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Sander Canadense
The sauger (''Sander canadensis'') is a freshwater perciform fish of the family Percidae that resembles its close relative, the walleye. The species is a member of the largest vertebrate order, the Perciformes.Jaeger, Matthew. 2004. Montana's Fish Species of Special Concern: Sauger. Montana Cooperative Fisheries Research Unit. http://www.fisheriessociety.org/AFSmontana/SSCpages/Sauger%20Status.htm. (Accessed May 2011). It is the most migratory percid species in North America.Kuhn et al. 2008. Habitat Use and Movement Patterns by Adult Saugers from fall to Summer in an Unimpounded Small-River System. ''North American Journal of Fisheries Management''. 28: 360-367. American Fisheries Society. 2008. Saugers have two dorsal fins; the first is spiny and the posterior dorsal fin is soft-rayed. Their paired fins are in the thoracic position and their caudal fin is truncated, which means squared off at the corners, a characteristic of the family Percidae. Another physical characterist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Griffith (zoologist)
Edward Griffith (1790–1858) was a British natural history, naturalist and solicitor. He wrote ''General and Particular Descriptions of the Vertebrated Animals'' (1821) and translated Georges Cuvier's ''Règne animal'', making considerable additions (1827–35). Life The son of William Griffith of Stanwell, Middlesex, he entered St. Paul's School, London in 1800 and left it in 1806, entering the Court of Common Pleas (England), Common Pleas office as a clerk. He afterwards became a solicitor and a master in the Court of Common Pleas. He was one of the original members of the Zoological Society of London, Zoological Society, and a fellow of the Linnean (1822), Antiquaries, and Royal Societies. Griffith died on 8 January 1858. Works In 1821 he published the first part of what was intended to be an extensive work, ‘General and Particular Descriptions of the Vertebrated Animals,’ with coloured plates. This first part dealt only with monkeys and lemurs. Incomplete, it may ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sander (fish)
''Sander'' (formerly known as ''Stizostedion'') is a genus of predatory ray-finned fish in the family Percidae, which also includes the perches, ruffes, and darters. They are also known as "pike-perch" because of their resemblance to fish in the unrelated Esocidae (pike) family. They are the only genus in the monotypic tribe Luciopercini, which is one of two tribes in the subfamily Luciopercinae, Characteristics ''Sander'' species have elongated and laterally compressed bodies and they range in total length from in the Volga pikeperch (''S. volgensis'') to in the zander (''S. lucioperca''). The species within the genus share canine-like teeth that are at their largest in the zander, and although they are not present in adult Volga pikeperches, they do possess them as juveniles. in addition, they have thin rows of teeth on their jaws, vomer, and palatines, the preopercle shows strong serrations along its edges, a continuous lateral line reaches all the way from the head to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can contain suspended solid matter consisting of particles of many different sizes. While some suspended material will be large enough and heavy enough to settle rapidly to the bottom of the container if a liquid sample is left to stand (the settable solids), very small particles will settle only very slowly or not at all if the sample is regularly agitated or the particles are colloidal. These small solid particles cause the liquid to appear turbid. Turbidity (or haze) is also applied to transparent solids such as glass or plastic. In plastic production, haze is defined as the percentage of light that is deflected more than 2.5° from the incoming light direction. Causes and effects Turbidity in open water may be caused by growth of phyto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spawning
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and reptiles, reproduce through the process of spawning. Spawn consists of the reproductive cells (gametes) of many aquatic animals, some of which will become fertilized and produce offspring. The process of spawning typically involves females releasing ova (unfertilized eggs) into the water, often in large quantities, while males simultaneously or sequentially release spermatozoa (milt) to fertilize the eggs. Most fish reproduce by spawning, as do most other aquatic animals, including crustaceans such as crabs and shrimps, molluscs such as oysters and squid, echinoderms such as sea urchins and sea cucumbers, amphibians such as frogs and newts, aquatic insects such as mayflies and mosquitoes and corals, which are actually small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overexploitation
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term applies to natural resources such as water aquifers, grazing pastures and forests, wild medicinal plants, fish stocks and other wildlife. In ecology, overexploitation describes one of the five main activities threatening global biodiversity. Ecologists use the term to describe populations that are harvested at an unsustainable rate, given their natural rates of mortality and capacities for reproduction. This can result in extinction at the population level and even extinction of whole species. In conservation biology, the term is usually used in the context of human economic activity that involves the taking of biological resources, or organisms, in larger numbers than their populations can withstand. The term is also used and defined some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetation, revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost, suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation. There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat Loss
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby reducing biodiversity and species abundance. Habitat destruction is the leading cause of biodiversity loss. Fragmentation and loss of habitat have become one of the most important topics of research in ecology as they are major threats to the survival of endangered species. Activities such as harvesting natural resources, industrial production and urbanization are human contributions to habitat destruction. Pressure from agriculture is the principal human cause. Some others include mining, logging, trawling, and urban sprawl. Habitat destruction is currently considered the primary cause of species extinction worldwide. Environmental factors can contribute to habitat destruction more indirectly. Geological processes, climate change, introdu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migratory Barrier
Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum length of time Natural sciences Biology * Migration (ecology), the large-scale movement of species from one environment to another ** Animal migration ** Bird migration * Plant migration, see Seed dispersal, the movement or transport of seeds away from the parent plant * Gene migration, a process in evolution and population genetics * Cell migration, a process in the development and maintenance of multicellular organisms ** Collective cell migration, describing the movements of group of cells Physics and chemistry * Molecular diffusion, in physics * Migration (chemistry), type of reaction in organic chemistry * Seismic migration, in seismic and ground penetrating radar data processing * Microscopic motion of material caused by an external f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Language
French ( or ) is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the Latin spoken in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French ( Francien) largely supplanted. French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the ( Germanic) Frankish language of the post-Roman Frankish invaders. Today, owing to France's past overseas expansion, there are numerous French-based creole languages, most notably Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French. French is an official language in 29 countries across multiple continents, most of which are members of the ''Organisation internationale de la Francophonie'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
