Greenland shark attacks a man. Polar shark. Enemies of this predator

Sleptsova E.V. oneSavvina S.R. one

Vakhrusheva A.V. one Ivanova A.P. 2

1 Municipal educational budgetary institution secondary school No. 21 of the urban district "city of Yakutsk"

2 IPC SB RAS

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INTRODUCTION

City lakes are of great ecological importance for the city, as they are a source of domestic water supply, a habitat for fish, and a place for people to relax. In connection with the deterioration of the ecological situation in the urban environment, it becomes necessary to conduct observations of the hydrobiological composition of the aquatic environment.

The purpose of the work is to identify the species composition of phytoplankton to assess the current state of the reservoir and develop recommendations for improving the ecological situation of Lake Soldatskoye.

Research Hypothesis: it can be assumed that the timely implementation of protective measures will save Lake Soldatskoye, and will also make it possible to create a buffer zone within the city.

To achieve this goal, the following tasks :

1. Determine the composition of phytoplankton.
2. Identify species-indicators of saprobity.
3. Assess the current state of phytoplankton and develop recommendations for improving the state of the reservoir.

Scientific and practical significance. The materials of this work can serve as a basis for environmental monitoring of urban water bodies, as well as be used as promotional materials on the improvement of urban infrastructures and issues of caring for the elements of nature.

Chapter 1. Phytoplankton of water bodies

A water body as an ecosystem is a complex of all organisms and inanimate elements, as a result of the interaction of which a stable structure and circulation of substances are created by the energy flow in a given place (Lasukov, 2009).

The main components of the aquatic ecosystem:

1) incoming energy from the Sun;

2) climate and physical factors;

3) inorganic compounds;

4) organic compounds;

5) producers of organic compounds, or producers(from lat. produceris- creating) - rooted, free-floating plants and the smallest algae (phytoplankton, from the Greek. phytos- plant, plankton- wandering, soaring);

6) primary consumers, or primary consumers(from lat. consumo- I consume), eating plants - zooplankton (animal plankton), molluscs, larvae, tadpoles;

7) secondary consumers, or secondary consumers- predatory insects and fish;

8) detritus(from lat. detritus- worn) - products of decay and decomposition of organisms;

9) destroyers, destructors, decomposers(from lat. reducenti s - returning, restoring), detritivores(from Greek. phagos- eater), saprotrophs(from Greek. sapros- rotten and troph e - food) - bottom bacteria and fungi, larvae, mollusks, worms.

Plankton algae (phytoplankton) are an important component of lake ecosystems. Phytoplankton is the main producer of organic matter in water bodies, due to which the majority of aquatic animals live. They are sensitive to environmental changes and play an important bioindicative role. Phytoplankton influences the development of invertebrates in plankton (zooplankton), which in turn is a natural filter and food base for fish.

Phytoplankton include protococcal algae, diatoms, dinoflagellates, coccolithophores, and other unicellular algae (often colonial), as well as cyanobacteria. It lives in the photic zone of water bodies, inhabiting the water column. The abundance of phytoplankton in various parts of water bodies depends on the amount of nutrients necessary for it in the surface layers. Limiting in this respect mainly phosphates, nitrogen compounds, and for some organisms (diatoms, siliceous) and silicon compounds. Since small plankton animals feed on phytoplankton, serving as food for larger ones, the areas of the greatest development of phytoplankton are also characterized by an abundance of zooplankton and nekton. Much less and only local importance in the enrichment of surface waters with nutrients is the river runoff. The development of phytoplankton also depends on the intensity of illumination, which in cold and temperate waters determines the seasonality in the development of plankton. In winter, despite the abundance of nutrients carried into the surface layers as a result of winter mixing of waters, phytoplankton is scarce due to lack of light. In spring, the rapid development of phytoplankton begins, followed by zooplankton. As phytoplankton use nutrients, and also as a result of eating them by animals, the amount of phytoplankton decreases again. In the tropics, the composition and quantity of plankton are more or less constant throughout the year. Abundant development of phytoplankton leads to the so-called "bloom" of water, changing its color and reducing the transparency of water. During the “blooming” of some species, toxic substances are released into the water, which can cause mass death of planktonic, nekton animals, as well as cause allergic skin reactions, conjunctivitis and gastrointestinal upset in humans.

According to size plankton is divided into:

1) megaloplankton (megalos - huge) - which include organisms larger than 20cm;

2) macroplankton (makros - large) - 2-20 cm;

3) mesoplankton (mesos - medium) -0.2-20 mm;

4) microplankton (mikros - small) - 20-200 microns;

5) nanoplankton (nanos - dwarf) - 2-20 microns;

6) picoplankton - 0.2-2 microns;

7) femtoplankton (ocean viruses) -< 0,2 мкм.

However, the boundaries of these size groups are not generally accepted. Many plankton organisms have developed devices that facilitate soaring in water: reducing the specific body weight (gas and fat inclusions, water saturation and gelatinization of tissues, thinning and porosity of the skeleton) and increasing its specific surface area (complex, often highly branched outgrowths, flattened body).

Phytoplankton biomass varies in different water bodies and their areas, as well as in different seasons. In the lakes of the city of Yakutsk, the biomass varies within 0.255-3.713 mg/l (Ivanova, 2000). With depth, phytoplankton becomes less diverse and its number rapidly decreases, the maximum values ​​are at a depth of 1-2 transparencies. The transparency of water in hydrology and oceanology is the ratio of the intensity of light passing through a layer of water to the intensity of light entering the water. Water transparency is a value that indirectly indicates the amount of suspended particles and colloids in water. The annual production of phytoplankton in the World Ocean is 550 billion tons (according to the Soviet oceanologist VG Bogorov), which is almost 10 times higher than the total production of the entire animal population of the ocean.

Phytoplankton, especially lakes, in the process of formation and development can undergo a number of changes due to the nature of the ecological habitat: the location and morphometry of the reservoir, the specific chemical composition of the water, level fluctuations, the supply of nutrients in the water, the result of human economic activity, etc. This leads to the replacement of some types of algae by others, more specialized. In general, the overall species diversity and composition of phytoplankton can serve as good ecological indicators. Of great relevance are comparative studies of the regularities in the distribution of the composition, structure, and productivity of phytoplankton in water bodies of various natural zones, which form the basis for developing their trophic status and predicting environmental changes in aquatic ecosystems under the influence of anthropogenic load (Ermolaev, 1989).

The modern taxonomy of algae includes 13 departments:

Cyanoprocaryota- blue-green algae (cyanobacteria);

Euglenophyta- euglena algae;

Chrysophyta- chrysophyte algae;

Xanthophyta- yellow-green algae;

Eustigmatophyta- eustigmatous algae;

Bacillariophyta- diatoms;

Dinophyta- dinophyte algae;

Cryptophyta- cryptophyte algae;

Raphydophyta- rafidophyte algae;

Rhodophyta- red algae;

Phaeophyta- brown algae;

Chlorophyta- green algae;

Streptophyta- streptophyte algae.

Chapter 2. Material and methods of hydrobiological research

To identify the current composition of the phytoplankton of Lake Soldatskoye, sampling was carried out in the summer of 2017 (May 23, June 21, July 12). Water samples were taken from the surface horizon of the reservoir in the littoral. Sampling was carried out at two stations: near the Ryzhikov square (section 1) and near the Panda restaurant (section 2). Information about sampling points is given in Table 1 (Photos 1 and 2).

Table 1

Water sampling points for the study of phytoplankton

	Sample No. p/n	the date	Name of the sampling point		Qual / count	Volume, filtered water (l)
			Plot No. 1 (near the square named after Ryzhikov)
			Plot No. 2
			Plot No. 1 (near the square named after Ryzhikov)
			Plot No. 2 (near the Panda and the Crane Restaurant)
			Plot No. 1 (near the square named after Ryzhikov)
			Plot No. 2 (near the Panda and the Crane Restaurant)
PHOTO 1. Sampling at site 1 (near the square named after Ryzhikov)				PHOTO 2. Sampling at site 2 (near Panda Cafe)

The choice of phytoplankton sampling method depends on the type of reservoir, the degree of development of algae, research objectives, available instruments, equipment, etc. Apply various methods of preliminary concentration of microorganisms. One such method is filtering water through plankton nets.

The plankton net consists of a brass ring and a conical bag sewn to it from a mill silk or nylon sieve No. 30 (Fig. 1). The pattern of the net cone pattern for the plankton net is shown in Figure 2. The narrow outlet of the cone-shaped bag is tightly attached to the cup, which has an outlet tube closed with a tap or Mohr's clamp. In small bodies of water, plankton samples can be collected from the shore by throwing a net on a thin rope into the water and carefully pulling it out. In large reservoirs, plankton samples are taken from a boat. At the same time, it is recommended to pull the plankton net behind a moving boat for 5-10 minutes. After completing the collection of plankton samples, the plankton net is rinsed, lowering it several times into the water to the upper ring, in order to wash off the algae that have lingered on the inner surface of the net. The concentrated sample in the plankton net cup is poured through the outlet tube into a clean jar or bottle prepared in advance. Before and after the end of sampling, it is necessary to rinse the net well, after finishing work, dry it and put it in a special case. These samples can be studied in the living and fixed state. For long-term storage, a 40% formalin solution is added to the sample at the rate of 2-3 drops per 10 ml.

For quantitative accounting of phytoplankton, samples of a certain volume are taken. For these purposes, network fees can also be used, provided that the amount of water filtered through the network and the volume of the sample collected are taken into account. Usually, sampling for the quantitative accounting of phytoplankton is carried out with special devices - bottles of various designs. When studying the phytoplankton of the surface layers of water, samples are taken by scooping water into a vessel of a certain volume. In reservoirs with poor phytoplankton, it is desirable to take samples of at least 1 liter in parallel with net collections, which make it possible to capture small, relatively large objects.

In reservoirs with rich phytoplankton, the volume of a quantitative sample can be reduced to 0.5 and even to 0.25 liters (for example, when the water "blooms"). We filtered 10 liters of water with a bucket through an Apstein net and also fixed with 40% formalin.

Labeling and keeping a field diary

All collected samples are labeled. On the labels, with a simple pencil, indicate the sample number, reservoir, station number, sampling horizon, the volume of filtered water, if this sample was taken for quantitative analysis, the date and name of the collector. The label is dropped into the sample container. The same data are entered in the field diary, in addition, they indicate the air and water temperature, a schematic drawing of the reservoir indicating sampling stations, make up a detailed description of the reservoir under study and higher aquatic vegetation, and other information (wind, cloudiness, etc.).

Methods for qualitative study of the material

The collected material is preliminarily examined under a microscope in a living state on the day of collection in order to note the qualitative state of the algae before the onset of changes caused by the storage of living material or fixation of samples (formation of reproductive cells, colonies, loss of flagella and motility, etc.). In the future, the collected material continues to be studied in a fixed state. Algae were studied using light microscopes of various brands using different systems of eyepieces and objectives in transmitted light, following the usual rules of microscopy.

Preparations are prepared for microscopic examination of algae: a drop of the liquid under study is applied to a glass slide and covered with a coverslip. With a long study of the preparation, the liquid under the coverslip gradually dries up, so it should be added. To reduce evaporation, a thin layer of paraffin is applied along the edges of the coverslip.

Methods for measuring the size of algae and determining the division value of an eyepiece micrometer

When studying the species composition of algae, their sizes are measured, which are important diagnostic features. To measure microscopic objects, an eyepiece-micrometer with a measuring ruler is used. The division value of the eyepiece micrometer is determined using an object micrometer individually for each microscope and objective. The object-micrometer is a glass slide with a ruler printed on it, the length of which is 1 mm. The ruler is divided into 100 parts so that each part is equal to 0.01 mm or 10 µm. In order to find out what one division of the eyepiece-ruler is equal to at a given magnification, it is necessary to establish a correspondence between the divisions (strokes) of the measuring eyepiece-ruler and the object-micrometer. For example: 10 divisions of the eyepiece micrometer are the same as 5 divisions of the object micrometer (i.e. equal to 0.05 mm). So one division of the eyepiece ruler is equal to 0.05 mm: 10 = 0.005 mm = 5 μ (µm). Such a calculation must be performed for each lens 3-4 times in order to obtain a more accurate division value.

When studying the linear dimensions of algae, it is desirable to measure the largest possible number of specimens (10-100) with subsequent statistical processing of the data obtained. When identifying algae, accuracy should be achieved. When studying the original material, it is necessary to note any, even minor, deviations from the diagnoses in size, shape, and other morphological features, and record them in your descriptions, drawings, and microphotographs.

In the practice of algological research, transmission and scanning electron microscopy is increasingly used. Methods for the preparation of preparations and study are described in the special literature.

Methods for quantitative accounting of algae

Only quantitative samples of phytoplankton can be subject to quantitative accounting. Data on the abundance of algae are the initial data for determining their biomass and recalculating other quantitative indicators (the content of pigments, proteins, fats, carbohydrates, vitamins, nucleic acids, ash elements, respiration rate, photosynthesis, etc.) per cell or per unit of biomass. The number can be expressed in the number of cells, coenobia, colonies, segments of threads of a certain length, etc.

The number of algae is counted on special counting glasses (divided into stripes and squares), on the surface of which a drop of water from a thoroughly mixed test sample is applied with a pipette of a certain volume (mostly 0.1 cm 3). To account for the number of algae, Nageotte counting chambers with a volume of 0.01 cm 3, "Uchinskaya" (0.02 cm 3) are also used. In addition, you can use cameras used to count blood cells - Goryaev, with a volume of 0.9 mm 3, Fuchs-Rosenthal, etc. When using Goryaev and Fuchs-Rosenthal cameras, the cover glass is carefully ground to the side surfaces of the subject counting glass until rings appear Newton, and then fill the chamber with a drop of the test sample using a pipette. Depending on the number of organisms in the test sample, either all or part of the tracks (squares) on the surface of the counting glass can be counted. It is imperative to recount several (at least three) drops from the same sample, each time taking a sample for counting with a pipette after thoroughly agitating the sample.

In the study of quantitative samples of phytoplankton, the recalculation of the number of organisms per 1 liter of water is carried out according to the formula

N=¾¾¾, where

N - number (cell / l),

n is the average number of cells counted in the chamber,

V 1 - the volume of filtered water (l),

V 2 - sample volume (ml),

V 3 - chamber volume (ml).

The quantitative content of algae in samples most fully reflects the indicators of their biomass, which are determined using counting-volume, weight, volumetric, various chemical (radiocarbon, chlorophyll, etc.) methods.

To determine the biomass by the counting-volume method, it is necessary to have data on their abundance in each specific sample for each species separately and their average volumes (for each species from each specific sample). There are different methods for determining the body volume of algae. The most accurate is the stereometric method, when using which the body of the algae is equated to some geometric body or a combination of such bodies, after which their volumes are calculated using formulas known in geometry based on the linear dimensions of specific organisms. Sometimes they use ready-made, previously calculated average body volumes for different types of algae, which are given in the works of many authors. Biomass is calculated for each species separately, and then the data are summarized. The counting-volume method for determining biomass is widely used in the practice of hydrobiological research when studying the quantitative ratios of various components of biocenoses, patterns of algae distribution in different biotopes of the same reservoir or in different reservoirs, seasonal and long-term dynamics of algae development, etc.

The biomass of algae is determined according to the generally accepted method (Makarova et al., 1970) by equating individual cells to geometric figures (Fig. 3) using standard tables (Kuzmin, 1984) and the biomass is calculated by the formula:

N is the number of cells in 1 l (cells/l);

W - cell weight (mg).

In the absence of standard tables, we calculate the volume and weight of the cell (W) using geometric formulas (Fig. 3): for a cylinder with a very small height (B) V = πr 2 h; a cylinder whose base is an ellipse (A)

V = pabh; cube V \u003d l 3; parallelepiped V = abc;

ball V = - πr 3 ; cone V = - πr 2 h; ellipsoid V = - πabc;

(c + 2b)ah (c + 2b)ah

wedge V = ————; 2 wedges V = ————

Any equating to the figures is conditional, therefore, errors are possible both in the direction of increasing and in the direction of decreasing the "true" volume of the cell. With this in mind, it is necessary to equate each type of cell, as far as possible, with the geometric figure that best corresponds to the true volume of this cell. After we calculate the volume according to the formula, you need to multiply the resulting volume by 10 -9. Weight is measured in mg. For a more accurate determination of the phytoplankton biomass, it is necessary to take into account the mucus surrounding the cell, as well as the thickness of the shell in diatoms.

With intensive development of algae, you can use the weight method. In this case, the test sample is filtered through a pre-dried and weighed paper filter (in parallel, distilled water is filtered through the control filters). The filters are then weighed and dried in an oven at 100°C to constant weight. Based on the data obtained, the dry and wet weights of the sediment are calculated. Subsequently, by burning the filters in a muffle furnace, it is possible to determine the content of organic matter in the sediment. The disadvantage of this method is that it gives an idea only of the total mass of all organic substances suspended in the sample, living organisms and non-living impurities, of animal and plant origin. The contribution of representatives of individual taxa to this total mass can only be approximately expressed in mass fractions after counting their ratio under a microscope in several fields of view. The most complete picture of the biomass of algae can be obtained by combining several different research methods.

Method for determining the frequency of occurrence

With the qualitative processing of samples, it is desirable to determine the frequency of occurrence of individual species, using symbols for this. There are various scales for the frequency of occurrence of algae:

The frequency of occurrence of the species (h) according to the scale of Levander (Levander, 1915) and Ostelfeld (Ostenfeld, 1913) in the modification of Kuzmin (Kuzmin, 1976) has a numerical expression from 1 to 6:

rr - very rarely (from 1 to 10 thousand cells / l) - 1;

r - rarely (from 10 thousand cells / l to 100 thousand cells / l) - 2;

rc - often (from 100 thousand cells / l to 1 million cells / l) - 3;

c - often (from 1 million cells / l to 10 million cells / l) - 4;

ss - very often (from 10 million cells / l to 100 million cells / l) - 5;

ccc - mass, "flowering" (from 100 million cells / l and more) - 6.

The frequency of occurrence of the species (h) according to the Starmach scale (Starmach, 1955):

Very rare (the species is not present in every preparation);

1 - singly (1-6 copies in the preparation);

2 - few (7-16 copies in the preparation);

3 - decently (17-30 copies in the preparation);

4 - many (31-50 copies in the preparation);

5 - very many, absolute predominance (more than 50 copies in the preparation).

The use of algae for biological water analysis

Biological analysis of water, along with other methods, is used in assessing the state of reservoirs and monitoring water quality. Algae, due to the stenotopicity of many species, their high sensitivity to environmental conditions, play an important role in the biological analysis of water. The structure of phytoplankton is very sensitive to environmental conditions. Along with the abundance, biomass, and abundance of species, indices of species diversity and informational indices can be promising as indicators of water pollution.

The quality or degree of water pollution by the composition of algae is assessed in two ways: a) by indicator organisms; b) based on the results of a comparison of the community structure in areas with different degrees of pollution and in the control area. In the first case, according to the presence or absence of indicator species or groups and their relative number, using previously developed systems of indicator organisms, a reservoir or its section is assigned to a certain class of waters. In the second case, the conclusion is made based on the results of a comparison of the composition of algae at different stations or sections of the reservoir, which are subject to pollution to a different extent.

In algology, the water saprobity system is used, which is estimated by the degree of their contamination with organic substances and their decay products. The system for determining saprobity proposed in 1908 by R. Kolkwitz and M. Marsson and its subsequent modifications received the greatest recognition. These authors believed that the decomposition of organic matter contained in wastewater was of a stepwise nature. In this regard, water bodies or their zones, depending on the degree of pollution with organic substances, are divided into poly-, meso-, and oligosaprobic.

In the polysaprobic zone, located near the place of wastewater discharge, the breakdown of proteins and carbohydrates occurs under aerobic conditions. This zone is characterized by an almost complete absence of free oxygen, the presence of undecomposed proteins in the water, significant amounts of hydrogen sulfide and carbon dioxide, and the reductive nature of biochemical processes. The number of algae species capable of developing in this zone is relatively small, but they are found in mass quantities.

In the mesosaprobic zone, pollution is less pronounced: there are no undecomposed proteins, there is little hydrogen sulfide and carbon dioxide, oxygen is present in appreciable amounts, however, there are still such weakly oxidized nitrogenous compounds in the water as ammonia, amino and amido acids. The mesosaprobic zone is subdivided into α- and β-mesosaprobic subzones. In the first, ammonia, amino and amido acids are found, but there is already oxygen. Blue-green algae of the genera Oscillatoria and Formidium are found in this zone. Mineralization of organic matter is mainly due to aerobic oxidation, in particular bacterial. The next mesosaprobic zone is characterized by the presence of ammonia and its oxidation products - nitric and nitrous acids. There are no amino acids, hydrogen sulfide occurs in small amounts, there is a lot of oxygen in the water, mineralization occurs due to the complete oxidation of organic matter. The species diversity of algae is greater here than in the previous subzone, but the abundance and biomass of organisms are lower. The most typical for this subzone are diatoms from the genera Melozira, diatom, navicula and green from the genera Cosmarium, Spirogyra, Cladophora, Scenedesmus.

In the oligosaprobic zone, hydrogen sulfide is absent, carbon dioxide is low, the amount of oxygen approaches normal saturation, and there are practically no dissolved organic substances. This zone is characterized by a high species diversity of algae, but their abundance and biomass are not significant.

The improvement of the system of R. Kolkwitz and M. Marsson proceeded by expanding the list and clarifying the types - indicators of pollution, as well as converting qualitative assessments into quantitative ones (saprobity index according to R. Pantle and G. Buk). A list of algae species - indicators of the degree of pollution of water bodies can be found in the special literature (Algae-indicators ..., 2000).

where h is the frequency of occurrence of the species;

s - saprobic value.

The saprobic value (s) is expressed as values ​​from 0 to 4 (Pantle and Buck, 1955):

χ (xenosaprobity) - 0;

o (oligosaprobicity) - 1;

β (β-μezosaprobity) - 2;

α (α-μezosaprobity) - 3;

p (polysaprobity) - 4.

The following values ​​are accepted for transition zones (Sladeček, 1967, 1973):

χ-o (0.4); β-α (2.4);

o-χ (0.6); α-β (2.6);

χ-β (0.8); β-p (2.8);

o-β (1.4); α-p (3.4);

β-o (1.6); p-α (3.6).

Handling collected and defined material

The obtained results of the determination of algae are drawn up as a systematic list. The main requirements for any information transfer system, including scientific nomenclature, are universality, uniqueness, and stability. These three basic requirements of the communication system used by taxonomists correspond to a set of rules - the International Code of Botanical Nomenclature (ICBN), which was adopted at the VII International Botanical Congress (Stockholm, 1950). Compliance with the ICBN rules is mandatory for all botanists, violation of these provisions may lead to instability of the botanical nomenclature

In the taxonomy of algae, taxonomic groups of organisms (taxa) are distinguished, which are also accepted in the taxonomy of higher plants. The ending of the names of all taxa of the same rank is standardized as follows:

department (divisio), -phyta

class (classis), -phyceae

order (ordo), -ales

family (familia), -aceae

species.

Taxa of intraspecific rank are often distinguished - subspecies (subspecies), variety (varietas), form (forma), and sometimes also subclass (-phycidae), suborder (-ineae) and other categories.

Each species necessarily belongs to a genus, a genus to a family, a family to an order, an order to a class, a class to a department, a department to a kingdom. Species as defined by the Russian botanist V.L. Komarov is a collection of related organisms characterized by morphophysiological and ecological-geographical features that are specific only to them. All individuals of the same species are characterized by a common phylogenetic origin, the same type of metabolism and the same range.

The species has a name consisting of two words (the principle of binary nomenclature). For example: Anabaenaflos- aquae(Lyngb.)Bréb. The first word - the name of the genus, indicates that in nature there is a group of related species. The second word - the specific epithet reflects the feature that distinguishes a particular species from other species of the genus. The name of the species must be accompanied by the surname of the author who described the species. Authors' names are abbreviated.

With the help of a systematic list of algae, it is possible to identify the structure of phytoplankton, the species diversity of families and orders and divisions of algae. In the taxonomic, ecological and geographical analysis of algae, it is necessary to indicate such features of species as saprobity, habitat, acidity, and geographical distribution. Many features are indicated in the guides of algae in the description of each species.

The identification of algae was carried out at the Institute of Biological Problems of the Permafrost of the Siberian Branch of the Russian Academy of Sciences using domestic and foreign determinants.

Chapter 3. Phytoplankton of Lake Soldatskoye

3.1. Taxonomic composition of phytoplankton

We found in the plankton of the lake 102 species belonging to 58 genera, 37 families, 21 orders, 14 classes and 9 divisions of algae (Appendix 1). The number of species was dominated by diatoms (41 species), green (26) and blue-green (14) algae (Table 2). Streptophytes (6 species), euglenoids (5), golden and yellow-green (4 species each) were few in number. Eustigmatophyte and dinophyte algae were sporadically encountered. Species of blue-green algae of the genus Oscillatoria, basically view Oscillatoria proboscidea.

table 2

Taxonomic spectrum of phytoplankton algae of the lake. soldier

orders

families

Cyanophyta

Euglenophyta

Chrysophyta

Xanthophyta

Eustigmatophyta

Bacillariophyta

Dinophyta

Chlorophyta

Streptophyta

The lake is divided into 2 unequal sections. In terms of species diversity, site No. 1 stands out; 82 species were found in it, and 63 species were found in site No. 2 (Table 2). This distribution can be explained by the fact that, according to hydrochemical indicators, site No. 1 is less polluted compared to site No. 2 (Appendix 2). The presence of biogenic elements causes the mass development of certain species and thus inhibits the development of others. Also important is the size of the water table and its overgrowth with higher aquatic vegetation. In our lake, duckweed covered area No. 2 almost completely compared to area No. 1, thereby reducing the influx of sunlight into the water column.

Samples taken in June during the determination visually differ in the number of cells from samples taken in July. The decrease in the number of cells is associated with the massive development of zooplankton, since phytoplankton is food for them.

3.2. Species - indicators of saprobity

Saprobicity is a complex of physiological and biochemical properties of an organism, which determines its ability to live in water with one or another content of organic substances, that is, with one or another degree of pollution.

We found 59 saprobic species in plankton, which is 57.8% of the total number of species (Appendix 1). Saprobic species with a coefficient of 2 or more amounted to 44 species: β-mesosaprobs - 30 species, α-β-mesosaprobes - 3 species, β-α-mesosaprobes - 5 species, α-mesosaprobes - 6 species, p-α - 1 species. It is impossible to calculate the saprobity index without quantitative indicators, but according to the composition of these species, it can be said that the saprobity index will exceed 2, which refers the water to the third class of purity with a slightly polluted discharge (Algae-indicators…, 2000).

This work was carried out in combination with hydrochemical and hydrobiological indicators. At the present stage, the lake is slightly transformed, high concentrations of compounds were found in water samples, indicating the accumulation of a number of biogenic and organic compounds in the water. This led to the massive development of blue-green algae, as well as zooplankton. The waters of this reservoir can be used for cultural and domestic and fisheries water uses only with the condition of additional purification. To save the lake, it is necessary to carry out the following types of work:

1. mechanical cleaning of the lake area;
2. control water quality;
3. improvement of the coastal territory of the lake;
4. introduction work.

As a result of the complex of works, the nutrition of the lake will improve, the quality of the water in the lake will increase, and a sanitary and environmentally favorable environment will be created on the territory adjacent to the lake, which will allow maintaining the lake in good sanitary condition in the future.

for lake restoration. soldier's

EVENT	IMPLEMENTATION	TERM	PERFORMERS
Mechanical cleaning of the lake area	Cleaning of coastal and water areas from household waste. Vykos coastal and aquatic vegetation.	period of intensive plant development (May-September 2018-2020)	volunteers
Water quality control	Water sampling	open water period (May-September 2017-2020)	Gerasimenko S., Vakhrusheva A.V., Gabysheva O.I.
Improvement of the coastal territory of the lake	1. Alignment and strengthening of the coastal slopes of the lake by sowing grasses on a layer of plant soil using a geogrid. 2. Formation of a recreation area for citizens	June-August 2019-2020	Guba district, Housing and communal services "Gubinsky", volunteers, employees of the IPC SB RAS
Introductory work	Introduction of biological objects to improve the state of lake water	open water period (May-September 2019-2020)	administration of school No. 21, Housing and communal services "Gubinsky", employees of the IPC SB RAS
Agitation work to preserve the ecological state of lakes	Speech at conferences of school, city, republican level	October-January 2017-2020	students of school number 21

CONCLUSION

The phytoplankton of Lake Soldatskoye is represented by 102 species belonging to 58 genera, 37 families, 21 orders, 14 classes, and 9 divisions of algae. Species of blue-green algae of the genus Oscillatoria, basically view Oscillatoria proboscidea. Plot No. 1 is richer in species diversity compared to Plot No. 2. According to the types of indicators, the water of the lake belongs to the third class of purity.

To preserve the lake, it is necessary to carry out mechanical cleaning of the territory of the reservoir; improve the coastal area and carry out introduction work.

To create favorable conditions in this reservoir, it is necessary to carry out restoration work with the involvement of the public, housing and communal services and volunteers represented by students of school No. 21 and residents of the Gubinsky district. We plan to continue our research in the future. We sincerely hope that by joint efforts we will create a beautiful place for the citizens to relax.

Bibliography

Algae-indicators in assessing the quality of the environment. Part I. Barinova S.S. Methodical aspects of the analysis of the biological diversity of algae. Part II. Barinova S.S., Medvedeva L.A., Anisimova O.V. Ecological and geographical characteristics of indicator algae. - Moscow: VNIIprirody, 2000. - 150 p.

Algae: A Handbook / Vasser S.P., Kondratieva N.V., Masyuk N.P. etc. - Kyiv: Nauk. Dumka, 1989. - 608 p.

Ermolaev V.I. Phytoplankton of water bodies of the Sartlan Lake basin. - Novosibirsk: Nauka, 1989. - 96 p.

Ivanova A.P. Algae of urban and suburban lakes of the Middle Lena Valley. - autoref. dissertation for an apprenticeship step. cand. biol. Sciences. - Moscow, 2000. - 24 p.

Kuzmin G.V. Plankton algae of the Sheksna and adjacent parts of the Rybinsk Reservoir // Biology, Morphology and Systematics of Aquatic Organisms. - Moscow: Nauka, 1976. - Issue. 31 (34). - pp. 3-60

Kuzmin G.V. Tables for calculating the biomass of algae. Preprint. - Magadan, 1984. - 48 p.

Lasukov R.Yu. Water dwellers. Pocket identifier. - Moscow: Forest Country, Ed. 2nd, rev., 2009. - 128 p.

Makarova I.V., Pichkily A.O. On some issues of the methodology for calculating phytoplankton biomass // Botan. well. - 1970. - T. 55, No. 10. - S. 1488-1494.

Pantle F., Buck H. Die biologischeüberwachung der Gewasser und die Darstellung der Ergebnisse. Gas.- und Wasserbach. - 1955. - Bd.96, No. 18. - S. 1-604.

SladecekV. 1973. System of water quality from biological point of view. Ergebn.limnol. - 7:1-128.

Appendix 1

Systematic list of algae from Soldatskoye Lake

Seaweed	Plot 1	Plot 2	Habitat	Ga-frontality	Sa-prob-ness
CYANOPHYTA
ClassCyanophyceae
OrderSynechococcales
Family Merismopediaceae
Merismopediaglauca(Ehr.) Nag.
Merismopediamajor(Smith) Geitl.
OrderChroococcales
FamilyMicrocystaceae
Microcystisaeruginosa Kutz. emend. Elenk.
Microcystispulverea f. planctonica(G. W. Smith) Elenk.
FamilyAphanothecaceae
Aphanothecesaxicola Nag.
OrderOscillatoriales
FamilyOscillatoriaceae
Oscillatoria acutissima Kuff.
Oscillatoria amphibia Ag. f. amphibia
Oscillatoria chalybea(Mert.) Gom.
Oscillatorialimosa Ag.
Oscillatoriaplanctonica Wolosz. lot
Oscillatoria proboscidea gom. lot
Oscillatoriapseudogeminata G. Schmid
Ordernostocales
Family Aphanizomenonaceae
Aphanizomenonflos-aquae(L.) Ralfs
FamilyNostocaceae
Anabaena flos-aquae(Lyngb.) Breb.
EUGLENOPHYTA
ClassEuglenophyceae
Order Euglenales
FamilyEuglenaceae
Trachelomonashispida(Perty) Stein emend. defl.
Euglena granulata var. polymorpha(Dang.) Popova
Euglena hemichromata Skuja
Euglena viridis Err.
Phacus striatus France

continuation of appendix 1

CHRYSOPHYTA
ClassChrysophyceae
OrderChromulinales
FamilyDinobryonaceae
Dinobryon sociale Err.
ClassSynurophyceae
OrderSynurales
FamilySynuraceae
Mallomonas denticulate matv.
mallomonaslongiseta Lemm.
Mallomonas radiata Conrad
XANTHOPHYTA
ClassXanthophyceae
Ordermischococcales
FamilyBotrydiopsidaceae
Botrydiopsiseriensis Snow
FamilyPleurochloridaceae
Chloridellaneglecta(Pasch. et Geitl.)
Nephrodiellalunaris Pasch.
OrderTribonematales
FamilyTribonemataceae
Tribonemaaequale Pasch.
EUSTIGMATOPHYTA
ClassEustigmatophyceae
OrderEustigmatales
FamilyPseudocharaciopsidaceae
Ellipsoidion regular Pasch.
BACILLARIOPHYTA
Class Coscinodiscophyceae
OrderAulacoseirales
FamilyAulocosiraceae
Aulocosiraitalica(Kütz.) Simon.
Class Mediophyceae
OrderThalassiosirales
FamilyStephanodiscaceae
Cyclotellameneghiniana Kutz.
Cyclotella sp.
Handmanniacomta(Ehrenb.) Kociolek et Khursevich
Class Bacillariophyceae
OrderAraphales
FamilyFragilariaceae
Asterionellaformosa Hassall
Fragilaria capucina Desm.
Fragilariaintermedia Grun.
Ulnaria ulna(Nitzsch) Compère
Familydiatomaceae

continuation of appendix 1

Diatoma vulgaris Bory
FamilyTabellariaceae
Tabellaria fenestrata(Lyngb.)Kutz.
OrderRaphales
FamilyNaviculaceae
Caloneissilicula(Ehr.) Cl.
hippodontacapitata(Ehrenb.) Lange-Bert., Metzeltin et Witkowski
Naviculacryptocephala Kutz.
Navicula cuspidate f. primigena Dipp.
Naviculadigitoradiata(Greg.) A.S.
Naviculaelginensisvar.cuneata(M. Möller) Lange-Bertalot
Naviculamutica Kutz.
Naviculaoblonga Kutz.
Navicularadiosa Kutz.
Pinnularia gibba var. linearis Hust.
Pinnulariaviridis var. elliptica Meist.
Sellaphoraparapupula Lange Bert.
Stauroneisphoenicenteron Err.
FamilyAchnanthaceae
Achnanthesconspicua A. Mayer
Achnantheslanceolata var. elliptica Cl.
Achnantheslinearis(W. Sm.) Grun.
Cocconeisplacentula Err.
Planothidium lanceolatum(Bréb. ex Kütz.) Lange-Bert.
FamilyEunotiaceae
Eunotiafaba(Ehr.) Grun.
FamilyCymbellaceae
Amphora ovalis Kutz.
Cymbellacymbiformis(Ag. ?Kütz.) V.H.
Cymbellaneocistula Krammer
Cymbellatumida(Bréb.) V.H.
Familygomphonemataceae
Gomphonemaacuminatum var. coronatum(Ehr.) W. Sm.
gomphonemacapitatum Ehrenb.
gomphonemahelveticum Brun.
Gomphonemaparvulum(Kütz.) Grun.
Familyepithemiaceae
Epithemiaadnata(Kütz.) Breb.
FamilyNitzchiaceae
Nitzschiaacicularis W.Sm.
Nitzschiapalea(Kütz.) W. Sm.
NitzschiapaleaceaeGrun.

continuation of appendix 1

DINOPHYTA
ClassDinophyceae
Order Gonyaulacales
Family Ceratiaceae
Ceratium hirundinella T. furcoides(Lev.) Schroder
CHLOROPHYTA
ClassChlorophyceae
Order Chlamydomonadales
FamilyChlamydomonadaceae
Chlamydomonas sp.
OrderSphaeropleales
FamilySphaerocystidaceae
Sphaerocystisplanctonica(Korsch.)
FamilyHydrodictyaceae
Pediastrumboryanum(Turp.) Menegh.
Pediastrum duplex Meyen var. duplex
Pediastrum tetras(Ehr.) Ralfs
Tetraödroncaudatum(Corda) Hansg.
Tetraödron minimum(A. Br.) Hansg.
FamilySelenastraceae
Monoraphidiumcontortum(Thur.) Kom.-Legn.
Monoraphidiumirregulare(G. M. Smith) Kom.-Legn.
Monoraphidium komarkovae Newg.
Monoraphidium minute(Näg.) Kom.-Legn.
Messastrum gracile(Reinsch) T.S. Garcia
FamilyScenedesmaceae
Coelastrummicroporum Nag.
Crucigeniafenestrata(Schm.) Schm.
Scenedesmusacuminatus(Lagerh.) Chod.
Scenedesmusarcuatus(Lemm.) Lemm.
scenedesmusellipticus Corda
scene desmus falcatus Chod.
Scenedesmusobliquus(Turp.) Kutz.
Scenedesmus quadricauda(Turp.) Breb.
tetrastrumtriangulare(Chod.) Kom.
Class Oedogoniophyceae
OrderOedogoniales
FamilyOedogoniaceae
Oedogonium sp.

ending application 1

Class Trebouxiophyceae
Order Chlorellales
Family Chlorellaceae
Actinastrumhantzschii Lagerh.
Dictyosphaeriumpulchellum Wood.
FamilyOocystaceae
Oocystisborgei Snow
Oocystislacustris Chod.
STREPTOPHYTA
K lass Zygnematophyceae
OrderZygnematales
Family Mougeotiaceae
Mougeotia sp.
OrderDesmidiales
FamilyClosteriaceae
Closteriummoniliferum(Bory) Err.
FamilyDesmidiaceae
Staurastrumtetracerum Ralfs
Cosmarium botrytis Menegh.
Cosmariumformosulum hoff
Cosmarium sp.

Note: habitat: p - plankton, b - benthos, o - foulers; blasphemy: i - indifferent, hl - halophile, GB - halophobe, mzb - mesohalob.

Appendix 2

Characteristics of surface water quality in section No. 1 "SQUARE"

Characteristics of the quality of surface waters of site No. 2 "PANDA"

Microscopic algae are called, freely "floating" in the water column. In order to live in such a state, in the process of evolution, they developed a number of adaptations that contribute to a decrease in the relative density of cells (accumulation of inclusions, formation of gas bubbles) and an increase in their friction (processes of various shapes, outgrowths).

Freshwater phytoplankton is represented mainly by green, blue-green, diatoms, pyrophytes, golden and euglena algae.

The development of phytoplankton communities occurs with a certain frequency and depends on various factors. For example, the growth of microalgae biomass up to a certain point occurs in proportion to the amount of absorbed light. Green and blue-green algae reproduce most intensively with round-the-clock illumination, diatoms - with a shorter photoperiod. The beginning of phytoplankton vegetation in March-April is largely associated with an increase in water temperature. Diatoms are characterized by a low temperature optimum, while green and blue-green ones have a higher one. Therefore, in spring and autumn, at water temperatures from 4 to 15, diatoms dominate in reservoirs. An increase in water turbidity caused by mineral suspensions reduces the intensity of phytoplankton development, especially blue-green ones. Diatoms and protococcal algae are less sensitive to increased water turbidity. In water rich in nitrates, phosphates and silicates, mainly diatoms develop, while green and blue-green ones are less demanding on the content of these biogenic elements.

The species composition and abundance of phytoplankton are also influenced by the waste products of the algae themselves, therefore, as noted in the scientific literature, antagonistic relationships exist between some of them.

Of the variety of freshwater phytoplankton species, diatoms, green and blue-green algae are the most numerous and especially valuable in terms of food.

The cells of diatoms are equipped with a bivalve shell of silica. Their clusters are distinguished by a characteristic, yellowish-brown color. These microphytes play an important role in the nutrition of zooplankton, but due to the low content of organic matter, their nutritional value is not as significant as, for example, that of protococcal algae.

A distinctive feature of green algae is a typical green color. Their cells, containing a nucleus and a chromatophore, vary in shape, often equipped with spines and setae. Some have a red eye (stigma). Of the representatives of this department, protococcal algae are objects of mass cultivation (chlorella, scenedesmus, ankistrodesmus). Their cells are microscopic in size and are easily accessible to filtering aquatic organisms. The calorie content of the dry matter of these algae approaches 7 kcal/g. They have a lot of fat, carbohydrates, vitamins.

The cells of blue-green algae do not have chromatophores and nuclei and are uniformly colored blue-green. Sometimes their color can acquire purple, pink and other shades. Caloric content of dry matter reaches 5.4 kcal/g. The protein is complete in amino acid composition, however, due to its low solubility, it is inaccessible to fish.

Phytoplankton plays a key role in creating the natural food base of water bodies. Microphytes as primary producers, assimilating inorganic compounds, synthesize organic substances that are utilized by zooplankton (primary consumer) and fish (secondary consumer). The structure of zooplankton largely depends on the ratio of large and small forms in phytoplankton.

One of the factors limiting the development of microphytes is the content of soluble nitrogen (mainly ammonium) and phosphorus in water. For ponds, 2 mg N / l and 0.5 mg R / l are considered the optimal norm. The increase in phytoplankton biomass is facilitated by the fractional application of 1 c/ha of nitrogen-phosphorus and organic fertilizers per season.

The production potential of algae is quite large. Using the appropriate technology, up to 100 tons of dry matter of chlorella can be obtained from 1 ha of water surface.

The industrial cultivation of algae consists of a number of successive stages using various types of reactors (cultivators) on liquid media. The average yield of algae ranges from 2 to 18.5 g of dry matter per 1 m2 per day.

A measure of the productivity of phytoplankton is the rate of formation of organic matter in the process of photosynthesis.

Algae is the main source of primary production. Primary production - the amount of organic matter synthesized by eutrophic organisms per unit of time - is usually expressed in kcal / m2 per day.

Phytoplankton most accurately determines the trophic level of a reservoir. For example, oligotrophic and mesotrophic waters are characterized by a low ratio of phytoplankton abundance to its biomass, while hypertrophic waters are characterized by a high ratio. The biomass of phytoplankton in hypertrophic reservoirs is more than 400 mg/l, in eutrophic - 40.1-400 mg/l, in dystrophic - 0.5-1 mg/l.

Anthropogenic eutrophication - increased saturation of the reservoir with biogens - is one of the topical problems. It is possible to determine the degree of activity of biological processes in a reservoir, as well as the degree of its intoxication, with the help of phytoplankton organisms - indicators of saprobity. There are poly-, meso- and oligosaprobic water bodies.

An increase in eutrophication, or excessive accumulation of organic matter in a water body, is closely related to an increase in photosynthesis processes in phytoplankton. The mass development of algae leads to a deterioration in the quality of water, its "bloom".

Flowering is not a spontaneous phenomenon, it is prepared for quite a long time, sometimes two or more growing seasons. Prerequisites for a sharp increase in the number of phytoplankton are the presence of algae in the reservoir and their ability to reproduce under favorable conditions. The development of diatoms, for example, largely depends on the iron content in the water, nitrogen is the limiting factor for green algae, and manganese is the limiting factor for blue-green algae. Water bloom is considered weak if the phytoplankton biomass is in the range of 0.5-0.9 mg/l, moderate - 1-9.9 mg/l, intense - 10-99.9 mg/l, and with hyperblooming it exceeds 100 mg/l.

The methods of combating this phenomenon are not yet so perfect that the problem can be considered finally solved.

As algicides (chemical means of controlling flowering), urea derivatives - diuron and monouron - are used in doses of 0.1-2 mg / l. For temporary cleaning of individual sections of reservoirs

add aluminum sulfate. However, pesticides should be used with caution, as they are potentially dangerous not only for aquatic organisms, but also for humans.

In recent years, herbivorous fish have been widely used for this purpose. So, the silver carp consumes various types of protococcal, diatom algae. Blue-greens, which produce toxic metabolites during mass development, are less well absorbed by them, however, they can make up a significant proportion in the diet of adult individuals of this fish. Phytoplankton is also willingly eaten by tilapia, silver carp, bighead carp, and with a lack of basic food - whitefish, large-mouthed buffalo, paddlefish.

Macrophytes can also limit the intensity of water bloom to a certain extent. In addition to releasing substances harmful to phytoplankton into the water, they shade the surface of nearby areas, preventing photosynthesis.

When calculating the food base of a reservoir and the production of phytoplankton, it is necessary to determine the species composition, the number of cells and the biomass of algae according to the content in a certain volume of water (0.5 or 1 l).

The sample processing technique includes several stages (fixation, concentration, reduction to a given volume). There are many different fixatives, but formalin is most commonly used (2-4 ml of a 40% formalin solution per 100 ml of water). Algae cells stand for two weeks (if the sample volume is less than 1 liter, the settling period is shortened accordingly). Then the upper layer of settled water is carefully removed, leaving 30-80 ml for further work.

Phytoplankton cells are counted in small portions (0.05 or 0.1 ml), then their content in 1 liter is determined from the results obtained. If the number of cells of one or another type of algae exceeds 40% of their total number, then this species is considered dominant.

Determination of phytoplankton biomass is a laborious and lengthy process. In practice, to facilitate the calculation, it is conditionally assumed that the mass of 1 million cells of freshwater phytoplankton is approximately equal to 1 mg. There are other express methods. Given the great role of phytoplankton in the ecosystem of water bodies, in shaping their fish productivity, it is necessary that all fish farmers, from scientists to practitioners, master these methods.

Ambre hakarla resembles the smell that prevails in unkempt public toilets. And hakarl looks like cheese cut into cubes. But this is not even why a normal person would not want to eat hakarl. He is terrible in his origin. Hakarl is nothing more than the meat of a harmless Greenland giant shark rotten to the last muscle cell. In Iceland, this delicacy is included in the mandatory program of festivities at Christmas and New Year.

To eat rotten shark meat means to be persistent and strong, like a real Viking. After all, a true Viking has iron not only armor, but also a stomach.

Hakarl- the most specific dish from Viking cuisine. It is decomposed shark meat, which for a long time (6-8 weeks) lay in a sand and gravel mixture in a box, or even buried in the ground, to ensure the desired degree of decomposition.

Then the rotten pieces of meat are taken out of the ground and hung on hooks and left in the fresh air for another 2-4 months. In total, after six months of aging, the finished dish is decorated with steamed vegetables and served on the table for lovers of acute gastronomic sensations, most of whom gobble up this delicacy on both cheeks.

The taste of hakarl is something between sturgeon and squid, but the smell is unbearable, and the price is generally sky-high. A portion of such a treat costs no less 100 euro*.

The meaning of this ugly food is that the giant shark is a rather weighty food product, but when fresh, its meat is poisonous, contains a lot of uric acid and trimethylamine, which disappear when the product rots. Ready hakarl for shops is packaged like our squids for beer from a stall. Inexperienced eaters are advised to plug their nose at the first tasting, because the smell is much stronger than the taste. It looks like a very spicy whitefish or Jewish mackerel.

Hakarl comes in two varieties: from a rotten stomach and from rotten muscle tissue.

And here is what Alex P writes about this dish.

Here is what I read in one tourist guide about Icelandic cuisine:

Traditional Icelandic cuisine is based, not surprisingly, on fish and seafood. In traditional recipes, a lot of extremely peculiar, although not always edible for a stomach unaccustomed to such "frills", dishes that have come down to our days since the distant Middle Ages, have been preserved. The basis of the diet is fish of all kinds, especially cod, herring and salmon in all forms. The famous marinated salmon "gravlax", herring marinated with spices - "seald", a variety of fish sandwiches, fried or dried fish "hardfiskur", as well as fish "with a smell" "hakarl" or meat, which are necessarily offered to tourists as local exotic marine mammals.

Of the drinks, coffee is the most popular. Unlike most Scandinavian countries, beer is not so widespread (mostly due to its rather high price). The traditional Icelandic drink is brennyvin (a cross between vodka and whiskey).

Of course, being on this Sevrny Island, I decided to take a sip of exotics and ordered it, namely HAKARL, since SEAL-HERRING is banal, GRAVLAX, judging by the name, seemed to me to be something like a potion for diarrhea, well, on HARDFISKUR - it was simply impossible to pronounce, and indeed I didn’t really want an Icelandic ram.

After asking me several times if I really wanted to order hakarl, the waitress, with a sweet smile, lifted me up and led me to the end of the hall, where there were three empty tables in a small glass room.

A very prudent move, given that hakarl is DECEPTED SHARK MEAT. Yes, yes, they catch a shark, bury it in the sand for 3-4 months, then take it out, cook it and serve it to the table, pre-decorating it with vegetable stew. But before making me happy with such a dish, the waitress put on the table a decanter with 200 g of brennevin - local vodka, which the Icelanders themselves actually call the “black death” and do not drink under any circumstances, preferring Bourbon or banal Finnish vodka. Well, the black liquid was not black, but rather cloudy, beyond all measure. Which, in general, is not surprising, given that brennevin is driven from potatoes, and then flavored with cumin.

By that time, on the sad experience of my wallet, I was already convinced how high the prices for alcohol in Iceland were, so I suggested that the girl take the “death” back.

However, she politely but insistently said that she would leave the decanter on the table for my own good.

The foresight of the waitress became clear when she, smiling slyly, brought a plate of hakarl into the room. The sweetish-sugary, with hints of sourness, the smell of rotting roasted meat spread rapidly around the room. Until the very end, I did not believe that I would have the willpower to allow the hakarl to end up in the stomach.

However, to refuse treats when the eyes of everyone in the hall are fixed on you was not in Russian.

I cut off an impressive piece of the shark (or rather, what was left of it), I put it in my mouth. Never had a worse feeling in my life. It felt like a small chemical weapons factory had exploded in his mouth. Or I took a sip from the hygienic bag that is usually left on the backs of the seats on the plane. My hand involuntarily reached for the jug, I poured 50 grams of brennevin into the glass and knocked them into my mouth. The Black Death paid off. For the first few seconds, I thought for a long time and painfully which was more disgusting - hakarl or this vodka, because the latter left behind such an oily-sweet aftertaste that made me want to climb on the wall.

Indeed, after such an attack on my receptors, the taste that I had hitherto considered the most disgusting in my life - peppercorns, snacking on cake, seemed like real ambrosia. Having somehow mastered half of the hakarl (later the waitress said that this was a record for the last three years), I trudged to the exit from the glass prison with the face of a martyr.

At the door I ran into a still cheerful Japanese. The poor man, not knowing his fate himself, ordered another local delicacy - khritspungur, that is, lamb eggs marinated in sour milk and then pressed into a pie.

Greenland sharks are deadly killers, just like their white shark relatives. Examination of the stomach contents of dead sharks in Greenland revealed the remains of polar bears, and in one case, a whole reindeer, without antlers. Greenland sharks have been seen due to the carelessness of deer that came too close to the water's edge. Truly, they are crocodiles on the sea!

Reaches a length of up to 6.5 m, weighs about 1 ton. And the largest ones can reach almost 8 m and weigh up to 2.5 tons (i.e., comparable in size to a white shark).
Widespread in the north of the Atlantic Ocean, off the coast of Greenland and Iceland - the most "northern" and most cold-loving of all shark species.
The main food is fish, but sometimes the shark also hunts seals. On occasion, it also eats carrion: cases are described when the remains of polar bears and reindeer were found in the stomachs of polar sharks.

If for most representatives of the shark family the acceptable temperature of ocean water starts from +18 degrees, then the genus of sharks Somniosidae (straight-mouthed) has chosen really cold waters for itself and considers temperatures from -2 to +7 degrees quite tolerable. But how is this even possible - after all, sharks are extremely thermophilic, even those whose body is able to raise the temperature above the temperature of the surrounding water?

The most famous representative among the genus Somniosidae is the Atlantic (aka Greenland, aka small-headed) polar shark (Somniosus microcephalus). Its permanent habitat is the northwestern coast of Europe and the coast of Greenland, sometimes it can also be found off the northern coast of Russia. Outwardly, this fish is very similar to a torpedo, and its dorsal fins, which have become the hallmark of sharks, are small in size. It is these sharks that live longer than all others - about 100-200 years! The polar shark has become a long-liver due to the slow flow of all life processes in its body. It grows very slowly: an individual of such a shark was kept at a scientific institute, where it was studied for a long time - in 16 years the predator grew only by 8 cm.

The predator has the largest liver among all other sharks, it reaches 20% of its total weight - because of this organ, about 30 thousand individuals were annually caught on polar sharks for centuries, technical fat was rendered from the liver. It is not interesting for anglers-athletes to fish this fish - there is practically no struggle, after the predator is brought to the surface of the ocean, it rises into the boat just as if it were a log.

The polar shark does not swim away from the Arctic waters, in summer it stays 500-2000 meters deep, hibernates near the ocean surface - the water temperature is higher here. It feeds on any local living creatures, be it fish or pinnipeds, and attacks careless animals that find themselves in the water. For a long time, this shark was considered to feed on carrion: it is always slow, so this fish is often called sleepy - where can it keep up with prey! However, in 2008, the bones of a polar bear, eaten by fish "fresh", were found in the stomach of a captured polar shark. This find was the subject of a serious dispute among scientists - could a polar shark attack and kill a polar bear?

Theoretically, an adult predator is quite capable of drowning a bear, because her height and weight are twice as large - 6 meters and 1,000 kg, respectively. In the legends of the native inhabitants of Greenland - the Inuit Eskimos - there are stories of polar sharks attacking kayaks and caribou deer who dared to come close to ice openings.

The polar shark ranks sixth in size among other types of predators, but in terms of aggressiveness it is not far from the whale shark. The teeth of this predator are small - their length does not exceed 7 mm, the upper ones are needle-shaped, the lower ones are strongly bent. The mouth itself is small and not able to swing wide open.

And finally, how does the polar shark survive in the icy waters of the Arctic? And she succeeds because among the organs of her body there are no kidneys and urinary tracts - the removal of ammonia and urea occurs through the skin of a predator. Therefore, the muscle tissue of a shark contains large amounts of nitrogen trimethylamine, which is also a “natural antifreeze” (osmolite), which does not allow the body of a predator to freeze even at low temperatures.

It is known that trimethylamine, contained in fresh polar shark meat, causes an effect similar to intoxication in dogs that have eaten it - dogs cannot rise to their paws for some time. By the way, the Eskimos of Greenland call a drunk person a "sick shark." Most likely, it is because of the content of nitrogen in the body of trimethylamine that the polar shark is so slow.

The meat of these sharks can be eaten, provided that it is kept in the sun for several months, placed in a natural glacier for a period of about six months, or boiled in repeatedly replaced water. The national dish of Icelanders, hakarl, is prepared from shark meat.

Greenland Shark
scientific classification
International scientific name
somniosus microcephalus (Bloch & Schneider, 1801)
Synonyms
Squalus microcephalus(Bloch and Schneider, 1801) Squalus carcharias(Gunnerus, 1766) Squalus squatina(Pallas, 1814) Squalus norwegianus(Blainville, 1816) Squalus/Somniosus brevipinna(LeSueur, 1818) Squalus borealis(Scoresby, 1820) Scymnus gunneri(Thienemann, 1828) Scymnus glacialis(Faber, 1829) Scymnus micropterus(Valenciennes, 1832) Leiodon echinatum(Wood, 1846) Somniosus antarcticus(Whitley, 1939)
area
conservation status
Systematics on Wikispecies Images at Wikimedia Commons ITIS NCBI EOL

Teeth and jaws of the Greenland shark

Greenland Shark, or small-headed polar shark, or Atlantic polar shark(lat. Somniosus microcephalus) - a species of the genus of polar sharks of the family of somnios sharks of the katra-like order. It lives in the waters of the North Atlantic. The range extends further north than other sharks. Reproduces by ovoviviparity. These slow sharks feed on fish and carrion. They are an object of fishing. The maximum recorded length is 6.4 m.

Taxonomy [ | ]

The species was first scientifically described in 1801 as Squalus microcephalus. The specific name comes from the Greek words κεφαλή - "head" and μικρός - "little" . In 2004, it was established that the previously considered Greenland sharks living in the South Atlantic and the Southern Ocean are an independent species. Somniosus antarcticus .

area [ | ]

These are the northernmost and most cold-loving of all sharks. They are widespread in the north of the Atlantic Ocean - off the coast of Greenland, Iceland, Canada (Labrador, New Brunswick, Nunavut, Prince Edward Island), Denmark, Germany, Norway, Russia and the USA (Maine, Massachusetts, North Carolina). They are found on the continental and insular shelves and in the upper part of the continental slope from the water surface to a depth of 2200 m. In winter in the Arctic and North Atlantic, bowhead sharks are caught in the surf zone, in shallow bays and estuaries near the surface of the water. In summer, they stay at depths of 180 to 550 m. In the lower latitudes (Gulf of Maine and the North Sea), these sharks are found on the continental shelf, migrating to shallow waters in spring and autumn. The temperature in their habitats is 0.6–12 ° C. Marked in late spring under the ice near Baffin Island, the sharks preferred to stay at depth in the morning, and by noon they would rise to shallow water and spend the night there.

Description [ | ]

The maximum recorded length is 6.4 m and the mass is about 1 ton. The largest individuals can reach 7.3 m and weigh up to 1.5 tons. However, on average, the length of these sharks ranges from 2.44-4.8 m, and the weight does not exceed 400 kg.

The head is elongated, the distance from the tip of the snout to the pectoral fins of a shark 2.99 m long was 23% of the total size. The snout is short and rounded. The massive body has the shape of a cylinder. Spines at the base of both dorsal fins are absent. The dorsal fins are small and uniform in size. The base of the first dorsal fin is located closer to the ventral than to the pectoral fins. The distance between the dorsal fins exceeds the distance between the tip of the snout and the second gill slit. There are no lateral carinae on the caudal peduncle. The tail stem is short. The distance between the bases of the second dorsal and caudal fins is less than twice the length of the base of the second dorsal fin.

Gill slits are very small for a shark of this size. The color ranges from pale gray-cream to black-brown. As a rule, it is uniform, but there may be white spots or dark stripes on the back. The upper and lower teeth are very different: the lower ones are wide, with a large flattened root and apices strongly beveled towards the corners of the mouth; upper narrow and symmetrical.

Lifespan[ | ]

The analysis of scientists showed that the average life expectancy of the Greenland sharks reaches at least 272 years, which makes them long-lived champions among vertebrates. The researchers estimated the age of the largest shark (502 centimeters long) at 392 ± 120 years, and individuals whose size was less than 300 centimeters turned out to be younger than a hundred years.

Biology [ | ]

Greenland sharks are apex predators. The basis of their diet is fish such as small sharks, rays, eels, herring, capelin, char, cod, sea bass, slingshots, catfish, lumpfish and flounder. However, they sometimes also prey on seals. Tooth marks on the bodies of dead seals off the coast of Sable Island and Nova Scotia suggest that arctic harp sharks are their main winter predators. On occasion, carrion is also eaten: cases are described when the remains of polar bears and reindeer were found in the stomachs of polar sharks. They are known to be attracted to the water by the smell of rotting meat. They often congregate in large numbers around fishing boats.

Greenland sharks are one of the slowest sharks. Their average speed is 1.6 km/h and their maximum speed is 2.7 km/h, which is half the maximum speed of seals. Therefore, scientists have long wondered how these clumsy fish are able to hunt such fast prey. There is evidence that the polar bowhead sharks lie in wait for sleeping seals.

The Greenland polar shark is recognized by scientists as the longest-lived species of vertebrates (previously the bowhead whale was considered such). Biologists believe that the animal can live for about 500 years. In 2010-2013, scientists measured the length of the body and radiocarbon analysis of the lens of the eye of 28 Greenland sharks. As a result, it turned out that the longest of them (more than five meters) was born 272-512 years ago (the Greenland shark, according to scientists, grows on average one centimeter every year). Such a high life expectancy of sharks is explained by low metabolism - for example, females reach puberty at 150 years old.

reproduction [ | ]

Sexual maturity in Greenland sharks occurs at the age of about 150 years. Females mature at a body length of 450 cm, and males at a body length of 300 cm. Greenland sharks are ovoviviparous. The breeding season is in the summer. The female carries about 500 soft ellipsoidal eggs. The eggs are about 8 cm long and lack a horn capsule. There are about 10 newborns in the litter, 90 cm long.

Human interaction[ | ]

From the middle of the 19th century until the 1960s, fishermen in Greenland and Iceland harvested up to 50,000 bowhead sharks per year. In some countries, fishing continues to this day. Sharks are harvested for liver fat. Raw meat is poisonous due to the high content of urea and trimethylamine oxide; it causes poisoning not only in humans, but also in dogs. This poisoning is accompanied by convulsions and can lead to death. Through prolonged processing, the traditional Icelandic dish hakarl is prepared from the meat of polar sharks. Sometimes these sharks are taken as bycatch when halibut and shrimp are caught. The International Union for Conservation of Nature has given this species a Near Threatened conservation status.

Eskimo Legends of Greenland Sharks[ | ]

The tissues of the Greenland shark are high in urea, which was the reason for creating a legend about the origin of sharks. According to legend, a woman washed her hair with urine and stretched it out to dry on a line next to a rag. The wind picked up the rag and threw it into the sea. This is how the skalugsuak appeared - the Greenland polar shark.

When a young Eskimo girl told her father that she wanted to marry a bird, he killed her fiancé and threw her daughter over the side of the kayak into the sea, but she clung to the side with her hands. Then he cut off her fingers. The girl, whose name was Sedna, went into the depths, where she became a goddess, and each of her cut off fingers turned into some kind of sea animal, including the Greenland polar shark. The shark was instructed to avenge Sedna and one day, when the girl's father was fishing, she overturned the kayak and ate him. When an Eskimo dies like this, the natives say that Sedna sent the shark.

Notes [ | ]

1. Reshetnikov Yu. S. , Russ T. S. , Five-language dictionary of animal names. Fish. Latin, Russian, English, German, French. / under the general editorship of acad. V. E. Sokolova. - M.: Rus. yaz., 1989. - S. 36. - 12,500 copies. - ISBN 5-200-00237-0.
2. Bloch, M.E. & Schneider, J.G.(1801) M.E. Blochii Systema Ichthyologiae iconibus ex illustratum. Post obitum auctoris opus inchoatum absolvit, correxit, interpolavit. J.G. Schneider, Saxo: 584 p., 110 pl.
3. Large Ancient Greek Dictionary (indefinite) (unavailable link). Retrieved October 1, 2013. Archived from the original on February 12, 2013.
4. Kyne P.M., Sherrill-Mix S.A. & Burgess G.H. somniosus microcephalus (indefinite) . IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.(2006). Retrieved April 4, 2013. Archived from the original on April 10, 2013.
5. Herdendorf, C.E. and Berra, T.M. 1995. A Greenland shark from the wreck of the SS Central America at 2,200 meters // Transactions of the American Fisheries Society. - 1995. - Vol. 124, No. 6. - P. 950–953. - DOI:10.1577/1548-8659(1995)124<0950:AGSFTW>2.3.CO;2.