INTERTIDAL ZONATION Robert Perry. Copyrights: All Rights Reserved © Robert Perry zalophus@ucla.edu...

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INTERTIDALZONATION

Robert Perry

Copyrights:

All Rights Reserved© Robert Perry

zalophus@ucla.edu

All the images in this presentation are copyrighted and are protected under United States and international copyright laws. They are the exclusive property of Robert Perry unless otherwise noted. The images are used here by exclusive arrangement with UCLA as part of this presentation only. The photographs may not be downloaded, reproduced, copied, stored, used or altered in any way without the express written permission of Robert Perry (or other sources as indicated). No images are within the Public Domain. The purpose of this presentation is non-profit education. Any other unauthorized use of this show is a violation of copyright law.

PREVIEW OUTLINE:

A. THE INTERTIDAL ZONE & ZONATIONB. FACTORS CONTROLLING ZONATION 1. Tides

a. Activity cycles & inter-specific competitionb. Desiccationc. Temperatured. Terrestrial & atmospheric forces

2. Wavesa. Wave shockb. Increased submergence

3. Slope of the shore 4. Substrate type

a. Attachment of larvaeb. Porosity of substratec. Movement of substrate

THE INTERTIDAL ZONE:

HighTideLine

LowTideLine

THE INTERTIDAL ZONE

A zone of life between the high tide line andthe low tide line on any beach.

High tide lineHigh tide line

Low tide lineLow tide line

Illustration: Stephenson & Stephenson (1972)

Distinct bands of life consisting of separatecommunities of organisms distributed from the

high tide line to the low tide line.

INTERTIDAL ZONATIONINTERTIDAL ZONATION

(more ocean water= more ocean life)

Increase in abundanceand diversity of life

as you move seaward.

INTERTIDAL ZONATION

Illustration: Stephenson & Stephenson (1972)

High tide lineHigh tide line

Low tide lineLow tide line

Major environmental factors controlling intertidal zonation:

MAJORFACTORS 1. Tides

2. Waves

3. Slope of the shore

4. Substrate type

Among all of the factors that control intertidalzonation, 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 eachenvironmental factor.

very hightolerance

very lowtolerance

What are TIDES ?

Tides are the regular and predictable variations in sea level

...that are caused by the gravitationalpull of the Moon and the Sun.

MAJORFACTOR

1. TIDES

1. TIDES

MAJORFACTOR

Q. What type of tide do we have herein southern California ?

(Calendar courtesy ofTidelines, Inc)

A. mixed semidiurnal tide.

Two unequal HIGH tides, and

(Calendar courtesy ofTidelines, Inc)

Two unequal LOW tides a day.

Intertidal Total Exposure to AirZone 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

Exposure to air causes bands orzones of life along the beach.

Data modified from Hedgepeth, Ricketts and Calvin (1968).

1. TIDES

MAJORFACTOR

MAJORFACTOR 1. TIDES

Southern California hard substrateindicator species for each zone:

Zone: Name: Species:1 Splash snails2 Upper-mid barnacles3 Low-middle mussels4 Low algae

MAJORFACTOR

1. TIDES

Intertidal Zonesat La Jolla, California

Stephenson & Stephenson (1972)

snails

barnacles

mussels

algae

Alternate exposure to air and watercaused by the TIDES

results in intertidal organisms occupyingspecific zones according to their rangeof tolerance to dryness, temperature,predation, feeding, respiration andreproduction. This pattern can be

observed world wide.

MAJORFACTOR

1. TIDES

SUB-FACTORS

a. Activity cycles & inter-specific competition

b. Desiccation

c. Temperature

d. Terrestrial & atmospheric forces

Sub-factors that are related to TIDES:

MAJORFACTOR

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).

MAJORFACTOR

1. TIDES

Sub-factors that are related to TIDES:

a. Activity cycles & inter-specific competition

Predators have a range oftolerance. Beyond this range

their prey survive.Example: distribution of mussels.

MAJORFACTOR

1. TIDES

Low tide lineLow tide line

High tide lineHigh tide line

Intertidalzonation ona pier piling

Snailzone

Barnaclezone

Musselzone

Algaezone

young, littlemussels

old, largemussels

Low tide lineLow tide line

High tide lineHigh tide line

range of Pisaster - determined by thetides - it cannotmove up fartheror it cannot getback down tothe water line

at low tide.

young, littlemussels - above

the range of Pisaster

old mussels - too large to be

eaten by Pisaster

Pisaster

Sub-factors that are related to TIDES:

b. Desiccation.

The term desiccation means to losevital body fluids and dry up due to

exposure to the atmosphere.

MAJORFACTOR

1. TIDES

Sub-factors that are related to TIDES:

b. Desiccation.

There is a range of tolerance todesiccation among intertidal

organisms. Those that lose fluids fast

live in lower zones.

MAJORFACTOR

1. TIDES

Barnacles, Barnacles, BalanusBalanus sp., can close up sp., can close uptight to prevent water loss. Thus theytight to prevent water loss. Thus theysurvive in the survive in the upper intertidal zones. intertidal zones.

Algae, and the sea star, Algae, and the sea star, PisasterPisaster sp., sp.,tend to dry out easily. Thus theytend to dry out easily. Thus they

survive in the survive in the low intertidal zones. intertidal zones.

The sea anemone, The sea anemone, AnthopleuraAnthopleura,,closes up tight and has bits ofcloses up tight and has bits of

rocks and shells glued to its body.rocks and shells glued to its body.It also lives in moist crevices in theIt also lives in moist crevices in the

low intertidal. intertidal.

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.

MAJORFACTOR

1. TIDES

Sub-factors that are related to TIDES:c. Temperature.

During high tide periods, temperatures areuniform and stable. But during low tide

periods temperatures can fluctuate widely.

MAJORFACTOR

1. TIDES

Sub-factors that are related to TIDES:

c. Temperature.

There is a range of tolerance totemperature among intertidal

organisms.Organisms with a wide range of temperature

tolerance tend to live in upper zones.

MAJORFACTOR

1. TIDES

HIGH TIDEOrganisms coveredby water of uniform

and stable temperature.

LOW TIDEOrganisms exposedto extreme ranges of

dry air, sun, wind,etc.

Sub-factors that are related to TIDES:

d. Terrestrial & atmospheric forces.

There is a range of tolerance toTerrestrial & atmospheric forces among

intertidal organisms.

MAJORFACTOR

1. TIDES

Sub-factors that are related to TIDES:d. Terrestrial & atmospheric forces.

Exposure at LOW tide to such forcesas hot sun, snow, wind, rain, as well

as surviving terrestrial predators such asracoons, crows, coyotes and humans may

effect the distribution of organisms.

MAJORFACTOR

1. TIDES

SUB-FACTORS

a. Activity cycles & inter-specific competition

b. Desiccation

c. Temperature

d. Terrestrial & atmospheric forces

Sub-factors that are related to TIDES:

MAJORFACTOR

1. TIDESR E V I E W !

MAJORFACTOR

2. WAVES

SUB-FACTORS a. Wave shock

b. Increased submergence

Sub-factors that are caused by WAVES:

MAJORFACTOR

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.

MAJORFACTOR

2. WAVES

HERE !Imagine you were anintertidal organism living….

a. Wave shock

Sub-factors that are caused by WAVES:b. Increased submergence

Waves move waterfarther up the beach and

expand the intertidal zone.

MAJORFACTOR

2. WAVES

MAJORFACTOR

2. WAVES

Zones are expandedand shifted landward.

Left side =protected beach

Right side =exposed beach

Sub-factors that are caused by WAVES:b. Increased submergence

Intertidal zones are expandedand shifted upward on beachesexposed to waves as compared

to beaches protected from waves.

MAJORFACTOR

2. WAVES

SUB-FACTORS a. Wave shock

b. Increased submergence

Sub-factors that are caused by WAVES:

MAJORFACTOR

2. WAVES R E V I E W !

MAJORFACTOR

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 .

MAJORFACTOR

3. SLOPE of the beach.

90O

45O

0O

MAJORFACTOR

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.

MAJORFACTOR

3. SLOPE of the beach.

Slope andzonation.

Note narrowzones as beach

nears vertical, andwide zones asbeach nearshorizontal.

MAJORFACTOR

4. SUBSTRATE TYPE

Rocky shore Sandy shore

Beaches are made of different materials.

SUB-FACTORS

a. Attachment of larvae

b. Porosity of substrate

c. Movement of substrate

MAJORFACTOR

4. SUBSTRATE TYPESub-factors of the

SUBSTRATE TYPE:

MAJORFACTOR

4. SUBSTRATE TYPEa. Attachment of larvae

Many larvae have theability to detect thesubstrate type andmay delay their settle-ment until a preferredsubstrate type hasbeen reached.

The substratedetermines wherelarvae settle out, attach and grow.This shapes the nature of zones.

MAJORFACTOR

4. SUBSTRATE TYPEa. Attachment of larvae

MAJORFACTOR

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.

4. SUBSTRATE TYPEb. Porosity of the substrate

Different substrateshold different amounts

of water.

MAJORFACTOR

4. SUBSTRATE TYPEb. Porosity of the substrate

The porosity, or amount of space within asubstrate, determines the amount

of water that substrate can hold. This results indifferent patterns of zonation on beaches

with different kinds of substrates.

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.

MAJORFACTOR

4. SUBSTRATE TYPEc. Movement of the substrate

Movement of the substrate.SUB-FACTOR

The larger the substrate particle, the less often it moves. The less often it moves,

the more stable the environment.

MAJORFACTOR

4. SUBSTRATE TYPEc. Movement of the substrate

R E V I E W !

SUB-FACTORS

a. Attachment of larvae

b. Porosity of substrate

c. Movement of substrate

MAJORFACTOR

4. SUBSTRATE TYPESub-factors that are causedby the SUBSTRATE TYPE:

REVIEW OUTLINE:

A. THE INTERTIDAL ZONE & ZONATIONB. FACTORS CONTROLLING ZONATION 1. Tides

a. Activity cycles & inter-specific competitionb. Desiccationc. Temperatured. Terrestrial & atmospheric forces

2. Wavesa. Wave shockb. Increased submergence

3. Slope of the shore 4. Substrate type

a. Attachment of larvaeb. Porosity of substratec. Movement of substrate

T H EE N D