Download The Intertidal Zone - Malibu High School

Perry
Marine Biology - An Introduction to Life in the Sea
Chapter
Chapter
10.
The Intertidal Zone.
L
aypersons and students of Marine Ecology alike can easily access the
Intertidal Zone. The Intertidal Zone is defined as the narrow strip of
territory which is found at the air-land-sea interface and lies between
the tidemarks on all beaches. From the nearly dry high tide line down to the
almost always wet low tide line, the Intertidal Zone exists on rocky shores,
sandy beaches, and mud flats. Even man-made structures such as wharves,
jetties and pier pilings create intertidal habitats. Thus, coastal human
populations can easily study the intertidal zone, whereas the study of other
marine environments may require special vessels, preparations, and
provisions.
The Intertidal Zone is a harsh environment. Many environmental stresses
and forces act upon organisms in the intertidal which are not found in
strictly marine or strictly terrestrial environments. Being continually
covered and uncovered by the water, exposed and then unexposed to the air,
and suffering the tremendous force of crashing surf, the intertidal may be
thought of as natures' proving-ground. Only those animals and plants which
can withstand all of these environmental conditions survive and reproduce in
this region.
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In this Chapter, we shall discuss various patterns of distribution of animals
and plants within the intertidal zone. Likewise we shall find that these
patterns of distribution are the outcome of measurable environmental
factors. Each of these factors will be considered in detail.
Intertidal Zonation.
As we begin to study the distribution or arrangement of marine organisms in
the Intertidal Zone, no matter where it may be located geographically, we
will see that intertidal inhabitants form distinct horizontal bands between
the tidemarks. For example, on rocky beaches one encounters a visible
community or band of organisms near the high tide mark. This group
normally consists of certain species of snails and a few barnacles that live
near the landward portion of the intertidal. These snails and barnacles
receive very little moisture every month except during extreme high tide
periods or from the spray generated by crashing waves. As we look closer to
the sea, this uppermost grouping or band of organisms is followed by another
cluster in which mussels, gooseneck barnacles and other organisms are
found. This region is not as dry as the upper zone and can be observed
covered by water twice each day. Farther toward the water, other bands or
clusters of organisms will be observed only when the tide is low.
These communities of organisms, distributed in horizontal bands or
groupings, are observed to change in their abundance and diversity as one
moves from the upper, drier portions of the intertidal zone towards the lower,
wetter parts. The formation of separate and distinct communities arranged
vertically between the tidemarks is known as intertidal zonation. Intertidall zonation has been
the subject of study for decades.
The phenomenon of intertidal zonation is evident on all shorelines. The range, composition,
number and width of vertical zones may differ from place to place. Vertical zonation is much
easier to observe on hard substrates such as a rocky beach, jetty or pier piling. Zonation is also
present within soft substrates such as sand or mud, but the detection of zones is accomplished
only by hours of digging and sifting so the visual pattern of zonation may be lessened.
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Marine Biology - An Introduction to Life in the Sea
Here are a few characteristics of vertical zonation common to all intertidal habitats, in all parts of
the world:
1. There is an increase in the abundance and diversity of organisms as one proceeds in a
seaward direction across the intertidal. Simply put: the more submergence in water, the more
marine life.
2. Vertical zones or bands within the intertidal are usually communities of
organisms, not populations of a single species.
3. Since vertical zonation is an ecological phenomenon created by the minds
of marine ecologists, there may be any number of so-called “zones” on a given
beach, depending on the definitions and degrees of refinement imposed by
the observer.
4. Despite the human factor, organisms living between the tidemarks on a
beach tend to form vertical bands or communities that are readily observable
by anyone at low tide. Such zones are generally distributed as follows:
The High Intertidal Zone is characterized by a low abundance and
diversity of organisms. This region is rarely covered by water except during
the highest high tides or during periods of storm surf, so there are very few
benthic plants and the animals show great anatomic modification for
moisture retention.
The Mid-Tide Zone is alternately covered and uncovered by normal tides,
so this region is much wetter than the High Intertidal. Hence, the Mid-Tide
Zone is characterized by increase in the abundance and diversity of life.
Small benthic plants are possible. Larger dominant species such as mussels
provide shelter for numerous smaller understory animals that hide beneath
them.
The Low-Tide Zone, as the name implies, is nearest to the waters’ edge. It
is wet most of the time and rarely exposed to air except during the lowest low
tide periods. The predominance of water results in an abundance and
diversity of life that is the highest of all zones. Algae are generally quite
abundant and a variety of delicate forms of animal life may hide amongst
them. A tide table must be consulted in order to plan research in the Low
Intertidal Zone to coincide with the lowest low tide cycles. In the following
sections we shall discuss, in detail, some of the factors and subfactors
responsible for these vertical zonation patterns.
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terrestrial environment
Ligia occidentalis
Littorina planazix
Pachygrapsus
crassipes
Chthamalus fissus
Collisella digitalis
Balanus glandula
Tegula funebralis
Lotia gigantea
Mytilus edulis
Mytilus californianus
Pollicipes polymerus
Mopalia mucosa
Anthopleura spp.
Strongylocentrotus spp.
Haliotis cracherodii
Balanus tintinabulum
Balanus amphitrite
Phyllospadix torreyii
Egregia laevigata
mean low low
water line
Pisaster ochraceus
misc. foliaceous
Rhodophyta
misc. Coralline algae
subtidal zone
Octopus
bimaculatus
Figure # 45 - Vertical zonation: Malibu rocky intertidal.
Only superficial species are shown. When understory
species are considered, abundance and diversity
increases greatly in a seaward direction.
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Environmental factors controlling zonation.
1. Tides and factors associated with tides.
A
n oceanic tide may be defined as a regular and predictable fluctuation in
sea level caused by the gravitational effect of the moon and, to a lesser
extent, the sun. There are coastlines characterized by only one high and one
low tide per lunar day of 24.8 hours. This type of a tide is a diurnal tide, or
daily tide. Other coasts experience two high tides and two low tides per
lunar day and this tidal pattern is known as a semidiurnal tide, or
semidaily tide. Sometimes the high tides and low tides of a semidiurnal tide
are of equal heights or levels, a pattern known as a regular semidiurnal
tide. Other semidiurnal tides are irregular because the two high tides are
not the same height, and the two low tides are also at different levels. This
pattern is known as mixed semidiurnal tide.
Extreme high and low tide periods are known as spring tides. They occur
twice per lunar month, which is 27.5 days long. Spring tides follow the new
moon and full moon phases by approximately one and a half days. Periods of
quarter moon phases are characterized by less tidal fluctuation, high tides
are not very high and low tides are not very low. Such tidal periods are
known as neap tides. Spring tides and neap tides also vary in their extent
during the year, depending on the season and location. The tides along the
West Coast of the United States are generally mixed semidiurnal, while the
East Coast receives regular semidiurnal tides. The Hawaiian Islands also
have a mixed semidiurnal tide, but the State of Alaska, with its vast and
diverse coastline, exhibits a variety of different tidal patterns.
The overall biological effects of tidal fluctuations upon life in the intertidal
zone are best understood in terms of the time spent under water, called
submergence, and the time spent exposed to air, called emergence.
Vertical zonation is certainly effected by the ability of certain species of
animals and plants to withstand variations in emergence and submergence.
Those organisms living higher in the intertidal zone are able to withstand
greater exposure to air (and its side effects) than those living in the low
intertidal, near the waters’ edge. Those living in the low intertidal do so
because their anatomy, physiology and behavior simply requires more water.
Submergence and emergence patterns may directly effect sensitive newly
settled larvae and spores which may attempt to colonize the intertidal. There are always
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Water; LLW=Lower Low Water.
Figure # 46 - Relation between tides and zones. Showing a mixed semidiurnal tide and three
generalized intertidal zones. HHW=Higher High Water; LHW=Lower High Water; HLW=Higher Low
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Marine Biology - An Introduction to Life in the Sea
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exceptions to general rules, thus some organisms are not distributed according to submergence
and emergence patterns alone. Other factors must be of significance in determining the degree
and extent of vertical zonation.
Table 1 - Exposure of Intertidal Zones to Air
for the West Coast of the United States.*
Intertidal
Zone
Total Exposure to Air
Hours per Year
Zone 1
High Intertidal
7,200 - 8,760 hours/year
Zone 2
Upper-Middle
3,200 - 7,200
Zone 3
Lower-Middle
400 - 3,200
Zone 4
Low Intertidal
0 - 400
*data modified from Hedgepeth, Ricketts and Calvin (1968).
Not all marine biologists are in agreement about the environmental factors
causing vertical zonation within the intertidal. In the opinion of T.A. and
Anne Stephenson, for example, vertical zonation is not caused so much by
tides, but rather by a panorama of other factors. Factors such as the gradient
of moisture in the air due to diffusion, the gradient of spray and evaporation,
the gradient of solar penetration and sedimentation under the water, may
result in the stratification of life. Although this view is not shared by
everyone in the field, the Stephenson’s cite the presence of vertical zonation
in other habitats such as around freshwater lakes, on mountain peaks, and
in jungle canopy of tropical rain forests. This is suggested as evidence that
vertical zonation within the intertidal may not necessarily be related to the
fluctuation of the tides. Obviously such a disagreement between marine
biologists will not be settled until further field and laboratory experiments
provide better documentation. No such documentation exists at this time.
We will now turn to a consideration of the various subfactors implied or
associated with tides. In other words, what are the specific causes of the
distribution of plants and animals within the intertidal, due to tidal water
movement? Our discussion of tidal subfactors will consider the following four
things: a. Activity cycles and interspecific competition; b. Desiccation;
c. Temperature; and, d. Terrestrial and atmospheric forces.
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1. Tides and factors associated with tides.
a. Activity cycles and interspecific competition.
I
t has been suggested by J. R. Lewis (1964) that the greatest proportion of
intertidal activities are carried out when the tide is high. When the
organisms of the intertidal zone are submerged in water they are surrounded
by particulate food materials such as plankton and detritus, dissolved
oxygen, carbon dioxide and nutrient chemical substances are plentiful,
movement and locomotion are much easier. There is a definite relationship
between high water periods and vital life activities such as locating and
capturing food, digestion and waste elimination, gas exchange, finding a
mate and reproduction.
Owing to the increased movement and activity of marine organisms into and
around the intertidal during high tide, many of the intertidal inhabitants
may be confined to a particular intertidal zone by their predators. For
example, fast moving predatory species may feed high up in the intertidal
and retreat before the tide runs out. Accordingly, the distribution of certain
sessile invertebrates such as barnacles, sponges, and even mussels may be
explained more on the basis of predation versus movement, rather than
strictly as an adaptation to submergence and emergence. Perhaps
invertebrates found high in the intertidal might flourish lower if it were not
for the prevention of the attachment of their larvae and growth of adults by
predators.
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Snail
zone
High tide line
Barnacle
zone
young, little
mussels
Mussel
zone
old, large
mussels
Intertidal
zonation on
a pier piling
Algae
zone
Low tide line
Figure # 47 - Vertical Zonation on a southern California Pier Piling.
Showing age and size groupings of the mussel, Mytilus spp., caused
by the predatory sea star Pisaster ochraceus during high tide periods.
Pisaster appears to be less-adapted to air exposure than Mytilus,
and it retreats to lower levels on the piling when the tide is low. The
effect of predation and tides causes larger and more mature mussels
to live lower on the piling than younger and smaller specimens.
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The time of day of the low-low tides (and high-high tides) is also important.
If the low-low tides occur during the heat of the day, or during strong wind
periods, then organisms will be more greatly effected than if such low tides
occurred during the night or early morning hours.
Faster growth rates of certain sessile intertidal forms may also influence
intertidal zonation and distribution by crowding-out the slower growing
species. Another aspect of growth and development is the possible predation
(and even cannibalism!) of free-swimming larvae by already attached
suspension feeders, which of course prevents the settlement of subsequent
larvae and spores.
1. Tides and factors associated with tides.
b. Desiccation.
D
uring periods of low tide one of the major factors with which intertidal
organisms must contend is desiccation, the problem of drying out or
losing body moisture when exposed to the air, the sun and the wind. Any
discussion of the causes of intertidal distribution must include an analysis of
the ability of different species to withstand the drying effects of emergence in
air. During higher tides, organisms are bathed in seawater and desiccation
is not a problem. At low tide, organisms may tend to dry-out and eventually
die unless major anatomical, physiological and/or behavioral adaptations are
present to insure the survival of the species. Vertical zonation may also be
explained, therefore, by differing abilities to prevent desiccation. Zones of
tolerance to desiccation might even exist without tides, as suggested by the
Stephenson’s.
Among the adaptations which prevent desiccation in intertidal organisms,
one may find organisms which have evolved adhesive glands, like certain
anemones, to "glue-on" bits of shell and debris, thus retaining body moisture
longer. Gastropods and amphineurans clamp tightly to the hard substrate
and thus prevent the loss of body fluids. Free-moving species like octopods,
fishes, crabs may actively seek shelter under rocks, beneath larger algae or
in wet tide pools. Still other species build tubes, burrow under rocks, or
remain in the damp sand or mud. You will note a variety of these strategies
during your field observations in the intertidal.
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1. Tides and factors associated with tides .
c. Temperature.
A
s we learned in an early chapter, one of the most significant features of
the sea is its high heat capacity, its resistance to temperature changes.
The intertidal effect of high heat capacity is a uniform temperature during
high tide periods. During low water, however, intertidal life must contend
with great variations in temperature. In the tropics, extreme heat effects
these creatures and, in polar regions, subzero temperatures are encountered.
There can be no doubt that the varying ability of certain organisms to
withstand temperature variations as imposed on the intertidal by tides must
serve to distribute them according to this ability. Likewise the time of the
day and time of year of high-high tides and low-low tides are of extreme
importance. If, for example, the lower tides fall near midday in temperate or
tropical regions, the effect of temperature will be much greater than if such
tides occurred in early morning or during the darkness.
The temperature gradient imposed by distance to and from the water is
another isolated environmental factor that causes vertical zonation in the
Intertidal Zone.
Environmental factors controlling zonation.
1. Tides and factors associated with tides.
d. Terrestrial and atmospheric forces.
B
y definition the Intertidal Zone lies at the intersection of three distinct
environments: atmosphere, ocean and land. The terrestrial and
atmospheric forces with which intertidal marine organisms must contend are
especially effective during low tide periods. Direct solar radiation, as
opposed to light filtered and refracted by a layer of water, may "burn"
organisms. Inundation by fresh water in the form or rain may pose salinity
related problems. The harsh effects of wind and snow, which are obviously
not found underwater, can destroy tissues mechanically. Finally, predation
by terrestrial and atmospheric organisms such as birds, raccoons, coyotes,
insects, and humans with buckets in the tidepools, may take place at low
tide. These factors will determine the composition and extent of vertical
zones. As each successively seaward zone is covered for a longer total period
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of time, the effects of these terrestrial forces are severe in the upper intertidal and lesspronounced in the low intertidal. Indeed, there is a gradation of such effects which, whether
considered together or separately, could serve to induce a zonation pattern within the intertidal
as a secondary factor associated to tides.
2. Wave action .
S
ea surface waves which crash ashore dump thousands of liters of water
per square meter on the intertidal. Waves play an important role in
determining the nature and extent of the vertical zones of life. According to
some experts, wave action may play a larger role in determining zonation
than the tides themselves. Whether or not such is the case remains to be
tested. We can divide the biological effects of wave action on vertical
zonation into two lines of influence: a. Wave shock, and b. Increased
submergence.
2. Wave action .
a. Wave shock.
B
reaking waves cast an enormous crushing and shearing force upon the
organisms living in the intertidal zone. This is known as wave shock.
Accordingly, intertidal organisms may be distributed into vertical zones of
tolerance to this pressure. The intensity of wave action may shift with
varying tide levels, offshore and inshore topography, and the geographic
direction the intertidal faces with respect to prevailing swells.
In order to disperse the energy of a breaking wave and to insure survival in
the intertidal, many interesting anatomical, physiological and behavioral
adaptations can be recognized. Among the most conspicuous of these are the
hydrodynamic shape of certain limpets, chitons and barnacles which deflects
the destructive force of the waves. The ability to hold tenaciously to the
substrate is an adaptation which can prevent dislodgment. The evolution of
elasticized body attachments to the substrate serves the organism by
absorbing the shock of each wave. Such adaptations are seen in the byssus of mussels, tube
feet of asteroids and echinoids, and holdfasts of algae. Likewise a myriad of tiny specimens
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conceal themselves from the roaring surf by dwelling in the understory habitat, hiding temporarily
beneath larger algae and benthic animals. The ability of organisms to adapt to the environmental
stress of breaking waves directly influences the composition and arrangement of vertical zones in
the intertidal.
2. Wave action .
b. Increased submergence.
I
n addition to the crushing and shearing force which releases energy upon
the intertidal zone, waves also add water. As water from breaking waves
rushes up the beach and then washes back again, there is an addition of
large amounts of water over and above the tide level. This effect is called
increased submergence due to wave action, and its effect is best
illustrated when we compare a protected shoreline with little or no wave
action, to an exposed shore with frequent and severe wave action.
Figure # 48 - Vertical Displacement.
As a shore is impacted by increased wave action
the intertidal zones widen and are displaced
in a landward direction.
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As we see illustrated in Figure #48 on the preceding page, vertical zonation on a shore with
wave exposure differs from a more placid one. The vertical zones on an exposed beach tend to
be spread out and deflected landward. Each zone covers a wider extent of beach, and the
widening will generally be directed upward toward the land. Such an uplifting of zones, as
compared to the compressed zones on a protected shore, is understood in terms of the
increased time that each zone spends submerged under water.
If more water covers a spot for a longer period, then organisms normally
limited to lower zones can survive higher in the intertidal. This principle of
vertical displacement operates on as a gradient. As the size and
consistency of wave action increases, the zones widen and are displaced
vertically...to a point. There is a threshold beyond which the severity of force
is so intense that it exceeds the adaptive powers of intertidal creatures and
serves to be destructive. Sea surface waves, born of storm winds far out at
sea, are relatively unpredictable, hence geographic areas can be classified as
"exposed" or "protected" only in a general way. The increased submergence
waves bring has an undeniable effect on the arrangement and scope of
vertical zones in the intertidal.
3. Slope of the beach .
T
he nature of vertical zonation on a shore changes in accordance with the
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 0 O.
One immediate outcome of the slope of a beach is that the distance from high
tide mark to low tide mark will vary. The more horizontal, the greater the
flow of tidal waters, and the wider the intertidal zone. Beaches approaching
ninety degrees, or vertical, have much narrower vertical intertidal zones of
life.
There is some evidence that the settlement and attachment of certain larval
stages and spores is controlled by the slope of the beach. Some organisms
feed, reproduce, withstand environmental pressure, and thus survive better
on a vertical surface. Through natural selection the larvae of these
organisms can detect a particular inclination of the substrate. Some larvae can actually delay
their own metamorphosis and settlement for short periods until proper settling grounds are
recognized. Other species obviously do the same for horizontal environments.
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The slope of a beach may widen vertical zones on a horizontal beach or compress zonation on a
vertical beach. Associated factors which may be influenced by beach slope include the effects
of wave action, submergence time versus emergence time, various types of interspecific
predation, competition for living space, and the settlement of larvae. Since multiple factors
overlap, we can form a useful model of the complexity of the role slope plays in directing
vertical zonation in the intertidal.
terrestrial environment
subtidal zone
Figure # 49 - Slope of the beach and vertical zonation.
Shown as an isolated factor causing the expansion of
four arbitrary intertidal zones as slope changes from
vertical (shear cliff, pier piling) to horizontal (sand, mud habitat).
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4. Substrate type.
V
ertical zonation is a generalized pattern which can be recognized on any
beach to a greater or lesser extent. No matter whether we study a rock,
sand, mud or man-made intertidal surface, we will observe vertical zones of
life. Different types of substrates support distinct populations and
communities. We do not expect to observe mussels and barnacles attached to
sand any more than we expect clams and sand crabs on rocks. The nature of
the substrate plays an important role in determining the abundance and
diversity of life within the intertidal. The effects of substrate on vertical
zonation can be considered along the following three lines: a. Attachment of
larvae, b. Success of larvae and juvenile stages based on porosity of the
substrate, and c. Success based on movement of the substrate.
4 . Substrate type.
a. Attachment of larvae.
Just as certain larvae can recognize suitable slopes of the substrate, the
chemical composition of the substrate can attract larvae and influence their
attachment and development. This has been demonstrated in the laboratory
using planktonic megalops larvae of shore crabs that live along rocky
intertidal regions. These megalopa have the ability delay settlement and
metamorphosis if the water currents carrying them are over sand. Certainly
some physical or chemical parameter of the substrate is transmitted to the
larvae, which can then alter its behavior and physiology accordingly.
Vertical zonation, therefore, will be changed in terms of species composition
and abundance according to the type of substrate present.
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4. Substrate type.
b. Success of organisms based on the porosity of the substrate.
O
ne of the principal environmental side effects caused by variations in
substrate composition is the porosity of differing substrates. Porosity
refers to the amount of space or "pores" within a substrate. These spaces are
especially important for living organisms because they retain water and
moisture. Porosity has an effect on desiccation in the intertidal zone. It is
easy to visualize the fact that sand is more porous than rock. Sand beaches
hold water in the interstitial spaces between the grains than do rocky shores.
Rocks have less internal spaces for water. But there are porosity differences
between different kinds of rocks: granite, shale, sandstone, quartz, lava, and
others. Indeed each type of rock differs in its ability to retain water and this
effects the distribution of organisms because they differ in their ability to
retain body fluids at low tide.
The subtle differences in the porosity of different substrates results in
variations in the species composition of intertidal fauna and flora. 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. The gradient of
moisture imposed by porosity controls the extent of vertical zonation and is a
direct result of substrate type. This principal may be applied equally well to
adult organisms and larvae.
4 . Substrate type.
c. Success of organisms based on 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 for sessile and motile forms alike. Movement
effects larvae, juvenile and adult stages of benthic organisms. Larvae can
recognize and react to substrate movement. The survival of adult organisms
often depends on maintaining a preferred favorable position within the
intertidal. This favorable position is often changed for the worse if the
substrate shifts.
As shown in Figure # 50 on the next page, the frequency of movement of a
substrate is inversely proportional to substrate size. The smaller the
particles composing the substrate, the more often it will move. Conversely,
the larger the particle of substrate the less often it will move. Big boulders move less frequently
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Rock diameter in centimeters.
than small cobblestones. Cobble moves less often than gravel, and gravel less often than sand
grains. Organisms that require a stable substrate and a preferred location within the intertidal
will tend to settle out and survive best on big boulders or solid rock reef.
Average number of movements per year.
Figure # 50 - Frequency of movement vs. substrate size.
Showing the rate of movement per year and size
of rocks ranging in diameter from zero to one hundred centimeters. (Data
modified from Riedl).
Movement of a substrate may adversely effect sessile organisms by crushing
them. It may also change their relative position with respect to ambient
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light, prevailing currents, and wave action. Movement can also render them
vulnerable to predation. Vertical zonation in the intertidal zone differs with
respect to the type of substrate. One of the major factors related to substrate
composition is movement based on size of the substrate particle.
Summary.
Vertical zonation in the Intertidal Zone is a universal pattern which serves
as a wonderful example of the role of environmental factors on the
distribution of organisms. Marine ecologists have studied the Intertidal Zone
because it is easily accessible and is a rich field laboratory for multifactor
analysis. We have explored tides, wave action, slope and substrate
composition. Each of these environmental factors have been analyzed
separately in terms of their effect on vertical zonation. Of course, they do not
act independently in nature. The relative importance of each factor with
respect to the whole is yet to be determined. Intertidal biology is an
interesting field in which exciting avenues for further research are plentiful.
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Name________________________________________
CHAPTER 10 - INTERTIDAL ZONATION
Questions and Cover Page
1-Define: intertidal zone
2-Define: intertidal zonation
3-Prepare a full color diagram of intertidal zonation
4-List and describe the 4 main factors controlling zonation.
5-Define: tide
6-Define: mixed semidiurnal tide
7-prepare a tide curve for L.A. for November 26, 27 and 28, 2000.
8- List and discuss the 4 main things TIDES do.
9-Summarize why big mussels live low and little mussels live high.
10-List and discuss the 2 main things WAVES do.
11-Tell: a)the name, and b)the dominant species for the rocky intertidal in california:
zone one =
zone two =
zone three=
zone four =
12-Discuss SLOPE and its effects.
13-List and discuss the 3 things SUBSTRATE does.
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