The main reasons for the decline in species numbers. Why are animal species disappearing?
Which spread and live in various natural areas. Such biodiversity in different climatic conditions varies: some species adapt to harsh conditions Arctic and tundra, others learn to survive in deserts and semi-deserts, others love warmth tropical latitudes, the fourth inhabit forests, and the fifth spread over wide expanses of the steppe. That state of species which is this moment exists on Earth, formed over 4 billion years. However, one of them is the reduction of biodiversity. If it is not solved, then we will forever lose the world we know now.
Reasons for the decline in biodiversity
There are many reasons for the decline of animal and plant species, and all of them directly or indirectly come from people:
- expansion of the territories of settlements;
- regular emissions of harmful elements into the atmosphere;
- transformation of natural landscapes into agricultural sites;
- usage chemical substances in agriculture;
- pollution of water bodies and soil;
- construction of roads and position of communications;
- , requiring more food and territory for life;
- experiments on crossing species of plants and animals;
- destruction of ecosystems;
- caused by people.
Of course, the list of reasons goes on. Whatever people do, they influence the reduction of habitats of flora and fauna. Accordingly, the life of animals changes, and some individuals, unable to survive, die prematurely, and the population size is significantly reduced, often leading to the complete extinction of the species. Approximately the same thing happens with plants.
The value of biodiversity
Biological diversity different forms life - animals, plants and microorganisms is valuable in that it has genetic and economic, scientific and cultural, social and recreational, and most importantly - ecological significance. After all, the diversity of animals and plants makes up the natural world all around us, so it needs to be protected. People have already caused irreparable damage that cannot be repaired. For example, many species across the planet were destroyed:
Quagga
Silphium
Solving the problem of biodiversity conservation
In order to preserve biodiversity on earth, a lot of effort needs to be made. First of all, it is necessary that the governments of all countries pay attention to Special attention this problem and defended natural objects from encroachments different people. Also, work to preserve the world of flora and fauna is carried out by various international organizations, in particular Greenpeace and the UN.
Among the main measures that are being taken, it should be mentioned that zoologists and other specialists are fighting for every individual of an endangered species, creating nature reserves and natural parks, where animals are monitored, conditions are created for them to live and increase populations. Plants are also artificially bred to expand their ranges and prevent valuable species from dying.
In addition, it is necessary to take measures to preserve forests, protect water bodies, soil and atmosphere from pollution, use them in production and everyday life. Most of all, the conservation of nature on the planet depends on ourselves, that is, on each person, because only we make the choice: kill an animal or save its life, cut down a tree or not, pick a flower or plant a new one. If each of us protects nature, the problem of biodiversity will be overcome.
The main reasons for the decline in numbers and extinction of animal species
Animal world - this is the totality of all species and individuals of wild animals - mammals, birds, reptiles, amphibians, fish, insects, mollusks and other invertebrates inhabiting certain territory or environment and being in a state of natural freedom.
One of the main ecological functions of animals is participation in the biotic cycle of substances and energy. The stability of ecosystems is ensured primarily by animals as the most mobile element. All animal species form the common genetic pool of the planet: they are all necessary and useful. There are no absolutely beneficial or absolutely harmful animals in nature. It all depends on their numbers, living conditions and a number of other factors.
Human, having mastered fire and weapons, back in early periods his history began to exterminate animals. However, now the rate of extinction of species has increased sharply, and more and more new species are being drawn into the orbit of the disappearing ones, as a result of which the rate of spontaneous emergence of species is tens and even hundreds of times lower than the rate of extinction of species. Therefore, there are simplifications of both individual ecosystems and the biosphere as a whole.
Main reasonsloss biological diversity, population decline and extinction animals consist of violation of their habitat, excessive harvesting or fishing in prohibited areas, introduction (acclimatization) of alien species, direct destruction for the purpose of protecting products, accidental or unintentional destruction and environmental pollution.
Habitat disruption due to deforestation, plowing of steppes, drainage of swamps, flow regulation, creation of reservoirs and other anthropogenic impacts radically changes the breeding conditions of wild animals and their migration routes, which has a very negative impact on their numbers and survival. For example, in the 60-70s. XX century At the cost of great efforts, the Kalmyk saiga population was restored and its number exceeded 700 thousand animals. Currently, there are significantly fewer saigas in the Kalmyk steppes, and their reproductive potential has been lost. The reasons are intensive overgrazing of livestock, the use of wire fences, the development of a network of irrigation canals that cut natural ways migration of animals, as a result of which thousands of saigas drown in canals along the way of their movement.
By harvesting we mean any removal of animals from natural environment for various purposes. Excessive production serves main reason reductions, for example, in numbers large mammals(elephants, rhinoceroses, etc.) in African and Asian countries: high cost Ivory on the world market leads to the annual death of about 60 thousand elephants. At bird markets big cities Hundreds of thousands of small songbirds are sold to Russia every year. Volume international trade wild birds exceeds seven million copies, most of who die either on the way or shortly after arrival.
The introduction (acclimatization) of alien species also leads to a reduction in the number and extinction of animal species. Often local species due to the invasion of “aliens” they are on the verge of extinction. Known examples negative influence American mink on a European mink, Canadian beaver in European, muskrat in muskrat. However, it is considered possible to introduce new species into depleted anthropogenic ecosystems to balance them. It is quite acceptable, for example, to introduce herbivorous fish - silver carp, grass carp - into artificial canals, where they prevent them from overgrowing.
Others The reasons for the decline in numbers and extinction of animals are:
- Their direct destruction to protect agricultural products and fishing facilities (death birds of prey, ground squirrels, pinnipeds, coyotes, etc.).
- Accidental (unintentional) destruction on highways, during military operations, when mowing grass, on power lines, when regulating water flow, etc.
- Pesticide pollution, oil and petroleum products, air pollutants, lead and other toxicants.
For example, as a result of the construction of hydraulic dams in the bed of the Volga River, spawning grounds were completely eliminated salmon fish and anadromous herring, and the distribution area sturgeon fish decreased to 400 hectares, which is 12% of the previous spawning fund in the Volga-Akhtuba floodplain. In the central regions of Russia, 12-15% of field game perishes during manual haymaking, 25-30% when using horse-drawn mowers, and 30-40% during mechanized hay harvesting. In general, the death of game in the fields during agricultural work is seven to ten times higher than the volume of game caught by hunters.
The fauna is the totality of all species and individuals of wild animals (mammals, birds, reptiles, amphibians, fish, as well as insects, mollusks and other invertebrates) inhabiting a certain territory or environment and being in a state of natural freedom.
According to Federal law“On the Animal World” (1995), the basic concepts related to the protection and use of the animal world are formulated as follows:
Object of the animal world - organisms of animal origin or their population;
Biological diversity of the animal world - the diversity of objects of the animal world within one species, between species and in ecosystems;
Steady state of the animal world - the existence of objects of the animal world for an indefinitely long time;
Sustainable use of animal objects is the use of animal objects that does not lead in the long term to the depletion of the biological diversity of the animal world and in which the ability of the animal world to reproduce and exist sustainably is preserved.
The fauna is an integral element of the natural environment and biological diversity of the Earth, a renewable natural resource, an important regulating and stabilizing component of the biosphere. The most important ecological function of animals is participation in biotic cycle substances and energy. The stability of the ecosystem is ensured primarily by animals, as the most mobile element.
It is necessary to realize that the animal world is not only an important component of the natural ecological system and at the same time the most valuable biological resource. It is also very important that all species of animals form the genetic fund of the planet; they are all necessary and useful. There are no stepchildren in nature, just as there are no absolutely useful and absolutely harmful animals. It all depends on their numbers, living conditions and a number of other factors. One of the varieties of 100 thousand different types of flies, the housefly is a carrier of a number of infectious diseases. At the same time, flies feed a huge number of animals ( small birds, toads, spiders, lizards, etc.). Only some species (ticks, rodent pests, etc.) are subject to strict control.
Despite the enormous value of the animal world, man, having mastered fire and weapons, began to exterminate animals in the early periods of his history (the so-called “Pleistocene overhunting”, and now, armed modern technology, developed a “rapid attack” on the entire natural biota. Of course, on Earth and in the past, at any time, for a variety of reasons, permanent shift its inhabitants. However, now the rate of extinction of species has increased sharply, and more and more new species are being drawn into the orbit of extinctions, which were previously quite viable.
The main reasons for the loss of biological diversity, population decline and extinction of animals are as follows:
Habitat disturbance;
Overharvesting, fishing in prohibited areas;
Introduction (acclimatization) of alien species;
Direct destruction to protect products;
Accidental (unintentional) destruction;
Environmental pollution.
Habitat disturbance Due to deforestation, plowing of steppes and fallow lands, drainage of swamps, flow regulation, creation of reservoirs and other anthropogenic impacts, it radically changes the breeding conditions of wild animals and their migration routes, which has a very negative impact on their numbers and survival.
For example, in the 60-70s. At the cost of great efforts, the Kalmyk saiga population was restored. Its population exceeded 700 thousand heads. Currently, there are significantly fewer saiga in the Kalmyk steppes, and its reproductive potential has been lost. There are various reasons: intensive overgrazing of livestock, excessive use of wire fences, the development of a network of irrigation canals that cut off the natural migration routes of animals, as a result of which thousands of saigas drowned in canals along the way of their movement.
Something similar happened in the Norilsk region. The laying of a gas pipeline without taking into account the migration of deer in the tundra led to the fact that animals began to gather in huge herds in front of the pipe, and nothing could force them to deviate from their centuries-old path. As a result, many thousands of animals died.
Under mining This refers to both direct persecution and disruption of the population structure (hunting), as well as any other removal of animals and plants from the natural environment for various purposes.
IN Russian Federation there is a decrease in the number of a number of game species animals, which is primarily due to the current socio-economic situation and increased illegal production. Excessive hunting is the main reason for the decline in the number of large mammals (elephants, rhinoceroses, etc.) in Africa and Asia. The high cost of ivory on the world market leads to the annual death of about 60 thousand elephants in these countries. However, small animals are also destroyed on an unimaginable scale. The international trade in wild birds exceeds seven million, most of which die either en route or shortly after arrival.
The negative impact of such a factor of population decline as excessive hunting also manifests itself in relation to other representatives of the animal world. For example, stocks of East Baltic cod are currently at such a low level, which has not been recorded in the entire history of studying this species in the Baltic. By 1993, total cod catches had decreased by 16 times compared to 1984, despite increasing fishing efforts.
Sturgeon stocks in the Caspian and Azov Seas have been so depleted that, apparently, it will be necessary to introduce a ban on their industrial fishing. The main reason for this is poaching, which has everywhere reached a scale comparable to fishing. The ban on capelin fishing in the Barents Sea is expected to continue, as there is no hope of restoring the population, undermined by predatory consumption. Since 1994, fishing for Azov-Kuban herring in the Don has been prohibited due to the low population size.
The third most important reason for the decline in numbers and extinction of animal species is introduction (acclimatization) of alien species. The literature describes numerous cases of extinction of native (indigenous) species due to the influence of introduced species of animals or plants on them. There are even more examples where local species are on the verge of extinction due to the invasion of “aliens”. Examples of the negative impact of the American mink on the local species - the European mink, the Canadian beaver - on the European one, the muskrat on the muskrat, etc. are widely known in our country.
Other reasons for the decline in numbers and extinction of animals:
their direct destruction to protect agricultural products and commercial fisheries (death of birds of prey, ground squirrels, pinnipeds, coyotes, etc.);
accidental (unintentional) destruction(on highways, during military operations, when mowing grass, on power lines, when regulating water flow, etc.);
environmental pollution(pesticides, oil and petroleum products, atmospheric pollutants, lead and other toxicants).
Here are just two examples related to the decline of animal species due to unintentional human impact. As a result of the construction of hydraulic dams in the bed of the Volga River, the spawning grounds of salmon fish (whitefish) and migratory herring were completely eliminated, and the distribution area of sturgeon fish was reduced to 400 hectares, which is 12% of the previous spawning fund in the Volga-Akhtuba floodplain.
In the central regions of Russia, 12-15% of field game perishes during manual haymaking, 25-30% when using horse-drawn mowers, and 30-40% during mechanized hay harvesting. In general, the death of game in the fields during agricultural work is seven to ten times higher than the volume of game caught by hunters.
Numerous observations indicate that in nature, as a rule, several factors act simultaneously, causing the death of individuals, populations and species as a whole. When interacting, they can lead to serious negative results even with a low degree of expression of each of them.
And yet, numerous types of explanations for the causes of extinction are quite widespread among biologists, for example:
· Hypotheses of “internal” causes of extinction;
· Theories of “monodynamic” or “shock” factors of extinction;
· Hypotheses of the causes of extinction in the works of Darwin, Neumayr, Andrusov;
· Separate hypotheses for the causes of extinction regarding each species;
· Extinction, depending on local and regional changes in abiotic environmental conditions.
The immediate cause of the extinction of the species in natural conditions- a decrease in its number below a critical level, which depends on the population structure of the species and is determined by the laws of population genetics. The critical level is the population level below which the probability of inbreeding becomes quite large. This leads to a decrease in the genetic diversity of the species, the so-called reserve of hereditary variability. The consequence of such a decrease in numbers is therefore an increase in the proportion of descendants with congenital disorders, which increase mortality in new generations and reduce the adaptive capabilities and fertility of the survivors. As a result, the population declines irreversibly and after a small number of generations the species completely disappears. In this sense, in dangerous situation Many species are now found. For example, the cheetah, a unique “sprinter” among carnivorous mammals, is not only small in Africa, but also has very low levels of intraspecific genetic diversity. In fact, all African cheetahs turned out to be more or less closely related. They have the highest mortality rate of young animals among representatives of the cat family in the first days and weeks of life; they are more susceptible to infectious diseases than other cats.
As a rule, only one of the factors turns out to be the main limiter on the number of the species of interest to us. This factor is called limiting. For example, for most salmon, the limiting factor is the oxygen content in the water in which their large eggs develop. This determines the nature of salmon spawning rivers - low temperature And fast current, saturating water with oxygen, low content organic matter, the oxidation of which reduces the oxygen content in water, low mineralization of water. Pollution of spawning rivers quickly leads to a decline in salmon numbers. For squirrels in the taiga zone, the limiting factor is the yield of spruce seeds; for water rats in river floodplains, it is the level of the spring flood. It must be borne in mind that it is not always easy to single out a single limiting factor from a variety of biotic and abiotic factors, and sometimes the limiting factor is the interaction of two or more factors. For example, for many aquatic invertebrates, the temperature optimum is different at different salinities, and their numbers are limited by the interaction of these factors.
The Darwinian theory of evolution recognizes exclusively important biotic factors in the extinction of organic species. However, she never belittled the importance of abiotic factors, which in some cases can play a decisive role. After all interspecies relations, which can lead to the extinction of some species during the survival and even expansion of others, develop against the background of physical and chemical environmental conditions, on which the action of biotic factors undoubtedly depends.
Recognizing that the factors of extinction and survival of organic forms do not act equally in different latitudinal zones of the Earth, we, however, are by no means inclined to think that there are belts of our planet where biotic factors deprived of leading significance.
So, the density of populations, and the forms of struggle for existence, and the degree of intensity of competition between populations, and the very course of population extinction more or less depend on the general geographical situation.
More than a thousand species of vertebrates and many species of mollusks, insects and other invertebrates are at risk of extinction. This is the result of direct human persecution of animals or changes in their living conditions, which causes concern among biologists and conservationists around the world. The concepts of rare, endangered, and endangered species appeared. They are not clear enough, and at first even experts put different meanings into them.
Today, more than a thousand species of vertebrates and many species of mollusks, insects and other invertebrates are in danger of extinction.
The Convention includes three lists of species by risk of extinction, these lists are constantly being updated.
Since the initial values of the gas parameters in the container change with temperature changes, control of a possible increase in pressure and the danger of disappearance of the vapor phase can be carried out by calculation.
THE RED BOOK is an official publication containing a description and condition of animals and plants that are more or less in danger of extinction. The Red Book of the USSR and the Red Books of individual regions were published.
Preference is given to those areas that are less altered as a result of human economic activity, and first of all, the standards of those landscapes that are in danger of extinction are preserved. It is very important that the territories of nature reserves are sufficient to ensure self-regulation of the processes occurring in them and do not experience noticeable influence from neighboring anthropogenic territories.
Three groups of animals facing extinction - dart frogs, bears and sharks - represent amazing examples how important models for biomedical science are at risk of extinction due to human causes.
Even such a recognized and effective way of increasing forest productivity as drainage reclamation may have negative consequences. We will not talk in detail about the danger of the disappearance of the valuable, highly vitamin-rich cranberry ((Ojcycoccos palustris Pers. With vast areas of swamps and swamp forests in our country, there is no danger of a significant reduction in stocks, much less the disappearance of these berries, but in some areas, according to at least The European part of the USSR, this side cannot be ignored in the near future. We believe that in some other countries with the presence of swamps and swamp forests, where their intensive drainage is carried out, this issue is of interest. Of course, we are not talking about the priority of cranberries over wood. The solution to this issue may also have a special independent path. By the way, the mentioned circumstance reinforces the feasibility of ongoing experiments and work on a production scale to create specialized plantations of cranberries, blueberries and some other berries of the taiga and tundra, but the importance of protection natural resources this does not reduce it.
The change in living conditions occurring under the influence of human activity, accompanied by direct persecution and extermination of animals, leads to a depletion of their species composition and a reduction in the number of many species. Mitryushkin (1980), in 1600 there were approximately 4230 species of mammals on the planet; by now, 36 species have disappeared, and 120 species are in danger of extinction. Of the 8,684 bird species, 94 have disappeared and 187 are endangered. The situation is no better with subspecies: since 1600, 64 subspecies of mammals and 164 subspecies of birds have disappeared, 223 subspecies of mammals and 287 subspecies of birds are in danger.
Changes in living conditions occurring under the influence of human activity, direct persecution and extermination of animals lead to the depletion of their species composition and a reduction in the number of many species. According to K.P. Mitryushkin (1980), in 1600 there were approximately 4,230 species of mammals on the planet; by now, 36 species have disappeared, and 120 species are in danger of extinction. Of the 8,684 bird species, 94 have disappeared and 187 are threatened.
In a LP stereophony system, as a rule, microphones with a circular directivity characteristic are used (see page If too long distance between microphones or when a sound source moves from one microphone to another, jumps or discontinuities in the sound may appear. It should also be borne in mind that the smaller the distance between the microphones, the more correct the sound transmission of sound sources located at different angles to the axis of symmetry of the microphones will be. Minimum distance is limited by the risk of disappearance of the stereophonic effect and is selected empirically for each case separately.
Accordingly, there is reason to reject the belief that progress is irresistible, that nature must be endlessly humanized, or that technological and social planning can solve all our problems. To some extent we can shape our future, and in doing so we must understand to what state of nature and society we can arrive, in relation to moral assessments of the state of society and the world, which must be better than the present one in order to hope for progress. This is indeed a necessary precondition for the conservation of resources and the protection of endangered species and their vulnerable habitats, as well as for human well-being... But for this to be possible, it is necessary new form faith in progress. She is far from rejecting the humanistic secular tradition of the philosophers of the Enlightenment, Kant, Marx, Engels and others. The combination of its possibilities with the possibilities of the old Judeo-Christian tradition, suitably ennobled, can indeed give us the means to solve environmental problems without the invention of a new metaphysics and a new ethics
The catastrophic decline in the numbers of many plant and wildlife species is of grave concern. This condition is a consequence of the action of various negative natural and anthropogenic factors. According to rough estimates, about 2% of the fauna of modern amphibians and reptiles, 3.5% of freshwater fish, almost 5% of birds, over 6% of mammals, about 10% of vascular plant species in the world are on the verge of extinction.
However, very important factor, which dramatically affects wildlife, is economic activity person. In its relatively short history, man has radically changed the face of the Planet. Her influence was accompanied by both positive and negative consequences. Man has diversified cultivated plant species with varieties and domesticated animal species, replaced indigenous natural landscapes and ecosystems cultural, industrial, urbanized. This led to a sharp change in living conditions, biotic and abiotic environments, which negatively affected the population and species composition of flora and fauna. As a result, the ecological balance and ecological balance and stability of the biosphere are disrupted.
Each type of living organism is constantly exposed to various environmental factors, which act collectively and specifically, and therefore affect their condition differently. individual species(Table 12.1). It provides summary results on the causes of extinction of vertebrate species for the period from 1600 to 1974(Nilson, 1983).
Table 12.1.
Causes extinction |
Number of extinct species |
||||
Amphibians |
Reptiles |
Birds |
Mammals |
Together |
|
1. Fishing |
|||||
2. Habitat destruction |
|||||
3. Introduction of new species |
|||||
4. Direct destruction |
|||||
5. Diseases and other causes of death |
|||||
7. 3 unknown reasons |
Even more alarming are the data on the number of vertebrate species that, according to the International Red Book, are at risk of extinction (Table 12.2).
To reveal the nature of the action of these causes, it is necessary to analyze each of the factors more specifically, since they caused the extinction of some animal species and negatively affect plants.
The universal reason that leads to a reduction in numbers, and often to the extinction of entire populations of individual species and even groups of them, is destruction of animal habitats and plant growth.
Table 12.2.
Causes |
Number of species |
|||||
Fish |
Amphibians |
Reptiles |
Birds |
Mammals |
Together |
|
1. Overtime fishing |
||||||
2. Habitat destruction |
||||||
3. Impact of species introduction |
||||||
4. Direct destruction |
||||||
5. Diseases and other causes of death |
||||||
6. Natural factors |
||||||
7. Pollution |
||||||
8. Anxiety, disturbance of peace |
Economic development of the territory leaves less and less space for wild animals and plants to live.
Usually the first symptom of destruction of natural living environment is insularization - disintegration of a single area into small islands (Fig. 12.1). The disappearance of species as a result of habitat destruction occurs the faster the smaller the area of these islands of habitat and the more isolated they are. Theoretical research methods made it possible to calculate the rate of expected decrease in the number of species of large animals for this reason in 19 East African Serengeti national parks and others. It turned out that insularization can cause the loss of about 11% of large mammal species after 50 years, and after 500 years - 44%.
Rice. 12.1. An example of habitat insularization: a reduction in the area occupied by forests over 10 km in the state of Wisconsin (USA) from 1821 to 1950.
(according to E. Pianka, 1981).
A significant number of species of wild plants are lost from the flora of many regions due to livestock grazing, reclamation and plowing of natural lands, and deforestation.
As a result of this impact, the biotopes of many species undergo changes that are unable to ensure their existence. An interesting example would be a plant with the largest flower in the world, reaching more than one meter in diameter -Rafflesia arnoldi . It is common in tropical forests on
O. Sumatra (Indonesia) and is on the verge of extinction.
Habitat destruction - one of the strongest reasons for the disappearance or sharp decline in the number of many species of meadow and marsh plants natural flora and fauna of Ukraine.
Overfishing (removal of plants and animals from the natural environment for various purposes: collecting, making souvenirs, obtaining medicines, keeping in captivity, etc.) is the second important reason, which causes a sharp reduction in the number of species of industrial and ornamental animals, medicinal and early spring plants .
It is worth noting that due to these reasons, sturgeon and other fish have reduced their numbers. commercial fish, sea and land turtles, crocodiles, pheasants, parrots, songbirds, decorative butterflies, as well as cacti and other types of valuable wild plants.
The 1973 Washington Convention for Restrictions on International Trade in Rare and Endangered Species of Plants and Animals and Their Products and Articles was an attempt to warn and prevent the extermination of such species. In 1985, this convention was signed by 88 states. Due to massive poaching in African continent from 1970 to 1982, the number of rhinoceroses decreased 10 times; ivory trade volume increased from 400 tons/year in 1968 to 10 thousand tons/year in 1982 p ., which led to the death of about 100 thousand elephants in African and Asian countries (A.V. Yablokov, S.A. Ostroumov, 1985).
Unregulated collection for collecting and trade kills or sharply reduces the population of cacti and other succulents, orchids, lilies, pivonia and other ornamental, medicinal, and industrial plants.
Introduction of new species (introduction, migration, passive and accidental introduction and drift) in most cases has negative consequences. Aliens often aggressively and quickly conquer new territories, displacing local endemic species. For example: in 1978 at Hawaiian Islands was introduced 22 species of mammals, about 160 species of birds, about 1300 species of insects, more than 2 thousand species of flowering plants. This was the reason that since the discovery of these islands, up to 22 species of birds (30% of the native avifauna), 14 species of mollusks (34% of the native malacofauna) have become extinct. 70% of Hawaiian flora species are at risk of extinction.
There are known facts indicating an increased ability of introduced plants to suppress local species through allelopathy (chemical secretions unusual for natives).
Mentioned influence on local flora and fauna universe species is a natural phenomenon caused by the migration of people. He is the reason that the indigenous natural
The flora and fauna of the regions has changed to mixed (natives + introduced species). It is important to contain and regulate this process in order to preserve endemic and native species.
Technogenic pollution of the environment is one of the factors of a sharp negative impact on wildlife.
Artificial chemicalization of the environment has already reached such a scale and level that it has become a real threat to the normal functioning and existence of the biosphere. Imperfect industrial technologies, improper storage and use of mineral fertilizers and pesticides in agriculture have become a source of pollution in all environments of life (aquatic, land-air, soil) and have turned them unfavorable for many types of living organisms, including humans themselves, whose activities gave rise to this artificial factor.
The migration of toxicants and pollutants and their bioaccumulation in organisms within the trophic chain of biocenoses has caused a disruption in the stability of natural ecosystems, the disappearance of many valuable plant species and their animal companions. High concentrations of sulfur dioxide, nitrogen oxides, carbon, and soot in the air have a detrimental effect on plants, especially on green spaces in cities.
Like waste industrial enterprises Many metal compounds enter various environments, which, especially in excess quantities, are dangerous for animals. These are, in particular, heavy metals such as lead, mercury, selenium, cadmium, etc. They act on the animal’s body directly or through various links in the trophic chain.
Pesticides turned out to be very dangerous for animals - the main chemical product second half of the 20th century. A classic example of their action is the drug DDT. As a potent agent, it has been used successfully to combat carriers of vector-borne diseases (mosquitoes, flies, ticks, horseflies, mosquitoes), and pests in fields and gardens. The massive use of DDT and other pesticides in the 50-60s led to a sharp reduction in numbers and even to complete disappearance some species of fish, fish-eaters and other carnivorous birds in many countries of the world, the shells of their eggs became thinner by almost a third, and important vital functions were disrupted, especially reproductive ones. Numerous casualties among wild warm-blooded animals are a consequence of the uncontrolled use of zoocides to exterminate harmful rodents (mice, rats) and carriers of infectious diseases of birds and other harmful and dangerous vertebrate animals.
Undoubtedly, anthropogenic chemical pollution of the planet is one of the main reasons that threatens the life of wild animals, since they penetrate into all living environments, even in those regions that are very far from sources of pollution. The influence of various pollutants on living organisms has been studied very little, and therefore deserves special attention so as not to lose the biodiversity of nature from this.
A striking example demonstrating the negative consequences of chemical pollution of the environment is the adaptation of pests to insecticides (Fig. 12.2) and their bioaccumulation in the links of the trophic chain (Fig. 12.3).
Rice. 12.2. Increase in the number of insecticide-resistant forms of insects from 1920 to 1980 .
Rice. 12.3. Scheme bioaccumulation insecticide dieldrin in the trophic network of the coastal part of the sea.
Sea water: traces of dieldrin.
I - Phytoplankton: 1 billion -1. II - Zooplankton: 210 2 million -1. III - Crustaceans and microphage fish: 3 10 2
million -1 . IV - Kryachko, eggs: 0.2 million -1.
IV - Seagull, eggs: 0.1 million -1. IV - Predator fish: 0.2 million -1.
V - Cormorant, liver: 6 million -1, eggs: 2 million -1.
In addition to the above reasons, which are equally dangerous for plants and animals, there are also various specific and locally relevant ones that must be taken into account when solving many problems of protecting species populations in specific regions. They are the object of study in many special disciplines and applied branches of ecology and nature conservation.