Types of harmful effects of humans on the animal world. Human influence on the animal world
Despite the enormous value of the animal world, man, having mastered fire and weapons, even in the early periods of his origins began to exterminate animals (the so-called “Pleistocene industry”, and now, armed modern technology, developed a “rapid attack” on the entire natural biota. The main reasons for the loss of biological diversity, population decline and extinction of animals are as follows:
— disturbance of the habitat;
- over-harvesting, fishing in prohibited areas;
— direct destruction to protect products;
— accidental (unintentional) destruction;
— environmental pollution.
Habitat disruption due to deforestation, plowing of grasslands and fallow lands, 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. 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 grazing of livestock, excessive use of wire fences, development of a network of irrigation canals that cut natural ways migration of animals, as a result of which thousands of saigas drowned in canals along the way of their movement.
Something similar happened in the area of Norilsk in 2001. 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 around the pipe into huge herds, and nothing could force them to deviate from their centuries-old path. As a result, many thousands of animals died. In the 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 their increased illegal production
(for example poaching).
Excessive production serves main reason reductions and numbers large mammals(elephants, rhinoceroses, etc.) in African and Asian countries. High price 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. According to the calculations of world socialists in the field of zoology and general ecology and Russian corresponding members of the Russian Academy of Sciences and doctors of biological sciences A.V. Yablokov and S.A. Ostroumov, at poultry markets big cities In the European part of Russia, at least several hundred thousand small avian birds are sold annually. Volume international trade wild birds exceeds seven million copies.
Other reasons for the decline in numbers and disappearance of animals are their direct destruction to protect agricultural products and commercial objects (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.); environmental pollution (sticides, oil and petroleum products, atmospheric pollutants, lead and other toxicants).
Let us give just two examples related to the decline in animal species due to unintentional human impact. As a result of the construction of hydraulic dams in the bed of the Volga River, spawning grounds were completely eliminated salmon fish(whitefish) and migratory 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 Astrakhan region.
In the central regions of Russia, 12-15% of field game perishes during manual haymaking, and 30% during mechanized hay harvesting. In general, the death of game in the fields during agricultural work is seventy times greater than the volume of game caught by hunters.
Indirect human impact on animal world consists of polluting the habitat of living organisms, changing it or even destroying it. Thus, populations of amphibians and aquatic animals are greatly harmed by water pollution. For example, the size of the Black Sea dolphin population is not recovering, since as a result of entry into sea waters huge amount toxic substances the mortality rate of individuals is high.
Confirmed that this is the result of suppression immune system fish due to dumping into the Volga technical waste, as well as runoff from rice fields in the delta.
Often the reason for the decline in numbers and extinction of populations is the destruction of their habitat ref.rf, the fragmentation of large populations into small ones, isolated from each other. This can happen as a result of deforestation, road construction, new enterprises, and agricultural development of land. For example, the number Ussuri tiger sharply decreased due to human development of territories within the range of this animal and a reduction in its food supply.
The economic activities of the noils have a huge impact on animals. Deforestation, plowing of land, use of fertilizers and pesticides worsen the living conditions of animals. These conditions change with the draining of swamps, the creation of dams and irrigation systems, the development of mineral resources, and the construction of cities and transport highways. In all of these cases, humans have an indirect impact on animals by changing their habitat.
The direct influence of humans on animals is also great. Excessive hunting has led to the extinction of many animal species. For example, in just 27 years (1741-1768) Steller's cow was destroyed (Fig. 15) - sedentary and trusting sea animal, feeding on algae in shallow waters off the Commander Islands. Unfortunately, the animal had delicious meat and he was easy to hunt.
Rice. 15. Steller's cow
By the middle of the 18th century. Large (weighing up to 20 kg) flightless pigeons, the dodo, which lived on the Mascarene Islands, disappeared. The birds nested on the ground, so domestic animals brought by Europeans - dogs, cats, pigs, which ate eggs and chicks - brought great harm to them.
One of the most numerous birds North America life of the passenger pigeon (Fig. 16). It nested in trees in large colonies. Flocks of pigeons reached millions of individuals. The mass extermination of passenger pigeons by European settlers began in the 17th century. Birds were shot, caught in nets, and knocked down with sticks. Pigs were released at the sites of massacres to eat killed birds and chicks that had fallen from their nests. By the end of the last century, passenger pigeons had become rare, but no one could believe it. The last passenger pigeon died at the Cincinnati Zoo (USA) in 1914. Now a museum has been opened in this city. dedicated to the passenger pigeon. This is a sad example of man's deliberate destruction of a once thriving species.
Rice. 16. Passenger Pigeon
The list of animals exterminated by humans is extremely long. It includes the zebra quagga, marsupial wolf, European ibis. In the south of Europe, in Western Siberia, Kazakhstan and Central Asia disappeared wild Horse- steppe tarpan (Fig. 17). Until the middle of the 19th century. this species was still found in the Black Sea steppes. The last free Tarpan was killed in 1879, and in captivity, at a stud farm, he lived until 1918. Now this wild ancestor There are no modern horses on Earth. The forest tarpan was also exterminated. Apparently, Przewalski's horse has also disappeared from nature by now.
Rice. 17. Steppe Tarpan
The fauna of Australia, New Zealand, and the ocean islands have suffered especially hard from the direct and indirect impact of people. There, many species were on the verge of extinction due to human fault. Realizing that the disappearance of any animal species is an irreparable loss, people began to protect rare species and take care of preserving the number of game animals. In 1966, the World (International) Union for Conservation of Nature and natural resources The Red Book was published containing a list of rare and endangered species of animals. Red color is an alarm signal.
The Red Book contains information about rare species - their distribution, numbers, causes of their plight and conservation measures. This information is updated regularly. Later Red Books were created rare species animals different countries. There is a Red Book of Rare Species of Animals Russian Federation. Each country is responsible for the conservation of species listed in the Red Book to its people and all humanity. Naturally, causing any harm to such animals is a crime.
To preserve rare animals, their habitats and everything natural complex biosphere, state, and republican reserves have been created. So. in Russia, in the Volga delta, exists since 1919 Astrakhan Nature Reserve for the protection of nesting places of rare aquatic and semi-aquatic birds and their habitats. During their migrations, northern birds stop here to rest and feed.
In cases where the number of a species in nature becomes so low. that he himself cannot recover, he is bred in captivity, and then released into natural environment a habitat. This is what they did with the California condor. It is now bred in several zoos and then released in those places where condors lived before. Scientists are monitoring how released birds feel. In our country, several nurseries have been created for breeding noble falcons (saker falcons, peregrine falcons) and other birds of prey. There is a nursery for birds of prey in the Galichya Gora Nature Reserve in the Lipetsk Region, and cranes are bred in the Oksky Nature Reserve.
Rational use and protection of wildlife are the most important state and public tasks, caring for our national heritage.
Exercises based on the material covered
- Give examples of the negative impact of humans on the number and diversity of animals.
- Name those animals that have disappeared as a result of human activity.
- What measures are being taken in our country and in the world to preserve rare animals?
Direct- human impact directly on individuals of the species (hunting, use chemicals, feeding birds in winter).
Indirect- when a person does not touch the animals themselves, but changes their habitat and thus influences this type(draining swamps and mowing meadows). The consequences of the second type are much more dangerous, since it affects many species of organisms living in a given area. The plowing of virgin lands and deforestation leads to a sharp reduction in the ranges of many wild ungulates, and this leads to a reduction in the number of predators and an increase in the number of rodents.
Reckless interference in the life of a biocenosis can lead to quick and unpleasant consequences.
The destruction of sparrows in China contributed to an increase in the number of insect pests, the elimination of wolves in the northern Canadian territories initially led to an increase in the number of deer, but then to the spread of diseases among them and a sharp decline in their numbers.
Main threats biological diversity resulting from human activities are the destruction of habitats, their fragmentation and degradation, including pollution, global change climate, overexploitation of species by humans, invasion exotic species and the increasing spread of disease. About a third of all mammals in Russia are listed in the Red Book (Fig. 2), which means that saving them will not be easy.
Rice. 2. Red Book of Russia ()
True, there are examples when it was possible to restore the number of some animals, for example, the number of saiga, sable, beaver, fur seal(Fig. 3).
Rice. 3. Animals that are experiencing an increase in numbers ()
Fishing- direct removal of organisms by humans from nature. This is the most ancient look human impact on the animal world. Trades are named after the organisms or products they produce: hunting, fishing, fur fishing, crab fishing, sea cucumber fishing, and so on. There are groups of animals that are considered commercial animals. Any fishery can be successful only if the biology of the game animal is understood. To do this, one condition must be met - the number of the hunted animal must be constantly restored through reproduction.
Habitat disruption due to deforestation, plowing of steppes, drainage of swamps, 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.
In our country, fishing for some animals is completely prohibited due to the need to protect them, for example whales and dolphins.
The domestication of wild animals and their transformation into domestic ones began millions of years ago. Excavation of settlements primitive man proved that before other animals, back in the Mesolithic era, the dog was domesticated, later the pig, sheep, goat, and only then the horse. There are no more than twenty-five domestic animal species. For domestication, it is necessary for the animal to bear offspring, and after that to make a selection and, preserving individuals with the most valuable properties, in a few hundred years get a real domestic animal. The domestication of animals is carried out at the present time, work on domestication is known capercaillie, bustard And moose(Fig. 4), in addition, in different time And different places domestication work is underway muskox, deer, eland(Fig. 5).
Rice. 4. Species that are undergoing the process of domestication ()
Rice. 5. Species that are undergoing the process of domestication ()
Work is underway to domesticate mink, arctic fox, quail, pheasant (Fig. 6), as well as silver carp and grass carp (Fig. 7).
Rice. 6. Species that are undergoing the process of domestication ()
Rice. 7. Types of fish that are undergoing the process of domestication ()
The domestication of wild animals took place in different ways. There was also a natural rapprochement between man and animal, when animals gradually got used to being near human habitation. Man and animals were neighbors, they existed next to each other. There was also forced domestication, when people caught wild animals and kept them in captivity. In the process of domestication, under the influence of new environmental conditions, animals developed characteristics that distinguish them from wild ones. The size and shape of the body changed, for example in a pig, sheep, horse. This had the least impact on animals such as camels and reindeer, whose living conditions in captivity are close to natural.
Nowadays people even use insects - bumblebees and flies. The first is for pollinating greenhouse plants and the second is for recycling manure on pig farms and obtaining animal protein. These insects are no different from wild forms and, of course, cannot be considered domestic; real domestic animals are honey bee and silkworm (Fig. 8).
Rice. 8. Domestication of bees and silkworm ()
The domestication of animals is a long process, it is believed that the domestication of reindeer and dogs occurred eighteen thousand years BC, sheep were domesticated eight thousand years ago, goats and pigs - six and a half thousand years ago, cows - five thousand years, and silkworm - four and a half thousand years ago.
Domestication took place in natural places habitats: horses - in the steppes of Eurasia, chickens - in India, guinea fowl - in Africa, turkeys - in America, ducks and silkworms - in China, pigeons, geese and cats - in Egypt.
Domestication of pigs, horses and goats occurred independently in several places in the range. After domestication, the spread of animals was facilitated by trade, wars, and accidental introductions. The relocation of animals from one place to another did not always benefit nature and people. There are many known disasters caused by such relocations: rabbits and cats brought to Australia destroy local flora and fauna, goats in North Africa, Spain and Turkey can destroy entire forests.
The domestication of animals involves its further development and selection. Breeds that are interesting to humans are selected important role The absence of aggression plays a role; most often, selection is made to obtain some kind of product - eggs, meat, milk, wool, fur. The domestication of an animal radically changes the conditions for further development kind. Natural evolutionary development is replaced by artificial selection according to breeding criteria, thus changing within the framework of domestication genetic properties kind.
Animals have acquired signs that distinguish them from wild ones, and these are all the more significant as more work and time was spent by man on obtaining animals with the properties he needed. Body size and shape in to the greatest extent changed in animals whose living conditions are very different from those wild habitat(large cattle, pigs, sheep, horses) and to a lesser extent in animals such as camels and reindeer, whose living conditions in captivity are close to natural. The so-called protective painting; Pets come in a variety of colors. Compared to wild animals, they have a lighter skeleton, less strong bones, and thinner skin. Has undergone changes and internal organs. Many domestic animals have less developed lungs, hearts, and kidneys, but their mammary glands and reproductive organs function better than wild animals (domestic animals, as a rule, are more fertile); many of them have lost seasonality in reproduction. Most domesticated animals are characterized by a decrease in brain size and a decrease in reactivity nervous system, simplification of behavioral reactions, changes in the phenotypic expression of mutations under the influence of an altered gene pool, a general increase in variability.
We discussed the human impact on the animal world and the domestication of animals. Domestication of wild animals on a par with cultivation useful to people plants had great value in development human society. Human-created breeds of domestic animals and varieties of cultivated plants have become important new means of producing food and raw materials for the manufacture of clothing, shoes and other items.
Bibliography
- Latyushin V.V., Shapkin V.A. Biology Animals. 7th grade. - Bustard, 2011.
- Sonin N.I., Zakharov V.B. Biology. Diversity of living organisms. Animals. 8th grade. - M.: Bustard, 2009.
- Konstantinov V.M., Babenko V.G., Kuchmenko V.S. Biology: Animals: Textbook for 7th grade students educational institutions/ Ed. prof. V.M. Konstantinov. - 2nd ed., revised. - M.: Ventana-Graf.
Homework
- What types of impacts on fauna do you know?
- What contributes to the domestication of animals?
- For what purpose does man domesticate insects?
- Internet portal Worldcam.ru ( ).
- Internet portal Alfares.ru ().
- Internet portal Worldofanimals.ru ().
Human impact on wildlife consists of direct influence and indirect change natural environment. One of the forms direct impact on plants and animals - forest cutting. Selective and sanitary cuttings, which regulate the composition and quality of the forest and are necessary to remove damaged and diseased trees, do not significantly affect the species composition of forest biocenoses. Another thing is clear cutting of trees. Finding themselves suddenly in an open habitat, plants lower tiers forests are adversely affected by direct solar radiation. In shade-loving plants of the herbaceous and shrub layers, chlorophyll is destroyed, growth is inhibited, and some species disappear. Light-loving plants that are resistant to elevated temperature and lack of moisture. The animal world is also changing: species associated with the tree stand disappear or migrate to other places.
Tangible impact on condition vegetation cover provides massive visits to forests by vacationers and tourists. In these cases bad influence consists of trampling, soil compaction and contamination. The direct influence of man on the animal world is the extermination of species that provide food or other material benefits to him. It is believed that since 1600, more than 160 species and subspecies of birds and at least 100 species of mammals have been exterminated by humans. IN long list of extinct species is listed as tour – wild bull, who lived throughout Europe. In the 18th century was exterminated, described by the Russian naturalist G.V. Steller sea cow(Steller's cow) – aquatic mammal, belonging to the sirenaceae order. A little over a hundred years ago, the wild Tarpan horse, which lived in southern Russia, disappeared. Many animal species are on the verge of extinction or are preserved only in nature reserves. Such is the fate of the bison, which inhabited the prairies of North America by the tens of millions, and the bison, formerly widespread in the forests of Europe. On Far East The sika deer has been almost completely exterminated. Intensified fishing for cetaceans has brought several species of whales to the brink of destruction: gray, bowhead, and blue.
The number of animals is also influenced by human economic activities not related to fishing. The number of Ussuri tigers has sharply decreased. This occurred as a result of the development of territories within its range and a reduction in the food supply. IN Pacific Ocean Every year, several tens of thousands of dolphins die: during the fishing season, they get caught in nets and cannot get out of them. Until recently, before fishermen adopted special measures, the number of dolphins dying in nets reached hundreds of thousands. For marine mammals the effects of water pollution are very unfavorable. In such cases, a ban on catching animals is ineffective. For example, after the ban on catching dolphins in the Black Sea, their numbers have not recovered. The reason is that in the Black Sea from river water and through the straits from Mediterranean Sea There are a lot of toxic substances coming in. These substances are especially harmful to baby dolphins. high mortality rate which prevents the growth of the population of these cetaceans.
The disappearance of a relatively small number of animal and plant species may not seem very significant. Each type takes specific place in the biocenosis, in the chain, no one can replace him. The disappearance of one or another species leads to a decrease in the stability of biocenoses. More importantly, each species has unique properties that are unique to it. The loss of genes that determine these properties and were selected during long-term evolution deprives a person of the opportunity in the future to use them for his practical purposes (for example, for selection).
Radioactive contamination of the biosphere. The problem of radioactive contamination arose in 1945 after the explosion atomic bombs, dropped on the Japanese cities of Hiroshima and Nagasaki. Tests nuclear weapons, produced before 1963 in the atmosphere, caused global Nuclear pollution. When atomic bombs explode, very strong ionizing radiation is generated; radioactive particles are scattered over long distances, contaminating the soil, water bodies, and living organisms. Many radioactive isotopes have long half-lives, remaining dangerous throughout their existence. All these isotopes are included in the cycle of substances, enter living organisms and have a detrimental effect on cells.
Testing nuclear weapons (and even more so when using these weapons for military purposes) has another negative side. At nuclear explosion a huge amount of fine dust is formed, which remains in the atmosphere and absorbs a significant part solar radiation. Scientists' calculations various countries world show that even with limited, local application nuclear weapons, the resulting dust will trap most solar radiation. There will be a long-term cooling (“nuclear winter”), which will inevitably lead to the death of all life on Earth.
Currently, almost any territory of the planet from the Arctic to Antarctica is subject to diverse anthropogenic influences. The consequences of destruction have become very serious natural biocenoses and pollution environment. The entire biosphere is under increasing pressure from human activity, so environmental protection measures are becoming an urgent task.
Acidic atmospheric deposition on land. One of the most acute global problems modernity and the foreseeable future is the problem of increasing acidity atmospheric precipitation And soil cover. Areas of acidic soils do not experience droughts, but their natural fertility is reduced and unstable; They are quickly depleted and their yields are low. Acid rain cause not only acidification surface waters and upper soil horizons. Acidity with downward flows of water spreads across the entire soil profile and causes significant acidification of groundwater. Acid rain occurs as a result economic activity humans, accompanied by the emission of colossal amounts of oxides of sulfur, nitrogen, and carbon. These oxides, entering the atmosphere, are transported over long distances, interact with water and are converted into solutions of a mixture of sulfuric, sulfuric, nitrous, nitric and carbonic acids, which fall in the form of “acid rain” on land, interacting with plants, soils, and waters. The main sources in the atmosphere are the combustion of shale, oil, coal, and gas in industry, agriculture, and everyday life. Human economic activity has almost doubled the release of oxides of sulfur, nitrogen, hydrogen sulfide and carbon monoxide into the atmosphere. Naturally, this affected the increase in acidity of atmospheric precipitation, surface and groundwater. To solve this problem, it is necessary to increase the volume of systematic representative measurements of compounds of air pollutants over large areas.
3. Nature conservation and prospects for rational environmental management.
Nowadays consumer attitude to nature, the consumption of its resources without taking measures to restore them is becoming a thing of the past. Problem rational use natural resources, the protection of nature from the destructive consequences of human economic activity has acquired enormous national significance. Society, in the interests of present and future generations, accepts necessary measures for the protection and scientifically based, rational use of land and its subsoil, water resources, flora and fauna, to maintain clean air and water, ensure reproduction natural resources and improving the human environment. Nature conservation and rational environmental management- the problem is complex, and its solution depends both on the consistent implementation of government measures and on the expansion of scientific knowledge.
The extinction of some and the appearance of other animal species is inevitable and natural. This happens during evolution, with changes in climatic conditions, landscapes, and as a result of competitive relationships. Under natural conditions, this process proceeds slowly. According to calculations by D. Fisher (1976), before the appearance of humans on Earth, the average lifespan of a bird species was about 2 million years, and that of mammals was about 600 thousand years. Man has accelerated the death of many species.
Human economic activity has a strong impact on animals, causing an increase in the numbers of some, a decrease in the populations of others, and the extinction of others. Human impact on animals can be direct or indirect.
Direct impact(persecution, extermination and relocation) are experienced mainly by commercial animals, which are hunted for fur, meat, fat, etc. As a result, their numbers decrease, and individual species disappear.
Direct effects include introduction and acclimatization animals to new areas. Along with targeted relocation, cases of unintentional, spontaneous importation of certain, often harmful, animals to new, sometimes distant places are quite common.
Indirect influence humans on animals is associated with changes in the habitat due to deforestation, plowing of steppes, drainage of swamps, construction of dams, construction of cities, villages, roads, changes in vegetation as a result of pollution of the atmosphere, water, soil, etc. This radically changes the natural landscapes and living conditions of animals.
Most animal species cannot adapt to the conditions changed by humans; they either move to new places or die.
Shallowing of rivers, drainage of swamps and floodplain lakes, reduction of the area of sea estuaries suitable for nesting, molting and wintering waterfowl, caused a sharp decline in their natural reserves. The negative impact of humans on animals is becoming increasingly widespread. To date, approximately 150 species and subspecies of birds have disappeared in the world. According to the IUCN, one species (or subspecies) of vertebrates is lost every year. More than 600 species of birds and about 120 species of mammals, many species of fish, amphibians, reptiles, mollusks, and insects are at risk of extinction.
2.3. Animal protection
Protection of aquatic invertebrates. Marine and freshwater animals - sponges They lead an attached lifestyle and form colonies in areas with hard rocky soil. To preserve the role of sponges as biofilters, it is necessary to reduce their fishing, use fishing gear that does not cause damage to aquatic ecosystems, and reduce the entry of various pollutants into water bodies.
Coral polyps – marine colonial organisms. Of particular interest is the order of madrepore corals - the largest group of the coelenterate type.
Shellfish – a type of marine and freshwater, less often terrestrial, invertebrate animals, which are characterized by a hard calcareous shell covering the body. Shellfish serve as food for fish, birds and mammals. They have nutritional value and for humans. They catch oysters, mussels, scallops, squid, cuttlefish, and octopus. There is a fishery for pearl mussels and mother-of-pearl shells.
Crustaceans – animals, different in lifestyle, body shape and size (from fractions of a millimeter to 80 cm).
Crustaceans play an important role in aquatic ecosystems; they serve as intermediaries between algae and fish, making organic substances created by algae available to fish. On the other hand, they use dead animals for food, ensuring the cleanliness of the reservoir.
Pollinating insects pollinate about 80% of all flowering plants. The absence of pollinating insects changes the appearance of the vegetation cover. In addition to the honey bee (the income from its pollination of plants is 10-12 times higher than the income from honey and wax), pollen is carried by 20 thousand species of wild bees (of which 300 are in central Russia and 120 in Central Asia). Bumblebees, flies, butterflies, and beetles take part in pollination.
They bring great benefits different types ground beetles, lacewings, ladybugs and other insects, exterminating pests of agricultural and forest plants.
Insect nurses belong to the family of beetles and Diptera. These are widespread groups of carrion beetles, dung beetles, calorie beetles and flies, numbering thousands of species.
Fish protection. IN protein nutrition Fish make up from 17 to 83% of humans. Global fish catches are rapidly increasing due to the development of the edge of the continental shelf and the depths of the open sea, where up to 85% of fish are now caught, including new ones. commercial species. The permissible annual removal of fish from the World Ocean is estimated at 80-100 million tons, of which more than 70% is currently caught. In inland waters of most countries, including Russia, fish catch has reached its limit, stabilized or decreased.
Overfishing – a phenomenon common in many marine and inland waters. At the same time, young fish that have not reached sexual maturity are caught, which reduces the population size and can lead to the extinction of the species. Combating overfishing is the most important task of fisheries, protection and rational use of fish resources.
Water pollution negatively affects the state of fish stocks. Pollution of marine and freshwater bodies of water with various substances has become widespread and continues to increase. Particularly dangerous for fish are pollution from industrial wastewater containing salts of heavy metals, synthetic detergents, radioactive waste and oil.
Hydraulic structures have a negative impact on fish numbers. Dams on rivers block access of migratory fish to spawning grounds and disrupt natural reproduction. A number of measures are being taken to eliminate this adverse impact.
Shallowing of rivers reduces fish stocks. It is associated with deforestation of banks and watersheds, and with water withdrawal for irrigation. Measures have been developed to increase water levels in rivers and inland seas, which is of great importance for fisheries, Agriculture, for climate mitigation, etc. One of the drastic measures is afforestation of the banks, which requires constant care over a long period of time.
Protection of amphibians and reptiles. These two groups of animals have a small number of species (amphibians - 4500, reptiles 7000), but their importance in natural biocenoses is very great. Amphibians are carnivores; among reptiles there are also herbivorous species.
Amphibians, feeding on insects and other invertebrates, regulate their numbers and, in turn, provide food for reptiles, birds and mammals. Some amphibians (giant salamander, pond frog, edible frog, Chinese frog, bullfrog, etc.) are consumed by humans; Amphibians are widely used in laboratories for biological experiments.
Reptiles, no less than other groups of animals, suffer from overfishing. Great damage was caused to populations of commercial reptiles: crocodiles, turtles, monitor lizards and some snakes. Turtles and their eggs are used as food in many tropical countries.
Protection and attraction of birds. Very important birds in the national economy (except poultry farming) is explained by their participation in the extermination of forest and agricultural pests. Most bird species are insectivorous and insectivorous-herbivorous. During the nesting season they feed the chicks mass species insects, including many pests. To combat insect pests, birds are attracted by hanging feeders and artificial nesting boxes. Hollow nesters deserve special attention: tits, flycatchers, wagtails, which most often use artificial nests.
Mammal conservation. Representatives of the class of mammals, or animals, are important for humans. Breeding ungulates is the basis of animal husbandry; rodents and carnivores are used in fur farming. The most important terrestrial species for fishing are rodents, lagomorphs, and carnivores, and the aquatic species are cetaceans and seals.
All of these measures are aimed at the protection and rational use of mammals. Recently, more attention has been paid to the protection of wild animals. 245 species of mammals live on the territory of Russia, of which 65 species are included in the Red Book of the Russian Federation.