A message on the topic of the diversity of fish in nature. Variety of bony fish

>>Variety of fish. Class cartilaginous fish

§ 42 Variety of fish. Class cartilaginous fish

Adaptations to living conditions.

Representatives sturgeon order belong to the cartilaginous subclass. These are the most ancient bony fish in origin, with some features reminiscent of sharks. Their axial skeleton is represented by a notochord, which persists for life. The vertebral bodies are undeveloped, but their cartilaginous arches are laid down. But sturgeons have gill covers, a swim bladder, and bony parts of the skeleton. Modern cartilaginous fishes are demersal forms. This includes sterlet, sturgeon, stellate sturgeon, beluga, Kaluga. Unlike cartilaginous fish, they form false skull bones, bony gill covers, a bony base of the skull, and three or five rows of large bone plaques and small bone grains between them are located along the body outside. Sturgeons feed on animal food, most often invertebrates. Food is collected using the rostrum, digging at the bottom. Large sturgeon ( beluga And Kaluga) can feed on fish and sometimes young seals. Beluga lives in the waters of the Volga-Caspian basin sometimes up to 100 years and reaches a mass of up to 1,000 kg. It is not inferior in size to the Far Eastern Kaluga- “Queen of Cupid”.

A typical representative of sturgeon - Russian sturgeon, inhabitant of the Volga-Caspian and Black Sea basins. This is an anadromous fish that lives in the sea, but goes into rivers to spawn. The sturgeon has no teeth, and it gropes for food with its antennae, and then extends its mouth (rostrum) and draws it into the throat. It feeds on mollusks. For the winter it lies in deep holes, most often at the mouth of the river. In spring, it goes against the current into rivers to spawn. Eggs develop in the bottom layer of water. The young slide down rivers into the seas, where they live until maturity.

Sterlet, unlike other sturgeons, spends its entire life in fresh water. She is the smallest of them. Feeds on insects. Its weight reaches 3-6 kg.

Sturgeon are of great commercial importance. Meat, caviar (black) and even chord are eaten. But due to overfishing and a number of environmental changes, sturgeon numbers have declined significantly. Therefore, fishing for them has decreased. Some species - sterlet, sturgeon, Black Sea beluga - are listed in the Red Book.

Herring order

Representatives order of herrings have a flat body of a silvery color, a very short lateral line, or it is completely absent. The head of the herring is not covered with scales, the fins are soft. The swim bladder is constantly connected to the intestines.

Most herring live in the water column and feed on plankton. About 300 species of these valuable commercial fish are known. Most common Atlantic And Pacific herring. Their body length is 40-50 cm. Atlantic herring, living in the Baltic Sea, is called herring. Lives in the Black Sea black sea herring(body length up to 40 cm, weight up to 1 kg). Some of the individuals leaving for spawning in the river. Danube, called Danube herring. Found in the Black Sea Black Sea sprat, sprat and others. Herrings include anchovy fish: European anchovy, or anchovy, of great commercial importance.

Order Salmonidae

Their body is round or slightly compressed from the sides. A characteristic feature is the presence of an adipose fin located on the dorsal side in front of the caudal fin.

Most salmon are anadromous fish ( salmon), but some species live permanently in fresh water bodies ( trout, whitefish, omul and etc.). Many salmon are common in the Far East, for example chum salmon, pink salmon, red salmon, Chinook salmon etc. During spawning, they migrate over a distance of several thousand kilometers (chum salmon - 1,000 km, Chinook salmon - 4,000 km). In the reservoirs of the CIS countries there are salmon such as European grayling, trout, Danube and Black Sea salmon. Trout lives in mountain rivers, it is artificially bred in Transcarpathia and Crimea.

Salmon are commercial fish, highly valued for their high-quality meat (“red fish”) and red caviar.

Order Cyprinidae

Order Cyprinidae has about 3,000 species, most of which live in fresh water bodies. Some of them go to the seas to spawn ( vobla, ram). They have soft fins and a swim bladder like herrings. There are no teeth, but there are pharyngeal teeth used for grinding food.

Best known domestic carp, whose ancestor is carp living in fresh water bodies. Carp have been artificially bred for a long time. Breeders have bred various breeds of carp: mirror, Ukrainian, etc. Carp can have a weight of up to 20 kg and a length of 1 m. They are grown in fish farms to a marketable weight of 500-2,000 g in 2-3 years. Carp becomes sexually mature in 3-5 years. Very prolific: lays 600,000-800,000 eggs. Among the carp species found in our reservoirs are: crucian carp, tench, bream, roach, White amur, silver carp, blue, silver bream, saberfish and etc. Cyprinids are excellent objects of fishing and sport fishing.

Order perch

Order perch- about 6,500 species. A characteristic feature is that their swim bladder loses connection with the intestines and exists independently. Fins with spines. The body length is from 1 cm to 5 m, and the weight reaches 500 kg. For example, swordfish— length 4 m, weight 300 kg. When chasing prey, it can reach speeds of up to 120 km per hour. Perch include tuna(up to 3 m long and 680 kg weight), horse mackerel, bulls.

In the Black Sea there are: common mackerel, horse mackerel, tuna, bulls. The following commercial species are common in the country's fresh water bodies: river perch, zander. A number of representatives of perch species - common saffron goby, golden goby, striped ruff - are listed in the Red Book.

Subclass lobe-finned

Subclass lobe-finned is an ancient and almost entirely extinct branch of vertebrates that lived in shallow freshwater bodies. Currently, only one species of living lobe-fins is known - coelacanth, or coelocanthus. The discovery of this fish in 1938 caused a real sensation in the scientific world, since at that time it was believed that lobe-finned fish were extinct. Since then, several specimens of these fish have been caught off the eastern coast of South Africa (1952). When studying them, it turned out that due to the migration of the wild ancestors of the coelacanth to the ocean and their revitalization of the bottom spaces, some parts of their respiratory apparatus disappeared: there are no through nostrils, the lung is filled with fat. However, the paired fins, as organs of movement on the ground, completely retained the structural features characteristic of ancient lobe-finned fish. Coelacanth- a predator living at a depth of 400-1,000 m, its length is up to 180 cm. Its weight is up to 90 kg. It is of great importance for studying the origin of terrestrial vertebrates.

Subclass lungfish

Subclass lungfish is a small group of fish that combines features of a primitive organization with features of specialization and adaptability to life in water bodies depleted of oxygen. Representative of the lungfish - neoceratod- the largest living fish of this group (length up to 175 cm). Along with gills, the neoceratod also has an organ for breathing atmospheric air - the pulmonary sac. This fish lives in the rivers of Eastern Australia. In summer, when bodies of water become shallow and depleted of oxygen, it breathes mainly with its lungs, often rising to the surface and swallowing air. Spending their lives in never-drying bodies of water, neoceratodes do not hibernate. In contrast, another representative of the lungfish, widespread in the fresh waters of Africa, is protopterus- when the reservoir dries out, it buries itself in the silt and goes into hibernation, which lasts about 5 months. At this time, he breathes only with paired lungs.

>>Variety of fish. Class bony fish. General Traits of Fishes

§ 43. Variety of fish. Class bony fish. General Traits of Fishes

Class bony fish

Bony fish are freshwater and marine and have a partially ossified or bony skeleton. The gill slits are covered with a cover. Usually available swim bladder, but in some it does not develop. Most fish (more than 19,000 species) belong to the class of bony fish. 82 Let's get acquainted with some orders of bony fish.

Order Sturgeon.

In sturgeons (!), most of the skeleton is cartilaginous, with bones only in the head. They can be distinguished immediately by the peculiar appearance and arrangement of the scales: thick, diamond-shaped scales run along the body in five rows - one on the back, two on the sides and two on the abdomen. The front part of the head is elongated into a more or less long protrusion - rbstrum. With this rostrum, they dig at the bottom in search of food, obtaining various invertebrates hidden there.

Most sturgeon are anadromous fish.

Thus, the sturgeon, reaching a mass of 30 kg, lives in the Black and Caspian Seas, and goes to spawn in the rivers flowing into them. The beluga, the largest of the sturgeons, weighs up to 1,000 kg, does the same. A freshwater species of sturgeon - sterlet, weighing 3-6 kg, lives in various rivers of our country in its European part and in Western Siberia. All sturgeon have excellent quality meat and very valuable black caviar.

Order Cypriniformes- mostly freshwater fish 82 . These include carp, crucian carp, roach, bream and many other commercial fish. Cypriniformes feed on plant matter and various invertebrate animals. They have no teeth on the jaws (or they are poorly developed), but in the depths of the pharynx there are pharyngeal teeth, which are used for grinding food.

Order Herring.

The main representatives of this order are herrings. Most of them live in the sea and live in large flocks, traveling in search of food and for spawning. Herring feed on small crustaceans living in the water column and are of great commercial importance.

Order Codfish.

Most cod are marine fish. Their distinctive feature is the presence of a mustache on the chin.

They stay near the bottom, but do not lie on it, but constantly move in search of food. They feed on bottom invertebrates and smaller fish. They live in cold seas. In the northern seas of the USSR there are such fish as cod (weighing up to several kilograms, and some individuals - more than 20 kg) and smaller ones - haddock, herring, navaga. The only freshwater representative of cod, distributed in fresh waters almost throughout the country, is the burbot weighing 3-5 kg, some individuals - up to 20 kg. Burbot, although it lives in the middle zone in relatively warm waters, has retained the habits of its cold-water relatives. So, in the summer, when all our other freshwater fish are most active, burbot, on the contrary, climbs somewhere deeper, into holes, under snags, where it is colder, and here spends the whole summer motionless. It comes to life only in late autumn, and spawns in December or January.

All cod are day game fish 82 . Of particular value is their liver, from which medical fish oil containing vitamin B is extracted.

Order Cystic-finned.

Currently, there is only one representative of this order - coelacanth (!). This is a large fish up to 1.5 m long, found in the Indian Ocean off the coast of Africa. All other lobe-finned fish that lived both in the sea and in fresh waters died out 70-100 million years ago. The structure of the skeleton and muscles of the paired fins of lobe-finned fish is very similar to the structure of the limbs of terrestrial vertebrates. However, this will be discussed further later. 92 .

ANTHROPOGENIC INFLUENCE ON THE ICHTHYOFAUNA OF OUR RIVERS.

Atroshchenko Olga Vladimirovna

student of class 10A

MBOU secondary school No. 26

Art. Chelbasskaya,

Kanevsky district,

Krasnodar region

Head Dyumina Galina Ivanovna,

Honorary Worker of General Education,

teacher of biology and ecology, Municipal Educational Institution Secondary School No. 26

Art. Chelbasskaya

INTRODUCTION…………………………………………………………………………………3

I. Analysis of literary sources………………………………………………………………………………5

P. Characteristics of small steppe rivers of the Kuban………………………………………………………………...6

Species diversity of fish…………………………………………………………………………………...8

Description of research points………………………………………………………..13

V. Methods and results of studying the ichthyofauna of the Chelbas and Beysug rivers………………………...16

Study of fish species diversity………………………………………………………...16

Fishing intensity at different points……………………………………………………………………..18

Anomalies and deformities of fish……………………………………………………………...19

CONCLUSIONS…………………………………………………………………………………...21

LITERATURE………………………………………………………………………………...22

APPENDIX………………………………………………………………………………….23

INTRODUCTION.

The current state of small steppe rivers causes alarm and concern.

Due to the fact that we live in an area where such rivers flow and we can clearly observe deviations from the norm in their condition, we decided to write this work.

We nominated hypothesis that anthropogenic pressure negatively affects the ecosystems of small rivers of the Kuban and causes abnormal changes in the development of inhabitants more and more every year. The goal was set: based on studying the state of fish populations of the Chelbas River, to identify the degree of anthropogenic influence on the ecosystems of our rivers. The following results emerged from this goal: tasks:

Study the state of the issue in literary sources.

Determine the species diversity of fish in our river.

Determine and compare the degree of river pollution at different study points.

Identify deviations in the development of fish and find their causes.

Assess the impact of net fishing on the state of fish populations.

Conduct an analysis and draw conclusions about the anthropogenic load on the ecosystems of small steppe rivers and try to find ways to solve this problem.

The materials for writing the work were the observation and analysis of the problems of the Chelbas and Beysug rivers, water basins directly adjacent to the Chelbasskaya village. To obtain the necessary results, a study of a 17-kilometer section of the Chelbas River was carried out at five points. All points are tied to areas with powerful domestic, industrial and agricultural wastewater.

An analysis of the physicochemical state of rivers at fishing points showed that there is an excess of impurities in the water, and the acidity is approaching critical. This state of the rivers has led to a reduction in the diversity and quantity of fish in the reservoirs. The number of fish is affected by the intensity of fishing.

When observing fish anomalies, which was based on studies of more numerous species, disturbances in the structure of the fins, changes in the scaly cover and lateral line were discovered.

Anthropogenic pressure on steppe rivers leads to the degradation of fish populations and even their disappearance.

Currently, it is necessary to carry out serious work to change the current situation.

In addition to identifying the causes of the destruction of fish ecosystems, we tried to predict their further ecological state, as well as propose measures necessary to restore ecological balance in these communities.

ANALYSIS OF LITERARY SOURCES.

The literature we have studied contains quite a lot of information about the ecological state of small steppe rivers and their ichthyofauna.

The state of the rivers of our region is widely covered in the textbook “Physical Geography of the Krasnodar Territory” edited by L. V. Pogorelov, which shows the dependence of water availability, hydrological regime and water quality on the surface catchment area, and shows the reasons for deviations from average statistical zonal and regional indicators.

The book “Nature of the Krasnodar Territory”, edited by V.I. Korovin, describes the main species of fish in fresh water bodies of the Kuban, ensuring high productivity of fish stocks, their commercial importance and endurance to unfavorable conditions are indicated. These are: carp, bream, silver bream, silver carp, pike, catfish, pike perch, perch, grass carp, silver carp.

In the fresh water bodies of the region there are more than 80 species and subspecies of fish belonging to

18 families. In practice, this figure is far from being confirmed.

A frequently encountered fish species is crucian carp. B. E. Raikov’s book “Zoological Excursions” points out the unpretentiousness of crucian carp to water quality, which ensures their widespread and widespread distribution.

The different attitudes of fish to oxygen are shown in the textbook for students “Zoology of Vertebrates” by S. P. Naumov. They consume a relatively small amount of oxygen - about 4 cm 3 per liter: roach, perch, ruff; withstand very low oxygen saturation of water and live even at 1/2 cm per liter: carp, tench, crucian carp. These types of fish are most often found in our polluted water bodies.

Having analyzed the data from literary sources, the need arose for a more in-depth study of the ecological state of the rivers directly adjacent to our village.

CHARACTERISTICS OF SMALL STEPPE RIVERS OF THE KUBAN.

Small steppe rivers flow through the territory of the Azov-Kuban lowland in a northwestern direction, flowing into the Sea of ​​Azov. They are usually called steppe rivers. One of the features of small rivers is the dependence of water content and water quality on the condition of the catchment surface. Unlike medium and large rivers, small rivers are mostly at the uncontrolled disposal of local land users. This leads to the plowing of valley slopes, pollution of small rivers, and indiscriminate construction of dams.

The largest of the steppe rivers of the Krasnodar Territory are: Eya (length 311 km), Chelbas (288 km), Kirpili (202 km), Beisug (193 km). (Annex 1)

Steppe rivers have poorly developed valleys in the upper reaches, which widen noticeably in the lower reaches. The width of the channels varies from 5-30 m in the upper reaches to 60-100 m in the middle reaches and 15-200 m in the lower reaches. The river beds are straight. Maximum current speeds are no more than 0.6-0.8 m/s.

Food is supplied mainly by snow waters. The river regime is characterized by a clearly defined spring flood, a decrease in water content in the summer and a slight increase in flow in the fall. In winter, with the onset of freeze-up, the flow decreases again, because... Under these conditions, rivers are fed only by small reserves of groundwater.

On small rivers, during a friendly spring, melt water is discharged in 5-8 days. Rain floods are rare. The flow of steppe rivers has a large number of ponds. The construction of ponds leads to a fundamental change in sediment flow. At the bottom of Beisug and Chelbas, a layer of silt 5-7 m thick and even more has accumulated. The reason for such intense siltation is the peculiarities of the construction of ponds: rivers were blocked by earthen dams, which, under the pressure of flood waters, were often destroyed and tens of thousands of cubic meters of soil were deposited at the bottom. Rapid silting is also facilitated by continuous plowing of the slopes to the water's edge. Thick layers of silt deposits block the springs that feed rivers and prevent the unloading of groundwater, which is one of the factors for land flooding. Aquatic vegetation quickly develops on the shallow, silted bottom. This leads to increased transpiration and irretrievable water loss.

Ponds retain the unstable runoff of melt and rainwater. From the surface of the ponds

Almost a meter of water evaporates every year. During the dry season, these rivers dry up in places, shallow reaches are formed, overgrown with reeds, reeds and sedges, and are characterized by high mineralization of water. High hardness and mineralization, pollution with industrial wastewater determine their poor economic characteristics.

The Chelbas River flows to the northwest, near the village of Iskra it changes direction to the west and, before reaching the Sea of ​​Azov, forms a series of large estuaries connecting with the vast Beysugsky estuary. The main right-bank tributaries of the Chelbas are the small rivers Borisovka and Tikhonkaya. On the left, near the village of Kanevskaya, the Middle Chelbas River flows into Chelbas, on the bank of which the station is located. Chelbasskaya. (Appendix 1) About 120 ponds were built on the Chelbas River and its tributaries. The heavily overgrown and silted Chelbas is a striking example of a river in a state of old age and decline. Sulfate and sodium ions predominate in water.

The Beysug River is the third longest and second largest river in the Azov-Kuban Lowland. Its sources are springs located 9 km northwest of Kropotkin. The Beysug flows into the Beysugsky estuary at st. Brinkovskaya. Its most significant tributaries are the Beysuzhek left (or South) and the Beysuzhek right, 12 kilometers from which the station is located. Chelbasskaya. The banks of the Beisug are mostly flat, and their height is 5-7 m. The Beisug and its tributaries are blocked by numerous dams, forming up to 200 ponds. The water level in the river experiences significant fluctuations throughout the year. The river is fed by precipitation and springs. The river waters are highly mineralized; sulfate and sodium ions also predominate in them.

III.

FISH SPECIES DIVERSITY.

The species diversity of fish in these rivers is very poor. This is explained by increased mineralization of water, changes in the hydrological regime due to the construction of numerous dams, which turned rivers into stagnant ponds with a disrupted self-purification system.

The steppe rivers are home to about 20 species of fish: pike, roach, rudd, tench, common gudgeon, bleak, silver bream, bream, common redfish, gold and silver crucian carp, carp, sandpiper goby and tsutsik, perch, pike perch, common ruffe, catfish, shemeya, silver carp. (Appendix 2)

COMMON PIKE.

It can reach a length of more than 1.5 m and a weight of 32 kg. The body is elongated and spotted.

It may have a gray-green, gray-yellow or gray-brown color, the back is dark, the belly is whitish with gray specks. The dorsal, anal and caudal fins are brownish with black spots; Thoracic and abdominal - yellow-red. Tolerates acidic environment well. When attacking prey, it is guided by vision and the lateral line. Females begin to reproduce in the third year of life, males most often in the fourth year. Pike spawn at a temperature of +3-6 0, at a depth of 0.5-1 m. One female, depending on the size, spawns 18-215 thousand eggs, large, with a diameter of up to 3 mm. The development of eggs lasts 8-14 days.

The length of the rudd reaches 32-36 cm, weight 1500 g. Most often it stays in the water column, in coastal thickets or near them, consuming plant and animal food: shoots of young plants, filamentous algae, insect larvae, caviar.

Reaches sexual maturity at 3-4 years. Life expectancy is 6-9 years. With age, the fertility of females increases. Spawning occurs in late May - early June at a temperature of +18-20 0.

TENCH.

It got its name from the word “molt”, since, when taken out of the water, it immediately changes color. The body of the tench is quite thick, covered with densely sessile scales, and small bright red eyes are located on the head. The mouth is very small, with a short antennae at its corners. The color is adaptive and depends on the color of the water in the reservoir. The length of the line reaches

60 cm and weight 7.5 kg. Prefers to stay in river bays overgrown with reeds or small underwater vegetation. The outer rays of the male's ventral fins are greatly thickened, so it can be easily distinguished from the female. Tench is a heat-loving fish, spawns in June at a temperature of +19-20 0. Spawning lasts 1.5-2 months.

The body is covered with cycloid scales, there are no whiskers. Body color ranges from olive-brown to bright silver. The body shape is fish-like. It has a keel that extends from the ventral fins to the anus. Spawning begins at a temperature of +12-15 0. In the south - at the end of April - May, in the north - at the end of May - June.

VERKHOVKA.

A small fish with relatively dense scales and an incomplete lateral line. This is one of the smallest species of our fauna, its maximum length is about 9 cm. It lives in the bays of rivers with a slow current. It feeds mainly on zooplankton and aerial insects.

Reaches sexual maturity at a length of 3.8-4 cm, in the second year of life. Spawning begins at a temperature of +15 0 and lasts about 2 months. The verkhovka lays its eggs on the lower surface of floating leaves. The development of the eggs occurs rather slowly, but the hatched larvae are immediately able to swim and hunt for food.

GUSTER.

Outwardly, it is somewhat similar to an ordinary bream, but has larger scales. The body color is silvery, the unpaired fins are gray, the pectoral and ventral fins are reddish, especially at the base. In autumn and spring they form huge flocks. It reaches a length of 35 cm and a weight of 1.2 kg.

In most reservoirs it matures in 3-4 years. The minimum length of females spawning for the first time is up to 5-8 cm, their fertility ranges from 0.6 to 4.5 thousand eggs; The fertility of larger ones is tens and hundreds of thousands of eggs. Mixed diet: insect larvae, mollusks, vegetation.

SHEMAYA.

Outwardly, it somewhat resembles a bleak that has grown to gigantic proportions. Reaches a length of 22 - 40 cm. It also forms semi-anadromous forms, feeding in the sea, and rising low into rivers for spawning. The fish is characterized by a dark back with a green tint, and silvery sides and belly. All fins, except the caudal one, are pink at the base and gray at the edges. It feeds on plankton, insect and fish larvae. Spawns in early and mid-May at a water temperature of about +18 0. The fertility of shemaya in different rivers ranges from 2.6 to 23.5 thousand eggs. Spawning occurs at dusk and at night in areas with rocky and pebble soil. Development of the embryo lasts 2-3 days. After emergence, the larvae develop for a long time in dark places on the bottom.

CARP.

It is distinguished by a wide, thick body, covered with dense large scales, and

long, slightly notched dorsal fins. Currently, man has settled

carp and its cultural form, carp, throughout the globe.

Carp prefers quiet and calm waters. It grows very quickly. The growth rate depends on the richness of the food supply. Carp feeds most intensively at a temperature of +25-29 0. Under favorable conditions, in the second year of life it can reach a length of 30 cm and a weight of 500-600 g. Its maximum length is more than 100 cm and its weight is more than 20 kg.

The carp reaches sexual maturity at 4-6 years. The fertility of carp is high; large females lay from 600 thousand to 1.5 million eggs. Spawning occurs in the spring at a water temperature not lower than +13-15 0. The spawned and fertilized eggs stick to the branches of underwater vegetation. After 3-6 days, tiny larvae hatch and stick to plant branches. After a few days, the larvae begin to capture food: first small rotifers, ciliates, cyclops, then larger plankton.

CRUCCIAN.

They are represented by two species, which, like the carp, have a long dorsal fin, spiny rays in the dorsal and anal fins, but differ in the absence of antennae.

Golden crucian carp.

It differs from the other species in having a smaller number of gill rakers on the first arch. The back of crucian carp is often dark brown, with a greenish tint, the sides are dark golden, sometimes with a copper-red tint, and the paired fins are slightly reddish.

Crucian carp are attached to waters with silty soils. For the winter, they bury themselves in silt and survive even when, in cold, snowless winters, small standing reservoirs freeze to the very bottom. They show the same resistance during summer droughts.

Crucian carp exhibits significant variability depending on living conditions. It becomes sexually mature in the 4th year of life, males mature somewhat earlier than females. Spawning begins at a temperature not lower than +14 0. Sticky eggs are washed onto underwater vegetation. Spawning lasts 2-3 days. The fertility of females is high, up to 300 thousand eggs. Juvenile crucian carp feed on plankton. The food of adult crucian carp consists of plant and animal organisms, as well as detritus.

Silver crucian carp.

It differs from the common (golden) crucian carp in the large number of gill rakers, the silver coloring of the sides and abdomen, and the black color of the peritoneum. It grows somewhat faster than goldfish. Reaches a length of 45 cm and a weight of 1 kg. Zoo- and phytoplankton are of great importance in nutrition. Sexual maturity occurs at 3-4 years, fertility is 160-400 thousand eggs. There are usually fewer males than females. Most often there are populations where there are no males at all. Females of bisexual and unisexual populations differ in the number of chromosomes. Females with a triploid set of chromosomes reproduce with the participation of males of other fish species that are similar in reproductive ecology.

Silver carp.

The first days after switching to active feeding, it consumes zooplankton, but after reaching a length of 16 cm, it begins to feed on phytoplankton. Maximum length 1 m, weight 16 kg. Males reach sexual maturity at 2 years, females at 3 years. Fertility 490 - 540 thousand eggs.

ROACH.

Characteristic is the orange color of the iris and a red spot in its upper part. The body shape is varied, usually has a semi-lower mouth, single-row pharyngeal teeth. It reaches 13-15 cm in length. Puberty occurs at 3 - 5 years, with a length of about 12 cm. It lives quite a long time: 12-15 years. Spawns in late April - early May.

IV. DESCRIPTION OF RESEARCH POINTS.

An analysis of the state of the river was carried out in sections at 5 points. (Appendix 3)

POINT #1.

It is located in the Chelbassky forest, planted more than a century ago and transformed into an autonomous ecological system. The water in the river is relatively clean compared to other points. The accumulation of silt here is up to three meters; the banks are overgrown with reeds and sedges, which indicates the presence of organic matter. Human intervention here is very weak. There is no work to apply fertilizers and pesticides to the soil nearby. The only manifestation of human activity is the dam; it forms a small waterfall. The diameter of the pipe through which water flows is about 1.3 meters.

POINT #2.

Located in close proximity to the fields of the Volya Agricultural Association and the vegetable garden, two kilometers away there is a livestock complex (team No. 3), where a huge amount of organic matter accumulates in the form of waste, animal urea flows into lagoons, which, overflowing, flow down the slope into the river . This affects the ecological state of the river in this area. The banks are very overgrown with reeds and sedges due to the huge amount of harmful substances in the water. They are flat, the river here is very silted, the layer of silt exceeds the five-meter mark. There is a poultry farm on the shore, where organic matter also comes from, causing a large amount of algae to form.

POINT #3.

This section of the river is located in the center of the village in front of the dam, which has two equal pipes with a diameter of about one meter. The bottom is silted, the thickness of the silt layer is about five meters. Reeds grow on the shore. Nearby there are private houses from which wastewater is discharged directly into the river through sewer pipes; this can be especially often seen on Bazarnaya Street. In this area, in the immediate vicinity of the river, there are vegetable gardens, which contradicts environmental standards, according to which a protective zone of natural vegetation should remain along the river at a distance of 100 meters. Another important problem is the improper plowing of vegetable gardens (across the river). As a result, fertilizers and pesticides flow from the gardens into the river.

POINT #4.

This point is located at the river exit from the village. The coast here is bare, there is practically no vegetation, and in some places you can see algae. Warm water flows into this part of the river from a pumping station. The layer of silt at the bottom is about 3 meters, and here it is formed mainly due to the expansion of the banks. But in this place, streams flow into the river, which partially purify the water.

POINT #5.

The point is represented by a five-kilometer section of the Beysug River. Siltation on the river reaches only 1 m, since the river was partially cleansed. Near the point there are fields treated with pesticides, and a small dam is located nearby. But the pollution here is not as strong as in the center of the village.

We carried out a physical and chemical analysis of the water at selected points in the study area and obtained the following results.

Table No. 1. Physico-chemical indicators of the state of the river at fishing points.

According to the standards, there should be no floating impurities in the water, transparency up to 10 cm, odor - 1 point, pH - 6.5-8.5, sulfates - 500 mg/l.

The table shows that the water in the studied sections of the river contains an excessive amount of impurities, the smell is swampy, only in the forest area the smell of water approaches the smell of clean water (1 point), the water is polluted with mineral fertilizers. Acidity in places close to human activities is approaching a critical point. The content of nitrates and sulfates exceeds the permissible level. This indicates excessive pollution of the river with wastewater from private farms, fertilizers from fields and slurry from livestock farms. This physical and chemical state of rivers leads to a reduction in the diversity and quantity of fish in water bodies.

IV.

METHODS AND RESULTS OF STUDYING THE ICHTHYOFAUNA OF THE CHELBAS AND BEISUG RIVERS.

1. Study of fish species diversity.

We conducted a study of a 17-kilometer section of the Chelbas River in the area of ​​the Chelbas forest, the fields of the Volya Agricultural Association and the center of the station. Chelbasskaya and a 5-kilometer section of the Beysug River, bordering the fields of the Volya Agricultural Association. Various points of steppe rivers were taken, tied to the forest, to areas of powerful industrial and domestic wastewater, in the center of the village and in areas of agricultural work in the fields.

Based on our materials and survey data, it was revealed that in these rivers there are such species of fish as pike, rudd, tench, bream, common verkhovka, crucian carp, carp, perch, common ruff, and ram.

Greater species diversity of fish was noted in sections of the Beisuga River (point 5) and the forest section of the Chelbas River (point 1), where 9 species of fish are more common: pike, tench, bream, verkhovka, crucian carp, perch, ram, silver bream, ruffe.

In areas 2 and 3, species diversity is poorer and sharply reduced. Pike, tench, crucian carp are found here, the number of species again increases to 7. (Appendix 4)

Table No. 2.

Pike perch and catfish have become extremely rare. The main background species, sharply predominant in number (up to 50-70%) at all fishing points, is crucian carp. This species is distinguished by its eurybiontism and plasticity. It is found not only in a variety of standing and flowing waters, but even in the smallest insignificant bodies of water. Golden, or round, crucian carp with a high body, the width of its body is half its length. The sides are golden or copper-red. Silver, or oblong, crucian carp has a narrower body, the width of which is equal to 2/5 of its length. The sides are silvery, sometimes very dark. The caudal fin has a deeper notch.

Research has shown that goldfish are more common in less polluted water. Due to increased siltation of rivers, the number of silver crucian carp, a species more typical of stagnant waters, is sharply increasing.

Table No. 3. Occurrence of golden and silver crucian carp.

For fishing, nets with cells of 2 cm, 3 cm, 5 cm were used, which were installed motionless in the reservoir. The accounting was carried out for two catches and the weight of fish caught in April and June in percentage terms.

Another numerous species in the Chelbass and Beysug rivers is tench. It is found in almost all locations and accounts for up to 30% of the catch. The average size of the tench found is 10 - 15 cm. Having traced the size of the tench at different fishing points, the following pattern was established: in the more polluted sections of the river they are increased.

Table No. 4.

Average sizes of tench at different fishing points.

In the deepest places of the Chelbas and Beisug rivers, such a rare predator as catfish has been preserved. But it is extremely rare. Small catfish weighing up to 3 kg are occasionally caught by fishermen on the Beisug River.

Also extremely rare were rudd, verkhovka, and carp.

2. Intensity of fishing at different points.

The number of fish and its diversity is affected by the intensity of fishing. When examining the fishing points, it was found that at the point located in the center of the village, at the time of the survey there was the largest number of nets, which blocked the river several times. The fewest nets were found in the river in the forest zone (point 1). This problem is of great concern, as the pressure on the aquatic ecosystem increases, which affects the state of the river’s fish fauna.

Table No. 5. Number of nets in the area of ​​the river points under study and fishing results.

The table shows that the greatest load on the river ecosystem is in the center of the village (point 3).

3. Anomalies and deformities of fish.

From the description of the fishing points, we can come to the conclusion that rivers are exposed to a powerful cumulative effect of various chemicals and pollutants discharged into the water and accumulated in the bodies of river organisms, vegetation, and fish bodies.

An indicator of this is the number of individuals of different species that have anomalies in the appearance and structure of internal organs. Such individuals are most often found at points 2 and 3.

During the observation, which was based on the study of changes in the most numerous fish found at these points (ram, crucian carp, tench), various anomalies were identified.

1). Disturbances in the structure of the skull and skeleton.

Such deviations include a head with shortened jaws, a head width greater than that of normal individuals (such changes are often found in silver crucian carp), and other fish are characterized by changes in the spine, especially the caudal region. (Appendix 5)

2). Visual impairment.

Most often, the eyes are either reduced or have a telescopic appearance. Thus, there are fish that are blind in one or two eyes, or with skin-covered eye sockets. Such phenomena are also typical for silver crucian carp.

3). Change in lateral line.

Such anomalies are characterized by curvature or discontinuity of the lateral line; in addition, there are cases when it may be bifurcated or absent in the lateral section. (Appendix 6)

4). Violation in the structure of the fins.

They are usually represented by their curvature and reduction in size. (Appendix 6)

5). Changes in scaly cover.

The appearance of a large number of the above anomalies and many other deformities in fish is due to the emergence and increasingly worsening of unfavorable conditions for the development of eggs and juveniles in water saturated with various pollutants. Most likely, such deviations are hereditary.

Table No. 6.

Accounting for the number of fish species with different anomalies.

Anomalies were counted for the most numerous and most frequently occurring fish species, based on the results of 7 catches. The table data shows that changes most often occur in the structure of the scaly cover: shape, length and width of the scales, its size, color, density. Significant disturbances were also revealed in the structure of the fins.

After conducting research on the ichthyofauna of our steppe rivers (the Chelbas River and the Beysug River), we concluded that it is declining every year. This happens not only due to unplanned fishing and poaching, but also due to deteriorating environmental conditions. Over time, our small steppe rivers become increasingly silted and blocked in many places by dams (as a result of which the flow speed slows down). The banks are being eroded and the river is becoming overgrown with reeds and algae. All this is indisputable evidence that our rivers are dying. People, through their economic activities, worsen their condition; industrial and agricultural waste is discharged directly into the river.

River pollution leads to an increase in fish diseases, which causes degradation of fish populations and, often, their disappearance.

There is an urgent need at this time carry out serious propaganda work with the population and heads of enterprises. Stop or reduce to a minimum the discharge of industrial and agricultural waste into the river, appoint administrative penalties for ejectionsewage waste into the river, the creation of unplanned landfills, andThe money received will be used to improve the environmental situation and green the village.It is necessary to maintain strict control over fishing and take measures toattempts to create special fish hatcheries. To restore the river, it is necessary to clean both the banks and the bottom of silt. Coastal cleaning work is carried out annually by students from our school.

The ecological state of small steppe rivers depends on human compliance with basic ecological principles. To do this, it is necessary to increase the population’s literacy in these issues and make environmental welfare a state policy.

LITERATURE.

Pogorelov A.V. Physical geography of the Krasnodar region. Tutorial. - Krasnodar, 2000

Korovin V.I. Nature of the Krasnodar region. - Krasnodar: Book. publishing house, 1979

Raikov B. E., Rimsky-Korsakov. Zoological excursions. - M.: Topikal, 1994.

Naumov S.P. Zoology of vertebrates. Textbook for students of pedagogical institutes in biology - 4th ed., - M.: Education, 1982.

Chizhov N.I., Abaev Yu.I. Fishes of reservoirs of the Krasnodar region. - Krasnodar, 1982

Lotyshev I.P. Geography of the Krasnodar Territory.

Regional textbook for secondary school students.

ANNEX 1

Location of the Chelbas River in the region.

APPENDIX 2

Perch is a plentiful fish in our rivers.

APPENDIX 3

Location of research points for the Chelbas River and the Beysug River.

APPENDIX 4

Fishing results at point 1.

Fishing results at point 3.

APPENDIX 5

And such specimens of fish can be found in our rivers.

APPENDIX 6

Curvature of the lateral line in some fish.

Anomalies of fins and color of fish scales.

Class: 7

Presentation for the lesson

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The purpose of the lesson: get acquainted with the variety of fish; identify characteristics of the main classes of fish; develop the ability to compare and identify the most common orders of fish; cultivate respect for nature

Tasks:

Educational: reveal the diversity of fish, study the characteristics of classes and orders of fish.

Educational:

• learn to recognize studied fish,
• be able to compare the structural features of fish,
• be able to work with the material,

Educational: to form the needs (motives, motivations) of behavior and activities aimed at protecting animals, rational environmental management,

Equipment: presentation “Diversity of fish”, tables “Marine fish”, “Freshwater and anadromous commercial fish”, “Type Chordata. Pisces class", projector, computer, photographs of fish, table. systematic groups of fish.

During the classes.

1. Organizational moment.

2. Explanation of the material

Teacher- Guys, today we will go on a ship of knowledge to the open sea, entering rivers and canals, we will go under the water and get acquainted with aquatic inhabitants, namely fish. Give up the mooring line, let's go!

While we are swimming to the first dive, let’s think about who we might meet on our way. Before you is a diagram that names the main classes and orders of fish (slide 3). We are sailing on a scientific journey, so we must write down our observations.

Teacher distributes tables and small photographs of fish. (Appendix 1)

Well, we swam to the place, we all got into the submersible and dived. Oh, oh, oh, who is this in front of us (slide 4).

Students- It's a shark. A fast and powerful fish with a cartilaginous skeleton that lives in the seas and oceans. It has no swim bladder and lacks neutral buoyancy. This fish has sharp scales, which are called placoid, as well as dangerous teeth, it has internal fertilization and is characterized by the process of viviparity.

Teacher– well done, let’s look at some types of sharks (slide 6) (slide 7)

And here is the whale shark (slide 8). She slowly moves forward, opening her huge mouth. As water enters the gills, small fish and plankton become entangled in the "hair mats" that cover the gill slits. These comb-like sieves are called gill rakers. The animal can only swallow food. Oh look who is it? (slide 8,9)

Students - This is a stingray. These fish are listed as dangerous animals, but in general they are harmless and harmless. Some have a menacing and ferocious appearance, some can stab, poison or stun a person, but there has never been a case of any of them making an unprovoked attack on people. Most of them have a flat body, and their pectoral fins have flattened, expanded and turned into “wings” that are integral with the head and sides.

Teacher- We return to the ship and check what we have learned. The table is read out.

There is a freshwater strait ahead, and what kind of fish is this? (slide 12)

Student - Sturgeon. A small group of fish. Ancient features have been preserved in the structure of sturgeons, emphasizing their similarity to cartilaginous fish. Throughout their lives, sturgeons retain their notochord and osteochondral skeleton. The body is elongated, the head begins with a flattened snout, on the lower side of which there are two pairs of antennae and a mouth in the form of a transverse semilunar slit. The jaws are devoid of teeth. In the skin layer on the sides along the body and on the ridge there are five rows of large bone plaques, with small bone plates randomly scattered between them. The pectoral and ventral fins are attached horizontally to the body. The caudal fin is unequally lobed, reminiscent of a shark's tail. There is a swim bladder.

Representatives of the sturgeon family are found mainly in the northern hemisphere of temperate latitudes of Europe, Northern Asia and North America. As adults, these fish spend most of their lives in the seas. Baikal sturgeon, American lake sturgeon and sterlet are considered freshwater fish. (slide 12)

Sturgeon meat is valued for its excellent taste. It is eaten fresh, salted, and smoked. Sturgeon caviar is a very valuable nutritious product.

Teacher– we’re in the sea again, look how the water glistens, who is it? (slide 14,15)

Students- These are herring-shaped ones. Fishes of this order have an elongated body, slightly compressed laterally. The color of the back is dark blue or greenish, the belly is white with a silver tint. Paired and unpaired fins are soft. The lateral line is invisible. The body length is usually 5-75 cm, sometimes up to 5 m. Most herrings live in the seas, there are also anadromous ones - moving from seas to rivers for reproduction and vice versa.

Few representatives of the order live in fresh water bodies. They feed on planktonic invertebrates. Large individuals, as a rule, are predators that eat small fish.

The order consists of three families. The most famous fish are from the herring family, relatively small or medium in size, usually 35-45 cm long, less often - more. Herrings live mainly in the seas. Oceanic (Atlantic, Baltic, White Sea, Pacific) herring, sardine, and willow are of commercial importance. The smallest fish of commercial importance are sprat and sprat, which live in the Baltic, Black and Caspian seas.

Teacher– we’ve almost reached the destination of our journey, but who is ahead?

(slide 16,17)

Student- This is salmon, from the salmon order. The commonly used names in everyday life “salmon” and “trout”, contrary to the stereotype, do not correspond to any type of fish. These are collective names of either an entire family or subfamily (typical of the name “salmon”), or a large group of species united by one property (trout).

Actually, salmon is considered to be salmon in general, or salmon during spawning. On the other hand, the term “salmon” is present in the name of more than a dozen different species of fish from different subfamilies, as well as in the name of two genera - Noble salmon and Pacific salmon.

All salmon species of commercial importance: salmon, Caspian, Black Sea, Aral salmon, whitefish and others are under special protection of the Ministry of Fishing Industry of the Russian Federation, therefore fishing for any salmon and in any way, including spinning, can only be carried out with a special purpose. permits issued by the Ministry or local authorities regulating fisheries, or in areas specifically designated for sport fishing.

Salmon fish are either anadromous, which live in the sea and only enter rivers for spawning during spawning, or freshwater, which live in rivers and do not go to the sea at all. Salmon are the fish of the north. But some of them are found in the Black, Caspian and Aral seas. This is explained by the geological past of the named seas, which were once connected to the Arctic Ocean.

The salmon is very beautiful: its body is slender, elongated, with small bright silver scales, among which, above the lateral line, there are a small number of X-shaped dark spots scattered; her back is dark, with a blue steel tint; belly white; the caudal and dorsal fins are dark gray, and the rest are somewhat lighter. The mouth of the salmon is large, the jaws are cartilaginous and bony with rather large teeth and are very strong. Salmon in the sea feeds on small fish and grows up to 1.5 m in length, feeding up to 32 kg or more of excellent-tasting meat. A distinctive feature of salmon, like all salmonids in general, is the adipose fin, located on the back near the powerful tail.

Teacher- but here we are almost home, there is fresh water ahead, what a beautiful fish - straight from a fairy tale - a goldfish. And who is this? (slides 18,19,20)

Student- carp Carp, a fish of the carp family, is a cultivated (domesticated) form of carp. Carp is a schooling fish, yellow-green and brown in color. The characteristic features of a carp are two whiskers on each side of the upper jaw. The body color of this fish can vary depending on its habitat. Its back is usually dark, even black, with a greenish tint, its sides are yellowish and its belly is lightish. The slightly notched dorsal fin is dark gray, the ventral, pectoral and anal fins are light gray with a purple tint, the caudal fin is red-brown.

Carp are very unpretentious, although heat-loving fish (tolerate temperatures up to 35 ° C, live in ponds with a small amount of oxygen, (tolerate significant pollution), quarries, irrigation and drainage canals, rivers. If a carp gets into a river, it prefers to stay in in quiet, overgrown backwaters with a slow flow, river carp have a more elongated body and, when caught on a hook, exhibit greater resistance compared to their relatives from standing reservoirs.

In the reservoirs of Russia, the most common representatives of cyprinids are roach, dace, asp, tench, barbel, bream, vimba, bleak, sabrefish, carp, crucian carp, carp, all of which are of great commercial importance. A number of species are artificially bred in pond farms.

Teacher- and now let’s ask the fishermen - do you know the following fish that are now swimming past us. (slide 21,22)

Students– perch. The order Perciformes is the most numerous group of fish in terms of species composition (Fig. 5). They are distributed in water bodies of all continents and oceans. A characteristic feature of perciformes is the presence of two dorsal fins with sharp spines. Some of them lack a swim bladder. Body length from 1 cm to 5 m and weight from less than a gram to 1000 kg or more. Almost all fish of the order Perciformes are edible and are objects of commercial as well as recreational fishing. Small fish of this group live and reproduce well in aquariums.

Teacher- Well done, a little more and we’ll be home, oh, oh, look who’s almost on the shore. And it’s blue too, let’s go get acquainted. (slide 23,24)

Students- Yes, this is coelacanth. On Christmas Day 1938, fishermen fishing in the Indian Ocean, off the coast of South Africa, discovered a very strange creature among the fish raised by trawl from a depth of 69 meters. It was the size and weight of a short person - its length was 1.5 -1.8 m, and the weight was 57 kg. The fish had a magnificent bluish hue with a metallic sheen, was covered with large thick scales and had powerful, oar-shaped fins. When the captain bent down to get a better look at this creature, it opened its mouth full of sharp teeth and bit into his hand. none of those on the ship saw such an animal. When the ship moored at one of the docks in East London, this creature was taken to the local museum. The famous ichthyologist immediately realized that this was the most important discovery that scientists had been able to make at sea. He determined that this was one of the specimens of fish that had been hiding in the depths of the seas for millions of years, hundreds of meters from the surface. They named it after the museum curator who told him about the find, Miss Courtney Latimer. In 1952, another coelacanth was recovered from the depths of the sea between Africa and Madagascar. More than a dozen such living fossils were later caught in the same area, members of a branch long thought extinct - a branch that connects vertebrates that live on land and sea.

3. Consolidation

Teacher– we returned from our trip, let’s summarize what we did (Checking the table). Now let’s summarize the cards with the appearance of fish in front of you - add those parts of the body that are missing and determine which classes and orders they belong to. (Appendix 2).

Look, the film that we shot during the trip, the camera filmed only those moments that we lost sight of due to our extensive research activities (slide 25).

4. Reflection.

Well done, they did a great job, each of you when boarding the ship received 3 fish - cheerful, sad and thoughtful, there are 3 aquariums in front of you, release the fish into the aquarium that best suits your mood in this lesson.

5. Homework: repeat paragraphs 22,23

Bibliography:

1. V.V. Latyushin V.A. Shapkina “Biology. Animals. 7th grade" -M. Bustard 2009
2. V.V. Latyushin G.A. Ufimtseva “Biology. Animals. 7th grade: thematic and lesson planning for the textbook by V.V. Latyushin V.A. Shapkina “Biology. Animals. 7th grade" -M. Bustard, 2008
3. A.V. Onishchenko “Biology in tables and diagrams” St. Petersburg LLC “Victoria Plus” 2010
4. http://www.learnbiology.ru/19.htm
5. http://www.zooeco.com/0-rib/0-ribi3-1.html
6. http://images.yandex.ru
7. http://900igr.net
8. http://ru.wikipedia.org
9. http://fish-book.ru