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Encyclopedia > Trophic cascade

Trophic cascades occur when predators in a food chain suppress the abundance of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate trophic level is an herbivore). For example, if the abundance of large piscivorous fish is increased in a lake, the abundance of their prey, zooplanktivorous fish, should decrease, large zooplankton abundance should increase, and phytoplankton biomass should decrease. This theory has stimulated new research in many areas of ecology. Trophic cascades may also be important for understanding the effects of removing top predators from food webs, as humans have done in many places through hunting and fishing activities. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... This article or section does not adequately cite its references or sources. ... Prey can refer to: Look up Prey in Wiktionary, the free dictionary A prey animal eaten by a predator in an act called predation. ... In ecology, the trophic level (Greek trophē, food) is the position that an organism occupies in a food chain - what it eats, and what eats it. ... [[Image:Hawk eating prey. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... In ecology, the trophic level (Greek trophē, food) is the position that an organism occupies in a food chain - what it eats, and what eats it. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... This page is a candidate to be moved to Wiktionary. ... A man-made lake in Keukenhof, Netherlands A lake is a body of water or other liquid of considerable size contained on a body of land. ... Prey can refer to: Look up Prey in Wiktionary, the free dictionary A prey animal eaten by a predator in an act called predation. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... Switchgrass, a hardy plant used in the biofuel industry in the United States Rice chaff. ... Ernst Haeckel coined the term oekologie in 1866. ...

Contents

Origins and Theory

Nelson G. Hairston, Frederick E. Smith and Lawrence B. Slobodkin are generally credited with originating the concept of a trophic cascade, although they did not use the term. Hairston, Smith and Slobodkin argued that predators reduce the abundance of herbivores, allowing plants to flourish[1]. This is often referred to as the green world hypothesis. The green world hypothesis is credited with bringing attention to the role of top-down forces (eg predation) and indirect effects in shaping ecological communities. The prevailing view of communities prior to Hairston, Smith and Slobodkin was trophodynamics, which attempted to explain the structure of communities using only bottom-up forces (eg resource limitation). Smith may have been inspired by the experiments of a Czech ecologist, Hrbáček, whom he met on a United States State Department cultural exchange. Hrbáček had shown that fish in artificial ponds reduced the abundance of zooplankton, leading to an increase in the abundance of phytoplankton [2]. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... [[Image:Hawk eating prey. ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... The United States Department of State, often referred to as the State Department, is the Cabinet-level foreign affairs agency of the United States government, equivalent to foreign ministries in other countries. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... A pond is typically a man made body of water smaller than a lake. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ...


Hairston, Smith and Slobodkin argued that the ecological communities acted as food chains with three trophic levels. Subsequent models expanded the argument to food chains with more than or fewer than three trophic levels[3]. Lauri Oksanen argued that the top trophic level in a food chain increases the abundance of producers in food chains with an odd number of trophic levels (such as in Hairston, Smith and Slobodkin's three trophic level model), but decreases the abundance of the producers in food chains with an even number of trophic levels. Additionally, he argued that the number of trophic levels in a food chain increases as the productivity of the ecosystem increases. A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... Figure 1. ... Figure 1. ... This article or section does not adequately cite its references or sources. ... Primary productivity is the amount of light energy converted to chemical energy in a given amount of time. ... Figure 1. ... Primary productivity is the amount of light energy converted to chemical energy in a given amount of time. ... Figure 1. ... This article or section does not adequately cite its references or sources. ... An ecosystem, a contraction of ecological and system, refers to the collection of biotic and abiotic components and processes that comprise and govern the behavior of some defined subset of the biosphere. ...


Criticisms

Although the existence of trophic cascades is not controversial, ecologists have long debated how ubiquitous they are. Hairston, Smith and Slobodkin argued that terrestrial ecosystems, as a rule, behave as a three trophic level trophic cascade, which provoked immediate controversy. Some of the criticisms, both of Hairston, Smith and Slobodkin's model and of Oksanen's later model, were: Terrestrial literally means of the earth and is used in a variety of contexts: In biology and in the general sense, terrestrial means indicates ground-dwelling (compare aquatic). ... In ecology, an ecosystem is a community of organisms (plant, animal and other living organisms - also referred as biocenose) together with their environment (or biotope), functioning as a unit. ... In ecology, the trophic level (Greek trophē, food) is the position that an organism occupies in a food chain - what it eats, and what eats it. ...

  1. Opponents of pointed out that plants possess numerous defenses against herbivory, and that these defenses also contribute to reducing the impact of herbivores on plant populations [4].
  2. Additionally, herbivore populations may be limited by factors other than food or predation, such as nesting sites or available territory[5].
  3. For trophic cascades to be ubiquitous, communities must generally act as food chains, with discrete trophic levels. Most communities, however, have complex food webs. In real food webs consumers often feed at multiple trophic levels (omnivory), organisms often change their diet as they grow larger, cannibalism occurs, and consumers are subsidized by inputs of resources from outside the local community, all of which blur the distinctions between trophic levels[6]

u fuck in ua ... Plants have evolved an enormous array of mechanical and chemical defenses against the animals that eat them. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... Figure 1. ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... Figure 1. ... Figure 1. ... In nutrition, the diet is the sum of food consumed by a person or other organism. ... This article or section does not cite its references or sources. ...

Classic Examples

Although Hairston, Smith and Slobodkin formulated their argument in terms of terrestrial food chains, the earliest empirical demonstrations of trophic cascades came marine and, especially, aquatic ecosystems. Some of the most famous examples are: Terrestrial literally means of the earth and is used in a variety of contexts: In biology and in the general sense, terrestrial means indicates ground-dwelling (compare aquatic). ... Figure 1. ... Marine is an umbrella term for things relating to the ocean, as with marine biology, marine geology, and as a term for a navy, etc. ... Look up aquatic in Wiktionary, the free dictionary. ... In ecology, an ecosystem is a community of organisms (plant, animal and other living organisms - also referred as biocenose) together with their environment (or biotope), functioning as a unit. ...

  1. In North American lakes, piscivorous fish can dramatically reduce populations of zooplanktivorous fish, zooplanktivorous fish can dramatically alter freshwater zooplankton communities, and zooplankton grazing can in turn have large impacts on phytoplankton communities. Removal of piscivorous fish can change lake water from clear to green by allowing phytoplankton to flourish[7].
  2. In the Eel River, in Northern California, fish (steelhead and roach) consume fish larvae and predatory insects. These smaller predators prey on midge larvae, which feed on algae. Removal of the larger fish increases the abundance of algae[8].
  3. In Pacific kelp forests, sea otters feed on sea urchins. In areas where sea otters have been hunted to extinction, sea urchins increase in abundance and decimate kelp[9]

World map showing North America A satellite composite image of North America. ... Lake Clearwater, Ontario, Canada A lake is a large body of water, usually fresh water, surrounded by land. ... This page is a candidate to be moved to Wiktionary. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... This page is a candidate to be moved to Wiktionary. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... A man-made lake in Keukenhof, Netherlands A lake is a body of water or other liquid of considerable size contained on a body of land. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... The Eel River is a major river of the northern Pacific coast of California in the United States. ... Official language(s) English Capital  Sacramento Largest city  Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... It has been suggested that this article or section be merged into Rainbow trout. ... For other uses, see Roach. ... Orders Subclass Apterygota Symphypleona - globular springtails Subclass Archaeognatha (jumping bristletails) Subclass Dicondylia Monura - extinct Thysanura (common bristletails) Subclass Pterygota Diaphanopteroidea - extinct Palaeodictyoptera - extinct Megasecoptera - extinct Archodonata - extinct Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Blattodea (cockroaches) Mantodea (mantids) Isoptera (termites) Zoraptera Grylloblattodea Dermaptera (earwigs) Plecoptera (stoneflies) Orthoptera (grasshoppers, crickets... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Midges on a Toyota Midges are small, two-winged flying insects. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... The Pacific Ocean (from the Latin name Mare Pacificum, peaceful sea, bestowed upon it by the Portuguese explorer Ferdinand Magellan)is the largest body of water on Earth – at 165. ... Kelp Forest Kelp forests are a type of marine ecosystem established around colonies of kelp; they contain rich biodiversity. ... Binomial name Enhydra lutris (Linnaeus, 1758) The Sea Otter (Enhydra lutris) is a large otter native to the North Pacific, from northern Japan and Kamchatka west across the Aleutian Islands south to California. ... Subclasses Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida Perischoechinoidea Order Cidaroida (pencil urchins) Sea urchins are small spiny sea creatures... Binomial name Enhydra lutris (Linnaeus, 1758) The Sea Otter (Enhydra lutris) is a large otter native to the North Pacific, from northern Japan and Kamchatka west across the Aleutian Islands south to California. ... Hunter and Huntress redirect here. ... The Dodo, shown here in illustration, is an often-cited[1] example of extinction. ... Subclasses Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida Perischoechinoidea Order Cidaroida (pencil urchins) Sea urchins are small spiny sea creatures... Families Alariaceae Chordaceae Laminariaceae Lessoniaceae Phyllariaceae Pseudochordaceae Kelp are large seaweeds (algae), belonging to the brown algae and classified in the order Laminariales. ...

Terrestrial Trophic Cascades?

The fact that the earliest documented trophic cascades all occurred in lakes and streams lead Donald Strong to speculate that fundamental differences between aquatic and terrestrial food webs made trophic cascades primarily an aquatic phenomenon[10]. Strong argued that trophic cascades were restricted to communities with relatively low species diversity, in which a small number of species could have overwhelming influence and the food web could operate as a linear food chain. Additionally, well documented trophic cascades at that point in time all occurred in food chains with algae as the primary producer. Trophic cascades, Strong argued, may only occur in communities with fast-growing producers which lack defenses against herbivory. A man-made lake in Keukenhof, Netherlands A lake is a body of water or other liquid of considerable size contained on a body of land. ... Butchers Creek, Omeo, Victoria A stream, brook, beck, burn or creek, is a body of water with a detectable current, confined within a bed and banks. ... Figure 1. ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... Rainforests are among the most biodiverse ecosystems on earth Biodiversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... The term primary producer (or autotroph) describes a trophic level in an ecosystem that includes all organisms which make their own food. ...


Subsequent research has documented trophic cascades in terrestrial ecosystems, including:

  1. In the coastal prairie of Northern California, yellow bush lupines are fed upon by a particularly destructive herbivore, the root-boring caterpillar of the ghost moth. Entomopathogenic nematodes kill the caterpillars, and can increase the survival and seed production of lupines[11] [12].
  2. In Costa Rican rain forest, a Clerid beetle specializes in eating ants. The ant Pheidole bicornis has a mutualistic association with Piper plants: the ant lives on the Piper and removes caterpillars and other insect herbivores. The Clerid beetle, by reducing the abundance of ants, increases the leaf area removed from Piper plants by insect herbivores[13]

Critics pointed out, however, that published terrestrial trophic cascades generally involved smaller subsets of the food web (often only a single plant species). This was quite different from aquatic trophic cascades, in which the biomass of producers as a whole were reduced when predators were removed. Additionally, most terrestrial trophic cascades did not demonstrate reduced plant biomass when predators were removed, but only increased plant damage from herbivores[14]. It was unclear if such damage would actually result in reduced plant biomass or abundance. In a recent meta-analysis, trophic cascades were generally weaker in terrestrial ecosystems, meaning that changes in predator biomass resulted in smaller changes in plant biomass[15]. California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon. ... Official language(s) English Capital  Sacramento Largest city  Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... Nematodes emerging from a wax moth cadaver. ... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... A rainforest is a forested biome with high annual rainfall. ... Families See text. ... Suborders Adephaga Archostemata Myxophaga Polyphaga See subgroups of the order Coleoptera Beetles are the most diverse group of insects. ... Wikipedia does not yet have an article with this exact name. ... Subfamilies Aenictogitoninae Agroecomyrmecinae Amblyoponinae (incl. ... Ant-aphid mutualism: the aphids are protected against predators by the ants who cultivate the aphids for their secretions of honeydew, a food source. ... Species See text. ... Caterpillar of the Emperor Gum Moth A caterpillar is the larval form of a lepidopteran (a member of the insect order comprised of butterflies and moths). ... Orders See taxonomy Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species—more than all other animal groups combined. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... A meta-analysis is a statistical practice of combining the results of a number of studies. ...


See Also

Food web, Soil food web, Lake ecology, Stream ecology Figure 1. ... Soil Food Web The Soil food web describes a complex living system in the soil and how it interacts with the environment, plants, and animals. ... Fig. ... This brook is an example of a lotic system. ...


Notes

  1. ^ Hairston NG, Smith FE, Slobodkin LB (1960) Community structure, population control and competition. American Naturalist 94:421-425
  2. ^ Hrbáček J, Dvořakova M, Kořínek V, Procházkóva L (1961) Demonstration of the effect of the fish stock on the species composition of zooplankton and the intensity of metabolism of the whole plankton association. Verh. Internat. Verein. Limnol. 14: 192-195
  3. ^ Oksanen L, Fretwell SD, Arruda J, Niemala P (1981) Exploitation ecosystems in gradients of primary productivity. American Naturalist 118:240-261
  4. ^ Murdoch WM (1966) Community structure, population control, and competition -- a critique. American Naturalist 100:219-226
  5. ^ Murdoch WM (1966) Community structure, population control, and competition -- a critique. American Naturalist 100:219-226
  6. ^ Polis GA, Strong DR (1996) Food web complexity and community dynamics. American Naturalist 147: 813-846
  7. ^ Carpenter SR, Kitchell JF, Hodgson JR (1985) Cascading trophic interactions and lake productivity. Bioscience 35:634-639
  8. ^ Power ME (1990) Effects of fish in river food webs. Science 250: 811-814
  9. ^ Estes JA, Palmisano JF (1974) Sea otters: their role in structuring nearshore communities. Science 185: 1058-1060
  10. ^ Strong DR (1992) Are trophic cascades all wet? Differentiation and donor-control in speciose ecosystems. Ecology 73:747-754
  11. ^ Strong DR, Whipple AV, Child AL, Dennis B (1999) Model selection for a subterranean trophic cascade: Root-feeding caterpillars and entomopathogenic nematodes. Ecology 80:2750-2761
  12. ^ Preisser EL (2003) Field evidence for a rapidly cascading underground food web. Ecology 84: 869-874
  13. ^ Letourneau DK, Dyer LA (1998) Experimental test in lowland tropical forest shows top-down effects through four trophic levels Ecology 79:1678-1687
  14. ^ Polis GA, Sears ALW, Huxel GR, et al. (2000) When is a trophic cascade a trophic cascade? Trends in Ecology & Evolution 15: 473-475
  15. ^ Shurin JB, Borer ET, Seabloom EW, Anderson K, Blanchette CA, Broitman B, Cooper SD, Halpern BS (2002) A cross-ecosystem comparison of the strength of trophic cascades. Ecological Letters 5:785-791

 
 

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