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

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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.

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.

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)

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)

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.

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.

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.

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

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.

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.

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 7,200 - 8,760 Zone 2 Upper-Middle 3,200 - 7,200 Zone 3 Lower-Middle 400 - 3,200 Zone 4 Low Intertidal 0 - 400 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).

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.

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).

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)

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.

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?

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.

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.

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

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

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.

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?

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.

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.

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).

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.

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?

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?

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.

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?

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?

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.

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.

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?

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?

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

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?

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

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?

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.

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?

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

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?

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?

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.

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.

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 ?

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?

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?”

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

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?

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.

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?

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. .

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.

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?

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