An invasive species is a species, not native to a specific location, that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health. The criteria for invasive species has been controversial, as divergent perceptions exist among researchers as well as concerns with the subjectivity of the term "invasive". Several alternate usages of the term have been proposed; the term as most used applies to introduced species that adversely affect the habitats and bioregions they invade economically, environmentally, or ecologically. Such invasive species may be either plants or animals and may disrupt by dominating a region, wilderness areas, particular habitats, or wildland–urban interface land from loss of natural controls; this includes non-native invasive plant species labeled as exotic pest plants and invasive exotics growing in native plant communities. It has been used in this sense by government organizations as well as conservation groups such as the International Union for Conservation of Nature and the California Native Plant Society.
The European Union defines "Invasive Alien Species" as those that are, outside their natural distribution area, secondly, threaten biological diversity. The term is used by land managers, researchers, horticulturalists and the public for noxious weeds; the kudzu vine, Andean pampas grass, yellow starthistle are examples. An alternate usage broadens the term to include indigenous or "native" species along with non-native species, that have colonized natural areas. Deer are an example, considered to be overpopulating their native zones and adjacent suburban gardens, by some in the Northeastern and Pacific Coast regions of the United States. Sometimes the term is used to describe a non-native or introduced species that has become widespread. However, not every introduced. A nonadverse example is the common goldfish, found throughout the United States, but achieves high densities. Notable examples of invasive species include European rabbits, grey squirrels, domestic cats and ferrets. Dispersal and subsequent proliferation of species is not an anthropogenic phenomenon.
There are many mechanisms by which species from all Kingdoms have been able to travel across continents in short periods of time such as via floating rafts, or on wind currents. Charles Darwin, a British naturalist, performed many experiments to better understand long distance seed dispersal, was able to germinate seeds from insect frass, faeces of waterfowl, dirt clods on the feet of birds, all of which may have traveled significant distances under their own power, or be blown off course by thousands of miles. Invasion of long-established ecosystems by organisms from distant bio-regions is a natural phenomenon, accelerated via hominid-assisted migration although this has not been adequately directly measured; the definition of "native" is controversial in that there is no way to determine nativity. For example, the ancestors of Equus ferus evolved in North America and radiated to Eurasia before becoming locally extinct. Upon returning to North America in 1493 during their hominid-assisted migration, it is debatable as to whether they were native or exotic to the continent of their evolutionary ancestors.
Scientists include species and ecosystem factors among the mechanisms that, when combined, establish invasiveness in a newly introduced species. While all species compete to survive, invasive species appear to have specific traits or specific combinations of traits that allow them to outcompete native species. In some cases, the competition is about rates of reproduction. In other cases, species interact with each other more directly. Researchers disagree about the usefulness of traits as invasiveness markers. One study found that of a list of invasive and noninvasive species, 86% of the invasive species could be identified from the traits alone. Another study found invasive species tended to have only a small subset of the presumed traits and that many similar traits were found in noninvasive species, requiring other explanations. Common invasive species traits include the following: Fast growth Rapid reproduction High dispersal ability Phenotype plasticity Tolerance of a wide range of environmental conditions Ability to live off of a wide range of food types Association with humans Prior successful invasionsTypically, an introduced species must survive at low population densities before it becomes invasive in a new location.
At low population densities, it can be difficult for the introduced species to reproduce and maintain itself in a new location, so a species might reach a location multiple times before it becomes established. Repeated patterns of human movement, such as ships sailing to and from ports or cars driving up and down highways offer repeated opportunities for establishment. An introduced species might become invasive if it can outcompete native species for resources such as nutrients, physical space, water, or food. If these species evolved under great competition or predation the new environment may host fewer able competitors, allowing the invader to proliferate quickly. Ecosystems which are being used to their fullest capacity by native species can be modeled as zero-sum systems in which any gain for the invader is a loss for the native. However, su
Mean sea level is an average level of the surface of one or more of Earth's oceans from which heights such as elevation may be measured. MSL is a type of vertical datum – a standardised geodetic datum –, used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and aircraft flight levels. A common and straightforward mean sea-level standard is the midpoint between a mean low and mean high tide at a particular location. Sea levels can be affected by many factors and are known to have varied over geological time scales; however 20th century and current millennium sea level rise is caused by global warming, careful measurement of variations in MSL can offer insights into ongoing climate change. The term above sea level refers to above mean sea level. Precise determination of a "mean sea level" is difficult to achieve because of the many factors that affect sea level. Instantaneous sea level varies quite a lot on several scales of space.
This is because the sea is in constant motion, affected by the tides, atmospheric pressure, local gravitational differences, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point and use it as a datum. For example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. Still-water level or still-water sea level is the level of the sea with motions such as wind waves averaged out. MSL implies the SWL further averaged over a period of time such that changes due to, e.g. the tides have zero mean. Global MSL refers to a spatial average over the entire ocean. One measures the values of MSL in respect to the land. In the UK, the Ordnance Datum is the mean sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the vertical datum was MSL at the Victoria Liverpool. Since the times of the Russian Empire, in Russia and other former its parts, now independent states, the sea level is measured from the zero level of Kronstadt Sea-Gauge.
In Hong Kong, "mPD" is a surveying term meaning "metres above Principal Datum" and refers to height of 1.230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and offers the longest collapsed data about the sea level, it is used for main part of Africa as official sea level. As for Spain, the reference to measure heights below or above sea level is placed in Alicante. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, which dates back to the 1690s. Satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001 and the Ocean Surface Topography Mission on the Jason-2 satellite in 2008. Height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum, it is used in aviation, where some heights are recorded and reported with respect to mean sea level, in the atmospheric sciences, land surveying.
An alternative is to base height measurements on an ellipsoid of the entire Earth, what systems such as GPS do. In aviation, the ellipsoid known as World Geodetic System 84 is used to define heights; the alternative is to use a geoid-based vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, variations in elevation are shown by contour lines; the elevation of a mountain denotes the highest point or summit and is illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, the elevation AMSL is negative. For one such case, see Amsterdam Airport Schiphol. To extend this definition far from the sea means comparing the local height of the mean sea surface with a "level" reference surface, or geodetic datum, called the geoid. In a state of rest or absence of external forces, the mean sea level would coincide with this geoid surface, being an equipotential surface of the Earth's gravitational field.
In reality, due to currents, air pressure variations and salinity variations, etc. this does not occur, not as a long-term average. The location-dependent, but persistent in time, separation between mean sea level and the geoid is referred to as ocean surface topography, it varies globally in a range of ± 2 m. Adjustments were made to sea-level measurements to take into account the effects of the 235 lunar month Metonic cycle and the 223-month eclipse cycle on the tides. Several terms are used to describe the changing relationships between sea level and dry land; when the term "relative" is used, it means change relative to a fixed point in the sediment pile. The term "eustatic" refers to global changes in sea level relative to a fixed point, such as the centre of the earth, for example as a result of melting ice-caps; the term "steric" refers to global changes in sea level due to thermal expansion and salinity variations. The term "isostatic" refers to changes in
Pudong is a district of Shanghai located east of the Huangpu River across from the historic city center of Shanghai in Puxi. The name refers to its historic position as "The East Bank" of the Huangpu River, which flows through central Shanghai, although it is now administered as the Pudong New Area, a state-level new area which extends all the way to the East China Sea; the traditional area of Pudong is now home to the Lujiazui Finance and Trade Zone and the Shanghai Stock Exchange and many of Shanghai's best-known buildings, such as the Oriental Pearl Tower, the Jin Mao Tower, the Shanghai World Financial Center, the Shanghai Tower. These modern skyscrapers directly face Puxi's historic Bund, a remnant of former foreign concessions in China; the rest of the new area includes the Port of Shanghai, the Shanghai Expo and Century Park, Zhangjiang Hi-Tech Park, Shanghai Pudong International Airport, the Jiuduansha Wetland Nature Reserve, the Shanghai Disney Resort. Pudong—literally "The East Bank of the Huangpu River"—originally referred only to the less-developed land across from Shanghai's Old City and foreign concessions.
The area was farmland and only developed, with warehouses and wharfs near the shore administered by the districts of Puxi on the west bank: Huangpu and Nanshi. Pudong was established as a county in 1958 until 1961 which the county was split among Huangpu, Nanshi and Chuansha County. In October 1, 1992 the original area of Pudong County and Chuansha County merged and established Pudong New Area. In 1993, the Chinese government set up a Special Economic Zone in Chuansha, creating the Pudong New Area; the western tip of the Pudong district was designated as the Lujiazui Finance and Trade Zone and has become a financial hub of modern China. Several landmark buildings were constructed, including the Oriental Pearl Tower, the Jin Mao Building, the supertall Shanghai World Financial Center 494 m and Shanghai Tower; these buildings—all along Century Avenue and visible from the historic Bund—now form the most common skyline of Shanghai. On May 6, 2009, it was disclosed that the State Council had approved the proposal to merge Nanhui District with Pudong and comprise the majority of eastern Shanghai.
In 2010, Pudong was host to the main venues of the Shanghai Expo, whose grounds now form a public park. Pudong New Area consist of the original Pudong County, Chuansha County, Nanhui County. Districts of the direct-controlled municipality of Shanghai are administratively on the same level as prefecture-level cities. However, the government of Pudong has a status equivalent to that of a sub-provincial city, a half-level above a prefecture-level city; this is due to Pudong's importance as the financial hub of China. The Pudong Communist Party Secretary is the top office of the district, followed by the district governor of Pudong; the Pudong party chief is customarily a member of the Shanghai Party Standing Committee. On April 27, 2015, People's Government of Pudong New Area is working with China Pilot Free-Trade Zone Administrative Committee. Pudong means "East Bank". Pudong is bounded by the East China Sea in the east. Pudong is distinguished from Puxi, the older part of Shanghai, it has an area of 1,210.4 square kilometres and according to the 2010 Census, a population of 5,044,430 inhabitants, 1.9 million more than in 2000.
At least 2.1 million of residents of Pudong are newcomers from other provinces or cities in China. Pudong is the most populous district in Shanghai. According to the 2010 Census, it has 5,044,430 people in 1,814,802 families, around 1/4 of Shanghai's total population, an explosive growth since the last census thanks to immigrants. Pudong's resident population growth is well above national average because it is a popular immigration destination; the 2010 census shows a 58.26% increase in the last decade, or an annual pace of 4.7%. In particular, the district saw am immigration growth of 189.5%, or an annual pace of 11.22%. Excluding immigrants, the birth rate is 0.806% while the death rate is 0.729, resulting a net growth of 0.077%. The total fertility rate is 1.03, well below the replacement level. The district has a negative registered household population growth if immigrants are excluded, thus the growth is purely driven by immigration; the 2010 Census shows a population density of 3,909/km2.
About 3/4 of the population live in the northern part and part of city center called "Northern Territory". 1/4 live in the "Southern Territory", the Nanhui District. The Northern Territory has a 6,667 population density, while the Southern Territory has 1,732/km2. Suburbs saw a greater increase in population during 2000-2010 with the help of the city's suburb expansion policy; some counties in the traditional city center saw a population decrease. * – Liuzao town merged into Chuanshaxin town. ** – Luchaogang town and Shengang Subdistrict merged and form Nanhui Xincheng town. Shanghai Maritime University Shanghai Dianji University Shanghai Fisheries University China Executive Leadership Academy in Pudong Fudan University in Zhangjiang New York University Shanghai ShanghaiTech University Public schools: No. 2 High School Attached to East China Normal University Jianping High School Dongchang High School of ECNU Pudong Foreign Languages School of Shanghai International Studies UniversityInternational schools: Dulwich College Shanghai French School of Shanghai Pudong Campus Nord Anglia International School Shanghai Pudong German School Shanghai Pudong Campus Shanghai American School Pudong Campus Shanghai Japanese School Pudong Campus, SJS Senior
A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any vessel. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour. Mines can be laid in many ways: by purpose-built minelayers, refitted ships, submarines, or aircraft—and by dropping them into a harbour by hand, they can be inexpensive: some variants can cost as little as US$2000, though more sophisticated mines can cost millions of dollars, be equipped with several kinds of sensors, deliver a warhead by rocket or torpedo. Their flexibility and cost-effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare; the cost of producing and laying a mine is between 0.5% and 10% of the cost of removing it, it can take up to 200 times as long to clear a minefield as to lay it. Parts of some World War II naval minefields still exist because they are too extensive and expensive to clear.
It is possible for some of these 1940s-era mines to remain dangerous for many years to come. Mines have been employed as offensive or defensive weapons in rivers, estuaries and oceans, but they can be used as tools of psychological warfare. Offensive mines are placed in enemy waters, outside harbours and across important shipping routes with the aim of sinking both merchant and military vessels. Defensive minefields safeguard key stretches of coast from enemy ships and submarines, forcing them into more defended areas, or keeping them away from sensitive ones. Minefields designed for psychological effect are placed on trade routes and are used to stop shipping from reaching an enemy nation, they are spread thinly, to create an impression of minefields existing across large areas. A single mine inserted strategically on a shipping route can stop maritime movements for days while the entire area is swept. International law requires nations to declare when they mine an area, to make it easier for civil shipping to avoid the mines.
The warnings do not have to be specific. Precursors to naval mines were first invented by Chinese innovators of Imperial China and were described in thorough detail by the early Ming dynasty artillery officer Jiao Yu, in his 14th century military treatise known as the Huolongjing. Chinese records tell of naval explosives in the 16th century, used to fight against Japanese pirates; this kind of naval mine was loaded in a wooden box, sealed with putty. General Qi Jiguang made several timed, to harass Japanese pirate ships; the Tiangong Kaiwu treatise, written by Song Yingxing in 1637 AD, describes naval mines with a rip cord pulled by hidden ambushers located on the nearby shore who rotated a steel wheellock flint mechanism to produce sparks and ignite the fuse of the naval mine. Although this is the rotating steel wheellock's first use in naval mines, Jiao Yu had described their use for land mines back in the 14th century; the first plan for a sea mine in the West was by Ralph Rabbards, who presented his design to Queen Elizabeth I of England in 1574.
The Dutch inventor Cornelius Drebbel was employed in the Office of Ordnance by King Charles I of England to make weapons, including a "floating petard" which proved a failure. Weapons of this type were tried by the English at the Siege of La Rochelle in 1627. American David Bushnell developed the first American naval mine for use against the British in the American War of Independence, it was a watertight keg filled with gunpowder, floated toward the enemy, detonated by a sparking mechanism if it struck a ship. It was used on the Delaware River as a drift mine. In 1812 Russian engineer Pavel Shilling exploded an underwater mine using an electrical circuit. In 1842 Samuel Colt used an electric detonator to destroy a moving vessel to demonstrate an underwater mine of his own design to the United States Navy and President John Tyler. However, opposition from former President John Quincy Adams scuttled the project as "not fair and honest warfare." In 1854, during the unsuccessful attempt of the Anglo-French fleet to seize the Kronstadt fortress, British steamships HMS Merlin, HMS Vulture and HMS Firefly suffered damage due to the underwater explosions of Russian naval mines.
Russian naval specialists set more than 1500 naval mines, or infernal machines, designed by Moritz von Jacobi and by Immanuel Nobel, in the Gulf of Finland during the Crimean War of 1853-1856. The mining of Vulcan led to the world's first minesweeping operation. During the next 72 hours, 33 mines were swept; the Jacobi mine was designed by German-born, Russian engineer Jacobi, in 1853. The mine was tied to the sea bottom by an anchor. A cable connected it to a galvanic cell which powered it from the shore, the power of its explosive charge was equal to 14 kilograms of black powder. In the summer of 1853, the production of the mine was approved by the Committee for Mines of the Ministry of War of the Russian Empire. In 1854, 60 Jacobi mines were laid in the vicinity of the Forts Pavel and Alexander, to deter the British Baltic Fleet from attacking them, it phased out its direct competitor the Nobel mine on the insistence of Admiral Fyodor Litke. The Nobel mines were bought from Swedish industrialist Immanuel Nobel who had entered into collusion with Russian head of navy Alexander Sergeyevich Menshikov.
Despite their high cost t
Shanghai Pudong International Airport
Shanghai Pudong International Airport is one of two international airports of Shanghai and a major aviation hub of China. Pudong Airport serves international flights, while the city's other major airport Shanghai Hongqiao International Airport serves domestic and regional flights. Located about 30 kilometres east of the city center, Pudong Airport occupies a 40-square-kilometre site adjacent to the coastline in eastern Pudong; the airport is operated by Shanghai Airport Authority. The airport is the main hub for China Eastern Airlines and Shanghai Airlines, a major international hub for Air China, as well as secondary hub of China Southern Airlines, it is the hub for owned Juneyao Airlines and Spring Airlines, an Asia-Pacific cargo hub for UPS and DHL. The DHL hub, opened in July 2012, is said to be the biggest express hub in Asia. Pudong Airport has two main passenger terminals, flanked on both sides by four operational parallel runways. A third passenger terminal has been planned since 2015, in addition to a satellite terminal and two additional runways, which will raise its annual capacity from 60 million passengers to 80 million, along with the ability to handle six million tons of freight.
Pudong Airport is a fast-growing hub for both cargo traffic. With 3,703,431 metric tons handled in 2017, the airport is the world's third-busiest airport by cargo traffic. Pudong Airport served a total of 70,001,237 passengers in 2017, making it the second-busiest airport in China, fifth-busiest in Asia, the ninth-busiest in the world, it is the busiest international gateway of mainland China, with 35.25 million international passengers. By the end of 2016, Pudong Airport hosted 104 airlines serving more than 210 destinations. Shanghai Pudong is the busiest international hub of China, about half of its total passenger traffic is international. Pudong Airport is connected to Shanghai Hongqiao Airport by Shanghai Metro Line 2 and the Shanghai Maglev Train via Pudong International Airport Station. There are airport buses connecting it with the rest of the city. Prior to the establishment of Pudong International Airport, Shanghai Hongqiao International Airport was the primary airport of Shanghai. During the 1990s, the expansion of Hongqiao Airport to meet growing demand became impossible as the surrounding urban area was developing and an alternative to assume all international flights had to be sought.
After deliberation, the municipal government decided to adopt the suggestion from Professor Chen Jiyu of East China Normal University, who wrote a letter to the Mayor of Shanghai Xu Kuangdi suggesting that the new airport should be constructed on the tidal flats of the south bank of the Yangtze River estuary, on the coast of the Pudong development zone to the east of Shanghai. Construction of the first phase of the new Shanghai Pudong International Airport began in October 1997, took two years to build at a cost of RMB 12 billion, was opened on October 1, 1999 It covers an area of 40 square kilometres and is 30 kilometres from downtown Shanghai; the first phase of the airport has one 4E category runway along with two parallel taxiways, an 800,000-square-metre apron, seventy-six aircraft positions and a 50,000 m2 cargo warehouse. A second runway was opened on March 17, 2005, construction of phase two began in December 2005 and started operation on March 26, 2008, in time for the Beijing 2008 Summer Olympics.
In November 2011, Pudong Airport received approval from the national government for a new round of expansion which includes two runways. The 3,800-metre fourth runway, along with an auxiliary taxiway and traffic control facilities, is projected to cost 2.58 billion yuan. The 3,400-metre fifth runway, along with a new traffic tower, will cost 4.65 billion yuan. Construction has doubled the capacity of the airport. Pudong International Airport started the third phase of the Pudong International Airport expansion with the construction on a new south satellite terminal on December 29, 2015; the new satellite terminal will be the world's largest single satellite terminal with a total construction area of 622,000 square meters, larger than the Pudong International Airport T2 terminal building. The satellite terminal is composed of S1 and S2, forming an H-shaped structure, it will have an annual design capacity of 38 million passengers, The total cost of the project is estimated to be about 20.6 billion yuan.
Halls S1 and S2 will have 83 gates. A high capacity People mover connecting T1 to SI and T2 to S2 will be constructed. After the completion of the satellite terminal in 2019, Pudong International Airport will have an annual passenger capacity of 80 million passengers, ranking among the top ten airports in the world; the airport has 70 boarding bridges along with 218 parking positions. Five runways are parallel to the terminals: one 4,000-metre runway with 4E rating, two 3,800-metre runways with 4F rating, two 3,400-metre runways with 4F rating. Pudong airport has 5 runways. Rwy 35L/17R and Rwy 34R/16L are used for landing while Rwy 35R/17L and Rwy 34L/16R are used for takeoff. Runway 15/33 is not in operation. Terminal 1 was opened on October 1999 along with a 4000-metre runway and a cargo hub, it was built to handle the demand for tra
Chinese mitten crab
The Chinese mitten crab known as the Shanghai hairy crab, is a medium-sized burrowing crab, named for its furry claws, which resemble mittens. It is native to rivers and other coastal habitats of eastern Asia from Korea in the north to the Fujian province of China in the south, it has been introduced to Europe and North America where it is considered an invasive species. This species' distinguishing features are the dense patches of dark setae on its claws; the crab's body is the size of a human palm. The carapace is 3–10 centimetres wide, the legs are about twice as long as the carapace is wide. Mitten crabs spend most of their life in fresh return to the sea to breed. During their fourth or fifth year in late summer, the crustaceans migrate downstream and attain sexual maturity in the tidal estuaries. After mating, the females continue seaward, they return to brackish water in the spring to hatch their eggs. After development as larvae, the juvenile crabs move upstream into fresh water, thus completing the life cycle.
It moves from freshwater habitats to saltwater habitats. The types of estuaries suitable for the mitten crab is large brackish waters for the larva to develop in, large shallow waters for the growth of the juvenile crabs; the Chinese mitten crab originates from Hong Kong to the border of Korea. It prefers coastal areas. In the Yangtze, the largest river in its native range, Chinese mitten crabs have been recorded up to 1,400 km upstream, it is known to settle in rice fields by the sea and rivers inland. The crab is found in temperate regions. Phylogenetically the crab belongs to the Varunidae family, the newest group of brachyuran crustaceans. Spawning crabs average around 5.5 cm in length. Since crabs spawn at the end of their life spans and perish at the end of the breeding cycle, the crabs can live up to 7 years old; the mitten crab diet is omnivorous. Their main prey consists of worms, snails, dead organic material, other small crustaceans and fish. Starts off as a fresh-water organism. In late August the crab’s sexual instinct is awakened and they begin migrating downstream to the sea, away from their feeding grounds.
It is during this migration where the crabs develop their sex organs. Late fall is; the males stay in the brackish waters all winter. The females arrive; the eggs are laid within 24 hours of mating. They are attached to the abdomen of the female crab. After the eggs are attached, the female leaves heading to the mouth of the river; the larvae hatch from the eggs during summer and they float and drift about the brackish waters. Because the journey to breed for crabs is so great, they only breed once during their lifetimes; the breeding age is toward the end of their life spans. Since these crabs only breed once, they have sizeable egg production counts. After the crabs reproduce, they have little energy and begin to waste away. Different life stages of the mitten crab: 1) Eggs require pure salt water to mature. 2) Larvae hatch from the eggs in brackish waters. 3) The larvae move from brackish water to fresh water. 4) The final stage of the larvae is the megalopa, 3-4mm in length. 5) The megalopa develop into small mitten crabs in the freshwater.
This species has been spread from Asia to North America and Europe, raising concerns that it competes with local species, its burrowing nature damages embankments and clogs drainage systems. The crabs can make significant inland migrations, it was reported in 1995 that residents of Greenwich saw Chinese mitten crabs coming out of the River Thames, in 2014 one was found in the Clyde, in Scotland. The crabs have been known to take up residence in swimming pools. In some places the crabs have been found hundreds of miles from the sea. There is concern in areas with a substantial native crab fishery, such as the Chesapeake Bay in Maryland and the Hudson River in New York, as the impact of the invasion by this species on the native population is unknown, it is illegal to import, transport, or possess live Chinese mitten crabs in the United States, as accidental release or escape risks spreading these crabs to uninfested waters. In addition, some states may have their own restrictions on possession of mitten crabs.
California allows fishing for mitten crabs with some restrictions. The Chinese mitten crab has been introduced into the Great Lakes several times, but has not yet been able to establish a permanent population; the Smithsonian is tracking the spread of the Chinese mitten crab and seeking help to determine the current distribution status of the mitten crab in the Chesapeake Bay region. People are encouraged to report any mitten crab sightings, along with details and a close-up photograph or specimen if possible; the first confirmed record along the East coast of the United States was in the Chesapeake Bay near Baltimore, Maryland, in 2005. Chinese mitten crabs have invaded German waters, where they destroy fishing nets, hurt native fish species and damage local dams, causing damage of up to 80 million Euros; these crabs migrated from China to Europe as early as 1900, were first documented by official German reports in 1912 from Aller River. After investigation by German scientists in 1933, it was thought that the crabs migrated to Europe through ballas
China the People's Republic of China, is a country in East Asia and the world's most populous country, with a population of around 1.404 billion. Covering 9,600,000 square kilometers, it is the third- or fourth-largest country by total area. Governed by the Communist Party of China, the state exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities, the special administrative regions of Hong Kong and Macau. China emerged as one of the world's earliest civilizations, in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies, or dynasties, beginning with the semi-legendary Xia dynasty in 21st century BCE. Since China has expanded, re-unified numerous times. In the 3rd century BCE, the Qin established the first Chinese empire; the succeeding Han dynasty, which ruled from 206 BC until 220 AD, saw some of the most advanced technology at that time, including papermaking and the compass, along with agricultural and medical improvements.
The invention of gunpowder and movable type in the Tang dynasty and Northern Song completed the Four Great Inventions. Tang culture spread in Asia, as the new Silk Route brought traders to as far as Mesopotamia and Horn of Africa. Dynastic rule ended in 1912 with the Xinhai Revolution; the Chinese Civil War resulted in a division of territory in 1949, when the Communist Party of China established the People's Republic of China, a unitary one-party sovereign state on Mainland China, while the Kuomintang-led government retreated to the island of Taiwan. The political status of Taiwan remains disputed. Since the introduction of economic reforms in 1978, China's economy has been one of the world's fastest-growing with annual growth rates above 6 percent. According to the World Bank, China's GDP grew from $150 billion in 1978 to $12.24 trillion by 2017. Since 2010, China has been the world's second-largest economy by nominal GDP and since 2014, the largest economy in the world by purchasing power parity.
China is the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget; the PRC is a permanent member of the United Nations Security Council as it replaced the ROC in 1971, as well as an active global partner of ASEAN Plus mechanism. China is a leading member of numerous formal and informal multilateral organizations, including the Shanghai Cooperation Organization, WTO, APEC, BRICS, the BCIM, the G20. In recent times, scholars have argued that it will soon be a world superpower, rivaling the United States; the word "China" has been used in English since the 16th century. It is not a word used by the Chinese themselves, it has been traced through Portuguese and Persian back to the Sanskrit word Cīna, used in ancient India."China" appears in Richard Eden's 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. Barbosa's usage was derived from Persian Chīn, in turn derived from Sanskrit Cīna.
Cīna was first used including the Mahābhārata and the Laws of Manu. In 1655, Martino Martini suggested that the word China is derived from the name of the Qin dynasty. Although this derivation is still given in various sources, it is complicated by the fact that the Sanskrit word appears in pre-Qin literature; the word may have referred to a state such as Yelang. The meaning transferred to China as a whole; the origin of the Sanskrit word is still a matter of debate, according to the Oxford English Dictionary. The official name of the modern state is the "People's Republic of China"; the shorter form is "China" Zhōngguó, from zhōng and guó, a term which developed under the Western Zhou dynasty in reference to its royal demesne. It was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state under the Qing, it was used as a cultural concept to distinguish the Huaxia people from perceived "barbarians". The name Zhongguo is translated as "Middle Kingdom" in English.
Archaeological evidence suggests that early hominids inhabited China between 2.24 million and 250,000 years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, were discovered in a cave at Zhoukoudian near Beijing; the fossilized teeth of Homo sapiens have been discovered in Fuyan Cave in Hunan. Chinese proto-writing existed in Jiahu around 7000 BCE, Damaidi around 6000 BCE, Dadiwan from 5800–5400 BCE, Banpo dating from the 5th millennium BCE; some scholars have suggested. According to Chinese tradition, the first dynasty was the Xia, which emerged around 2100 BCE; the dynasty was considered mythical by historians until scientific excavations found early Bronze Age sites at Erlitou, Henan in 1959. It remains unclear whether these sites are the remains of the Xia dynasty or of another culture from the same period; the succeeding Shang dynasty is the earliest to be confirmed by contemporary records. The Shang ruled the plain of the Yellow River in eastern China from the 17th to the 11th century BCE.
Their oracle bone script