinct bands of life consisting of separate
High tide line
Low tide line
INTERTIDAL ZONATION
THE INTERTIDAL ZONE IS A PLACE, WHILE INTERTIDAL ZONATION IS A PATTERN OF DISTRIBUTION. LET’S EXPLORE THESE FUNDAMENTAL TERMS.
Distinct bands of life consisting of separate
communities of organisms distributed from the
high tide line to the low tide line.
Illustration: Stephenson & Stephenson (1972)

6. INTERTIDAL ZONATION Increase in abundance and diversity of life
High tide line
INTERTIDAL ZONATION
Increase in abundance
and diversity of life
as you move seaward.
(more ocean water
= more ocean life)
ONE UNIVERSAL PATTERN CAN BE SEEN ALONG ANY INTERTIDAL REGION: THE AMOUNT OF LIFE INCREASES AS YOU GET CLOSER TO THE WATER. IN THIS SLIDE, THE TERM ABUNDANCE REFERS TO THE NUMBER OF INDIVIDUAL ORGANISMS, AND DIVERSITY MEANS THE NUMBER OF DIFFERENT KINDS (OR SPECIES) OF ORGANISMS.
Low tide line
Illustration: Stephenson & Stephenson (1972)

7. Major environmental factors controlling intertidal zonation:
1. Tides
2. Waves
3. Slope of the shore
4. Substrate type
AS YOU KNOW FROM THE PREVIEW OUTLINE, THERE ARE 4 PHYSICAL OR ENVIRONMENTAL FACTORS THAT DETERMINE THE NATURE OF ZONATION WITHIN THE INTERTIDAL.

8. Among all of the factors that control intertidal
very low
tolerance
very high
tolerance
Among all of the factors that control intertidal
zonation, one common point stands out:
Organisms differ in their ability to survive.
There is a “normal curve” that represents the
range of tolerance of organisms to each
environmental factor.
ONE FINDS A RANGE OF TOLERANCE TO EACH OF THE 4 FACTORS THAT CONTROL ZONATION, NOT TO MENTION THE FACT THAT THESE 4 THINGS DO NOT EXIST INDEPENDENTLY BUT USUALLY ACT TOGETHER IN CONCERT.

9. What are TIDES ? 1. TIDES Tides are the regular and predictable
MAJOR
FACTOR
1. TIDES
What are TIDES ?
Tides are the regular and predictable
variations in sea level
...that are caused by the gravitational
pull of the Moon and the Sun.
FIRST WE’LL CONSIDER TIDES.

10. MAJOR
FACTOR
1. TIDES
AT HIGH TIDE THE SEA LEVEL RISES, AND AT LOW TIDE IS FALLS.

11. Q. What type of tide do we have here in southern California ?
THESE TIDE CURVES SHOW THE REGULAR AND PREDICTABLE RISING AND FALLING OF THE SEA LEVEL IN SOUTHERN CALIFORNIA.
(Calendar courtesy of
Tidelines, Inc)
A. mixed semidiurnal tide.

12. Two unequal HIGH tides, and
THIS TIDE PATTERN IS KNOWN AS A MIXED SEMI-DIURNAL TIDE.
(Calendar courtesy of
Tidelines, Inc)
Two unequal LOW tides a day.

13. Exposure to air causes bands or zones of life along the beach.
MAJOR
FACTOR
Exposure to air causes bands or
zones of life along the beach.
1. TIDES
Intertidal Total Exposure to Air
Zone Hours per Year
Zone 1 High Intertidal 7, ,760
Zone 2 Upper-Middle 3, ,200
Zone 3 Lower-Middle ,200
Zone 4 Low Intertidal
TIDES ALTERNATIVELY COVER ORGANISMS IN THE INTERTIDAL ZONE WITH WATER (HIGH TIDE) AND EXPOSE THEM TO AIR (LOW TIDE). OF COURSE, AS THIS CHART FROM RICKETTS AND CALVIN SHOWS, THE FARTHER UP YOU GO (AWAY FROM THE OCEAN) IN THE INTERTIDAL, THE MORE EXPOSURE TO AIR (AND THE LESS COVERAGE BY WATER).
Data modified from Hedgepeth, Ricketts and Calvin (1968).

14. MAJOR
FACTOR
1. TIDES
IN THIS IMAGE I HAVE SUPERIMPOSED A TYPICAL MIXED SEMI-DIURNAL TIDE CURVE ON THE SCHEMATIC OF VERTICAL ZONES TO THE RIGHT. THE BLUE AREA REPRESENTS OCEAN SUBMERGENCE AND THE WHITE REGION ABOVE THE TIDE CURVE REPRESENTS EXPOSURE TO AIR. THINK OF THIS AS A VISUAL REPRESENTATION OF THE DATA YOU SAW ON THE PREVIOUS SLIDE. AS YOUR EYES MOVE ACROSS THE CHART FROM LEFT TO RIGHT, STUDY THE AMOUNT OF “BLUE,” OR SUBMERGENCE , YOU SEE COMPARED TO “WHITE,” OR EXPOSURE TO AIR. NOW YOU ARE GETTING THE IDEA ABOUT HOW TIDES CAUSE INTERTIDAL ZONATION.

15. 1. TIDES Southern California hard substrate
MAJOR
FACTOR
1. TIDES
Southern California hard substrate
indicator species for each zone:
Zone: Name: Species:
1 Splash snails
2 Upper-mid barnacles
3 Low-middle mussels
4 Low algae
ON THE WEST COAST OF THE USA WE DESIGNATE THE INTERTIDAL ZONES IN THREE WAYS: BY NUMBER, BUY NAME AND BY DOMINANT SPECIES. THESE ARE THE DOMINANT SPECIES ON HARD SUBSTRATES (ROCKY SHORES, PIER PILINGS, WHARVES, JETTIES, AND SO FORTH).

16. Intertidal Zones at La Jolla, California
snails
barnacles
mussels
algae
THE FOUR INDICATOR OR DOMINANT SPECIES ON THE ROCKY SHORE CAN BE SEEN IN THIS CLASSIC ILLUSTRATION OF A ROCK REEF AT LA JOLLA, CALIFORNIA BY STEPHENSON AND STEPHENSON (1972). SPECIES NAMES CAN BE SEEN IN THE BOXES.
Intertidal Zones
at La Jolla, California
Stephenson & Stephenson (1972)

17. 1. TIDES Alternate exposure to air and water caused by the TIDES
MAJOR
FACTOR
1. TIDES
Alternate exposure to air and water
caused by the TIDES
results in intertidal organisms occupying
specific zones according to their range
of tolerance to dryness, temperature,
predation, feeding, respiration and
reproduction. This pattern can be
observed world wide.
Now let’s take a more detailed look at the role played by tides in causing zonation.

18. 1. TIDES Sub-factors that are related to TIDES: SUB- FACTORS
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
SUB-
FACTORS
a. Activity cycles & inter-specific competition
b. Desiccation
c. Temperature
d. Terrestrial & atmospheric forces
We’ll explore these 4 sub-factors. In other words, when we say “tides are partly responsible for zonation,” what exactly does that mean?

19. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
a. Activity cycles & inter-specific competition
Most intertidal activities are carried out
during HIGH TIDE periods.
(Life functions occur better under water).
Activity cycles and competition are linked to tide cycles.

20. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
a. Activity cycles & inter-specific competition
Predators have a range of
tolerance. Beyond this range
their prey survive.
Example: distribution of mussels.
Let’s see exactly how this works in the next slide.

21. Intertidal zonation on a pier piling Snail zone High tide line
Barnacle
zone
young, little
mussels
Mussel
zone
old, large
mussels
Intertidal
zonation on
a pier piling
Notice that within the “mussel zone” there is a vertical gradation of mussel sizes with young/small individuals up high and mature/large individuals down low. This has to do with the range of tolerance to desiccation of the predatory sea star, Pisaster. Pisasters cannot reach the upper levels on the piling because they would tend to dry out. And they cannot feed as easily on the large individual mussels down low because they are too big.
Algae
zone
Low tide line

22. High tide line young, little mussels - above the range of Pisaster
old mussels -
too large to be
eaten by Pisaster
range of Pisaster -
determined by the
tides - it cannot
move up farther
or it cannot get
back down to
the water line
at low tide. .
Pisaster
Low tide line

23. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
b. Desiccation.
The term desiccation means to lose
vital body fluids and dry up due to
exposure to the atmosphere.
In the mussel and sea star example, we noted that the sea star, Pisaster, had a vertical range in which it could safely operate. This has to do with desiccation.

24. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
b. Desiccation.
There is a range of tolerance to
desiccation among intertidal
organisms.
Those that lose fluids fast
live in lower zones.
What is meant by desiccation?

25. Barnacles, Balanus sp., can close up
tight to prevent water loss. Thus they
survive in the upper intertidal zones.
Organisms that live in Zone One, the high intertidal ort “barnacle zone,” have evolved mechanisms for surviving long periods of exposure to the air, sun and wind.

26. Algae, and the sea star, Pisaster sp.,
tend to dry out easily. Thus they
survive in the low intertidal zones.
Organisms without mechanisms for surviving desiccation tend to live in the lower zones.

27. The sea anemone, Anthopleura, closes up tight and has bits of
rocks and shells glued to its body.
It also lives in moist crevices in the
low intertidal.
There are many mechanisms for surviving desiccation including anatomical (note the adhesive glands on the body column of Anthopleura), physiological, and behavioral (note the colonization and aggregation of indivuduals in moist, shady areas by Anthopleura).

28. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
c. Temperature.
One of the most significant features of the sea is its high heat capacity,
its resistance to temperature change.
Another thing tides do as they come and go is bring temperature changes.

29. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
c. Temperature.
During high tide periods, temperatures are
uniform and stable. But during low tide
periods temperatures can fluctuate widely.
Which tide phase is most beneficial to marine life?

30. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
c. Temperature.
There is a range of tolerance to
temperature among intertidal
organisms.
Organisms with a wide range of temperature
tolerance tend to live in upper zones.
How to ranges of tolerance determine zonation patterns?

31. and stable temperature.
HIGH TIDE
Organisms covered
by water of uniform
and stable temperature.
LOW TIDE
Organisms exposed
to extreme ranges of
dry air, sun, wind,
etc.
Notice the same exact shoreline at high and low tide.

32. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
d. Terrestrial & atmospheric forces.
There is a range of tolerance to
Terrestrial & atmospheric forces among
intertidal organisms.
What is meant by terrestrial and/or atmospheric forces?

33. 1. TIDES Sub-factors that are related to TIDES:
MAJOR
FACTOR
1. TIDES
Sub-factors that are related to TIDES:
d. Terrestrial & atmospheric forces.
Exposure at LOW tide to such forces
as hot sun, snow, wind, rain, as well
as surviving terrestrial predators such as
racoons, crows, coyotes and humans may
effect the distribution of organisms.
Which tide phase results in more exposure to terrestrial and atmospheric forces?

34. R E V I E W ! 1. TIDES Sub-factors that are related to TIDES: SUB-
MAJOR
FACTOR
R E V I E W !
1. TIDES
Sub-factors that are related to TIDES:
SUB-
FACTORS
a. Activity cycles & inter-specific competition
b. Desiccation
c. Temperature
d. Terrestrial & atmospheric forces
Summary outline for the effects of tides.

35. MAJOR
FACTOR
2. WAVES
Waves are the second most important factor in causing zonation. Oh, by the way, these factors do not operate independently of each other. Keep this in mind as you click along.

36. 2. WAVES Sub-factors that are caused by WAVES: SUB- FACTORS
MAJOR
FACTOR
2. WAVES
Sub-factors that are caused by WAVES:
SUB-
FACTORS
a. Wave shock
b. Increased submergence
What are the 2 major effects of waves in causing intertidal zonation?

37. 2. WAVES Sub-factors that are caused by WAVES: a. Wave shock
MAJOR
FACTOR
2. WAVES
Sub-factors that are caused by WAVES:
a. Wave shock
Wave shock is the pounding and
shearing force of the water as it rushes
across the intertidal organisms.
What is wave shock?

38. intertidal organism living…. HERE !
a. Wave shock
If you lived here, it might be shocking! 
Imagine you were an
intertidal organism living….
HERE !

39. 2. WAVES Waves move water farther up the beach and
MAJOR
FACTOR
2. WAVES
Sub-factors that are caused by WAVES:
b. Increased submergence
Waves move water
farther up the beach and
expand the intertidal zone.
Why do waves cause increased submergence of organisms?

40. 2. WAVES Zones are expanded and shifted landward. Left side =
MAJOR
FACTOR
2. WAVES
Zones are expanded
and shifted landward.
Left side =
protected beach
How does the increased submergence caused by waves effect the nature of zonation patterns?
Right side =
exposed beach

41. 2. WAVES Sub-factors that are caused by WAVES:
MAJOR
FACTOR
2. WAVES
Sub-factors that are caused by WAVES:
b. Increased submergence
Intertidal zones are expanded
and shifted upward on beaches
exposed to waves as compared
to beaches protected from waves.
How can you tell whether a beach is “protected” or “exposed” by looking at the distribution of life in the intertidal?

42. R E V I E W ! 2. WAVES Sub-factors that are caused by WAVES: SUB-
MAJOR
FACTOR
R E V I E W !
2. WAVES
Sub-factors that are caused by WAVES:
SUB-
FACTORS
a. Wave shock
b. Increased submergence
Review outline: waves effect zonation.

43. MAJOR
FACTOR
3. SLOPE of the beach.
The term slope refers to the angle at which the sea meets the substrate.
The intertidal zone may vary from shear vertical cliffs, rock faces and pier pilings with an effective slope of 90O, to broad sand or mud flat region which is nearly horizontal, a slope nearly 0O .
What is meant by the slope of a beach?

44. 3. SLOPE of the beach. 0O 45O 90O MAJOR FACTOR
What words would you use to describe a beach that has a slope of 0º, or 45º, or 90º ??
45O
90O

45. MAJOR
FACTOR
3. SLOPE of the beach.
The slope of a beach may widen vertical zones on a horizontal beach or compress zones on a vertical beach.
Associated factors which may be influenced by beach slope include the effects of wave action, submergence time, various types of interspecific predation, competition for living space, and the settlement of larvae.
How does the slope effect organisms on the shore?

46. 3. SLOPE of the beach. Slope and zonation. Note narrow zones as beach
MAJOR
FACTOR
3. SLOPE of the beach.
Slope and
zonation.
Note narrow
zones as beach
nears vertical, and
wide zones as
beach nears
horizontal.
What happens to the 4 intertidal zones when the slope becomes less and less?

47. 4. SUBSTRATE TYPE Rocky shore Sandy shore
MAJOR
FACTOR
4. SUBSTRATE TYPE
What does the word “substrate” mean? …substrate type?
Rocky shore
Sandy shore
Beaches are made of different materials.

48. 4. SUBSTRATE TYPE Sub-factors of the SUBSTRATE TYPE: SUB-
MAJOR
FACTOR
4. SUBSTRATE TYPE
Sub-factors of the
SUBSTRATE TYPE:
SUB-
FACTORS
a. Attachment of larvae
b. Porosity of substrate
c. Movement of substrate
Name 3 things that are affected by the type of substrate that help explain zonation patterns.

49. 4. SUBSTRATE TYPE a. Attachment of larvae Many larvae have the
MAJOR
FACTOR
4. SUBSTRATE TYPE
a. Attachment of larvae
Many larvae have the
ability to detect the
substrate type and
may delay their settle-
ment until a preferred
substrate type has
been reached.
How are larvae sophisticated in their behavior ?

50. 4. SUBSTRATE TYPE a. Attachment of larvae The substrate
MAJOR
FACTOR
4. SUBSTRATE TYPE
a. Attachment of larvae
The substrate
determines where
larvae settle out,
attach and grow.
This shapes the
nature of zones.
What do larvae have to do with zones?

51. 4. SUBSTRATE TYPE b. Porosity of the substrate
MAJOR
FACTOR
4. SUBSTRATE TYPE
b. Porosity of the substrate
If an organism requires more moisture, it may survive on rock surfaces which are porous and may die on surfaces which are not so porous.
What is meant by “porosity?”

52. hold different amounts
Different substrates
hold different amounts
of water.
It’s a fact, porous substrates are different from non-porous substrates.

53. 4. SUBSTRATE TYPE b. Porosity of the substrate
MAJOR
FACTOR
4. SUBSTRATE TYPE
b. Porosity of the substrate
The porosity, or amount of space within a
substrate, determines the amount
of water that substrate can hold. This results in
different patterns of zonation on beaches
with different kinds of substrates.
How does the porosity of a substrate influence intertidal zones?

54. c. Movement of the substrate
MAJOR
FACTOR
4. SUBSTRATE TYPE
c. Movement of the substrate
The success of many intertidal organisms is directly related to the frequency of substrate movement.
If the substrate moves or shifts around regularly, it is a less stable environment.
What would make a better place to live, a place that shifts and moves and rolls, or a stationary place that never moves? Think “earthquakes on steroids” and you’ll have a good idea what it would be like to be an intertidal organism growing on a small rock versus a large one.

55. Movement of the substrate.
FACTOR
Movement of the substrate.
The larger the rock, the less often it moves. The smaller, the more frequent. You could be the one to gather these data…how would it be done?

56. 4. SUBSTRATE TYPE c. Movement of the substrate
MAJOR
FACTOR
4. SUBSTRATE TYPE
c. Movement of the substrate
The larger the substrate particle, the less often it moves. The less often it moves, the more stable the environment. .

57. R E V I E W ! 4. SUBSTRATE TYPE Sub-factors that are caused
MAJOR
FACTOR
4. SUBSTRATE TYPE
Sub-factors that are caused
by the SUBSTRATE TYPE:
SUB-
FACTORS
a. Attachment of larvae
b. Porosity of substrate
c. Movement of substrate
Summary outline: substrate and zonation.

58. REVIEW OUTLINE: A. THE INTERTIDAL ZONE & ZONATION
B. FACTORS CONTROLLING ZONATION
1. Tides
a. Activity cycles & inter-specific competition
b. Desiccation
c. Temperature
d. Terrestrial & atmospheric forces
2. Waves
a. Wave shock
b. Increased submergence
3. Slope of the shore
4. Substrate type
a. Attachment of larvae
b. Porosity of substrate
c. Movement of substrate
Summary outline of the whole slideshow…did you understand each concept?

59. T H E
E N D
Thanks for viewing my Intertidal Zonation powerpoint show.