The Holocene extinction , if not referred to as the sixth extinction or Anthropocene extinction , is a species extinction event that was underway during the current Holocene period, mainly as a result of human activity. A large number of extinctions include many plant and animal families, including mammals, birds, amphibians, reptiles, and arthropods. With the immense degradation of very diverse habitats such as coral reefs and rainforests, as well as other areas, most of these extinctions are considered undocumented, because we are not even aware of the existence of species before they become extinct, or we have not found their extinction. The extinction rate of the species is currently estimated at 100 to 1,000 times higher than the natural background level.
The extinction of the Holocene includes the loss of large land animals known as megafauna, beginning at the end of the last Ice Age. Megafauna outside the African continent, which did not evolve with humans, proved very sensitive to the introduction of new predation, and many died shortly after early humans began to spread and hunt across the Earth (in addition, many African species have also become extinct in the Holocene). This extinction, which occurred near the Pleistocene-Holocene border, is sometimes referred to as the Quaternary extinction event.
The arrival of humans on various continents coincides with megafaunal extinction. The most popular theory is that human hunting of species is added to the existing stress conditions. While there is debate as to how much human predation affects their decline, a certain population decline has been directly correlated with human activity, such as the extinction events of New Zealand and Hawaii. In addition to humans, climate change may be a driving factor in megafaunal extinction, especially at the end of the Pleistocene.
The ecology of humanity has been noted as an unprecedented "global superpredator" that regularly preys on other top predator peaks and has a worldwide effect on the food web. Extinction of species has occurred in every land and sea, with many notable examples in Africa, Asia, Europe, Australia, North and South America, and on small islands. Overall, the extinction of Holocene can be characterized by human impact on the environment. The extinction of the Holocene continues into the 21st century, with meat consumption, overfishing, ocean acidification and the decline of amphibian populations into several wider examples of almost universal, cosmopolitan degradation in biodiversity. Human overpopulation (and sustainable population growth) along with wasteful consumption is considered to be a key driver of this rapid decline.
Video Holocene extinction
Definition
The extinction of Holocene is also known as the "sixth extinction", because it is likely to be the sixth mass extinction event, after the Ordovician-Silurian extinction event, the final Devonian extinction, the Permian-Triassic extinction event, the Triassic-Jurassic extinction event, and the Cretaceous-Paleogene extinction event. Mass extinctions are characterized by the loss of at least 75% of species in a geologically short period of time. There is no general agreement on where the Holocene, or anthropogenic, extinction begins, and the Quarter extinction event, which includes climate change that resulted in the end of the last ice age, ends, or if they should be regarded as a separate event altogether. Some have suggested that anthropogenic extinction may have begun as early as the first modern humans spread from Africa between 100,000 and 200,000 years ago, backed by the rapid megafaun extinction following recent human colonization in Australia, New Zealand and Madagascar, in a way that large, adapted predators move into new ecosystems (invasive species). In many cases, it is advisable even minimal hunting pressure is sufficient to remove large fauna, especially on islands that are geographically isolated. Only during the last part of the extinction, the plant also suffered huge losses.
In the Future of Life (2002), Harvard's Edward Osborne Wilson calculated that, if the current level of human disturbance to the biosphere continues, half of the higher Earth life forms will become extinct by 2100. A Poll 1998 conducted by the American Museum of Natural History found that seventy percent of biologists recognize the ongoing anthropogenic extinction event. Currently, the species extinction rate is estimated to be 100 to 1,000 times higher than the background extinction rate, the historically distinctive extinction rate (in terms of the planet's natural evolution) as well as the current extinction rate, therefore, 10 to 100 times higher than previous mass extinctions in Earth's history. A scientist estimates the current extinction rate may be 10,000 times the extinction rate of the background. However, most scientists predict the extinction rate is much lower than this remote estimate. Theoretical ecologist Stuart Pimm states, for plants, the extinction rate is 100 times higher than normal.
In a pair of studies published in 2015, extrapolations from the extinction observed from Hawaiian slugs lead to the conclusion that 7% of all species on Earth may have been lost.
Although there is widespread consensus in the scientific community that human activity accelerates the extinction of many species of animals through the destruction of wild land, the consumption of animals as a resource or luxury, and the persecution of species seen by humans as threats or competitors, some argue that this biotic destruction has not risen to level five mass extinction earlier. Stuart Pimm, for example, asserts that the sixth mass extinction "is something that has not happened - we are at the end." In November 2017, a statement, titled "World Warning Scientist for Humanity: A Second Notice," led by eight authors and signed by 15,364 scientists from 184 countries confirms that, among other things, "we have released an event mass extinction, the sixth in approximately 540 million years, in which many life forms today can be destroyed or at least committed to extinction by the end of the century. "
Anthropocene
The abundance of species of extinction is considered anthropogenic, or because of human activity, sometimes (especially when referring to hypothetized future events) collectively called "Anthropocene extinction". "Anthropocene" is a term introduced in 2000. It is now assumed by some that a new geological age has begun, characterized by the extinction of the most sudden and widespread species since the Cretaceous-Paleogene extinction 66 million years ago.
The term "anthropocene" is used more frequently by scientists, and some commentators may refer to current and future extinctions projected as part of a longer Holocene extinction. The boundary of the Holocene-Anthropocene is contrasted, with some commentators asserting significant human influences on climate for much of what is normally regarded as the Epoch Holocene. Other commentators put the Holocene-Anthropocene limit on the industrial revolution while also saying that, "[f] the ormal adoption of this term in the near future will depend largely on its usefulness, especially for earth scientists working on late Holocene succession."
It has been suggested that human activity has made the period after the mid-20th century quite different from the rest of the Holocene to regard it as a new geological age, known as Anthropocene, which is considered to be an implementation to the timeline of Earth history by the International Commission on Stratigraphy in 2016. The Holocene as an extinction event, scientists must determine when exactly anthropogenic greenhouse gas emissions start measurably altering the natural atmospheric level on a global scale and when these changes cause changes in the global climate. Employing chemical proxies from Antarctic ice cores, researchers have estimated the fluctuations of carbon dioxide (CO 2 ) and methane gas (CH 4 ) in Earth's atmosphere for the final Pleistocene and Epoch Holocene. Based on studies that estimate the fluctuations of carbon dioxide and methane in the atmosphere using chemical proxies from Antarctic ice cores, the general argument when the Anthropocene peak occurs relates to the time period in the previous two centuries; usually begins with the Industrial Revolution, when greenhouse gas levels are recorded by contemporary methods at the highest point.
Maps Holocene extinction
Influences
Competition by humans
Holocene extinction is mainly caused by human activity. The extinction of animals, plants, and other organisms caused by human actions can last until the end of the final Pleistocene, more than 12,000 years ago. There is a correlation between megafaunal extinction and human arrival, and excessive human population and human population growth, along with excessive consumption and consumption growth, most notably in the last two centuries, are considered as one cause of extinction.
Megafauna has been found in every continent in the world and large islands such as New Zealand and Madagascar, but is now almost exclusively found on the African continent, with remarkable comparisons in Australia and the previously mentioned islands of immediate population accidents and tropical cascades after the earliest human settlers. It has been argued that African megafauna survive because they evolved with humans. The time of the megafaunal extinction of South America emerged to precede the arrival of humans, although the possibility that human activity at that time impacted the global climate sufficient to cause such extinction has been suggested.
It has been noted, in the face of such evidence, that humans are unique in ecology as an unprecedented 'global superpredator', regularly preying on a large number of fully-fledged terrestrial and marine predators, and with much influence over the food web and the climate system in the whole world. Although there is a significant debate about how much human predation and indirect effects are contributing to prehistoric extinctions, a particular population collision is directly correlated with human arrival. A 2018 study published in PNAS found that since the dawn of human civilization, 83% of wild mammals, 80% of marine mammals, 50% of plants and 15% of fish have disappeared. Currently, cattle make up 60% of all mammals on earth, followed by humans (36%) and wild mammals (4%). As for birds, 70% are domesticated, like poultry, while only 30% are wild.
Agriculture
Human civilization develops in accordance with the efficiency and intensification of the prevailing subsistence system. Local communities with more subsistence strategies are increasing in number to combat the pressure of land use competition. Therefore, Holocene develops competition on the basis of agriculture. Agricultural growth then introduces new ways of climate change, pollution, and ecological development.
Human habitat destruction, including ocean damage, such as through overfishing and contamination; and modification and destruction of extensive soil and river systems around the world to meet only human-centered ends (with 13 percent of the Earth's ice-free surface now used as agricultural farming lines, 26 percent used as grassland, and 4 percent urban industrial areas), thereby replacing native local ecosystems. Other relevant humanitarian causes of the extinction event include deforestation, hunting, pollution, introduction in various regions of non-native species, and the spread of infectious diseases that spread through livestock and crops.
Recent investigations of burning hunter-gatherer landscapes have major implications for the current debate about the timing of Anthropocene and the role that humans may play in greenhouse gas production prior to the Industrial Revolution. The study of early hunter-gatherers raises questions about the use of current size or population density as a proxy for the number of land clearing and anthropogenic combustion occurring in pre-industrial times. Scientists have questioned the correlation between population size and initial territorial change. Ruddiman and Ellis's research paper in 2009 made the case that early farmers involved in agricultural systems use more land per capita than farmers later in the Holocene, which intensify their work to produce more food per unit area (thus, per labor ); states that agricultural involvement in rice production carried out thousands of years ago by a relatively small population has created significant environmental impacts through major deforestation measures.
While a number of human-derived factors are recognized as potentially contributing to an increase in atmospheric concentrations of CH 4 (methane) and CO 2 (carbon dioxide), deforestation and the practice of clearing areas associated with agricultural development may contribute most to this concentration globally. Scientists using archaeological and paleoecological data variance argue that the processes that contribute to enormous human modification of the environment spanned thousands of years ago on a global scale and thus did not originate as early as the Industrial Revolution. Gaining popularity on the hypothesis that unusual, palaeoclimatologist William Ruddiman in 2003, stipulates that in the early Holocene 11,000 years ago, atmospheric carbon dioxide and methane levels fluctuate in a pattern different from the previous Pleistocene age. He argues that the pattern of significant decrease in CO 2 levels during the last ice age of Pleistocene is inversely proportional to the Holocene where there has been a dramatic increase in CO 2 at around 8000 years ago and CH levels 4 3000 years after that. The correlation between the decrease in CO 2 in the Pleistocene and Holocene increase during spark implies that cause greenhouse gases into the atmosphere is a man of agricultural growth during the Holocene such as expansion of anthropogenic (human) land use and irrigation.
Islands
The arrival of humans in the Caribbean about 6,000 years ago correlates with the extinction of many species. Examples include many different genera of arboreal soil and sloth on all islands. These sloths are generally smaller than those found in the South American continent. Megalocnus is the largest genus of up to 90 kilograms (200 pounds), Acratocnus is an intermediate relative of a modern two-pointed end slope endemic to Cuba, Imagocnus also from Cuba, Neocnus and many others.
Recent research, based on archaeological and paleontological excavations on 70 different Pacific islands has shown that many species are extinct as people move across the Pacific, beginning 30,000 years ago in the Bismarck Islands and Solomon Islands. It is now estimated that among Pacific bird species, some 2000 species have become extinct since human arrival, representing a 20% decline in bird biodiversity worldwide.
The first settlers were thought to have arrived on the island between 300 and 800 CE, with the arrival of Europe in the 16th century. Hawaii is famous for plant endemism, birds, insects, mollusks and fish; 30% of the organisms are endemic. Many of its species are endangered or extinct, primarily because of species introduced by accident and grazing livestock. More than 40% of the bird species have become extinct, and this is the location of 75% of extinctions in the United States. Extinctions have been increasing in Hawaii for the past 200 years and are relatively well documented, with extinctions among indigenous snails used as estimates for global extinction rates.
Australia
Australia was once home to a large collection of megafauna, with many similarities to those found on the African continent today. Australian fauna is characterized by primarily marsupial mammals, and many reptiles and birds, all present as giant forms to date. Humans arrived on the continent very early, about 50,000 years ago. As far as human arrival contribute to controversy; Australia's climate drift 40,000-60,000 years ago was an unlikely cause, as it was less severe in the speed or magnitude than previous regional climate changes that failed to kill megafauna. Extinction in Australia continues from the original settlements to this day in both plants and animals, while more animals and plants have declined or are threatened with extinction.
Due to the long time frame and soil chemistry on the continent, very little evidence of subfossil preservation exists relative elsewhere. However, extinctions across the continent of the genera weigh more than 100 kilograms, and six of the seven genera weighing between 45 and 100 kilograms occurred about 46,400 years ago (4,000 years after human arrival) and the fact that the megafauna survived until later in the island that. Tasmania after the formation of a land bridge suggests direct hunting or disruption of anthropogenic ecosystems such as fire-stick farming as a possible cause. The first evidence of direct human predation that caused extinction in Australia was published in 2016.
Madagascar
Within 500 years of human arrival between 2,500-2,000 years ago, almost all the different, endemic, and geographically isolated Madagascar megafauna became extinct. The largest animal, more than 150 kilograms (330 pounds), has become extinct for very long after the arrival of the first human, with large and dying species dying after prolonged poaching pressures from an expanding human population moved to more remote areas of the island. about 1000 years ago. Lesser fauna experience an initial increase due to decreased competition, and then decline after the last 500 years. All fauna weighing more than 10 kilograms (22 pounds) die. The main reasons for this are human hunting and habitat loss from the start of aridification, both of which survive and threaten Madagascar's remaining taxa today.
Eight or more species of elephant birds, immense giants that can not fly in the genera Aepyornis and Mullerornis , are extinct because of too much hunting, as well as 17 species of lemurs, known as giant, lemurs subfossils. Some of these lemurs typically weigh more than 150 kilograms (330 pounds), and fossils have provided evidence of human cuts in many species.
New Zealand
New Zealand is characterized by geographic isolation and island biogeography, and has been isolated from the Australian mainland for 80 million years. It is the last great land which is colonized by man. The arrival of Polynesian settlers around the 12th century resulted in the extinction of all megafaunal birds of the island in several hundred years. The last Moa, the immense flyless rat, became extinct within 200 years of the arrival of the settlers. Polynesians also introduced Polynesian rats. This may have put pressure on other birds but at the time of early European contact (18th century) and colonization (19th century) bird life was fertile. With them, Europeans brought rats, possums, cats and mustelids that destroyed the lives of native birds, some of which have adapted to the habits of flying and the habit of laying the ground and others have no defensive behavior because they lack the predator of endemic mammals that still exist. Kakapo, the world's largest cockatoo, which can not fly, is now only in the livestock-managed shelters. New Zealand's national emblem, the kiwi, is on the list of endangered birds.
America
There has been a debate over the extent to which the loss of megafauna at the end of the last glacial period can be attributed to human activity by hunting, or even by slaughtering prey populations. Discoveries in Monte Verde in South America and at Meadowcroft Rock Shelter in Pennsylvania have caused controversy about Clovis culture. Most likely there will be human settlements before Clovis Culture, and human history in America can extend back thousands of years before the Clovis culture. The number of correlations between human arrivals and megafauna extinctions is debatable: for example, on Wrangel Island in Siberia the extinction of dwarf wool mammoths (around 2000 BC) does not coincide with human arrivals, nor is there mass megafaunal mass extinction on the South American continent, caused by anthropogenic effects elsewhere in the world may have contributed.
Comparisons are sometimes made between recent extinctions (roughly since the industrial revolution) and the extinction of the Pleistocene towards the end of the last glacial period. The latter is exemplified by the extinction of large herbivores such as hairy mammoths and carnivores who prey on them. Today's humans are actively pursuing mammoths and mastodons but it is unknown whether this hunt is the cause of massive ecological changes, widespread extinctions and climate change.
The ecosystem faced by the first Americans has not been exposed to human interaction, and may be much more resilient to man-made changes than the ecosystems faced by industrial-era humans. Therefore, the actions of Clovis people, though seemingly insignificant by today's standards, can indeed have a profound impact on ecosystems and wildlife that are not used by human influence at all.
Afroeurasia
Africa has the smallest decline in megafauna compared to other continents. This may be because of the idea that megafauna Afroeurasia evolved with humans, and thereby developed a healthy fear of them, unlike animals that are relatively benign from other continents. Unlike other continents, the Eurasian megafauna extinct for a relatively long period of time, possibly because of the fragmenting climatic fluctuations and the declining population, making them vulnerable to over-exploitation, as well as the bison steppe (Bison priscus ). Heating in the polar regions causes a rapid decline in pasture, which has a negative effect on the grazing megafauna in Eurasia. Most of what used to be the mammoth steppe has been converted into mud, making the environment unable to support them, especially the hairy mammoth.
Climate change
One of the main theories for extinction is climate change. Climate change theory has suggested that changes in climate near the end of the late Pleistocene emphasize megafauna to the point of extinction. Some scientists love abrupt climate change as a catalyst for the extinction of mega fauna at the end of the Pleistocene, but there are many who believe the rising hunt from early modern humans also plays a role, with others even suggesting that they interact. However, the average annual temperature of the current interglacial period for the last 10,000 years is not higher than the previous interglacial period, but several of the same megafauna survived the same temperature rise. In America, a controversial explanation for climate change is presented under the impact hypothesis of Younger Dryas, which states that the impact of the comet cools global temperatures.
Megafaunal Extinction
Megafauna play an important role in the lateral transport of mineral nutrients in an ecosystem, which tends to transplant them from high to low-abundance areas. They do so with their movement between the time they consume the nutrients and the time they release them through elimination (or, to a much lesser extent, through decomposition after death). In the Amazon Basin, South America, it is estimated that such lateral diffusion is reduced by more than 98% after megafaunal extinctions that occurred about 12,500 years ago. Given the availability of phosphorus is considered to limit productivity in most areas, the reduction of transport from the western part of the basin and from the floodplains (both obtaining their supply from the Andean appointment) to other areas is considered to significantly impact the ecology of the area, and its impact may not yet reach its limits. The extinction of mammoths allows the grasslands they defend through the habit of grazing to become birch forests. New forest and forest fires produced may have caused climate change. Such omission may be the result of modern human breeding; some recent research supports this theory.
The large population of primordivores has the potential to contribute greatly to the atmospheric concentration of methane, which is an important greenhouse gas. Modern ruminant herbivores produce methane as a byproduct of foregut ferment in digestion, and release it through belching or flatulence. Currently, about 20% of annual methane emissions come from the release of livestock methane. In Mesozoikum, it is estimated that sauropods can emit 520 million tons of methane to the atmosphere each year, contributing to the warmer climate of the day (up to 10 ° C warmer than it is today). This great emission comes from the very large estimates of sauropod biomass, and because the production of methane from individual herbivores is believed to be almost proportional to their mass.
Recent studies have shown that the extinction of megafaunal herbivores may have caused a decrease in methane in the atmosphere. This hypothesis is relatively new. One study examined methane emissions from bison that occupied the North American Plains prior to contact with European settlers. The study estimates that the removal of bison causes a decrease of 2.2 million tonnes per year. Another study examined changes in methane concentrations in the atmosphere at the end of the Pleistocene epoch after the megafauna extinction in America. After the early humans migrated to the Americas around 13,000 BP, their hunting and other associated ecological impacts led to the extinction of many megafaun species there. Calculations show that this extinction decreases methane production by about 9.6 million tons per year. This suggests that the absence of megafaunal methane emissions may have contributed to a sudden climate cooling at the start of Dryas Muda. The drop in atmospheric methane occurring at that time, as recorded in ice cores, is 2-4 times faster than other declines in the last half-million years, suggesting that unusual mechanisms are at work.
Disease
The hyperdisease hypothesis, proposed by Ross MacPhee in 1997, states that megafaunal desperately is due to the indirect transmission of disease by newly arrived aboriginal humans. According to MacPhee, natives or animals traveling with them, such as domestic dogs or livestock, introduce one or more deadly diseases into a new environment where the original inhabitants have no immunity to them, leading eventually to their extinction. K-selection animals, such as the extinct megafauna, are highly susceptible to disease, compared to r-selection animals that have shorter pregnancy periods and higher population sizes. Humans are perceived as the only reason the migration of other animals previously to North America from Eurasia did not cause extinction.
There are many problems with this theory, because the disease must meet several criteria: it must be able to defend itself in an environment without a host; it must have a high infection rate; and very deadly, with 50-75% mortality. The disease must be very deadly to kill all individuals in genus or species, and even deadly diseases such as West Nile Virus are unlikely to cause extinction.
However, the disease has been the cause of several extinctions. The introduction of bird malaria and avipoxvirus, for example, has a negative impact on Hawaiian endemic birds.
Defaunation
History
The loss of species from the ecological community, defaunation, is mainly driven by human activity. This has resulted in an empty forest, an ecological community exhausted from large vertebrates. This is not to be confused with extinction, as it includes loss of species and decreased abundance. The defaunation effect was first implied at the Animal-Plant Interaction Symposium at Campinas University, Brazil in 1988 in the context of neotropical forests. Since then, this term has gained wider use in conservation biology as a global phenomenon.
The population of large cats has greatly declined over the past half century and can face extinction within the next few decades. According to the IUCN estimate: the lion drops to 25,000, from 450,000; leopard dropped to 50,000, from 750,000; cheetah down to 12,000, from 45,000; tigers dropped to 3,000 in the wild, from 50,000. The December 2016 study by the Zoological Society of London, the Panthera Corporation and the Wildlife Conservation Society shows that cheetahs are much closer to extinction than previously thought, with only 7,100 remaining in the wild, and crammed in just 9% of their historical reach. Human pressure must be blamed for the collision of cheetah populations, including loss of prey from poaching by people, revenge killings from farmers, habitat loss and illegal wildlife trade.
The term pollination reduces the abundance of insects and other pollinating animals in many of the world's ecosystems beginning in the late twentieth century, and continues to this day. The pollinators, which are required for 75% of food crops, are declining globally both in abundance and diversity. A 2017 study led by Radboud University Hans de Kroon shows that the biomass of insect life in Germany has fallen by three quarters in the previous 25 years. Participating researcher Dave Goulson of the University of Sussex stated that their research shows that humans make up a large part of the planet uninhabitable for wildlife. Goulson characterized his situation as an approaching "ecological Armageddon," adding that "if we lose insects it will collapse."
Various species are predicted to become extinct in the near future, among them rhinos, non-human primates, pangolins, and giraffes. Hunting alone threatens bird and mammal populations around the world. Some scientists and academics claim that increasing industrial farming and meat demand contribute to significant loss of global biodiversity because it is a significant driver of deforestation and habitat destruction; species-rich habitats, such as significant parts of the Amazon region, are being converted to agriculture for meat production. A 2017 study by the World Wildlife Fund (WWF) found that 60% loss of biodiversity can be attributed to large-scale cultivation of feed crops needed to raise tens of billions of farm animals. In addition, a 2006 report by the United Nations Food and Agriculture Organization (FAO), Livestock's Long Shadow , also found that the livestock sector is the "ultimate player" in the loss of biodiversity. According to WWF's Living Planet Index 2016, global wildlife populations have fallen by 58% since 1970, primarily due to habitat destruction, excessive hunting and pollution. They project that if current trends continue, 67% of wildlife may disappear by 2020. 189 countries, which signed the Convention on Biological Diversity (Rio Accord), have committed to preparing the Biodiversity Action Plan, the first step to identifying certain endangered species. species and habitats, country by country.
Recent extinction
Recent extinctions are more directly caused by human influence, whereas prehistoric extinctions can be attributed to other factors, such as global climate change. The International Union for Conservation of Nature (IUCN) characterizes the 'recent' extinction as it has happened past the 1500 limit point, and at least 875 species have gone extinct since then and 2012. Some species, such as P ¨ Deer deer and Hawaiian crow, extinct in the wild, and survive only in the prison population. Other species, such as the Florida tigers, are ecologically extinct, survive in very low numbers that essentially have no impact on the ecosystem. Other populations are just extirpated locally, still present elsewhere, but are diminished in distribution, as with the gray whale extinction in the Atlantic, and leatherback turtles in Malaysia.
Habitat destruction
Global warming is widely accepted as a contributor to extinctions worldwide, in the same way that previous extinction events generally included rapid changes in the global climate and meteorology. It is also expected to disrupt sex ratios in many reptiles that have sex-dependent determination.
Elimination of land to open roads for oil palm plantations releases carbon emissions in peatlands in Indonesia. Palm oil primarily serves as cheap cooking oil, and also as a biofuel (controversial). However, peatland damage contributes to 4% of global greenhouse gas emissions, and 8% of them are caused by the burning of fossil fuels. Oil palm cultivation has also been criticized for other environmental impacts, including deforestation, which threaten endangered species such as orangutans and tree kangaroos. The IUCN declares by 2016 that the species can become extinct within a decade if steps are not taken to conserve the rainforest in which they live.
An increase in carbon dioxide levels causes the entry of this gas into the oceans, increasing its acidity. Marine organisms that have calcium carbonate or exoskeleton shells undergo physiological pressures because carbonates react with acids. For example, this has resulted in coral bleaching in various coral reefs around the world, providing valuable habitats and maintaining high biodiversity. Marine gastropods, bivalves and other invertebrates are also affected, as do organisms that eat them.
Some researchers claim that by 2050 there may be more plastics than fish in the ocean with weight, with about 8.8 million tons of plastic being dumped into the oceans each year. Disposable plastics, such as plastic shopping bags, are the largest part of this, and often can be digested by marine life, such as with sea turtles. These plastics can be degraded into microplastic, smaller particles that can affect larger species arrangements. Microplastic is the largest part of the Great Pacific Garbage Patch, and its smaller size is detrimental to cleaning efforts.
Over-exploitation
Overhunting can reduce the local game population of animals by more than half, as well as reduce population density, and can cause extinction for some species. Populations located closer to the village are significantly more at risk of thinning. Some conservation organizations, including IFAW and HSUS, assert that trophy hunters, especially from the United States, play an important role in the decline of giraffes, which they call "silent extinction".
The spike in mass killings by hunters involved in illegal ivory trade along with habitat loss threatens the population of African elephants. In 1979, their population reached 1.7 million; there are currently less than 400,000 remaining. Before European colonization, scientists believe that Africa is home to about 20 million elephants. According to the Big Elephant Census, 30% of African elephants (or 144,000 individuals) disappeared over a seven-year period, 2007 to 2014. African elephants can be extinct by 2035 if hunting levels continue.
Fisheries have had a very bad impact on the population of marine organisms for several centuries even before the explosion of destructive and highly effective fishing practices such as trawling. Humans are unique among predators because they regularly precede other mature peak predators, especially in the marine environment; bluefin tuna, blue whales, North Atlantic whales and various sharks are particularly susceptible to predatory pressure from human fishing. A 2016 study published in Science concluded that humans tend to hunt for larger species, and this could disrupt marine ecosystems for millions of years.
Disease
Decline in amphibian populations has also been identified as an indicator of environmental degradation. As well as habitat loss, predators and introduced pollution, Chytridiomycosis, a fungal infection unintentionally propagated by human travel, has led to severe population decline of some frog species, including (among others) the extinction of golden frogs in Costa Rica and frogs which stretched the stomach in Australia. Many other amphibian species are now facing extinction, including the reduction of tree-limbed tree-limbed trees, and the extinction of Panama's golden frogs in the wild. Chytrid fungus has spread in Australia, New Zealand, Central America and Africa, including countries with high amphibian diversity such as cloud forests in Honduras and Madagascar. Batrachochytrium salamandrivorans are the same infections currently threatening salamanders. Amphibians are now the most endangered vertebrate group, which has existed for over 300 million years through three other mass extinctions.
Millions of bats in the US have been dying since 2012 because of fungal infections spreading from European bats, which seem to be immune. Population drops have reached 90% within five years, and the extinction of at least one species of bat is estimated. There is currently no form of treatment, and the decline has been described as "unprecedented" in the evolutionary history of bats by Alan Hicks of the New York State Department of Environmental Conservation.
Source of the article : Wikipedia
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