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Sheldon Spectrum
The Sheldon spectrum is an empirically-observed feature of marine life by which the size of an organism is inversely correlated with its abundance in the ocean. The spectrum is named after Ray Sheldon, a marine ecologist at Canada’s Bedford Institute of Oceanography in Dartmouth, Nova Scotia. Sheldon and colleagues first suggested the existence of the inverse correlation based on seagoing measurements of plankton made with a Coulter counter in the late 1960s, most notably during the first circum-navigation of the Americas aboard the CCGS Hudson. The inverse correlation implies that biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. For example, when Sheldon and his colleagues analyzed a plankton sample in a bucket of seawater, they would tend to find that one third of the plankton mass was between 1 and 10 micrometers, another third was between 10 and 100 micrometers, and a third was between 100 micrometers and 1 mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orders Of Magnitude
An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic distributions are common in nature and considering the order of magnitude of values sampled from such a distribution can be more intuitive. When the reference value is 10, the order of magnitude can be understood as the number of digits in the base-10 representation of the value. Similarly, if the reference value is one of some powers of 2, since computers store data in a binary format, the magnitude can be understood in terms of the amount of computer memory needed to store that value. Differences in order of magnitude can be measured on a base-10 logarithmic scale in “decades” (i.e., factors of ten). Examples of numbers of different magnitudes can be found at Orders of magnitude (numbers). Definition Generally, the order of magnitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Organisms
Marine life, sea life, or ocean life is the aquatic plant, plants, aquatic animal, animals and other organisms that live in the seawater, salt water of seas or oceans, or the brackish water of coastal estuary, estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly marine microorganisms, microorganisms, oxygen cycle, produce oxygen and biosequestration, sequester carbon. Marine life in part shape and protect shorelines, and some marine organisms even help create new land (e.g. coral building coral reef, reefs). Most life forms evolved initially in marine habitats. By volume, oceans provide about 90% of the living space on the planet. The earliest vertebrates appeared in the form of fish, which live exclusively in water. Some of these evolved into amphibians, which spend portions of their lives in water and portions on land. One group of amphibians evolved into reptiles and mammals and a few subsets of each returned to the ocean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whaling
Whaling is the process of hunting of whales for their usable products such as meat and blubber, which can be turned into a type of oil that became increasingly important in the Industrial Revolution. It was practiced as an organized industry as early as 875 AD. By the 16th century, it had risen to be the principal industry in the Basque coastal regions of Spain and France. The industry spread throughout the world, and became increasingly profitable in terms of trade and resources. Some regions of the world's oceans, along the animals' migration routes, had a particularly dense whale population, and became the targets for large concentrations of whaling ships, and the industry continued to grow well into the 20th century. The depletion of some whale species to near extinction led to the banning of whaling in many countries by 1969, and to an international cessation of whaling as an industry in the late 1980s. The earliest known forms of whaling date to at least 3000 BC. Coasta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overfishing
Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in the species becoming increasingly underpopulated in that area. Overfishing can occur in water bodies of any sizes, such as ponds, wetlands, rivers, lakes or oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing can lead to critical depensation, where the fish population is no longer able to sustain itself. Some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire marine ecosystems. Types of overfishing include: growth overfishing, recruitment overfishing, ecosystem overfishing. The ability of a fishery to recover from overfishing depends on whether its overall carrying capacity and the variety of ecological conditions are suitable for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuna
A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: , weight: ) up to the Atlantic bluefin tuna (max length: , weight: ), which averages and is believed to live up to 50 years. Tuna, opah and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water. An active and agile predator, the tuna has a sleek, streamlined body, and is among the fastest-swimming pelagic fish – the yellowfin tuna, for example, is capable of speeds of up to . Greatly inflated speeds can be found in early scientific reports and are still widely reported in the popular literature. Found in warm seas, the tuna is commercially fished extensively as a food fish, and is popular as a bluewater game fish. As a result of overfishing, some tuna species, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krill
Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe * Norwegians, both a nation and an ethnic group native to Norway * Demographics of Norway *The Norwegian language, including ... word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are considered an important trophic level connection – near the bottom of the food chain. They feed on phytoplankton and (to a lesser extent) zooplankton, yet also are the main source of food for many larger animals. In the Southern Ocean, one species, the Antarctic krill, ''Euphausia superba'', makes up an estimated biomass (ecology), biomass of around 379,000,000 tonnes, making it among the species with the largest total biomass. Over half of this biomass is eaten by whales, Pinniped, seals, pen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Units (SI) equalling (SI standard prefix "micro-" = ); that is, one millionth of a metre (or one thousandth of a millimetre, , or about ). The nearest smaller common SI unit is the nanometre, equivalent to one thousandth of a micrometre, one millionth of a millimetre or one billionth of a metre (). The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 20 to . The longest human chromosome, chromosome 1, is approximately in length. Examples Between 1 μm and 10 μm: * 1–10 μm – length of a typical bacterium * 3–8 μm – width of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logarithmic Scale
A logarithmic scale (or log scale) is a way of displaying numerical data over a very wide range of values in a compact way—typically the largest numbers in the data are hundreds or even thousands of times larger than the smallest numbers. Such a scale is nonlinear: the numbers 10 and 20, and 60 and 70, are not the same distance apart on a log scale. Rather, the numbers 10 and 100, and 60 and 600 are equally spaced. Thus moving a unit of distance along the scale means the number has been ''multiplied'' by 10 (or some other fixed factor). Often exponential growth curves are displayed on a log scale, otherwise they would increase too quickly to fit within a small graph. Another way to think about it is that the ''number of digits'' of the data grows at a constant rate. For example, the numbers 10, 100, 1000, and 10000 are equally spaced on a log scale, because their numbers of digits is going up by 1 each time: 2, 3, 4, and 5 digits. In this way, adding two digits ''multiplies'' the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Biology
Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy. A large proportion of all life on Earth lives in the ocean. The exact size of this ''large proportion'' is unknown, since many ocean species are still to be discovered. The ocean is a complex three-dimensional world covering approximately 71% of the Earth's surface. The habitats studied in marine biology include everything from the tiny layers of surface water in which organisms and abiotic items may be trapped in surface tension between the ocean and atmosphere, to the depths of the oceanic trenches, sometimes 10,000 meters or more beneath the surface of the ocean. Specific habitats include estuaries, coral reefs, kelp forests, seagrass meadows, the surrounds of seamounts and therm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms biomass and biofuel interchangeably, while others consider biofuel to be a ''liquid'' or ''gaseous'' fuel used for transportation, as defined by government authorities in the US and EU. The European Union's Joint Research Centre defines solid biofuel as raw or processed organic matter of biological origin used for energy, such as firewood, wood chips, and wood pellets. In 2019, biomass was used to produce 57 EJ (exajoules) of energy, compared to 190 EJ from crude oil, 168 EJ from coal, 144 EJ from natural gas, 30 EJ from nuclear, 15 EJ from hydro and 13 EJ from wind, solar and geothermal combined. Approximately 86% of modern bioenergy is used for heating applications, with 9% used for transport and 5% for electricity. Most of the global b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCGS Hudson
CCGS ''Hudson'' was an offshore oceanographic and hydrographic survey vessel operated by the Canadian Coast Guard. The ship entered service in 1963 with the Canadian Oceanographic Service, stationed at the Bedford Institute of Oceanography, called CSS ''Hudson''. The ship made several significant scientific voyages, among them the first circumnavigation of the Americas in 1970. The ship was transferred to the Canadian Coast Guard in 1996 and decommissioned in 2022. A replacement is not scheduled for delivery until 2024–2025. Description The first Canadian ship built specifically for hydrographic and oceanographic survey work, ''Hudson'' was designed by the Montreal firm of Gilmore, German and Milne. ''Hudson'' is long overall and between perpendiculars with a beam of and a draught of The ship has a tonnage of , and a . ''Hudson'' is certified as Arctic class 2. The ship is powered by a diesel electric DC/DC system composed of four Alco 251D diesel engines and two Cate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
