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Rocky Intertidal Zonation—
What causes zonation?
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Rocky intertidal shore 岩岸潮間帶
Characteristics
1. Physical environmental factors associated with the tides
and wave force.潮汐 和浪的物理環境因子
2. Fishing from the rocks is a recent popular recreational
activity which may be disruptive to the long-term
conservation and preservation of species on rocky coast.
3. A complexity and inter-dependence of the organisms on
rocky shore. 生物的依賴
4. Broad zones of organisms could be found at different levels
on the shore and that these were modified according to the
local pattern and force of wave-action.
Why study rocky shores?
1. A suitable platform to analyze the processes governing
patterns of distribution分布, abundance豐度 and
diversity多樣性 of natural assemblages as rocky shores
are readily accessible from the land at low tide.
2. The intertidal rocky shore is an extreme habitat that is
in a state of almost constant change when compared to
land or the sea. 礁岩岸的狀況是持續變動的
3. Due to water movements associated with tides, waves
and spray, conditions affecting different levels on the
rocky shore vary continuously throughout the day.
潮汐、波、海浪對岩岸有不同影響程度
www.rockyshores.auz.info/back_info.htm
岩岸潮間帶環境
• Expose to air, potential desiccation,曝露空氣
中，有乾燥的危險
• Exposure to waves that create shear forces on
the rocks and could potentially dislodge
organisms. 浪沖擊岩石可能沖打生物
• Changes in salinity鹽度, dissolved oxygen
levels, and substrate基質 type and availability
of shelter.
Intertidal zones of assemblages 附著生物的垂直分布
1.Lowest level of shores:
algae海藻, ascidian海
鞘 +Limpets笠螺->tube
worms管蟲 (substitute
by calcareous algae in
sheltered shore)>barnacle藤壺->snail
Topics on rocky intertidal
1.Quantitative characteristics
2.Interaction between plants and animals (grazing
and the distribution of algae, algae and the lower
limit of distribution of limpets, algae and the
distribution of sessile animals, sessile animals and
the distribution of algae)動植物之間的關係
3.Interactions between sessile and grazing animals
草食動物與固著生物之間的關係
4.Positive interactions involving gastropods 軟體動
物的關係
• 5. Competitive (negative) interactions
(competition for space among sessile species,
competition for food among grazing gastropodsintraspecific competition and interspecific
competition and their relationships, effects of
competition on life histories) 競爭關係
• 6. Predation on rocky shore (e.g., whelks, crabs,
fish and birds) (predation by whelks Morula
marginalba drill and consume all shelled sessile
species and many of the gastropods; are welks
“keystone species’?) 礁岩岸的捕食
7. Disturbances to intertidal assemblages 潮間
帶生物的分布
8. Physical disturbances on rocky shore 礁岩的
物理影響因子
9. Relationship of settlement and recruitment to
patterns of distribution
Chiton 石鱉
sharon-taxonomy2009-p3.wikispaces.com
nipic.com
Limpet
(source:en.wikipedia.org)
This is a limpet that hold on to a rock to prevent itself to be washed away
(nofullstopinlife.blogspot.com)
barnacles 藤壺
• is a type of arthropod belonging to infraclass
Cirripedia in the subphylum Crustacea, and is
hence related to crabs and lobsters;
woodbridge.tased.edu.au
Supplimentary Reading
• http://www.durhambiodiversity.org.uk/pdfs/h
abitats/Rockyshores.pdf
Interaction between macroalgae大型
海藻 and animals
• Macroalgae could be prevented from
extending to higher levels because the grazing
sea snails found there consume them. Or
Rocks are already covered by encrusting algae.
• Intensive grazing by the gastropods軟體動物
removes virtually all early, microscopic stages
of the macroalgae. (Listen to grazing sound of
sea snail).
libertytimes.com.tw
Interaction between macroalgae大型
海藻and animals
• Algae and the lower limit of distribution of
limpets:
• Limpet which feed on microalgae and do not
eat macroalgae, tended to migrate away from
areas with well-established macroalgae algal
beds more than from areas with little
macroalgae.
nhm.ac.uk
Sessile animals and the distribution of
algae 固著生物和藻類分布
• Where macroalgae grow in profusion and occupy
most of the space at low levels on shores, they
can prevent the subsequent invasion of plankton
larvae of sessile animals (e.g., barnacle藤壺).
• In any low-shore area, if barnacle manage to
settle and attach to cleared surface, subsequent
rapid growth of algae kills them, by growing over
and smotheringthem.海藻生長
快速的生長會將藤壺覆蓋而死亡
masterfile.com
Sessile animals and the distribution of
algae 固著生物和藻類分布
• At mid-shore levels, the limpet consumes the
spores and early stages of many algae.
• Barnacles may reduce the effects of waveshock and probably trap moisture reducing
desiccation, which might affect the near-by
macroalge to survive better.
Sessile animals and the distribution of
algae 固著生物和藻類分布
• Interaction between sessile and grazing
animals
• Survival of newly settled tube-worms was
negatively affected by grazing activities of
snails and limpets. Grazing by limpets kills
juvenile barnacles.
• Effects of sessile species (barnacles) on grazers
(limpets):
Sessile animals and the distribution of
algae 固著生物和藻類分布
• There are effects of barnacles on limpets. More
juvenile limpets recruited to areas where
barnacles were present than to areas from which
barnacles were absent. Pre-emption of space by
barnacles prevents invasion by adult or juvenile
limpets.
• Barnacles probably provide protection from the
forces of breaking waves so that large sea snail
can live in the adjacent space.
Sessile animals and the distribution of
algae 固著生物和藻類分布
• Competition for space among sessile species:
• There is evidence for direct interference of
the tube-worm on the barnacle.
• Competition for food among grazing
gastropods:
• Negative interactions among grazers are widespread.
Predation捕食 on rocky shores
• Predation is an important determinant of
patterns of distribution and abundance of
many species on rocky shore.
• Starfish海星 are considered as keystone
species.
• The sea snail螺 drills and consumes almost all
shelled sessile species and many
of the gastropods.
Whelk 蛾螺
• The whelks prefer to eat barnacles藤壺 larger
than 4 mm; where these were present, the
juveniles survived for longer periods. Other
predators include crabs, fish and birds.
dailymail.co.uk
Mussel 貽貝
• Note the drill holes in the Mytilus edulisshells
around the whelk Nucella lapillus shown
above. only good way to determine when a
whelk is drilling is to listen for it.
lukemiller.org
Predation捕食 on rocky shores
• The role of crevices was important. Preys near
crevices will be susceptible to considerably
greater rates of predation by sea snails than
those further away.
• Differential effect of predation捕食的結果: the
interaction between the preferences shown by
the predator and the density of alternative prey
of different preference ranking. These combine to
influence the intensity of predation on a given
species of prey.
Disturbances to intertidal assemblages
• Storms and wave-action create space in
mussel beds. 貽貝生長在水流強的環境
• Movements of sand influence the patterns of
distribution of algae. 沙流動影響藻類分布
• Human disturbance 人為干擾
Factor affecting species diversity:
• Species-area relationship: Number of species
increase with increase in sampled area.區域變
廣物種數增加
• Intermediate disturbance model: More
species in areas of habitat suffering from
some, but not excessive, disturbance. The
availability of micro-habitats on the boulders
also increases the number of species present
• Tops of boulders tended to be covered by algae;
under-surfaces were covered with a variable
array of sessile animals (sponges, bryozoans苔蘚
虫, tube-dwelling polychaetes多毛類and
tunicates海鞘).
• Boulders of different sizes were subject to
disturbance of different magnitudes, due to
waves and the movement of sand.
Relationship of settlement and
recruitment to patterns of disturbance
1. The surface texture of rocks influenced the
numbers and/or types of species. Marine
larvae can discriminate very well among
different surface and different textures. Some
scientists supposed that larva might settle
preferentially on some shores rather than
others. However, larvae might settle in
variable numbers from place to place
regardless of substratum.
2. Shaded areas rather than those in direct
sunlight have more settled larvae, indicating
that larvae seek out shade places to settle.
3. Young worms were found almost exclusively
at heights occupied by adults.
4. Pre-emption優先佔用權of space by algae at
low levels on the shore can prevent
settlement of some species.
5. The distributions of adult organisms are
entirely determined by the patterns of
settlement of the larvae.