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| Ocean habitats |
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| aquatic ecosystem |
| continental shelf |
| neritic zone |
| littoral zone |
| intertidal |
| pelagic zone |
| demersal zone |
| benthic zone |
| benthic life |
| coral reefs |
| estuaries |
| seamounts |
| fishing banks |
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Intertidal ecology is the study of intertidal ecosystems, where organisms live between the low and high tide lines. A biome is a climatically and geographically defined area of ecologically similar climatic conditions such as communities of Plants Animals and An aquatic ecosystem is an Ecosystem located in water bodies. The continental shelf is the extended perimeter of each Continent and associated Coastal plain, which is covered during interglacial periods such The neritic zone, also called the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the Continental shelf, with a relatively Littoral refers to the coast of an ocean or sea or to the banks of a river lake or estuary Any water in the sea that is not close to the bottom is in the pelagic zone. The demersal zone is the part of the Sea or Ocean (or deep Lake) comprising the Water column that is near to (and is significantly affected The benthic zone is the ecological region at the lowest level of a Body of water such as an Ocean or a Lake, including the sediment surface and some sub-surface Benthos are the organisms which live on in or near the Seabed, also known as the Benthic zone. Coral reefs are Aragonite structures produced by living organisms found in marine waters with little to no nutrients in the water An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open A seamount is a Mountain rising from the Ocean Seafloor that does not reach to the water's surface ( Sea level) and thus is not an Island Anjajavy Forest is an element of the Madagascar dry deciduous forests situated on the Indian Ocean of northwest Madagascar. The Indian Ocean is the third largest of the world's Oceanic divisions covering about 20% of the water on the Earth 's surface An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood At low tide, the intertidal is exposed (or ‘emersed’) whereas at high tide, the intertidal is underwater (or ‘immersed’). Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community. Ecology (from Greek grc οἶκος oikos, "house(hold" and grc -λογία -logia) is the scientific study of Biological interactions result from the fact that Organisms in an Ecosystem interact with each other in the natural world no organism is an autonomous entity isolated The most important environmental and species interactions may vary based on the type of intertidal community being studied, the broadest of classifications being based on substrates - rocky shore and soft bottom communities. A rocky shore is an Intertidal area on Seacoasts where solid rock predominates
Organisms living in this zone have a highly variable and often hostile environment, and have evolved various adaptations to cope with and even exploit these conditions. An adaptation is a characteristic of an Organism that has been favored by Natural selection and One easily visible feature of intertidal communities is vertical zonation, where the community is divided into distinct vertical bands of specific species going up the shore. Species ability to cope with desiccation determines their upper limits, while competition with other species sets their lower limits. Desiccation is the state of extreme dryness or the process of extreme drying Competition can be defined as an interaction between Organisms or Species, in which the fitness of one is lowered by the presence of another
Intertidal regions are utilized by humans for food and recreation, but anthropogenic actions also have major impacts, with overexploitation, invasive species and climate change being among the problems faced by intertidal communities. Resource exploitation refers to the use of natural resources to satisfy our wants and needs Exploitation of natural resources is an essential condition of the Introduced species|Weed Invasive species is a phrase with several definitions Global warming is the increase in the average measured temperature of the In some places Marine Protected Areas have been established to protect these areas and aid in scientific research. Marine Protected Area (MPA is often used as an umbrella term covering a wide range of marine areas with some level of restriction to protect living non-living cultural and/or historic Scientific method refers to bodies of Techniques for investigating phenomena
Contents |
Types of intertidal communities
Intertidal habitats can be characterized as having either hard or soft bottoms or substrates. Rocky intertidal communities occur on rocky shores, such as headlands, cobble beaches, or human-made jetties. Their degree of exposure may be calculated using the Ballantine Scale. The Ballantine Scale is a biologically defined scale for comparing the degree of exposure of rocky shores the species present indicate the degree of the shore's exposure Soft-sediment habitats include sandy beaches, mudflats, and salt marshes. A salt marsh is a type of Marsh that is a transitional intertidal between land and salty or Brackish water (e These habitats differ in levels of ‘abiotic’, or non-living, environmental factors. In Biology, abiotic components are non-living Chemical and Physical factors in the environment. Rocky shores tend to have higher wave action, requiring adaptations allowing the inhabitants to cling tightly to the rocks. Soft-bottom habitats are generally protected from large waves but tend to have more variable salinity levels. Salinity is the Saltiness or dissolved salt content of a body of Water. They also offer a third habitable dimension—depth—thus, many soft-sediment inhabitants are adapted for burrowing.
Environment
Because intertidal organisms endure regular periods of immersion and emersion, they essentially live both underwater and on land and must be adapted to a large range of climatic conditions. The intensity of climate stressors varies with elevation (or ‘relative tide height’) because organisms living at higher tide heights are emersed for longer periods than those living at lower tide heights. This gradient of climate with tide height leads to patterns of intertidal zonation, with ‘high intertidal’ species being more adapted to emersion stresses than ‘low intertidal’ species. These adaptations may be behavioral (i. e. movements or actions), morphological (i. e. characteristics of external body structure), or physiological (i. e. internal functions of cells and organs). [1] In addition, such adaptations generally ‘cost’ the organism in terms of energy (e. g. to move or to grow certain structures), leading to ‘trade-offs’ (i. e. ‘spending’ more energy on deterring predators leaves less energy for other functions like reproduction).
Intertidal organisms, especially those in the high intertidal, must cope with a large range of temperatures. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature While they are underwater, temperatures may only vary by a few degrees over the year. However, at low tide, temperatures may dip to below freezing or may become scaldingly hot, leading to a temperature range that may approach 30°C (86°F) during a period of a few hours. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Many mobile organisms, such as snails and crabs, avoid temperature fluctuations by crawling around and searching for food at high tide and hiding in cool, moist refuges (crevices or burrows) at low tide. [2]Besides simply living at lower tide heights, non-motile organisms may be relatively more dependent on coping mechanisms. For example, high intertidal organisms have a stronger ‘stress response’, a physiological response of making proteins that help recovery from temperature stress just as the immune response aids in the recovery from infection.
Intertidal organisms are also especially prone to desiccation (drying out) during periods of emersion. Again, mobile organisms avoid desiccation in the same way as they avoid extreme temperatures: by hunkering down in mild and moist refuges. Many intertidal organisms, including Littorina snails, prevent water loss by having waterproof outer surfaces, pulling completely into their shells, and sealing shut their shell opening. Limpets (Patella) do not use such a sealing plate but occupy a home-scar to which they seal the lower edge of their flattened conical shell using a grinding action. They return to this home-scar after each grazing excursion, typically just before emersion. On soft rocks, these scars are quite obvious. Still other organisms, such as the algae Ulva and Porphyra, are able to rehydrate and recover after periods of severe desiccation.
The level of salinity can also be quite variable. Salinity is the Saltiness or dissolved salt content of a body of Water. Low salinities can be caused by rainwater or river inputs of freshwater. Estuarine species must be especially ‘euryhaline’, or able to tolerate a wide range of salinities. High salinities occur in locations with high evaporation rates, such as in salt marshes and high intertidal pools. Shading by plants, especially in the salt marsh, can slow evaporation and thus ameliorate salinity stress. In addition, salt marsh plants tolerate high salinities by several physiological mechanisms, including excreting salt through salt glands and preventing salt uptake into the roots.
In addition to these ‘exposure’ stresses (temperature, desiccation, and salinity), intertidal organisms experience strong ‘mechanical’ stresses, especially in locations of high wave action. A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. There are myriad ways in which the organisms prevent dislodgement due to waves. Morphologically, many mollusks (such as limpets and chitons) have low-profile, hydrodynamic shells. Types of substrate attachments include mussels’ tethering byssal threads and glues, sea stars’ thousands of suctioning tube feet, and isopods’ hook-like appendages that help them hold onto intertidal kelps. Higher profile organisms, such as kelps, must also avoid breaking in high flow locations, and they do so with their strength and flexibility. Finally, organisms can also avoid high flow environments, such as by seeking out low flow microhabitats. Additional forms of mechanical stresses include ice and sand scour, as well as dislodgment by water-borne rocks, logs, etc.
For each of these climate stresses, species exist that are adapted to and thrive in the most stressful of locations. For example, the tiny crustacean copepod Tigriopus thrives in very salty, high intertidal tidepools, and many filter feeders find more to eat in wavier and higher flow locations. Filter feeders (also known as suspension feeders) are Animals that feed by straining suspended matter and food particles from water typically by passing the water Adapting to such challenging environments gives these species competitive edges in such locations.
Food web structure
During tidal immersion, the food supply to intertidal organisms is subsidized by materials carried in seawater, including photosynthesizing phytoplankton and consumer zooplankton. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Phytoplankton are the Autotrophic component of the Plankton community These plankton are eaten by numerous forms of filter feeders—mussels, clams, barnacles, sea squirts, and polychaete worms—which filter seawater in their search for planktonic food sources. Plankton consist of any drifting Organisms ( Animals Plants Archaea, or Bacteria) that inhabit the Pelagic zone of Filter feeders (also known as suspension feeders) are Animals that feed by straining suspended matter and food particles from water typically by passing the water The common name mussel is used for members of several different families of Clams or Bivalve Molluscs, from both saltwater and freshwater habitats Clam is a word which can be used for all some or only a few Species of Bivalve Mollusks the word is a Common name which has A barnacle is a type of Arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence distantly related to Tunicate, also known as urochordata, tunicata (and by the common names of urochordates, sea squirts, and sea pork) is the The Polychaeta or polychaetes are a class of Annelid worms generally marine The adjacent ocean is also a primary source of nutrients for autotrophs, photosynthesizing producers ranging in size from microscopic algae (e. An autotroph (from the Greek autos = self and trophe = nutrition is an Organism that produces complex Organic compounds from simple Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms g. benthic diatoms) to huge kelps and other seaweeds. Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i Kelp are large Seaweeds ( Algae) belonging to the Brown algae and classified in the order Laminariales Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae. These intertidal producers are eaten by herbivorous grazers, such as limpets that scrape rocks clean of their diatom layer and kelp crabs that creep along blades of the feather boa kelp Egregia eating the tiny leaf-shaped bladelets. The name Limpet is used for many kinds of mostly saltwater but also freshwater Snails specifically those that have a simple shell which is more or less broadly conical Crabs are decapod Crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (βραχύ / brachy Crabs are eaten by jew fish (Goliath Grouper), which are then eaten by sharks. Higher up the food web, predatory consumers—especially voracious starfish—eat other grazers (e. Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. Starfish (also called sea stars) are any Echinoderms belonging to the class Asteroidea. g. snails) and filter feeders (e. The word snail is a Common name that can be used for almost all members of the Molluscan class Gastropoda which have coiled shells in the g. mussels). Finally, scavengers, including crabs and sand fleas, eat dead organic material, including dead producers and consumers. Scavenging, or necrophagy, is a Carnivorous Feeding behaviour in which a predator consumes Corpses or Carrion that were killed Amphipoda (amphipods are an order of animals that includes over 7000 described Species of Shrimp -like Crustaceans ranging from 1 mm to 140 mm
Species interactions
In addition to being shaped by aspects of climate, intertidal habitats—especially intertidal zonation patterns—are strongly influenced by species interactions, such as predation, competition, facilitation, and indirect interactions. Ultimately, these interactions feed into the food web structure, described above. Intertidal habitats have been a model system for many classic ecological studies, including those introduced below, because the resident communities are particularly amenable to experimentation.
One dogma of intertidal ecology—supported by such classic studies—is that species’ lower tide height limits are set by species interactions whereas their upper limits are set by climate variables. Classic studies by Robert Paine[3][4] established that when sea star predators are removed, mussel beds extend to lower tide heights, smothering resident seaweeds. Thus, mussels’ lower limits are set by sea star predation. Conversely, in the presence of sea stars, mussels’ lower limits occur at a tide height at which sea stars are unable to tolerate climate conditions.
Competition, especially for space, is another dominant interaction structuring intertidal communities. Space competition is especially fierce in rocky intertidal habitats, where habitable space is limited compared to soft-sediment habitats in which three-dimensional space is available. As seen with the previous sea star example, mussels are competitively dominant when they are not kept in check by sea star predation. Joseph Connell’s research on two types of high intertidal barnacles, a Balanus and a Chthamalus species, showed that zonation patterns could also be set by competition between closely related organisms. [5] In this example, Balanus outcompetes Chthamalus at lower tide heights but is unable to survive at higher tide heights. Thus, Balanus conforms to the intertidal ecology dogma introduced above: its lower tide height limit is set by a predatory snail and its higher tide height limit is set by climate. Similarly, Chthamalus, which occurs in a refuge from competition (similar to the temperature refuges discussed above), has a lower tide height limit set by competition with Balanus and a higher tide height limit is set by climate.
Although intertidal ecology has traditionally focused on these negative interactions (predation and competition), there is emerging evidence that positive interactions are also important. [6] Facilitation refers to one organism ‘helping’ another without harming itself (note: in predation, the prey ‘helps’ the predator, but at great harm to itself!). For example, salt marsh plant species of Juncus and Iva are unable to tolerate the high soil salinities when evaporation rates are high, thus they depend on neighboring plants to shade the sediment, slow evaporation, and help maintain tolerable salinity levels. [7] In similar examples, many intertidal organisms provide physical structures that are used as refuges by other organisms. Mussels, although they are tough competitors with certain species, are also good facilitators as mussel beds provide a three-dimensional habitat to species of snails, worms, and crustaceans.
All of the examples given so far are of ‘direct’ interactions: Species A eat Species B or Species B eats Species C. Also important are indirect interactions[8] where, using the previous example, Species A eats so much of Species B that predation on Species C decreases and Species C increases in number. Thus, Species A indirectly benefits Species C. Pathways of indirect interactions can include all other forms of species interactions. To follow the sea star-mussel relationship, sea stars have an indirect negative effect on the diverse community that lives in the mussel bed because, by preying on mussels and decreasing mussel bed structure, those species that are facilitated by mussels are left homeless. Additional important species interactions include mutualism, which is seen in symbioses between sea anemones and their internal symbiotic algae, and parasitism, which is prevalent but is only beginning to be appreciated for its effects on community structure. Mutualism is a Biological interaction between individuals of two different Species, where both individuals derive a fitness benefit for example increased Parasitism is a type of symbiotic relationship between Organisms of different Species.
Current topics
Humans are highly dependent on intertidal habitats for food and raw materials[9], and over 50% of humans live within 100 km of the coast. Therefore, intertidal habitats are greatly influenced by human impacts to both ocean and land habitats. Some of the conservation issues associated with intertidal habitats and at the head of the agendas of managers and intertidal ecologists are:
1. Climate change: Intertidal species are challenged by several of the effects of global climate change, including increased temperatures, sea level rise, and increased storminess. Climate change is any long-term significant change in the “average weather” that a given region experiences Sea-level rise is an increase in Sea level. Multiple complex factors may influence this change Ultimately, it has been predicted that the distributions and numbers of species will shift depending on their abilities to adapt (relatively quickly!) to these new environmental conditions. [9] Due to the global scale of this issue, scientists are mainly working to understand and predict possible changes to intertidal habitats.
2. Invasive species: Invasive species are especially prevalent in intertidal areas with high volumes of shipping traffic, such as large estuaries, because of the transport of non-native species in ballast water. Introduced species|Weed Invasive species is a phrase with several definitions Ballast is used in Sailboats to provide moment to resist the lateral forces on the Sail. [10] San Francisco Bay, in which an invasive Spartina cordgrass from the east coast is currently transforming mudflat communities into Spartina meadows, is among the most invaded estuaries in the world. Spartina, commonly known as cordgrass or cord-grass, contains 14 Species, native to the coasts of the Atlantic Ocean in western and southern Conservation efforts are focused on trying to eradicate some species (like Spartina) in their non-native habitats as well as preventing further species introductions (e. g. by controlling methods of ballast water uptake and release).
3. Marine protected areas: Many intertidal areas are lightly to heavily exploited by humans for food gathering (e. Marine Protected Area (MPA is often used as an umbrella term covering a wide range of marine areas with some level of restriction to protect living non-living cultural and/or historic g. clam digging in soft-sediment habitats and snail, mussel, and algal collecting in rocky intertidal habitats). In some locations, marine protected areas have been established where no collecting is permitted. The benefits of protected areas may spill over to positively impact adjacent unprotected areas. For example, a greater number of larger egg capsules of the edible snail Concholepus in protected vs. non-protected areas in Chile indicates that these protected areas may help replenish snail stocks in areas open to harvesting. [11] The degree to which collecting is regulated by law differs with the species and habitat.
See also
References
Cited
- ^ Somero, G. As Ocean surface waves come closer to Shore they break forming the foamy bubbly surface we call surf. N. 2002. Thermal physiology and vertical zonation of intertidal animals: optima, limits, and cost of living. Integrative and Comparative Biology 42:780-789.
- ^ Burnaford, J. L. 2004. Habitat modification and refuge from sublethal stress drive a marine plant-herbivore association. Ecology 85:2837-2849.
- ^ Paine, R. T. 1966. Food web complexity and species diversity. American Naturalist 100:65-75.
- ^ Paine, R. T. 1974. Intertidal community structure: experimental studies on the relationship between a dominant competitor and its principal predator. Oecologia 15:93-120. Oecologia is an international peer-reviewed English language journal that publishes original research into topics related to Ecology.
- ^ Connell, J. H. 1961. The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecology 42:710-723.
- ^ Bruno, J. F. , J. J. Stachowicz, and M. D. Bertness. 2003. Inclusion of facilitation into ecological theory. Trends in Ecology and Evolution 18:119-125.
- ^ Bertness, M. D. , and S. D. Hacker. 1994. Physical stress and positive associations among marsh plants. American Naturalist 144:363-372.
- ^ Menge, B. A. 1995. Indirect effects in marine rocky intertidal interaction webs: patterns and importance. Ecological Monographs 65:21-74.
- ^ a b Harley, C. D. G. , A. R. Hughes, K. M. Hultgren, B. G. Miner, C. J. B. Sorte, C. S. Thornber, L. F. Rodriguez, L. Tomanek, and S. L. Williams. 2006. The impacts of climate change in coastal marine systems. Ecology Letters 9:228-241.
- ^ Cohen, A. N. , and J. T. Carlton. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279:555-558.
- ^ Manriquez, P. H. , and J. C. Castilla. 2001. Significance of marine protected areas in central Chile as seeding grounds for the gastropod Concholepus concholepus. Marine Ecology Progress Series 215:201-211.
General
- Bertness, M. D. , S. D. Gaines, and M. E. Hay. 2001. Marine community ecology. Sinauer Associates, Inc. , Sunderland, Massachusetts, USA.
- Kozloff, E. N. 1973. Seashore life of the northern Pacific coast. University of Washington Press, Seattle, Washington, USA.
- Ricketts, E. F. , J. Calvin, and J. W. Hedgpeth. 1939. Between Pacific tides (5th Ed. ). Stanford University Press, Stanford, California, USA.
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