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Trophic Ecology
{{disambiguation ...
Trophic, from Ancient Greek τροφικός (''trophikos'') "pertaining to food or nourishment", may refer to: * Trophic cascade * Trophic coherence * Trophic egg * Trophic function * Trophic hormone * Trophic level index * Trophic level * Trophic mutualism * Trophic pyramid * Trophic species * Trophic state index See also * Tropic (other) The term tropic refers to the tropics, a region of the Earth surrounding the Equator. Tropic or Tropics may also refer to: Places and geography * Tropic of Cancer * Tropic of Capricorn * Tropic, Florida, a town in the United States * Tropic, Uta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Cascade
Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate trophic level is a herbivore). The trophic cascade is an ecological concept which has stimulated new research in many areas of ecology. For example, it can be important for understanding the knock-on effects of removing top predators from food webs, as humans have done in many places through hunting and fishing. A top-down cascade is a trophic cascade where the top consumer/predator controls the primary consumer population. In turn, the primary producer population thrives. The removal of the top predator can alter the food web dynamics. In this case, the primary consumers would overpopulate an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Coherence
Trophic coherence is a property of directed graphs (or directed networks). It is based on the concept of trophic levels used mainly in ecology, but which can be defined for directed networks in general and provides a measure of hierarchical structure among nodes. Trophic coherence is the tendency of nodes to fall into well-defined trophic levels. It has been related to several structural and dynamical properties of directed networks, including the prevalence of cycles and network motifs, ecological stability, intervality, and spreading processes like epidemics and neuronal avalanches. Definition Consider a directed network defined by the N\times N adjacency matrix A=(a_). Each node i can be assigned a trophic level s_i according to :: s_i=1+\frac\sum_j a_ s_j, where k_i^\text=\sum_j a_ is i's in-degree, and nodes with k_i^\text=0 (basal nodes) have s_i=1 by convention. Each edge has a ''trophic difference'' associated, defined as x_=s_i-s_j. The ''trophic coherence'' of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Egg
A trophic egg, in most species that produce them, usually is an unfertilised egg because its function is not reproduction but nutrition; in essence it serves as food for offspring hatched from viable eggs. The production of trophic eggs has been observed in a highly diverse range of species, including fish, amphibians, spiders and insects. The function is not limited to any particular level of parental care, but occurs in sub-social species of insects, such as the spider '' A. ferox'', as well as a few other species like the frogs ''Leptodactylus fallax'' and ''Oophaga'', and the catfish ''Bagrus meridionalis''. Parents of some species deliver trophic eggs directly to their offspring, whereas some other species simply produce the trophic eggs after laying the viable eggs; they then leave the trophic eggs where the viable offspring are likely to find them. The mackerel sharks present the most extreme example of proximity between reproductive eggs and trophic eggs; their viable offs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Function
A trophic function was first introduced in the differential equations of the Kolmogorov predator–prey model. It generalizes the linear case of predator–prey interaction firstly described by Volterra and Lotka in the Lotka–Volterra equation. A trophic function represents the consumption of prey assuming a given number of predators. The trophic function (also referred to as the functional response) was widely applied in chemical kinetics, biophysics, mathematical physics and economics. In economics, "predator" and "prey" become various economic parameters such as prices and outputs of goods in various linked sectors such as processing and supply. These relationships, in turn, were found to behave similarly to the magnitudes in chemical kinetics, where the molecular analogues of predators and prey react chemically with each other. These inter-disciplinary findings suggest the universal character of trophic functions and the predator–prey models in which they appear. They giv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Hormone
Trophic hormones are hormones of the anterior lobe of the pituitary. These hormones affect growth, function, or nutrition of other endocrine cells. Trophic hormones can be found in body systems including the endocrine, gastrointestinal, urinary, and nervous systems. The term ''trophic'' is from Ancient Greekτροφικός (''trophikós'') meaning "pertaining to food or nourishment", here used to mean "growth"; this is the same origin as '' atrophy.'' This should not be confused with ''tropic,'' as in the similar-sounding tropic hormone – the words and concepts are both unrelated. An example of this is thyroid-stimulating hormone stimulating the thyroid; excess thyroid-stimulating hormone can create a goitre. Trophic hormones from the anterior pituitary include: * Thyroid-stimulating hormone (TSH or thyrotropin) – stimulates the thyroid gland increasing the size and number of cells. * Adrenocorticotropic hormone (ACTH or corticotropin) – stimulates the adrenal cortex incre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Level Index
The trophic level index (TLI) is used in New Zealand as a measure of nutrient status of lakes. It is similar to the trophic state index but was proposed as alternative that suited New Zealand. The system uses four criteria, phosphorus and nitrogen concentrations, as well as visual clarity and algal biomass weighted equally. See also * Water pollution in New Zealand * Lakes of New Zealand *Environment of New Zealand The environment of New Zealand is characterised by an endemic flora and fauna which has evolved in near isolation from the rest of the world. The main islands of New Zealand span two biomes, temperate and subtropical, complicated by large mount ... External linksNew Zealand Ministry for the Environment- Trophic Level Index for lakesDefinitions of the 5 trophic states - Oligotrophic, Mesotrophic, Eutrophic, Supertrophic and Hypertrophic lakes References Water in New Zealand Water pollution {{NewZealand-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Level
The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way flow or a food "web". Ecological communities with higher biodiversity form more complex trophic paths. The word ''trophic'' derives from the Greek τροφή (trophē) referring to food or nourishment. History The concept of trophic level was developed by Raymond Lindeman (1942), based on the terminology of August Thienemann (1926): "producers", "consumers" and "reducers" (modified to "decomposers" by Lindeman). Overview The three basic ways in which org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Mutualism
Trophic mutualism is a key type of ecological mutualism. Specifically, "trophic mutualism" refers to the transfer of energy and nutrients between two species. This is also sometimes known as resource-to-resource mutualism. Trophic mutualism often occurs between an autotroph and a heterotroph. Although there are many examples of trophic mutualisms, the heterotroph is generally a fungus or bacteria. This mutualism can be both obligate and opportunistic. Examples *Rhizobia – Rhizobia are bacteria that conduct nitrogen fixation for legume plants. Specifically, these bacteria can be from genera ''Allorhizobium, Azorhizobium, Bradyrhizobium, Mesorhizobium, Rhizobium, or Sinorhizobium''.Vessey, K.J., K. Pawlowski, and B. Bergman, Root-based N2-fixing symbioses: Legumes, actinorhizal plants, Parasponiasp. and cycads. Plant and Soil 2005. 266(1-2): p. 205-230. In this mutualistic relationship, the bacteria grow on or within the root hair and penetrate into the plant tissuesTownsend, C.R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Pyramid
An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bioproductivity at each trophic level in a given ecosystem. A ''pyramid of energy'' shows how much energy is retained in the form of new biomass at each trophic level, while a ''pyramid of biomass'' shows how much biomass (the amount of living or organic matter present in an organism) is present in the organisms. There is also a ''pyramid of numbers'' representing the number of individual organisms at each trophic level. Pyramids of energy are normally upright, but other pyramids can be inverted or take other shapes. Ecological pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain. Biom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic Species
Trophic species are a scientific grouping of organisms according to their shared trophic (feeding) positions in a food web or food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det .... Trophic species have identical prey and a shared set of predators in the food web. This means that members of a trophic species share many of the same kinds of ecological functions. The idea of trophic species was first devised by Joel Cohen and Frederick Briand in 1984 to redefine assessment of the ratio of predators to prey within a food web. The category may include species of plant, animal, a combination of plant and animal, and biological stages of an organism. The reassessment grouped similar species according to habit rather than genetics. This resulted in a ratio of predator to prey in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic State Index
The Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed. The TSI of a water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: * oligotrophic (TSI 0–40, having the least amount of biological productivity, "good" water quality); * mesotrophic (TSI 40–60, having a moderate level of biological productivity, "fair" water quality); or * eutrophic to hypereutrophic (TSI 60–100, having the highest amount of biological productivity, "poor" water quality). The quantities of nitrogen, phosphorus, and other biologically useful nutrients are the primary determinants of a water body's TSI. Nutrients such as nitrogen and phosphorus tend to be limiting resources in standing water bodies, so increased concentrations tend to result in increased p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
