Difference between revisions of "Rocky shore habitat"

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This article describes the habitat of rocky shores in a tidal environment. It is one of the habitat sub-categories within the section dealing with biodiversity of [[marine habitats and ecosystems]]. It gives an introduction to the type of biota that lives there, the problems and adaptations the habitat is facing with and the importance of it in the marine environment.
This article describes the habitat of rocky shores. It is one of the habitat sub-categories within the section dealing with biodiversity of [[marine habitats and ecosystems]]. It gives an overview about the type of biota that lives there, the problems and adaptations the habitat is facing with and the importance of it in the marine environment.
 
  
  
 
==Introduction==
 
==Introduction==
  
[[image:Costa Vicentina.jpg|left|thumb|400px|caption|Rocky shore of the Costa Vicentina <ref>http://www.marbef.org – Sprung M.</ref>]]
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[[image:Costa Vicentina.jpg|left|thumb|350px|caption|Rocky shore of the Costa Vicentina <ref>http://www.marbef.org – Sprung M.</ref>]]
  
  
  
 
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Rocky intertidal areas are a biologically rich environment that can include several distinct habitat types like steep rocky cliffs, platforms, rock pools and boulder fields. Because of the permanent action of tides and waves, it is characterized by [[coast erosion|erosional]] features. Together with the wind, sunlight and other physical factors it creates a complex environment, see [[Rocky shore morphology]].   
 
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Organisms that live in this area experience large daily fluctuations in their environment. For this reason, they must be able to tolerate extreme changes in temperature, [[salinity]], moisture and wave action to survive.  
A rocky shore is an [[intertidal]] area that consists of solid rocks. It is often a biologically rich environment and can include many different habitat types like steep rocky cliffs, platforms, rock pools and boulder fields. Because of the continuously action of the [[tide|tides]], it is characterized by [[coast erosion|erosional]] features. Together with the wind, sunlight and other physical factors it creates a complex environment, see [[Rocky shore morphology]].   
 
Organisms that live in this area experience daily fluctuations in their environment. For this reason, they must be able to tolerate extreme changes in temperature, [[salinity]], moisture and wave action to survive.  
 
 
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==Zonation==
 
==Zonation==
  
Each region on the coast has a specific group of organisms that form distinct horizontal bands or zones on the rocks. The appearance of dominant species in these zones is called vertical [[zonation]]. It is a nearly universal feature of the intertidal zone.  
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Because the physical conditions and associated stresses differ greatly for different elevation zones, there are also major differences in the species composition for different elevation zones. Distinct horizontal bands or zones on the rocks are populated with specific groups of organisms; this is called vertical [[zonation]]<ref>Benson, K.R. 2002.The study of vertical zonation on rocky intertidal shores –a historic perspective. Integr. Comp. Biol. 42: 776–779</ref>. It is a nearly universal feature of the intertidal zone.  
  
  
 
===Supratidal zone===
 
===Supratidal zone===
 
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The upper regions around the high-tide mark are exposed to air during most of the time. The organisms in this region are subject to severe stresses related to respiration, desiccation, temperature changes and feeding. This upper region is called the supratidal or [[littoral|splash zone]]. It is moistened by the spray of breaking waves and it is only covered during the highest tides and during storms. Organisms are exposed to the drying heat of the sun in the summer and to low temperatures in the winter. Because of these severe conditions, there are only few species that can cope with these extreme conditions.  
When the tide retreats, the upper regions become exposed to air. The organisms that live in this region are facing problems like gas exchange, desiccation, temperature changes and feeding. This upper region is called the '''supratidal or''' [[littoral|'''splash zone''']]. It is only covered during storms and extremely high tides and is moistened by the spray of the breaking waves. Organisms are exposed to the drying heat of the sun in the summer and to extreme low temperatures in the winter. Because of these severe conditions, only a few resistant organisms live here.  
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Common organisms are lichens. They are composed of fungi and microscopic [[algae]] living in symbiosis and sharing food and energy for their growth. The fungi trap moisture for both themselves and their algal symbiont. The algae on the other hand produce [[nutrients]] by [[photosynthesis]]. They are capable of surviving on the moisture of the sea spray from waves. During winter, they are found lower on the intertidal rocks. The algae growing higher on the rocks gradually die when the air temperature changes. At the lower edge of the splash zone, rough snails (periwinkles) graze on various types of algae. These snails are well adapted to life out of the water by trapping water in their mantle cavity or hiding in cracks of rocks. Other adapted animals are isopods, barnacles, limpets,…  
Common organisms are lichens. They are composed of fungi and microscopic [[algae]] living together and sharing food and energy to grow. The fungi trap moisture for both themselves and their algal symbiont. The algae on the other hand produce [[nutrients]] by [[photosynthesis]]. Green algae and cyanobacteria can also be found on the rocks of the North Atlantic coasts. They are capable of surviving on the moisture of the sea spray from waves. During the winter, they are found lower on the intertidal rocks. The algae growing higher on the rocks gradually die when the air temperature changes. At the lower edge of the splash zone, rough snails (periwinkles) graze on various types of algae. These snails are well adapted to life out of the water by trapping water in their mantle cavity or hiding in cracks of rocks. Other common animals are isopods, barnacles, limpets,…  
 
  
  
 
===Intertidal zone===
 
===Intertidal zone===
 
The '''intertidal zone or littoral zone''' is the shoreward fringe of the sea bed between the highest and lowest limit of the tides. The upper limit is often controlled by physiological limits on species tolerance of temperature and drying. The lower limit is often determined by the presence of predators or competing species. Because the [[intertidal]] zone is a transition zone between the land and the sea, it causes heat stress, desiccation, oxygen depletion and reduced opportunities for feeding.
 
At low tide, marine organisms face both heat stress and desiccation stress. The degree of this water loss and heating is determined by the body size and body shape. When body size increases, the surface area decreases so the water loss is reduced. Shape has a similar effect. Long and thin organisms dry up much faster than spherical organisms. [[Intertidal]] organisms can avoid overheating by evaporative cooling combined with circulation of body fluids. Higher-[[intertidal]] organisms are better adapted to desiccation than lower-[[intertidal]] organisms, because they encounter more hours of sun.
 
The organisms are exposed directly to the air or they are enclosed in burrows. This results in oxygen depletion, so they can’t get rid of their metabolic waste. A solution for this problem is to reduce the metabolic rate.
 
 
  
 
[[image:Intertide zonation.jpg|right|thumb|250px|caption|Intertidal zonation: at low tide, the 3 typical intertidal zones can be seen <ref>http://en.wikipedia.org/wiki/Intertidal_zone</ref>]]
 
[[image:Intertide zonation.jpg|right|thumb|250px|caption|Intertidal zonation: at low tide, the 3 typical intertidal zones can be seen <ref>http://en.wikipedia.org/wiki/Intertidal_zone</ref>]]
  
 
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The intertidal zone or littoral zone is the shoreward fringe of the seabed between the highest and lowest limit of the tides. The upper limit is often controlled by physiological limits on species tolerance of temperature and drying. The lower limit is often determined by the presence of predators or competing species<ref> Connell, J. H. 1961. The influence of intra-specific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecology 42: 710–723</ref>. Because the [[intertidal]] zone is a transition zone between the land and the sea, organisms living in this zone are subject to stresses related to temperature, desiccation, oxygen depletion and reduced opportunities for feeding.
 
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At low tide, marine organisms face both heat stress and desiccation stress. The degree of heating and water loss is determined by the body size and body shape. When the body size increases, the surface area decreases so the water loss is reduced. Shape has a similar effect. Long and thin organisms dry out faster than spherical organisms. [[Intertidal]] organisms can avoid overheating by evaporative cooling combined with circulation of body fluids. Higher-[[intertidal]] organisms are better adapted to desiccation than lower-[[intertidal]] organisms, because they have evolved in an environment more exposed to the sun. Normally, respiration rates increase with temperature and so does the oxygen demand. However, marine organisms exposed to the air cannot feed or carry out gas exchange with seawater, so normal rates of aerobic respiration cannot be sustained. Therefore these organisms have evolved physiological mechanisms to tolerate a wide range of body temperatures, for example by reducing their metabolic rate (see the section on adaptation).
 
 
 
 
 
 
 
 
  
 
The [[intertidal]] zone can be divided in three zones:
 
The [[intertidal]] zone can be divided in three zones:
 
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* High tide zone or high intertidal zone. This region is only flooded during high tides. You can find here organisms such as anemones, barnacles, chitons, crabs, isopods, mussels, sea stars, snails,...  
* '''High tide zone or high intertidal zone'''. This region is only flooded during high tides. Organisms that you can find here are anemones, barnacles, chitons, crabs, isopods, mussels, sea stars, snails,...  
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* Middle tide zone or mid-littoral zone. This is a [[currents and turbulence by acoustic methods|turbulent]] zone that is dried twice a day. The zone extends from the upper limit of the barnacles to the lower limit of large brown algae (e.g. ''Laminariales'', ''Fucoidales''). Common organisms are snails, sponges, sea stars, barnacles, mussels, sea palms, crabs,...  
* '''Middle tide zone or mid-littoral zone'''. This is a [[currents and turbulence by acoustic methods|turbulent]] zone that is (un)covered twice a day. The zone extends from the upper limit of the barnacles to the lower limit of large brown algae (e.g. ''Laminariales'', ''Fucoidales''). Common organisms are snails, sponges, sea stars, barnacles, mussels, sea palms, crabs,...  
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* Low intertidal zone or lower littoral zone. This region is usually covered with water. It is only uncovered when the tide is extremely low. In contrast to the other zones, the organisms are not well adapted to long periods of dryness or to extreme temperatures. The common organisms in this region are brown seaweed, crabs, hydroids, mussels, sea cucumber, sea lettuce, sea urchins, shrimps, snails, tube worms,…
* '''Low intertidal zone or lower littoral zone'''. This region is usually covered with water. It is only uncovered when the tide is extremely low. In contrast to the other zones, the organisms are not well adapted to long periods of dryness or to extreme temperatures. The common organisms in this region are brown seaweed, crabs, hydroids, mussels, sea cucumber, sea lettuce, sea urchins, shrimps, snails, tube worms,…
 
 
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[[image:Tide pool.jpg|left|thumb|450px|caption|Tidal pool in Santa Cruz <ref>http://en.wikipedia.org/wiki/Tide_pool</ref>]]
 
[[image:Tide pool.jpg|left|thumb|450px|caption|Tidal pool in Santa Cruz <ref>http://en.wikipedia.org/wiki/Tide_pool</ref>]]
  
'''Tidal pools''' are rocky pools in the [[intertidal]] zone that are filled with seawater. They are formed by abrasion and weathering of less resistant rock and scouring of fractures and joints in the shore platform. This leaves holes or depressions in  where seawater can be collected at high tide. They can be small and shallow or deep. The smallest ones are usually found at the high [[intertidal]] zone, whereas the bigger ones are found in the lower intertidal zone. When the tide retreats, the pool becomes isolated. Because of the regular tides, the pool is not stagnant and new water regularly enters the pool. This is necessary to avoid temperature stress, [[salinity]] stress, nutrient stress,…
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Tidal pools are rocky pools in the [[intertidal]] zone that are filled with seawater. They are formed by abrasion and weathering of less resistant rock and scouring of fractures and joints in the shore platform. This leaves holes or depressions where seawater can be collected at high tide. They can be small and shallow or deep. The smallest ones are usually found at the high [[intertidal]] zone, whereas the bigger ones are found in the lower intertidal zone. When the tide retreats, the pool becomes isolated. The water does not remain stagnant, because new water enters the pool when the tide rises. This is necessary to avoid temperature stress, [[salinity]] stress, nutrient stress,…
Pools that are located higher on the beach are not regularly renewed by tides. These pools are basically freshwater or brackish water communities. It has different characteristics in comparison with other coastal habitats. Several taxa are more abundant in pools than the surrounding environment. These taxa are members of the algae and gastropods. There is also a difference between high and low located pools for the composition. In low located pools, whelks, mussels, sea urchins and ''Littorina littorea'' are common. Periwinkles and ''Littorina rudis'' are found in high located pools. Other organisms that are commonly found in pools are flatworms, rotifers, cladocerans, copepods, ostracods, barnacles, amphipods, isopods, chironomid larvae and oligochaetes. Vertical [[zonation]] also has been documented in tidal pools.<ref>Knox G.A. 2001. The ecology of seashores. CRC Press LLC. p. 557</ref>   
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Pools that are located higher on the beach are not regularly renewed by tides. These pools are basically freshwater or brackish water communities. It has different characteristics in comparison with other coastal habitats. Several taxa are more abundant in pools than the surrounding environment. These taxa are members of the algae and gastropods. There is also a difference in composition between high and low located pools. Low-located pools are home to whelks, mussels, sea urchins and the common periwinkle (''Littorina littorea''). Rough periwinkles (''Littorina rudis'') are found in high located pools. Other organisms that are commonly found in pools are flatworms (polycladida), marine worms (oligochaetes), rotifers, water fleas, small crustaceans (copepods, ostracods, amphipods, isopods), barnacles, and larvae of flies (chironomids). Vertical [[zonation]] also has been documented in tidal pools.<ref>Knox G.A. 2001. The ecology of seashores. CRC Press LLC. p. 557</ref>   
  
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===Subtidal zone===
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The subtidal zone or sublittoral zone is the region below the [[intertidal]] zone and is continuously covered by water. This zone is far more stable than the [[intertidal]] zone. There are no strong fluctuations in temperature, water pressure and sunlight radiation. Organisms do not dry out as often as organisms higher on the beach. They grow faster and are better competitors for the same [[niche]]. They extract essential [[nutrient]]s from the water and do not need to cope with extreme changes in temperature. <ref>Karleskint G. 1998. Introduction to marine biology. Harcourt Brace & Company.  p.378</ref> <ref>Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford university press. p.420</ref>
  
  
===Subtidal zone===
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==Stresses and adaptations==
  
The '''subtidal zone or sublittoral zone''' is the region below the [[intertidal]] zone and is continuously covered by water. This zone is much more stable than the [[intertidal]] zone. Temperature, water pressure and sunlight radiation remain nearly constant. Organisms do not dry out as often as organisms higher on the beach. They grow much faster and are better in competition for the same [[niche]]. More essential [[nutrient]]s are acquired from the water and they are buffered from extreme changes in temperature. <ref>Karleskint G. 1998. Introduction to marine biology. Harcourt Brace & Company.  p.378</ref> <ref>Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford university press. p.420</ref>
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In this section, stresses and adaptations are discussed in more detail. The regular strong fluctuations in environmental conditions imply that organisms have to be tolerant to the associated stresses, in particular stresses related to temporary aerial exposure. Adaptations are solutions to deal with these stresses and are necessary to survive.  
  
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===Oxygen===
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Most intertidal animals depend on aerobic respiration by extracting oxygen from water. An exception are some limpet species that live high on the shore and that have a mantle cavity adapted to breathe air, similar to a lung. Other intertidal animals have gills and cannot tolerate prolonged air exposure. Since gills only function when they are moist, these animals need to avoid desiccation. In response to desiccation stress, some sessile species (periwinkles) have adapted their gills to allow gas exchange with the air. Other species (barnacles) store air bubbles in cavities in the gills that supply oxygen to the moisture around the gills<ref name=S13>Smith, D. 2013. Ecology of the New Zealand Rocky Shore Community: A Resource for NCEA Level 2 Biology. New Zealand Marine Studies Centre Publ. ISBN: 978-0-473-23177-4</ref>. The main adaptation strategy of sessile animals to prolonged air exposure is to slow down their metabolism and associated oxygen consumption; some animals (snails) can temporarily switch to anaerobic respiration<ref name=HM>Hand, S.C. and Menze, M.A. 2007. Desiccation Stress. In: (Denny, M.W. and Gaines, S.D. eds. ) Encyclopedia of Tidepools and Rocky Shores. University of California Press, p. 173-177</ref>. Mobile animals (crabs, chitons) mainly adapt by moving with the tide to stay underwater.
  
==Problems and adaptations==
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===Temperature===
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Temperature differences can be very large in the intertidal zone. Most marine animals are ectothermic, that is, they cannot regulate their body temperature, but depend on the ambient temperature. As a result, they cannot tolerate large temperature differences. In water, temperature changes are buffered, but in the air, animals can be exposed to very cold or very hot temperatures. Especially animals with a small body weight have a hard time.
  
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In most animals the metabolism accelerates at high temperatures and thus also the oxygen demand. However, in the intertidal area the animals can hardly absorb oxygen when the tide is low. One way of adaptation is regulation of the membrane fluidity ([https://en.wikipedia.org/wiki/Homeoviscous_adaptation homeoviscous adaptation]). At high temperatures, the fluidity increases, the saturated fatty acids decrease and thus the rates of metabolism and respiration<ref>Somero, G.H. 2002. Thermal Physiology and Vertical Zonation of Intertidal Animals: Optima, Limits, and Costs of Living. Integ. and Comp. Biol. 42: 780–789</ref>. The opposite happens at low temperatures. Another adaptation to harmful high ambient temperatures is the production of heat shock proteins ([https://en.wikipedia.org/wiki/Heat_shock_protein HSP]). These proteins, which protect important enzymes against heat damage, are produced by many intertidal molluscs such as mussels, limpets, top shells and periwinkles<ref>Feder, M. E. and Hofmann, G. E. 1999. Heat shock proteins, molecular chaperones, and the stress response: Evolutionary and ecological physiology. Annu. Rev. Physiol. 61: 243–282</ref><ref> Tomanek, L. and Somero, G. N. 2000. Time course and magnitude of synthesis of heat-shock proteins in congeneric marine snails (genus Tegula) from different tidal heights. Physiol. Biochem. Zool. 73: 249–256</ref>. Many intertidal animals can tolerate much greater temperature changes than their estuarine relatives. Possible adaptations are also light colors to reflect light or a large surface (ribbed shells) to dissipate heat.  However, when cooled by evaporation, desiccation can lead to problems<ref>McMahon, R.F. 1990. Thermal tolerance, evaporative water loss, air-water oxygen consumption and zonation of intertidal prosobranchs: a new synthesis. Hydrobiologia 193: 241–260</ref>.
  
In this section, the problems and the adaptations are discussed. The continuously changing environment makes that organisms have to be tolerant for these changes.
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When the temperature is too low, the organisms must cope with physiological threats associated with cold stress. This can be the case in polar and temperate latitude coastal zones. The body fluids can then reach their freezing point and ice crystals develop. This causes damage to cell membranes and increase of the osmotic concentration of the nonfrozen fluid. Some organisms have developed antifreeze proteins (cryoprotectants). Increase of the concentration of [https://en.wikipedia.org/wiki/Osmolyte osmolytes] such as glycerol and sucrose in the body fluids increases the freezing tolerance<ref>Loomis, S.H. 1995. Freezing tolerance of marine invertebrates. Oceanogr. Mar. Biol. Ann. Rev. 33: 337-350</ref>. Another strategy is to control formation and spread of internal ice crystals. When the ice formation is intracellular, it is lethal but extracellular ice formation can be tolerated. Invertebrates found naturally in seawater of high salinity are more cold-tolerant than specimens inhabitating brackish waters. In molluscs, the cold tolerance can be increased by acclimating the animals to higher salinities. This is probably based on increased concentrations of intracellular solutes such as amino acids<ref>Aarset, A. V. 1982. Freezing tolerance in intertidal invertebrates - a review. Comp. Biochem. and Physiol. A 73: 571–580</ref>.
Adaptations are a solution for these problems and are necessary to survive.  
 
  
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Mobile organisms can avoid extreme temperatures by migrating to more suitable places; this is also a response to other stresses associated with emersion.
  
===Air===
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===Desiccation stress===
 
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Dehydration is the main environmental factor in the supralittoral and high intertidal zones, and the green macroalgae living in these zones are exposed regularly to air, yet still survive. Desiccation tolerance can be defined as the ability to survive drying to about 10% remaining water content. Dehydration-tolerance involves maintaining homeostasis during dehydration by minimizing or repairing any damage as fast as possible<ref name=HK>Holzinger, A. and Karsten, U. 2013. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological, and molecular mechanisms. Frontiers in Pant Science 4, 327</ref>. Highly mobile organisms can avoid the desiccation by migrating to a region that is more suitable. Less mobile organisms restrict various activities (reduced metabolism) and attach more firmly to the substrate. Physiological features to tolerate water loss include adaptations such as: deployment of desiccation-resistant egg cases for embryonic development, reduction of the exposed surface areas across which water loss takes place (thus accepting reduced gas exchange and concomitant anaerobic respiration with accumulation of metabolic end products), temporary depression in metabolic and developmental rates, maintenance of intracellular osmolytes for water retention and macromolecular protection and differential gene expression for the production of protective macromolecules<ref name=HM/>. Some sessile organisms can anticipate emersion by storing water in body cavities (e.g., anemones) or mantle cavities (e.g., barnacles, mussels) <ref name=S13/>.  
[[Intertidal]] organisms are regularly exposed to air and water. Air differs physically from seawater in diverse and important features. This influences the ability to exchange gas and their overall thermal balance with the surrounding environment. Under water, organisms are generally buoyant, because of their lower density. In air, gravity induces retraction of tentacles and other feeding organs. It also makes the body less resistant. For this reason, organisms need '''supporting structures''' when they are exposed to air. '''Attachment''' and '''body changes''' are also required.
 
When exposed to the air, organisms directly absorb solar radiation. The buffering capacity of water, because of the high rate of heat conductivity, disappears and the body temperature increases. In contrast to this, heat loss is much lower in air than in water.  
 
An adaptation to heating is the vaporization of internal water reserves.  
 
  
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===Biological clock===
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Many intertidal animals have a biological clock that allows them to anticipate changes as a result of tides (circatidal rhythmicity) or light (circadian rhythmicity). Different signals play a role in the setting of endogenous rhythmicity in some crustaceans and crabs: water agitation, hydrostatic pressure, immersion, light and temperature cycles. Once trained after a few tidal periods, the rhythmicity is maintained. Thanks to the biological clock, the animals can adapt in time, instead of waiting for an adverse situation to arise<ref>Naylor, E. 1976. Rhythmic behaviour and reproduction in marine animals. In: (Ed.: Newell, R.C) Adaptation to Environment: Essays on the Physiology of Marine Animals. Butterworth Publ., London, p. 393-429</ref>.
  
 
===Light===
 
===Light===
 
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Sunlight is another parameter that influences the organisms. When there is too much sunlight, organisms dry out and the capacity to capture light energy can be weakened. The light that is not used or dissipated can cause damage to subcellular structures.  
Sunlight is another parameter that influences the organisms. When there is too much sunlight, organisms dry out and the capacity to capture light energy can be weakened. The light that is not used or dissipated can cause damage to subcellular structures.
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Algae can protect themselves against an excess of sunlight by so-called [https://en.wikipedia.org/wiki/Non-photochemical_quenching non-photochemical quenching] (NPQ): the light energy absorbed by the chlorophyll is dissipated in the form of heat or in the form of fluorescence. NPQ is a quick and effective way to prevent damage from excess sunlight. There are also several other mechanisms, such as scavenging or deactivating free radicals produced from an excess of light<ref>Erickson, E., Wakao, S. and Niyogi, K.K. 2015. Light stress and photoprotection in Chlamydomonas reinhardtii. The Plant Journal 82: 449–465</ref>. Too little sunlight reduces the growth and reproduction of the organism, because [[photosynthesis]] is reduced.
Too little sunlight reduces the growth and reproduction of the organism, because [[photosynthesis]] is reduced. Algae can avoid absorbing too much light by changing the complement or amount of pigments they produce. They also can rearrange the pigmented organelles within their cells. When free radicals are produced from an excess of light, they can be scavenged and deactivated.
 
 
 
 
 
===Temperature===
 
 
 
The [[intertidal]] zone can experience extreme temperature changes. The organisms in this zone must be resistant to these changes to survive. Most of the marine organisms are '''ectothermic''' and need the warmth from the environment to survive.
 
When the organisms are submerged, they are buffered against temperature changes, because the water is isothermal. When the organisms become exposed to the air, they can experience cool or warm temperatures. When the temperature is too low, the organisms must cope with physiological threats associated with '''cold stress'''. This can be the case in polar and temperate latitude coastal zones. The body fluids can then reach their freezing point and ice crystals develop. This causes damage to cell membranes and increasing the osmotic concentration of the remaining fluids. To avoid this cold stress, organisms can migrate to habitats that are more suitable. This can be a problem for sessile organisms. They can develop physiological and behavioral adaptations such as gaping shells (mussels). Some organisms have developed antifreeze proteins. Increasing the concentration of small osmolytes such as glycerol in the body fluids can decrease the freezing point. Another strategy is to control ice crystal formation. Organisms can control the speed and the exact location of the ice crystals. When the ice formation is intracellular, it is lethal but extracellular ice formation can be tolerated.  
 
When the temperature is too high, '''heat stress''' appears. Heat stress accelerates rates of metabolic processes. This can be avoided by evaporative cooling combined with circulation of body fluids.
 
 
 
  
 
===Salinity stress===
 
===Salinity stress===
 
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Intertidal zone organisms can be subjected to varying salinity, especially those living in pools that are not regularly refreshed with new seawater. Rain can cause the salinity to drop and evaporation can cause the salinity to rise. Changes in salinity change the osmotic pressure in the cells of the body tissues, causing them to swell or shrink. Organisms living in estuaries have adaptations to deal with this, such as adaptation of the cell membrane, salt storage in vacuoles or glands to secrete salt. However, most intertidal organisms are osmoconformers: they cannot control the salt content of their body. In some species (e.g., periwinkle), the salinity of their tissues is similar to that of normal seawater, which is the environment that they evolved in and are adapted to<ref>Taylor, P. M. and Andrew, E. B. 1988. Osmoregulation in the intertidal gastropod Littorina littorea. Journal of Experimental Marine Biology and Ecology 122: 35-46</ref>. Osmoregulation is more generally provided by organic [https://en.wikipedia.org/wiki/Osmolyte osmolytes] that keep intracellular fluids at the same pressure as the marine environment to avoid cell shrinkage or dilatation<ref>Yancey, P.H. 2005. Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses. J. Exp. Biol. 208: 2819–2830</ref>.  
[[Salinity]] stress can occur in the external medium and in surface films. The concentration of the fluids determines whether or not the organism will lose water. When the osmolality of the cell is lower than the surrounding medium, the cell loses water from the internal fluids to the environment ('''hyperosmotic stress'''). When the intracellular osmolality is higher than the environment, there is an influx of water into the cell from the environment ('''hypoosmotic stress'''). Multicellular organisms respond to this [[salinity]] stress by compartmentalization. This buffers the cells from sharp changes in the osmotic environment. When the tissue has an immediate contact with the external medium, a solution can be to regulate intercellular osmotic pressure by actively excreting salts or water. Another solution is to change the internal osmolality. This can be done by incorporating ions or compatible solutes in the internal fluids.
 
 
 
 
 
===Desiccation stress===
 
 
 
Organisms are threatened by desiccation during emersion at low tides or when they are positioned in the high intertidal zones. '''Deshydratation''' due to evaporative water loss is the most common mechanism. Highly mobile organisms can avoid the desiccation by '''migrating''' to a region that is more suitable. Less mobile organisms restrict various activities ('''reduced metabolism''') and attach more firmly to the substrate. Physiological features to tolerate water loss are desiccation-resistant egg cases, reduction in water permeability of membranes, accumulation of metabolic end products, reduction of metabolic and developmental rates, maintenance of intracellular osmolytes and gene expression for production of protective macromolecules.  
 
 
 
  
 
===Predation===
 
===Predation===
 
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A wide variety of strategies to escape from predation exists. The first strategy is calcification, which makes it more difficult for the predator to eat these organisms. This strategy is applied by algae. It makes them tougher and less nutritious. A second one is the production of chemicals, usually produced as secondary metabolites. These (toxic) chemicals can be produced all the time, but other chemicals are only produced in response to stimuli (inducible defence). Another way to avoid predation is to have two distinct anatomical forms within one life cycle. This can be e.g. an alternation between a crusty form when the predator is present and a more delicate form (e.g. blade) when the predator is absent. Also the shape of the body can be a distinct evolutionary advantage.  
A wide variety of strategies to escape from predation exists. The first strategy is '''calcification'''. It makes it more difficult for the predator to eat these organisms. This strategy is applied by algae. It makes them tougher and less nutritious. A second one is the production of '''chemicals''', usually produced as secondary metabolites. These chemicals can be produced all the time such as toxins, but other chemicals are only produced in response to stimuli (inducible defence). Another way to avoid predation is to have two distinct anatomical forms within one life cycle. This can be e.g. an alternation between a crusty form when the predator is present and a more delicate form (e.g. blade) when the predator is absent. Also the shape of the body can be a distinct evolutionary advantage.  
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Bioluminescence is another strategy to avoid predators. Many intertidal and subtidal predators forage visually. The light is used for warning, blinding, making scare, misleading or attracting the predator. A commonly used form of protection against predation is camouflage. This can be visually or chemically. Visual camouflage means that the prey becomes invisible to the predator by using the same colors as the environment. Chemical camouflage is the passive adsorption of chemicals. The predator does not smell the prey anymore, because the smell is masked.  
'''Bioluminescence''' is another strategy to avoid predators. Many [[intertidal]] and [[subtidal]] predators visually forage. The light is used for warning, blinding, making scare, misleading or attracting the predator. A commonly used form of protection against predation is '''camouflage'''. This can be visually or chemically. Visual camouflage means that the prey becomes invisible to the predator by using the same colors as the environment. Chemical camouflage is the passive adsorption of chemicals. The predator does not smell the prey anymore, because the smell is masked.  
+
To escape seabird predation, some animals (periwinkles, chitons and apex shells) can hide in inaccessible crevasses or between seaweed. Others, such as beach crabs, bury themselves in the sediments that often accumulate under rocks.
 
 
  
 
===Wave action===
 
===Wave action===
 
+
One way to protect organisms from waves is permanent attachment. But this strategy cannot be used by organisms that have to move to feed themselves. These organisms make a compromise between mobility and attachment.  
One way to protect organisms from waves is permanent '''attachment'''. But this strategy cannot be used by organisms that have to move to feed themselves. These organisms have to make a compromise between mobility and attachment. Another way to be protected is to burrow themselves into the sediment. But an alternative is to seek protected habitats.  
+
Attachment can be done by different structures. Bivalves usually use threads (byssal threads) to attach to rocky surfaces or to other organisms, but they can also use a foot<ref>Aguilera, M.A., Thiel, M., Ullrich, N., Luna-Jorquera, G. and Buschbaum, C. 2017. Selective byssus attachment behavior of mytilid mussels from hard- and softbottom coastal systems. Journal of Experimental Marine Biology and Ecology 497: 61-70</ref>. Another one is cementation. This is the case for bivalves such as oysters, scallops and some other forms. They lay on their side, with the lower valve cemented firmly to the bottom. This can be combined by reduction or enlargement of certain muscles<ref name=D7>Trussel, G.C. and Ewanchuk, P.J. 2007. Predator avoidance. In: (Denny M.W. and Gaines S.D. eds.) Encyclopedia of tidepools & rocky shores. University of California Press. p. 440-443</ref><ref>Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford University Press. p. 420</ref>.
Attachment can be done by different structures. Bivalves usually use threads (byssal threads) to attach to rocky surfaces or to other organisms. But it can also be done by a foot. Another one is '''cementation'''. This is the case for bivalves such as oysters, scallops and some other forms. They lay on their side, with the lower valve cemented firmly to the bottom. This can be combined by reduction or enlargement of certain muscles. <ref>Denny M.W. Gaines S.D. 2007. Encyclopedia of tidepools & rocky shores. University of California Press. p. 705</ref> <ref>Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford University Press. p. 420</ref>
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Another way to be protected from waves is to burrow into the sediment or seek shelter, such as a  crevasse.
  
  
 
==Why are rocky shores important?==
 
==Why are rocky shores important?==
 
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* They are home to many organisms
 
+
* They provide a nursery area for many fish and crustacean species
* Providing a '''home''' for a lot of organisms
+
* They provide shelter in areas where seaweeds reduce the wave power
* '''Nursery''' area for many fish and crustacean species
+
* They provide food for fishes
* '''Shelter''' in areas where seaweeds break the waves power
+
* Algal beds are an important food source for rare and threatened species like sea turtles
* Providing '''food''' for fishes
+
* The are a feeding ground at low [[tide]] for wading birds
* Algal beds important food source for rare and threatened species like sea turtles
+
* They protect the hinterland
* Feeding ground at low [[tide]] for wading birds
 
* '''Stabilization''' inshore sediment
 
 
   
 
   
  
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[[Category:Coastal and marine habitats]]
 
[[Category:Coastal and marine habitats]]
 
[[Category:Coastal and marine ecosystems]]
 
[[Category:Coastal and marine ecosystems]]

Revision as of 18:24, 5 March 2021

This article describes the habitat of rocky shores in a tidal environment. It is one of the habitat sub-categories within the section dealing with biodiversity of marine habitats and ecosystems. It gives an introduction to the type of biota that lives there, the problems and adaptations the habitat is facing with and the importance of it in the marine environment.


Introduction

Rocky shore of the Costa Vicentina [1]


Rocky intertidal areas are a biologically rich environment that can include several distinct habitat types like steep rocky cliffs, platforms, rock pools and boulder fields. Because of the permanent action of tides and waves, it is characterized by erosional features. Together with the wind, sunlight and other physical factors it creates a complex environment, see Rocky shore morphology. Organisms that live in this area experience large daily fluctuations in their environment. For this reason, they must be able to tolerate extreme changes in temperature, salinity, moisture and wave action to survive.


Zonation

Because the physical conditions and associated stresses differ greatly for different elevation zones, there are also major differences in the species composition for different elevation zones. Distinct horizontal bands or zones on the rocks are populated with specific groups of organisms; this is called vertical zonation[2]. It is a nearly universal feature of the intertidal zone.


Supratidal zone

The upper regions around the high-tide mark are exposed to air during most of the time. The organisms in this region are subject to severe stresses related to respiration, desiccation, temperature changes and feeding. This upper region is called the supratidal or splash zone. It is moistened by the spray of breaking waves and it is only covered during the highest tides and during storms. Organisms are exposed to the drying heat of the sun in the summer and to low temperatures in the winter. Because of these severe conditions, there are only few species that can cope with these extreme conditions. Common organisms are lichens. They are composed of fungi and microscopic algae living in symbiosis and sharing food and energy for their growth. The fungi trap moisture for both themselves and their algal symbiont. The algae on the other hand produce nutrients by photosynthesis. They are capable of surviving on the moisture of the sea spray from waves. During winter, they are found lower on the intertidal rocks. The algae growing higher on the rocks gradually die when the air temperature changes. At the lower edge of the splash zone, rough snails (periwinkles) graze on various types of algae. These snails are well adapted to life out of the water by trapping water in their mantle cavity or hiding in cracks of rocks. Other adapted animals are isopods, barnacles, limpets,…


Intertidal zone

Intertidal zonation: at low tide, the 3 typical intertidal zones can be seen [3]

The intertidal zone or littoral zone is the shoreward fringe of the seabed between the highest and lowest limit of the tides. The upper limit is often controlled by physiological limits on species tolerance of temperature and drying. The lower limit is often determined by the presence of predators or competing species[4]. Because the intertidal zone is a transition zone between the land and the sea, organisms living in this zone are subject to stresses related to temperature, desiccation, oxygen depletion and reduced opportunities for feeding. At low tide, marine organisms face both heat stress and desiccation stress. The degree of heating and water loss is determined by the body size and body shape. When the body size increases, the surface area decreases so the water loss is reduced. Shape has a similar effect. Long and thin organisms dry out faster than spherical organisms. Intertidal organisms can avoid overheating by evaporative cooling combined with circulation of body fluids. Higher-intertidal organisms are better adapted to desiccation than lower-intertidal organisms, because they have evolved in an environment more exposed to the sun. Normally, respiration rates increase with temperature and so does the oxygen demand. However, marine organisms exposed to the air cannot feed or carry out gas exchange with seawater, so normal rates of aerobic respiration cannot be sustained. Therefore these organisms have evolved physiological mechanisms to tolerate a wide range of body temperatures, for example by reducing their metabolic rate (see the section on adaptation).

The intertidal zone can be divided in three zones:

  • High tide zone or high intertidal zone. This region is only flooded during high tides. You can find here organisms such as anemones, barnacles, chitons, crabs, isopods, mussels, sea stars, snails,...
  • Middle tide zone or mid-littoral zone. This is a turbulent zone that is dried twice a day. The zone extends from the upper limit of the barnacles to the lower limit of large brown algae (e.g. Laminariales, Fucoidales). Common organisms are snails, sponges, sea stars, barnacles, mussels, sea palms, crabs,...
  • Low intertidal zone or lower littoral zone. This region is usually covered with water. It is only uncovered when the tide is extremely low. In contrast to the other zones, the organisms are not well adapted to long periods of dryness or to extreme temperatures. The common organisms in this region are brown seaweed, crabs, hydroids, mussels, sea cucumber, sea lettuce, sea urchins, shrimps, snails, tube worms,…



Tidal pool in Santa Cruz [5]

Tidal pools are rocky pools in the intertidal zone that are filled with seawater. They are formed by abrasion and weathering of less resistant rock and scouring of fractures and joints in the shore platform. This leaves holes or depressions where seawater can be collected at high tide. They can be small and shallow or deep. The smallest ones are usually found at the high intertidal zone, whereas the bigger ones are found in the lower intertidal zone. When the tide retreats, the pool becomes isolated. The water does not remain stagnant, because new water enters the pool when the tide rises. This is necessary to avoid temperature stress, salinity stress, nutrient stress,… Pools that are located higher on the beach are not regularly renewed by tides. These pools are basically freshwater or brackish water communities. It has different characteristics in comparison with other coastal habitats. Several taxa are more abundant in pools than the surrounding environment. These taxa are members of the algae and gastropods. There is also a difference in composition between high and low located pools. Low-located pools are home to whelks, mussels, sea urchins and the common periwinkle (Littorina littorea). Rough periwinkles (Littorina rudis) are found in high located pools. Other organisms that are commonly found in pools are flatworms (polycladida), marine worms (oligochaetes), rotifers, water fleas, small crustaceans (copepods, ostracods, amphipods, isopods), barnacles, and larvae of flies (chironomids). Vertical zonation also has been documented in tidal pools.[6]

Subtidal zone

The subtidal zone or sublittoral zone is the region below the intertidal zone and is continuously covered by water. This zone is far more stable than the intertidal zone. There are no strong fluctuations in temperature, water pressure and sunlight radiation. Organisms do not dry out as often as organisms higher on the beach. They grow faster and are better competitors for the same niche. They extract essential nutrients from the water and do not need to cope with extreme changes in temperature. [7] [8]


Stresses and adaptations

In this section, stresses and adaptations are discussed in more detail. The regular strong fluctuations in environmental conditions imply that organisms have to be tolerant to the associated stresses, in particular stresses related to temporary aerial exposure. Adaptations are solutions to deal with these stresses and are necessary to survive.

Oxygen

Most intertidal animals depend on aerobic respiration by extracting oxygen from water. An exception are some limpet species that live high on the shore and that have a mantle cavity adapted to breathe air, similar to a lung. Other intertidal animals have gills and cannot tolerate prolonged air exposure. Since gills only function when they are moist, these animals need to avoid desiccation. In response to desiccation stress, some sessile species (periwinkles) have adapted their gills to allow gas exchange with the air. Other species (barnacles) store air bubbles in cavities in the gills that supply oxygen to the moisture around the gills[9]. The main adaptation strategy of sessile animals to prolonged air exposure is to slow down their metabolism and associated oxygen consumption; some animals (snails) can temporarily switch to anaerobic respiration[10]. Mobile animals (crabs, chitons) mainly adapt by moving with the tide to stay underwater.

Temperature

Temperature differences can be very large in the intertidal zone. Most marine animals are ectothermic, that is, they cannot regulate their body temperature, but depend on the ambient temperature. As a result, they cannot tolerate large temperature differences. In water, temperature changes are buffered, but in the air, animals can be exposed to very cold or very hot temperatures. Especially animals with a small body weight have a hard time.

In most animals the metabolism accelerates at high temperatures and thus also the oxygen demand. However, in the intertidal area the animals can hardly absorb oxygen when the tide is low. One way of adaptation is regulation of the membrane fluidity (homeoviscous adaptation). At high temperatures, the fluidity increases, the saturated fatty acids decrease and thus the rates of metabolism and respiration[11]. The opposite happens at low temperatures. Another adaptation to harmful high ambient temperatures is the production of heat shock proteins (HSP). These proteins, which protect important enzymes against heat damage, are produced by many intertidal molluscs such as mussels, limpets, top shells and periwinkles[12][13]. Many intertidal animals can tolerate much greater temperature changes than their estuarine relatives. Possible adaptations are also light colors to reflect light or a large surface (ribbed shells) to dissipate heat. However, when cooled by evaporation, desiccation can lead to problems[14].

When the temperature is too low, the organisms must cope with physiological threats associated with cold stress. This can be the case in polar and temperate latitude coastal zones. The body fluids can then reach their freezing point and ice crystals develop. This causes damage to cell membranes and increase of the osmotic concentration of the nonfrozen fluid. Some organisms have developed antifreeze proteins (cryoprotectants). Increase of the concentration of osmolytes such as glycerol and sucrose in the body fluids increases the freezing tolerance[15]. Another strategy is to control formation and spread of internal ice crystals. When the ice formation is intracellular, it is lethal but extracellular ice formation can be tolerated. Invertebrates found naturally in seawater of high salinity are more cold-tolerant than specimens inhabitating brackish waters. In molluscs, the cold tolerance can be increased by acclimating the animals to higher salinities. This is probably based on increased concentrations of intracellular solutes such as amino acids[16].

Mobile organisms can avoid extreme temperatures by migrating to more suitable places; this is also a response to other stresses associated with emersion.

Desiccation stress

Dehydration is the main environmental factor in the supralittoral and high intertidal zones, and the green macroalgae living in these zones are exposed regularly to air, yet still survive. Desiccation tolerance can be defined as the ability to survive drying to about 10% remaining water content. Dehydration-tolerance involves maintaining homeostasis during dehydration by minimizing or repairing any damage as fast as possible[17]. Highly mobile organisms can avoid the desiccation by migrating to a region that is more suitable. Less mobile organisms restrict various activities (reduced metabolism) and attach more firmly to the substrate. Physiological features to tolerate water loss include adaptations such as: deployment of desiccation-resistant egg cases for embryonic development, reduction of the exposed surface areas across which water loss takes place (thus accepting reduced gas exchange and concomitant anaerobic respiration with accumulation of metabolic end products), temporary depression in metabolic and developmental rates, maintenance of intracellular osmolytes for water retention and macromolecular protection and differential gene expression for the production of protective macromolecules[10]. Some sessile organisms can anticipate emersion by storing water in body cavities (e.g., anemones) or mantle cavities (e.g., barnacles, mussels) [9].

Biological clock

Many intertidal animals have a biological clock that allows them to anticipate changes as a result of tides (circatidal rhythmicity) or light (circadian rhythmicity). Different signals play a role in the setting of endogenous rhythmicity in some crustaceans and crabs: water agitation, hydrostatic pressure, immersion, light and temperature cycles. Once trained after a few tidal periods, the rhythmicity is maintained. Thanks to the biological clock, the animals can adapt in time, instead of waiting for an adverse situation to arise[18].

Light

Sunlight is another parameter that influences the organisms. When there is too much sunlight, organisms dry out and the capacity to capture light energy can be weakened. The light that is not used or dissipated can cause damage to subcellular structures. Algae can protect themselves against an excess of sunlight by so-called non-photochemical quenching (NPQ): the light energy absorbed by the chlorophyll is dissipated in the form of heat or in the form of fluorescence. NPQ is a quick and effective way to prevent damage from excess sunlight. There are also several other mechanisms, such as scavenging or deactivating free radicals produced from an excess of light[19]. Too little sunlight reduces the growth and reproduction of the organism, because photosynthesis is reduced.

Salinity stress

Intertidal zone organisms can be subjected to varying salinity, especially those living in pools that are not regularly refreshed with new seawater. Rain can cause the salinity to drop and evaporation can cause the salinity to rise. Changes in salinity change the osmotic pressure in the cells of the body tissues, causing them to swell or shrink. Organisms living in estuaries have adaptations to deal with this, such as adaptation of the cell membrane, salt storage in vacuoles or glands to secrete salt. However, most intertidal organisms are osmoconformers: they cannot control the salt content of their body. In some species (e.g., periwinkle), the salinity of their tissues is similar to that of normal seawater, which is the environment that they evolved in and are adapted to[20]. Osmoregulation is more generally provided by organic osmolytes that keep intracellular fluids at the same pressure as the marine environment to avoid cell shrinkage or dilatation[21].

Predation

A wide variety of strategies to escape from predation exists. The first strategy is calcification, which makes it more difficult for the predator to eat these organisms. This strategy is applied by algae. It makes them tougher and less nutritious. A second one is the production of chemicals, usually produced as secondary metabolites. These (toxic) chemicals can be produced all the time, but other chemicals are only produced in response to stimuli (inducible defence). Another way to avoid predation is to have two distinct anatomical forms within one life cycle. This can be e.g. an alternation between a crusty form when the predator is present and a more delicate form (e.g. blade) when the predator is absent. Also the shape of the body can be a distinct evolutionary advantage. Bioluminescence is another strategy to avoid predators. Many intertidal and subtidal predators forage visually. The light is used for warning, blinding, making scare, misleading or attracting the predator. A commonly used form of protection against predation is camouflage. This can be visually or chemically. Visual camouflage means that the prey becomes invisible to the predator by using the same colors as the environment. Chemical camouflage is the passive adsorption of chemicals. The predator does not smell the prey anymore, because the smell is masked. To escape seabird predation, some animals (periwinkles, chitons and apex shells) can hide in inaccessible crevasses or between seaweed. Others, such as beach crabs, bury themselves in the sediments that often accumulate under rocks.

Wave action

One way to protect organisms from waves is permanent attachment. But this strategy cannot be used by organisms that have to move to feed themselves. These organisms make a compromise between mobility and attachment. Attachment can be done by different structures. Bivalves usually use threads (byssal threads) to attach to rocky surfaces or to other organisms, but they can also use a foot[22]. Another one is cementation. This is the case for bivalves such as oysters, scallops and some other forms. They lay on their side, with the lower valve cemented firmly to the bottom. This can be combined by reduction or enlargement of certain muscles[23][24]. Another way to be protected from waves is to burrow into the sediment or seek shelter, such as a crevasse.


Why are rocky shores important?

  • They are home to many organisms
  • They provide a nursery area for many fish and crustacean species
  • They provide shelter in areas where seaweeds reduce the wave power
  • They provide food for fishes
  • Algal beds are an important food source for rare and threatened species like sea turtles
  • The are a feeding ground at low tide for wading birds
  • They protect the hinterland


Appendix Habitat classification of sea cliffs

In the habitat classification used by the European Union [25] there are four cliff types defined by the vegetation and their geographical location all considered to be composed of 'Hard' rock:

  • 1230 Vegetated sea cliffs - Atlantic & Baltic, PAL.CLASS.: 18.21
  • 1240 Vegetated sea cliffs - Mediterranean with endemic Limonium spp., PAL.CLASS.: 18.22
  • 1250 Vegetated sea cliffs with endemic flora of the Macaronesian coasts, PAL.CLASS.: 18.23 and 18.24
  • 4040 * Dry Atlantic coastal heaths with Erica vagans, PAL.CLASS.: 31.234

'Soft' rock sea cliffs are not classified although they can be considered to be included in 1230 above.


Related articles

Rocky shore morphology


References

  1. http://www.marbef.org – Sprung M.
  2. Benson, K.R. 2002.The study of vertical zonation on rocky intertidal shores –a historic perspective. Integr. Comp. Biol. 42: 776–779
  3. http://en.wikipedia.org/wiki/Intertidal_zone
  4. Connell, J. H. 1961. The influence of intra-specific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecology 42: 710–723
  5. http://en.wikipedia.org/wiki/Tide_pool
  6. Knox G.A. 2001. The ecology of seashores. CRC Press LLC. p. 557
  7. Karleskint G. 1998. Introduction to marine biology. Harcourt Brace & Company. p.378
  8. Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford university press. p.420
  9. 9.0 9.1 Smith, D. 2013. Ecology of the New Zealand Rocky Shore Community: A Resource for NCEA Level 2 Biology. New Zealand Marine Studies Centre Publ. ISBN: 978-0-473-23177-4
  10. 10.0 10.1 Hand, S.C. and Menze, M.A. 2007. Desiccation Stress. In: (Denny, M.W. and Gaines, S.D. eds. ) Encyclopedia of Tidepools and Rocky Shores. University of California Press, p. 173-177
  11. Somero, G.H. 2002. Thermal Physiology and Vertical Zonation of Intertidal Animals: Optima, Limits, and Costs of Living. Integ. and Comp. Biol. 42: 780–789
  12. Feder, M. E. and Hofmann, G. E. 1999. Heat shock proteins, molecular chaperones, and the stress response: Evolutionary and ecological physiology. Annu. Rev. Physiol. 61: 243–282
  13. Tomanek, L. and Somero, G. N. 2000. Time course and magnitude of synthesis of heat-shock proteins in congeneric marine snails (genus Tegula) from different tidal heights. Physiol. Biochem. Zool. 73: 249–256
  14. McMahon, R.F. 1990. Thermal tolerance, evaporative water loss, air-water oxygen consumption and zonation of intertidal prosobranchs: a new synthesis. Hydrobiologia 193: 241–260
  15. Loomis, S.H. 1995. Freezing tolerance of marine invertebrates. Oceanogr. Mar. Biol. Ann. Rev. 33: 337-350
  16. Aarset, A. V. 1982. Freezing tolerance in intertidal invertebrates - a review. Comp. Biochem. and Physiol. A 73: 571–580
  17. Holzinger, A. and Karsten, U. 2013. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological, and molecular mechanisms. Frontiers in Pant Science 4, 327
  18. Naylor, E. 1976. Rhythmic behaviour and reproduction in marine animals. In: (Ed.: Newell, R.C) Adaptation to Environment: Essays on the Physiology of Marine Animals. Butterworth Publ., London, p. 393-429
  19. Erickson, E., Wakao, S. and Niyogi, K.K. 2015. Light stress and photoprotection in Chlamydomonas reinhardtii. The Plant Journal 82: 449–465
  20. Taylor, P. M. and Andrew, E. B. 1988. Osmoregulation in the intertidal gastropod Littorina littorea. Journal of Experimental Marine Biology and Ecology 122: 35-46
  21. Yancey, P.H. 2005. Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses. J. Exp. Biol. 208: 2819–2830
  22. Aguilera, M.A., Thiel, M., Ullrich, N., Luna-Jorquera, G. and Buschbaum, C. 2017. Selective byssus attachment behavior of mytilid mussels from hard- and softbottom coastal systems. Journal of Experimental Marine Biology and Ecology 497: 61-70
  23. Trussel, G.C. and Ewanchuk, P.J. 2007. Predator avoidance. In: (Denny M.W. and Gaines S.D. eds.) Encyclopedia of tidepools & rocky shores. University of California Press. p. 440-443
  24. Levinton J.S. 1995. Marine biology: function, biodiversity, ecology. Oxford University Press. p. 420
  25. European Commission, 2007. Interpretation Manual of European Habitats. Natura 2000. European Commission, DG Environment, Nature and Biodiversity, Brussels. Source: http://ec.europa.eu/environment/nature/legislation/habitatsdirective/docs/2007_07_im.pdf.


The main author of this article is TÖPKE, Katrien
Please note that others may also have edited the contents of this article.

Citation: TÖPKE, Katrien (2021): Rocky shore habitat. Available from http://www.coastalwiki.org/wiki/Rocky_shore_habitat [accessed on 21-10-2021]