Algae message. Discussion: Where do algae live? Algae the most important information

Algae play a huge role in nature and human life. Firstly, they are active participants in the cycle of substances in natural environment(the simplest unicellular species).

Secondly, irreplaceable natural sources vital microelements (vitamins, minerals). They are also used in medicine, cosmetology, food industry and other industries.

Their breeding does not require difficult conditions, and they grow at a depth of several meters to 40-100.

The life cycles of algae have several stages, depending on the complexity of the structure. The same goes for the ability to reproduce.

What species, groups, names exist, in which sea is algae farming carried out, photographs and other interesting information - this is discussed in this article.

Description

Algae, unlike plants, grow in aquatic environment(although there are also plants that live in similar environments). There are also soil and rocky representatives.

Life in water has relative stability: the presence of liquid, constant light and temperature, as well as a number of other advantages. And as a result, each cell that is an integral part of the algae is identical to the others. Therefore, these aquatic “plants” (conventional name) practically do not have any pronounced features in their appearance (except for some, more “highly developed”).

Mostly algae live in coastal areas of the seas - rocky shores, less often - sand or pebbles. The maximum height at which these aquatic “plants” can live is surfaces slightly wetted by sea drops (an example of almost planktonic ones is sargassum), the minimum is several meters deep (an example of deep-sea ones is red ones).

There are algae that live in tidal pools of rocky surfaces. But such varieties of marine inhabitants must withstand the lack of moisture, variable temperature and degree of salinity.

Algae are used in medicine, agronomy (soil fertilization), human food production, industry, and so on.

Body

Algae in their structure consist of one or many cells.

This one system, which is cells of the same type layered on top of each other. There may be dissection here, but the presence of vegetative organs and other parts of the body of this aquatic “plant” is excluded.

The appearance of algae is somewhat similar to terrestrial non-woody plants.

The body of the algae consists of:

thallus (thallus);
trunk (may or may not be present);
grips (for fastening to surfaces - rocks, bottom, other similar plants);
trailers.

Types of algae

There are a huge number - from single-celled to complex (resembling higher plants). They also come in different sizes - huge (up to 60 meters) and microscopic.

In total there are about 30,000 species of algae. They are divided into the following departments:

blue-eyed;
prochlorophytes;
cryptophytes;
red;
golden;
dinophytes;
diatoms;
brown;
green;
yellow-green;
euglena;
characeae.

The division is also carried out into the following groups of algae (according to the degree of complexity of the structure):

amoeba-like (examples: golden, yellow-green, pyrophytic);
with a monad structure - unicellular, move thanks to flagella, some have an intracellular primitive structure (examples of algae: green, yellow-green, golden, euglenic, pyrophytic);
with a coccoid structure - unicellular, without any organelles, form colonies;
with a palmelloid structure - a combination of several coccoids into a common mass, have big sizes, attach to the substrate;
with a filamentous structure - these are already transitional from unicellular to multicellular algae, outwardly similar to a branched thread;
with a lamellar structure - multicellular, which are formed from filaments that are combined with subsequent layering in different planes, forming plates (there are single-layer and multilayer);
with a siphonal structure - consist of a multinucleated giant cell, similar to branching threads and balls.

Titles and photos

Types of algae in the images:

Unicellular - consist of a cell, a nucleus and flagella (trailers). They can only be seen under a microscope.
Multicellular - kelp, which is known to man under the name “sea kale”.

Life cycle

In algae, development occurs according to a cycle or cyclomorphosis (this depends on the complexity of the structure of the aquatic “plant” and, accordingly, the method of reproduction).

Algae that do not have (or have in exceptional cases) the ability to reproduce sexually, due to development, change only the structure of the body. The concept of cyclomorphosis is applicable to such aquatic plants (examples of algae: hyella, blue-green, glenodinium).

Cyclomorphosis is characterized by high degree plasticity. The passage of stages depends largely on the environmental conditions of the environment. The manifestation of strictly all stages of cyclomorphosis does not always occur; some may even “fall out” of the general sequence.

Strict passage of all stages of the life cycle of algae (in the diagram above) occurs exclusively in those aquatic plants that occupy the upper stage of evolution (for example, brown ones).

Brown algae

These are multicellular aquatic “plants” that belong to the ochrophytes. The name comes from the color of the pigment substance contained in the chromatophores: green (which means the ability to photosynthesize), as well as yellow, orange and brown, which, when mixed, form a brownish tint.

They grow at depths of 6-15 and 40-100 meters in all marine waters globe.

Brown algae, compared to others, have a more complex structure: they have similar organs and various tissues in their body.

The surfaces of cells consist of a cellulose-gelatinous substance, which contains proteins, salts, and carbohydrates.

Each algal cell contains a nucleus, chloroplasts (in the form of disks), and a nutrient (polysaccharide).

Life cycle of brown algae

This group of aquatic “plants” has several types of growth: through the apex or by cell division.

Brown sexually and asexually. This means that some of them are recreated by fragmenting their body (thallus), forming so-called buds or through spores.

Zoospores have flagella and are motile. They also produce a gametophyte, through which sex cells are formed.

There are gametes obtained from the sporophyte and having eggs and sperm in the haploid stage.

And these aquatic “plants” emit pheromones, which promotes the “meeting” of male and female reproductive cells.

Thanks to all these processes, alternations of generations occur in brown algae.

Uses of brown algae

The most popular representative of this group is kelp, or “sea kale”. This algae grows along the shores, forming thickets. Laminaria contains a fairly large number of macro- and microelements vital for humans, the most important of which is iodine. Besides food, it is also used as soil fertilizer.

Brown algae is also used in medicine and in the manufacture of cosmetics.

Characteristics of unicellular algae

These varieties of aquatic “plants” are an independent system that is capable of growing and developing, as well as self-reproducing.

In size, these are microscopic algae (not visible to the naked eye), which in essence can be considered a “factory” for the extraction of useful raw materials: through the process of absorption from environment carbon dioxide and mineral salts, with their subsequent processing into proteins, fats and carbohydrates.

The life support products of unicellular algae are oxygen and carbon dioxide, which allows them to be active participants in the natural cycle.

Algae farming

In which sea is the most widespread cultivation of these marine “plants”? According to reference data, the maximum amount of algae is found in the White Sea. On the shore there is the village of Rebolda (in the area of Solovetsky Island), where they extract and store these water gifts.

There are 2 types of brown algae: the famous kelp and fucus (“sea grapes”).

In addition to being eaten, these “plants” are used to produce biologically active substances that are used in medicine. This is very useful drugs, since they contain environmentally friendly algae from the White Sea.

Such products lower blood cholesterol levels, improve the functioning of the thyroid gland, prevent the development of age-related diseases associated with blood vessels, and so on. “Sea grapes” are good to use for problems with varicose veins, cellulite, and the appearance of wrinkles.

Role in nature and human life

Algae are studied by a specialized science - algology (or phycology), which is a branch of botany.

Collecting information about these aquatic “plants” is necessary to solve such problems. important tasks: general biological problems; economic tasks and so on.

This science is developing in the following areas:

Use of algae in medicine.
Use in solving environmental issues.
Accumulation of information about algae in order to solve other problems.

These marine “plants” currently both live in natural reservoirs and are grown on special farms.

Seaweed, as food and more, is popular in many countries of the world: Indonesia (annual harvest 3-10 million tons), Philippines, Japan, China, Korea, Thailand, Taiwan, Cambodia, Vietnam, Peru, Chile, England, USA ( California) and others.
In the Philippines has now been opened New Product nutrition - seaweed noodles (contains calcium, magnesium, iodine).
The beloved Japanese nori seaweed, which is dried in leaves and looks like square thin plates, is used in making sushi, rolls, and soups.
In Wales, a popular lawer bread is made from oats and red laver seaweed.
Edible gelatin, additives, and alginates (dressing materials used in dentistry) are made from algae.
Agar produced from these aquatic “plants” is used in the preparation of confectionery, desserts, drinks, and meat dishes.
Algae concentrates are used in preparations for weight loss. Also included in toothpastes, cosmetics and paints.
Alginates are used in industry (paper coatings, paints, gels, glue, textile printing).

Summary

The types of algae discussed in the article (with photos), names, groups, cultivation and application only indicate that these are truly important components not only of nature, but also of many aspects of human life (health, beauty, industrial raw materials, food, and so on) . Without them, there would be no notorious “seaweed”, marmalade, sushi and other such familiar dishes.

At first glance, it may seem that these simple natural “plants” are primitive (in their structure, life cycle) algae, but in reality everything is different. It turns out that even these aquatic “plants” have sexual reproduction, emit pheromones and support the circulation of substances in nature.

The concept of “algae” is scientifically vague. The word “algae” literally means only that these are plants that live in water, but not all plants in water bodies can be scientifically called algae, such plants as reeds, reeds, cattails, water lilies, egg capsules, small green plates of duckweed and etc., are seed (or flowering) plants. The scientific term “algae” does not apply to these plants; they are called aquatic plants

The concept of “algae” is not systematic, but biological. Seaweed ( Algae) is a collective group of organisms, the main part of which, according to modern ideas, belongs to the kingdom of Plants ( Plantae), in which it makes up two sub-kingdoms: purple algae, or red algae - Rhodobionta and real algae - Phycobionta(the third subkingdom of the plant kingdom includes higher (embryonic or leafy) plants - Embryobionta). The remaining organisms classified as algae are now no longer considered plants: blue-green and prochlorophyte algae are often considered an independent group or classified as bacteria, and euglena algae are sometimes classified as a subkingdom of animals - protozoa. Various groups of algae arose in different time and, apparently, from different ancestors, but as a result of evolution in similar living conditions they acquired many similar features.

Organisms classified as algae have a number of common characteristics. In morphological terms, the most significant feature for algae is the absence of multicellular organs - roots, leaves, stems, typical of higher plants. Such a body of algae that is not divided into organs is called a thallus, or thallus. .

Algae have a simpler (compared to higher plants) anatomical structure– there is no conducting (vascular) system, therefore algae classified as plants are avascular plants. Algae never form flowers or seeds, but reproduce vegetatively or by spores.

Algae cells contain chlorophyll, thanks to which they are able to assimilate carbon dioxide in the light (i.e., feed through photosynthesis); they are primarily inhabitants of the aquatic environment, but many have adapted to life in the soil and on its surface, on rocks, on tree trunks and in other biotopes.

Organisms classified as algae are extremely diverse. Algae belong to both prokaryotes (prenuclear organisms) and eukaryotes (truly nuclear organisms). The body of algae can be of all four degrees of complexity generally known for organisms: unicellular, colonial, multicellular and noncellular; their sizes vary within very wide limits: the smallest are comparable to bacterial cells(do not exceed 1 micron in diameter), and the largest sea brown algae reach 30–45 m in length.

Algae are divided into a large number of divisions and classes and their division into systematic groups (taxa) is made according to biochemical characteristics (set of pigments, composition of the cell membrane, type of reserve substances), as well as submicroscopic structure. However, modern systematics of algae is characterized by many different systems. Even at the highest taxonomic levels (superkingdoms, subkingdoms, divisions and classes), taxonomists cannot come to a consensus.

According to one of modern systems, algae are divided into 12 divisions: blue-green, prochlorophyte, red, golden, diatom, cryptophyte, dinophyte, brown, yellow-green, euglenophyte, green, charophyte. In total, about 30 thousand species of algae are known.

The science of algae is called algology or phycology, it is considered as an independent branch of botany. Algae are objects for solving issues related to other sciences (biochemistry, biophysics, genetics, etc.). Algology data is taken into account when developing general biological problems and economic problems. The development of applied algology proceeds in three main directions: 1) the use of algae in medicine and various areas farms; 2) to resolve environmental issues; 3) accumulation of data on algae to solve problems in other industries.

The structure of algae.

The main structural unit of the body of algae, represented by unicellular and multicellular forms, is the cell. Exist Various types algae cells, they are divided according to shape (spherical, cylindrical, etc.), functions (sexual, vegetative, capable and incapable of photosynthesis, etc.), location, etc. But the most important today is the classification of cells according to their characteristics their fine structure, detectable using an electron microscope. From this point of view, a distinction is made between cells containing typical nuclei (i.e., nuclei surrounded by nuclear membranes, membranes) and cells that do not have typical nuclei. The first case is the eukaryotic structure of the cell, the second is the prokaryotic structure . Blue-green and prochlorophyte algae have a prokaryotic cell structure, while representatives of all other divisions of algae have a eukaryotic cell structure.

The vegetative body of algae (thallus) is characterized by morphological diversity; algae can be unicellular, colonial, multicellular and noncellular. Their sizes within each of these forms vary widely - from microscopic to very large.

The peculiarity of unicellular forms of algae is determined by the fact that their body consists of one cell, therefore its structure and physiology combine cellular and organismal features. This is an autonomous system capable of growing and self-reproducing; a small, unicellular algae invisible to the naked eye is a kind of factory that extracts raw materials (absorbing solutions of mineral salts and carbon dioxide from the environment), processes and produces such valuable compounds as proteins, carbohydrates and fats. In addition, the important products of its vital activity are oxygen and carbon dioxide and, thus, it actively participates in the cycle of substances in nature. Single-celled algae sometimes form temporary or permanent aggregations (colonies).

Multicellular forms arose after the cell went through a long and complex path of development as an independent organism. The transition from a unicellular to a multicellular state was accompanied by a loss of individuality and associated changes in the structure and functions of the cell. Within the thalli of multicellular algae, qualitatively different relationships develop than between the cells of unicellular algae. With the emergence of multicellularity, differentiation and specialization of cells in the thallus appeared. From an evolutionary point of view, this should be considered as the first step towards the formation of tissues and organs.

Siphon algae constitute a unique group: their thalli are not divided into cells, however, they also have unicellular stages in their development cycle.

The color of algae is diverse (green, pink, red, orange, almost black, purple, blue, etc.), due to the fact that some algae contain only chlorophyll, while others contain a number of pigments that color them in different colors.

Algae (more precisely, blue-green algae, or cyanobacteria) were the first organisms on Earth that, through the process of evolution, acquired the ability to photosynthesize, the process of producing organic substances under the influence of light. Photosynthesis uses carbon dioxide (CO2) as a source of carbon, water (H2O) as a source of hydrogen, and as a result free oxygen is released.

Power type with the help of photosynthesis, in which the body, using the energy of photosynthesis, synthesizes all the necessary organic substances from inorganic ones, has become one of the main ways of feeding algae and other green plants. However, many algae can, under certain conditions, quite easily switch from the photosynthetic method of nutrition to the assimilation of various organic compounds, while the body uses ready-made organic substances for nutrition, or combines this method of nutrition with photosynthesis.

In addition to using organic compounds as a carbon source, algae can switch from assimilating inorganic nitrate nitrogen to assimilating nitrogen from organic compounds; some blue-green algae can do without bound forms of nitrogen altogether and fix free nitrogen from the atmosphere as nitrogen-fixing organisms.

The variety of feeding methods of algae allows them to have wide habitats and occupy a variety of ecological niches.

Reproduction of their own kind in algae occurs through vegetative, asexual and sexual reproduction.

Origin of algae.

The question of the origin and evolution of algae is very complex due to the diversity of these plants, especially their submicroscopic structure and biochemical characteristics; in addition, most algae have not been preserved in the fossil state and there are no connecting links between modern plant divisions in the form of organisms of intermediate structure.

The easiest way to solve the question is about the origin of prokaryotic (prenuclear) algae - blue-green algae, which have many common characteristics with photosynthetic bacteria. Most likely, blue-green algae originated from organisms close to purple bacteria and containing chlorophyll ().

There is currently no consensus on the origin of eukaryotic (nuclear) algae. There are two groups of theories, emanating from either a symbiotic or a non-symbiotic origin, however, each of these theories has its own objections.

According to the theory of symbiogenesis, chloroplasts and mitochondria of cells of eukaryotic organisms were once independent organisms: chloroplasts were prokaryotic algae, mitochondria were aerobic bacteria (). As a result of the capture of aerobic bacteria and prokaryotic algae by amoeboid eukaryotic organisms, the ancestors of modern groups of eukaryotic algae arose. Some researchers also attribute a symbiotic origin to chromosomes and flagella.

According to the theory of non-symbiotic origin, eukaryotic algae arose from an ancestor common with blue-green algae, which had chlorophyll and photosynthesis with the release of oxygen; in this case, modern photosynthetic prokaryotes (blue-green algae) are a side, dead-end branch of plant evolution.

The main factors influencing the development of algae.

The main factors influencing the development of algae are light, temperature, the presence of water, carbon sources, minerals and organic substances. Algae are widespread throughout the globe and can be found in water, in and on soil, on tree bark, on the walls of wooden and stone buildings, and even in inhospitable places such as deserts and glaciers.

Factors influencing the development of algae are divided into abiotic, not related to the activity of living organisms, and biotic, caused by this activity. Many factors, especially abiotic ones, are limiting, i.e. they are able to limit the development of algae. The life of all organisms, including algae, depends on the content of necessary substances in the habitat, the importance of physical factors, as well as the range of resistance of the organisms themselves to changes in environmental conditions. The level at which a specific factor can act as a limiting factor is different for different types of algae. In aquatic ecosystems, limiting factors include temperature, transparency, the presence of a current, the concentration of oxygen, carbon dioxide, salts and nutrients. In terrestrial habitats, the main limiting factors are climatic: temperature, humidity, light, etc., as well as the composition and structure of the substrate. These two groups of factors, together with population interactions, determine the nature of terrestrial communities and ecosystems.

For most algae, water is a permanent habitat, but many of their species can live outside of water. Among plants that live on land, based on their resistance to desiccation, they are divided into poikilohydric, which are unable to maintain a constant water content in tissues, and homohydric, which are capable of maintaining constant hydration of tissues. In poikilohydric algae (blue-green and some green algae), when cells dry out, they shrink without irreversible changes in ultrastructure and, therefore, do not lose viability; when moistened, their normal metabolism is restored. The minimum humidity at which normal activity of such plants is possible varies. Cells of homohydric algae die when they dry out, so such plants, as a rule, live in conditions of constant excess moisture. Homoyhydric algae include, for example, some types of green and yellow-green algae.

Salinity and mineral composition of water are the most important limiting factors affecting the distribution of algae.

Algae live in water bodies of varying salinity: from fresh water bodies, the mineralization of which usually does not exceed 0.5 g/l, to extremely saline (hyperhaline) water bodies, the salt concentration of which ranges from 40 to 347 g/l. Despite the fact that in general algae are characterized by such a wide range of salt tolerance, specific species for the most part stenohaline, i.e. are able to live only at a certain salinity level. Euryhaline There are relatively few species of algae that can exist at different salinities.

Water acidity is also a limiting factor. The tolerance of different algae taxa to changes in acidity (pH) varies as much as it does to changes in salinity. Some types of algae live only in alkaline waters, at high pH values, others live in acidic waters, at low pH.

The presence in the environment of macro- and microelements, which are necessary components of the algae body, is crucial for the intensity of their development.

Elements and their compounds, related to macroelements, are required by organisms in relatively large quantities. The most important are nitrogen and phosphorus; potassium, calcium, sulfur and magnesium are almost as necessary.

Microelements are needed by plants in extremely small quantities, but they have great value for their life, since they are part of many vital enzymes. Microelements often act as limiting factors. These include 10 elements: iron, manganese, zinc, copper, boron, silicon, molybdenum, chlorine, vanadium and cobalt.

Algae of different departments have unequal needs for macro- and microelements. For example, for the normal development of diatoms, a fairly significant amount of silicon is required, which is used to build their shell. With a lack of silicon, the shells of diatoms become thinner.

In almost all freshwater and marine ecosystems The limiting factor is the concentration of nitrates and phosphates in water. In fresh water bodies with a low carbonate content, the concentrations of calcium salts and some others can be considered limiting factors.

Algae need light as a source of energy for photochemical reactions and as a regulator of development. Its excess, as well as its deficiency, can cause serious disturbances in the development of algae. Therefore, light is also a limiting factor when there is too much or too little illumination.

The distribution of algae in the water column is largely determined by the availability of light necessary for normal photosynthesis. The layer of water above the habitat of photoautotrophic organisms is called euphotic zone. In the sea, the boundary of the euphotic zone is usually located at a depth of 60 m, occasionally dropping to a depth of 120 m, and in clear ocean waters - to approximately 140 m. In lake, much less transparent waters, the boundary of this zone usually runs at a depth of 10–15 m, and in the most transparent glacial and karst lakes - at a depth of 20–30 m.

Optimal light levels for different types of algae vary widely. In relation to light, heliophilic and heliophobic algae are distinguished. Heliophilus(light-loving) algae require a significant amount of light for normal functioning. These include most blue-green algae and a significant amount of green algae, which grow abundantly in summer time in surface layers of water. Heliophobic(bright light avoidant) algae are adapted to low light conditions. For example, most diatoms avoid the brightly lit surface layer of water and in low-transparent lake waters they develop intensively at a depth of 2–3 m, and in clear sea waters – at a depth of 10–15 m.

In algae of different divisions, depending on the composition of special light-sensitive pigments, maximum photosynthetic activity is observed at different light wavelengths. Under terrestrial conditions, the frequency characteristics of light are quite constant, so the intensity of photosynthesis is also constant. When passing through water, light from the red and blue regions of the spectrum is absorbed, and greenish light, weakly perceived by chlorophyll, penetrates into the depths. Therefore, mainly red and brown algae survive there, having additional photosynthetic pigments that can use the energy of green light. This makes clear the enormous influence of light on the vertical distribution of algae in the seas and oceans: in the near-surface layers, as a rule, green algae predominate, deeper - brown, and in the deepest areas - red. However, this pattern is not absolute. Many algae are able to exist in conditions of extremely low illumination, which is not typical for them, and sometimes in complete darkness. At the same time, they may experience certain changes in the pigment composition or in the way they feed. Thus, representatives of many divisions of algae are capable of switching to feeding in the absence of light and an excess of organic substances. organic compounds dead bodies or animal excrement.

For algae living in aquatic biotopes, water movement plays a huge role. The movement of water masses provides an influx nutrients and removal of algae waste products. In any continental and marine reservoirs there is a relative movement of water masses, therefore almost all algae of reservoirs are inhabitants flowing waters. The only exceptions are algae that develop in particularly extreme conditions (in the voids of rocks, thick ice, etc.).

Algae have very wide temperature tolerance ranges. Some of their species are able to exist both in hot springs, the temperature of which is close to the boiling point of water, and on the surface of ice and snow, where temperatures fluctuate around 0 ° C.

In relation to temperature, algae are distinguished: eurythermal species, existing in a wide temperature range (for example, green algae from the order Oedogoniales, sterile threads of which can be found in shallow water bodies from early spring to late autumn), And stenothermic, adapted to very narrow, sometimes extreme temperature zones. Stenothermals include, for example, cryophilic(cold-loving) algae that grow only at temperatures close to 0 ° C and thermophilic(heat-loving) algae that cannot exist at temperatures below 30° C.

Temperature determines geographical distribution algae growing in an aquatic environment. In general, with the exception of widespread eurythermal species, the distribution of algae exhibits geographic zoning: specific taxa of marine planktonic and benthic algae are confined to certain geographic zones. Thus, large brown algae (Macrocystis) dominate the northern seas. As you move south, more and more prominent role red algae begin to play, and brown algae fade into the background. The phytoplankton of tropical waters is extremely rich in dinophyte and golden algae. In the northern seas, phytoplankton is dominated by diatoms. Temperature also affects the vertical distribution of planktonic and benthic algae. Here it acts mainly indirectly, accelerating or slowing down the growth rate of individual species, which leads to their displacement by other species that grow more intensively in a given temperature regime.

Algae, being part of ecosystems, are connected with their other components by multiple connections. The direct and indirect impacts that algae undergo due to the vital activity of other organisms are classified as biotic factors.

In most cases, algae act as producers of organic matter in an ecosystem. Therefore, the most important factor limiting the development of algae in a particular ecosystem is the presence of animals that subsist by eating algae.

Different types of algae are able to influence each other by releasing chemicals into the external environment (this interaction between plants is called allelopathy). Sometimes this is an obstacle to their coexistence.

Some types of algae may develop competitive relations with each other for habitats.

Humans have a significant impact on natural ecosystems, which makes the anthropogenic factor very significant for the development of algae. By laying canals and constructing reservoirs, people create new habitats for aquatic organisms, often fundamentally different from reservoirs of this region according to hydrological and thermal regime. Wastewater discharges often lead to depletion of the species composition and death of algae or to the massive development of certain species. The first occurs when toxic waters are discharged, the second occurs when the reservoir is enriched with nutrients (especially nitrogen and phosphorus compounds). The consequence of excessive discharge of nutrients into a reservoir can be its eutrophication, which leads to the rapid development of algae (“water blooms”), oxygen deficiency, and the death of fish and other aquatic animals. Algae, especially aerophytic and soil algae, can also be affected by atmospheric emissions of toxic industrial waste. Very often, the consequences of human intervention in the life of ecosystems are irreversible.

Ecological groups of algae.

Algae are distributed throughout the globe and are found in various aquatic, terrestrial and soil biotopes. There are various known environmental groups these organisms: 1) planktonic algae; 2) neuston algae; 3) benthic algae; 4) terrestrial algae; 5) soil algae; 6) algae from hot springs; 7) algae of snow and ice; 8) algae of salt water bodies; 9) algae existing in a calcareous substrate.

Algae of aquatic habitats.

Planktonic algae.

Plankton is a collection of organisms that inhabit the water column of continental and marine reservoirs and are not able to resist transport by currents (i.e., as if floating in the water). Plankton includes phyto-, bacterio- and zooplankton.

Phytoplankton is a collection of small, mostly microscopic plants free-floating in the water column, the bulk of which are algae. Phytoplankton inhabit only the euphotic zone of water bodies (the surface layer of water with sufficient illumination for photosynthesis).

Planktonic algae live in a wide variety of bodies of water - from a small puddle to the ocean. They are absent only in reservoirs with a sharply anomalous regime, including thermal (at a water temperature above +80 ° C and dead (contaminated with hydrogen sulfide) reservoirs, in clean periglacial waters that do not contain mineral nutrients, as well as in cave lakes. Total The biomass of phytoplankton is small compared to the biomass of zooplankton (1.5 and more than 20 billion tons, respectively), but due to the rapid reproduction of its production in the World Ocean is about 550 billion tons per year, which is almost 10 times more than the total production of all animal population of the ocean.

Phytoplankton is the main producer of organic matter in water bodies, due to which aquatic heterotrophic animals and some bacteria exist. Phytoplankton is the starting point for most food chains in a reservoir: small planktonic animals feed on it, which feed on larger ones. Therefore, in areas of greatest phytoplankton development, zooplankton and nekton are abundant.

The composition and ecology of individual representatives of algal phytoplankton in different water bodies are extremely diverse. The total number of phytoplankton species in all marine and inland waters reaches 3000.

In inland water bodies there is a much greater diversity of ecological conditions compared to sea water bodies, which determines a significantly greater diversity of species composition and ecological complexes of freshwater phytoplankton compared to sea water. One of the significant features of freshwater phytoplankton is the abundance of temporary planktonic algae in it. A number of species, which are considered to be typically planktonic, in ponds and lakes have a bottom or periphytonic (attachment to any object) phase in their development.

Marine phytoplankton consists mainly of diatoms and dinophytes. Although marine environment relatively homogeneous over large areas; no homogeneity is observed in the distribution of marine phytoplankton. Differences by species composition and numbers are often expressed even in relatively small areas of sea water, but they are especially clearly reflected in the large-scale geographical zonality of distribution. Here the effect of the main environmental factors is manifested: water salinity, temperature, light and nutrient content.

Planktonic algae usually have special adaptations for living suspended in the water column. In some species these are various kinds of outgrowths and appendages of the body - spines, bristles, horny processes, membranes, parachutes; others form hollow or flat colonies and secrete mucus profusely; still others accumulate in their bodies substances whose specific gravity is less specific gravity water (fat droplets in diatoms and some green algae, gas vacuoles in blue-green algae). These formations are much more developed in marine phytoplankters than in freshwater ones. Another such adaptation is the small body size of planktonic algae.

Neuston algae.

The collection of marine and freshwater organisms that live near the surface film of water, attach to it, or move along it is called neuston. Neuston organisms live both in small bodies of water (ponds, water-filled pits, small bays of lakes) and in large ones, including the seas. In some cases, they develop in such quantities that they cover the water with a continuous film.

The composition of neuston includes unicellular algae that are part of different systematic groups (golden, euglenophytes, green, individual species yellow-green and diatoms). Some neuston algae have characteristic adaptations for existing at the surface of the water (for example, slimy or scaly parachutes that hold them on the surface film).

Benthic algae.

Benthic (bottom) algae include algae adapted to exist in an attached or unattached state on the bottom of reservoirs and on a variety of objects, living and dead organisms in the water.

The predominant benthic algae of continental water bodies are diatoms, green, blue-green and yellow-green multicellular (filamentous) algae, attached or not attached to the substrate.

The main benthic algae of the seas and oceans are brown and red, sometimes green, macroscopic attached thallous forms. All of them can be overgrown with small diatoms, blue-green and other algae.

Sometimes algae growing on objects introduced into water by humans (ships, rafts, buoys) are classified as periphyton. The identification of this group is justified by the fact that its constituent organisms (algae and animals) live on objects moving or flowing around water. In addition, these organisms are removed from the bottom and, therefore, are exposed to different light and temperature conditions, as well as other conditions for the supply of nutrients.

The possibility of benthic algae growing in specific habitats is determined by both abiotic and biotic factors. Among the latter, competition with other algae and the presence of animals that feed on algae (sea urchins, gastropods, crustaceans, fish) play a significant role. The influence of biotic factors leads to the fact that certain types of algae do not grow at all depths and not in all bodies of water with suitable light and hydrochemical conditions.

Abiotic factors include light, temperature, as well as the content of biogenic and biological substances in water. active substances, oxygen and inorganic carbon sources. The rate at which these substances enter the thallus is very important, which depends on the concentration of the substances and the speed of water movement.

Benthic algae, growing in conditions of moving water, receive advantages over algae growing in slow-moving waters. The same level of photosynthesis can be achieved in them with less light, which promotes the growth of larger thalli; the movement of water prevents the settling of silt particles on rocks and stones, which interfere with the fixation of algae buds, and also washes away algae-eating animals from the soil surface. In addition, despite the fact that during strong currents or strong surf the algae thalli are damaged or torn from the ground, the movement of water still does not prevent the settlement of microscopic algae and microscopic stages of large algae. Therefore, places with intense water movement (in the seas these are straits with currents, coastal areas of the surf, in rivers - stones on riffles) are characterized by the lush development of benthic algae.

The influence of water movement on the development of benthic algae is especially noticeable in rivers, streams, and mountain streams. In these reservoirs there is a group of benthic organisms that prefer places with a constant flow. In lakes where there are no strong currents, wave motion becomes of primary importance. In the seas, waves also have a significant impact on the life of benthic algae, in particular on their vertical distribution.

In the northern seas, the distribution and abundance of benthic algae is influenced by ice. Algae thickets can be destroyed (erased) by the movement of glaciers. Therefore, for example, in the Arctic, perennial algae are most easily found near the shore among boulders and rock ledges that impede the movement of ice.

The intensive development of benthic algae is also facilitated by the moderate content of nutrients in the water. IN fresh waters Such conditions are created in shallow ponds, in the coastal zone of lakes, in river backwaters, in the seas - in small bays. If in such places there is sufficient lighting, hard soils and weak water movement, then optimal conditions for the life of phytobenthos are created. In the absence of water movement and its insufficient enrichment with nutrients, benthic algae grow poorly.

Hot spring algae.

Algae that can withstand high temperatures are called thermophilic. In nature, they settle in hot springs, geysers and volcanic lakes. They often live in waters that, in addition to high temperatures, are characterized by a high content of salts or organic substances (heavily polluted hot wastewater from factories, factories, power plants or nuclear plants).

The maximum temperatures at which it was possible to find thermophilic algae, judging by different sources, range from 52 to 84 ° C. In total, about 200 species of thermophilic algae were discovered, but there are relatively few species that live only at high temperatures. Most of them can withstand high temperatures, but develop more abundantly at normal temperatures. Typical inhabitants of hot waters are blue-green algae, and to a lesser extent, diatoms and some green algae.

Algae of snow and ice.

Snow and ice algae make up the vast majority of organisms that settle on frozen substrates (cryobiotopes). The total number of algae species found in cryobiotopes reaches 350, but true cryophiles, capable of vegetating only at temperatures close to 0° C, are much smaller: slightly more than 100 species. These are microscopic algae, the vast majority of which are green algae (about 100 species); Several species include blue-green, yellow-green, golden, pyrophytic and diatom algae. All these species live in the surface layers of snow or ice. They are united by the ability to withstand freezing without damaging fine cellular structures and then, upon thawing, quickly resume vegetation using minimal amount warmth. Only a few of them have resting stages; most lack any special adaptations for transferring low temperatures.

Developing in large quantities, algae are capable of causing green, yellow, blue, red, brown, brown or black “blooming” of snow and ice.

Algae from salt water bodies.

These algae grow at high concentrations of salts in water, reaching 285 g/l in lakes with a predominance of table salt and 347 g/l in Glauberian (soda) lakes. As salinity increases, the number of algae species decreases; only a few can tolerate very high salinity. In extremely saline (hyperhaline) water bodies, single-celled mobile green algae predominate. They often cause red or green “blooms” in salt water bodies. The bottom of hyperhaline reservoirs is sometimes completely covered with blue-green algae. they play a big role in the life of salt water bodies. The combination of organic matter formed by algae and large quantity dissolved salts in water causes a number of unique biochemical processes characteristic of these reservoirs. For example, Chlorogloea sarcinoides (Chlorogloea sarcinoides) from the blue-greens, which develops in huge quantities in some salt lakes, as well as a number of other massively growing algae, are involved in the formation of medicinal mud.

Algae of non-aquatic habitats.

Aerophilic algae.

Aerophilic algae are in direct contact with the air around them. The typical habitat of such algae is the surface of various extra-soil solid substrates that do not have a clearly expressed physical and chemical effect on the settlers (rocks, stones, tree bark, etc.). Depending on the degree of moisture, they are divided into two groups: aerial algae, living in conditions of only atmospheric moisture and, therefore, experiencing a constant change of wetting and drying; And aquatic algae, subject to constant irrigation with water (spray from a waterfall, surf, etc.).

The conditions for the existence of algae in these communities are very unique and are characterized, first of all, by frequent and sharp changes in temperature and humidity. During the day, aerophilic algae become very warm, cool at night, and freeze in winter. Aerial algae are particularly susceptible to changing moisture conditions, as they are often forced to transition from a state of excess moisture (for example, after a rainstorm) to a state of minimal moisture (during dry periods), when they dry out enough to be ground into powder. Aquatic algae live in conditions of relatively constant moisture, however, they also experience significant fluctuations in this factor. For example, algae living on rocks irrigated by the spray of waterfalls experience a moisture deficit in the summer, when the flow decreases significantly.

To such unfavorable conditions Relatively few species (about 300) have adapted to existence. Aerophilic algae are represented by microscopic algae from the departments of blue-green, green and, to a much lesser extent, diatoms and red algae.

When aerophilic algae develop in large quantities, they usually take the form of powdery or slimy deposits, felt-like masses, soft or hard films or crusts. Algae growths are especially abundant on the surface of wet rocks. They form films and growths of various colors. As a rule, species equipped with thick mucous membranes live here. Depending on the light intensity, the mucus can be colored more or less intensely, which determines the color of the growths. They can be bright green, golden, brown, ocher, purple, brown or almost black, depending on the species that form them.

Thus, aerophilic algal communities are very diverse and arise both under quite favorable and extreme conditions. Their external and internal fittings to this lifestyle are diverse and similar to those found in soil algae, especially those developing on the soil surface.

Edaphilic algae.

Basic living environment edaphophilic algae is the soil. Their typical habitats are the surface and thickness of the soil layer, which has a certain physical and chemical effect on the algae. Depending on the location of algae and their lifestyle, three groups of communities are distinguished within this type. This terrestrial algae, massively developing on the soil surface under atmospheric moisture conditions; water-terrestrial seaweed, growing massively on the surface of the soil, constantly saturated with water (this group also includes algae of caves) and soil seaweed, inhabiting the soil layer. Typical conditions are life among soil particles under the influence of an environment that is very complex in terms of a complex of factors.

Soil as a biotope is similar to aquatic and aerial habitats: it contains air, and it is saturated with water vapor, which ensures breathing with atmospheric air without the threat of drying out. However, the soil is fundamentally different from the above-mentioned biotopes in its opacity. This factor has a decisive influence on the development of algae. Intensive development of algae as phototrophic organisms is possible only where light penetrates. In virgin soils this is a surface layer of soil up to 1 cm thick, but in such soils algae are found at a much greater depth (up to 2 m). This is explained by the ability of some algae to switch to heterotrophic nutrition in the dark. Many algae remain dormant in the soil.

To survive, soil algae must be able to tolerate unstable humidity, sudden temperature fluctuations and strong insolation. These properties are ensured by a number of morphological and physiological characteristics(smaller in size compared to aquatic forms of the same species, abundant mucus formation). The amazing viability of these algae is evidenced by the following observation: when soil algae, stored for decades in an air-dry state in soil samples, were placed in nutrient medium, they began to develop. Soil algae (mostly blue-green) are resistant to ultraviolet and radioactive radiation.

A characteristic feature of soil algae is the ability to quickly move from a dormant state to active life and vice versa. They are also able to tolerate varying variations in soil temperature. The survival range of a number of species lies from –20° to +84° C. It is known that terrestrial algae make up a significant part of the vegetation of Antarctica. They are almost black in color, so their body temperature is higher than the ambient temperature. Soil algae are also important components of biocenoses in the arid zone, where the soil heats up to 60–80° C in summer.

The listed properties of soil algae allow them to live in the most unfavorable habitats. This explains their wide distribution and rapid growth even with the short-term appearance of the necessary conditions.

The vast majority of soil algae are microscopic, but they can often be seen on the soil surface with the naked eye. The massive development of microscopic forms causes greening of the slopes of ravines and roadsides forest roads, “blooming” of arable soils.

The number of all types of soil algae is close to 2000. They are represented by blue-green, green, diatoms and yellow-green algae.

Lithophilic algae.

The main living environment of lithophilic algae is the opaque dense calcareous substrate surrounding them. As a rule, they live deep in solid rocks of a certain chemical composition, surrounded by air (i.e., out of water) or submerged in water. There are two groups of lithophilic communities: boring algae and tuff-forming algae.

Boring algae are organisms that penetrate into the calcareous substrate. These algae are not numerous in number of species, but they are extremely widespread: from the cold waters of the north to the constantly warm waters tropics. They live in both continental and marine reservoirs, near the surface of the water and at a depth of more than 20 m. Boring algae settle on calcareous rocks, stones, calcareous animal shells, corals, large algae soaked in lime, etc. All boring algae are microscopic organisms. Having settled on the surface of the limestone substrate, they gradually penetrate into it due to the release of organic acids that dissolve the lime underneath them. Algae grow inside the substrate, forming numerous channels through which they maintain contact with the external environment.

Tuff-forming algae – organisms that deposit lime around their body and live in the peripheral layers of the environment they deposit, within the limits accessible to the diffusion of light and water. The amount of lime produced by algae varies. Some species secrete it in very small quantities; in the form of small crystals it is located between individuals or forms cases around cells and filaments. Other species secrete lime so abundantly that they gradually become completely immersed in the sediment, which ultimately leads to their death.

Tuff-forming algae are found in water and in terrestrial habitats, in seas and fresh water bodies, in cold and hot waters.

Cohabitation of algae with other organisms

Of particular interest are cases of algae cohabiting with other organisms. Most often, algae use living organisms as a substrate, along with stones, concrete and wooden structures, etc. Based on the nature of the substrate on which fouling algae settle, they include: epiphytes, settling on plants, and epizoites living on animals.

Algae can also live in the tissues of other organisms: both extracellularly (in mucus, intercellular spaces of algae, in the membranes of dead cells) and intracellularly. Such algae are called endophytes. They are characterized by the presence of more or less permanent and strong ties between partners. A wide variety of algae can be endophytes, but the most numerous are endosymbioses of unicellular green and yellow-green algae with unicellular animals.

Among the symbioses formed by algae, the most interesting is their symbiosis with fungi, known as lichen symbiosis, as a result of which a peculiar group of plant organisms emerged, called “lichens”. This symbiosis shows a unique biological unity that led to the emergence of a fundamentally new organism. At the same time, each partner of the lichen symbiosis retains the features of the group of organisms to which it belongs. Lichens represent the only proven case of the emergence of a new organism as a result of the symbiosis of two.

Algae play a huge role in nature. They are the main producers of organic food and oxygen in the Earth's aquatic ecosystems, and, in addition, play a large role in the overall balance of oxygen on the planet. In terrestrial habitats, soil algae, along with other microorganisms, play the role of pioneers of vegetation. Algae are involved in the processes of formation of primitive soils on substrates devoid of soil cover, as well as in the processes of restoration of soils disturbed by severe pollution. Algae take part in the construction of coral reefs - the most ambitious geological formations created by living organisms. The geochemical role of algae is primarily associated with the cycle of calcium and silicon in nature.

Velika historical role seaweed The emergence of an oxygen-containing atmosphere, the emergence of living creatures on land and the development of aerobic forms of life that now dominate our planet are all the results of the activity of the most ancient photosynthetic organisms - blue-green algae. The massive development of algae in past geological epochs led to the formation of thick layers rocks. From algae came the plants that colonized the land.

It is difficult to overestimate the importance of algae for human life. Algae is given important role in solving a number global problems issues that concern all of humanity, including food, energy, environmental protection, development of the Earth's subsoil and the riches of the World Ocean, finding new sources of industrial raw materials, building materials, pharmaceuticals, biologically active substances and new biotechnology objects.

Natalya Novoselova

Brown algae, like red algae, almost always live in seas and oceans, that is, in salty waters. All of them are multicellular. Brown algae have the largest representatives of all algae. Mostly brown algae grow at shallow depths (up to 20 m), although there are species that can live at depths of up to 100 m. In the seas and oceans they form peculiar thickets. Most brown algae live in subpolar and temperate latitudes Oh. However, there are also those that grow in warm waters.

Brown algae, like green algae, are capable of photosynthesis, that is, their cells contain the green pigment chlorophyll. However, they also have many other pigments that have yellow, brown, and orange colors. These pigments “interrupt” green color plants, giving it a brownish tint.

As is known, all algae belong to lower plants. Their body is called a thallus, or thallus; there are no real tissues or organs. However, in a number of brown algae, the body is divided into organs, and different tissues can be distinguished.

Some species of brown algae have a complexly dissected thallus more than 10 m in length.

The vast majority of brown algae attach to underwater objects. They do this with the help of rhizoids or so-called basal disks.

Brown algae exhibit different types of growth. Some species grow from their apex, in others all the cells of the thallus retain the ability to divide, in others the surface cells divide, in others there are special zones of cells in the body, the division of which leads to the growth of tissues above and below them.

The cell walls of brown algae consist of an inner cellulose layer and an outer gelatinous layer, which includes various substances (salts, proteins, carbohydrates, etc.).

Cells have one nucleus and many small disc-shaped chloroplasts. Chloroplasts differ in structure from the chloroplasts of higher plants.

As a reserve nutrient, it is not starch that is deposited in the cells of brown algae, but another polysaccharide and one of the alcohols. The cells contain vacuoles with polyphenolic compounds.

Brown algae have both sexual and asexual reproduction. They can reproduce by fragmenting their thallus; some species form brood buds. Asexual reproduction also carried out by spores formed in sporangia. Most often, spores are motile (have flagella), that is, they are zoospores. The spores give rise to a gametophyte, which forms sex cells, the fusion of which gives rise to the sporophyte.

Thus, alternation of generations is observed in brown algae. However, in other species, gametes are formed by the sporophyte, that is, the haploid stage is represented only by eggs and sperm.

It has been noted that brown algae release pheromones, which stimulate the release of sperm and their movement towards eggs.

The most famous representative of brown algae is kelp, which people eat, calling it seaweed. It has rhizoids with which it attaches to underwater objects (stones, rocks, etc.). Laminaria has something like a stem (stem), this part of the plant is not flat, but cylindrical. The length of the stem is up to half a meter, and similar flat leaf plates extend from it (each several meters long).

Brown algae is not only used by humans for food, it is used in the food and textile industries, and some medicines are made from it.

Algae can be positioned as the most numerous organisms that are distributed throughout the globe. They live not only in fresh and salt waters, but also on land and even rocks. At the same time, on the surface of the water, algae are presented in the form of mud, and on wood - as green or blue-green mucus.

Where do algae live?

Certain types of algae are capable of attaching to rocks and stones. Most of these organisms live in the upper layers of the water cover. Some algae can exist freely at depths of up to 90 cm.

Moreover, a certain variety of such organisms can reproduce even in arctic cold conditions. Such algae crash into the ice floe and maintain a state of suspended animation.

Brown algae

Other species live in the soil, and some of them live on the surface of plants.

What do algae eat?

These organisms are characterized by an autotrophic mode of nutrition, so algae absorb inorganic substances from the environment. Subsequently, through photosynthesis, algae obtain the organic matter they need, releasing oxygen. As natural enemies These species can be considered a large number of animals and fish that consume algae as food.

Are algae dangerous for humans?

Algae are consumed by humans as food. Moreover, they are quite often used in the chemical and pharmaceutical industries. It should also be noted that there is a type of algae that is distinguished by the presence of a large amount of iodine content. Eating them may result in poisoning with this element. Another type of such organisms is capable of producing hydrogen sulfide, which causes diarrhea and vomiting in humans.

Brown algae

Brown algae is a division of true multicellular brown algae. This group of plants includes 250 genera and about 1,500 species. The most famous representatives are kelp, cystoseira, sargassum.

These are mainly marine plants, only 8 species are secondary freshwater forms. Brown algae are widespread in the seas of the globe, reaching particular diversity and abundance in cold water bodies of subpolar and temperate latitudes, where they form large thickets in the coastal strip. IN tropical zone The largest accumulation of brown algae is observed in the Sargasso Sea; their massive development usually occurs in winter, when the water temperature drops. Vast underwater forests are formed by kelp algae off the coast of North America.

Brown algae are usually attached to hard substrates, such as rocks, rocks, mollusk shells, and other algae thalli. In size they can reach from several centimeters to several tens of meters. The multicellular thallus is colored from olive green to dark brown, since the cells, in addition to chlorophyll, contain a significant amount of brown and yellow pigments. These plants have the most complex structure of all algae: in some of them, the cells are grouped in one or two rows, which resembles the tissues of higher plants.

Seaweed. Answers on questions

Species can be either annual or perennial.

Thallus. Algae of this group may have thalli various shapes: creeping or vertically “hanging” threads, plates (solid or cut) or branching bushes. The thalli are attached to the solid substrate by means of rhizoids (soles). Higher brown algae of the order Laminaria and Fucus are characterized by differentiation of tissue structures and the appearance of conducting systems. Unlike algae of other groups, brown algae are characterized by the presence of multicellular hairs with a basal growth zone.

Cell structure. The cover is a thick cell wall, consisting of two or three layers, highly mucus-producing. Structural components cell wall are cellulose and pectin. Each cell of brown algae contains one nucleus and vacuoles (from one to several). Chloroplasts are small, disc-shaped, and brown in color due to the fact that in addition to chlorophyll and carotene, they contain a high concentration of brown pigments - xanthophylls, in particular fucoxanthin. Also in the cytoplasm of the cell, reserves of nutrients are deposited: the polysaccharide laminarin, polyhydric alcohol mannitol and various fats (oils).

Propagation of brown algae. Reproduction is carried out asexually and sexually, rarely vegetatively. The reproductive organs are sporangia, both unilocular and multilocular. Usually there is a gametophyte and a sporophyte, and in higher algae they alternate in strict sequence, while in lower algae there is no clear alternation.

Meaning. The importance of brown algae in nature and human life is great. They are the main source of organic matter in the coastal zone of the seas. In the thickets of these algae, which occupy vast areas, many marine inhabitants find shelter and food. In industry they are used in the production of alginic acids and their salts, to obtain feed flour and powder for the production of medicines, containing high concentrations of iodine and a number of other trace elements. In aquariums, the appearance of brown algae is associated with insufficient lighting. Some species are eaten.

Types and habitats of algae

Phytoplankton is the main producer of organic matter in water bodies, due to which aquatic heterotrophic animals and some bacteria exist. Phytoplankton is the initial link in most food chains in a body of water: small planktonic animals feed on them, which feed on larger ones. Therefore, in areas of greatest phytoplankton development, zooplankton and nekton are abundant.

The abundance and species composition of phytoplankton depends on a complex of factors discussed above. In this regard, the species composition of planktonic algae in different reservoirs (and even in the same reservoir, but at different times of the year) is not the same. It depends on the physical and chemical regime in the reservoir. In each season of the year, one of the groups of algae (diatoms, blue-greens, golden, euglenaceae, green and some others) develops predominantly, and often only one species of one or another group dominates. This is especially pronounced in freshwater bodies of water. In inland water bodies there is a much greater diversity of ecological conditions compared to sea water bodies, which determines a significantly greater diversity of species composition and ecological complexes of freshwater phytoplankton compared to sea water. One of the significant features of freshwater phytoplankton is the abundance of temporary planktonic algae in it. A number of species, which are considered to be typically planktonic, in ponds and lakes have a bottom or periphytonic (attachment to any object) phase in their development.

Marine phytoplankton consists mainly of diatoms and dinophytes. Although the marine environment is relatively homogeneous over large areas, there is no uniformity in the distribution of marine phytoplankton. Differences in species composition and abundance are often pronounced even in relatively small areas of sea water, but they are especially clearly reflected in the large-scale geographic zonality of distribution. Here the effect of the main environmental factors is manifested: water salinity, temperature, light and nutrient content.

Planktonic algae usually have special adaptations for living suspended in the water column. In some species these are various kinds of outgrowths and appendages of the body - spines, bristles, horny processes, membranes, parachutes; others form hollow or flat colonies and secrete mucus profusely; still others accumulate in their bodies substances whose specific gravity is less than the specific gravity of water (fat droplets in diatoms and some green algae, gas vacuoles in blue-green algae). These formations are much more developed in marine phytoplankters than in freshwater ones. Another such adaptation is the small body size of planktonic algae.

The composition of neuston includes unicellular algae that are part of different systematic groups (golden, euglenophytes, green, certain species of yellow-green and diatoms). Some neuston algae have characteristic adaptations for existing at the surface of the water (for example, slimy or scaly parachutes that hold them on the surface film).

Benthic (bottom) algae include algae adapted to exist in an attached or unattached state on the bottom of reservoirs and on a variety of objects, living and dead organisms in the water.

The predominant benthic algae of continental water bodies are diatoms, green, blue-green and yellow-green multicellular (filamentous) algae, attached or not attached to the substrate.

The main benthic algae of the seas and oceans are brown and red, sometimes green, macroscopic attached thallous forms. All of them can be overgrown with small diatoms, blue-green and other algae.

Depending on the place of growth, benthic algae differ:

1) epiliths growing on the surface of hard soil (rocks, stones);

2) epipelites inhabiting the surface of loose soils (sand, silt);

3) epiphytes living on the surface of other plants;

4) endoliths, or boring algae that penetrate the calcareous substrate (rocks, mollusk shells, crustacean shells);

7) endosymbionts living in the cells of other organisms, invertebrates or algae;

8) epizoites living on some benthic animals.

Sometimes algae growing on objects introduced into water by humans (ships, rafts, buoys) are classified as periphyton. The identification of this group is justified by the fact that its constituent organisms (algae and animals) live on objects moving or flowing around water. In addition, these organisms are removed from the bottom and, therefore, are exposed to different light and temperature conditions, as well as other conditions for the supply of nutrients. The possibility of benthic algae growing in specific habitats is determined by both abiotic and biotic factors. Among the latter, competition with other algae and the presence of animals that feed on algae play a significant role ( sea urchins, gastropods, crustaceans, fish). The influence of biotic factors leads to the fact that certain types of algae do not grow at all depths and not in all bodies of water with suitable light and hydrochemical conditions.

Abiotic factors include light, temperature, as well as the content of biogenic and biologically active substances, oxygen and inorganic carbon sources in water. The rate at which these substances enter the thallus is very important, which depends on the concentration of the substances and the speed of water movement.

The intensive development of benthic algae is also facilitated by the moderate content of nutrients in the water. In fresh waters, such conditions are created in shallow ponds, in the coastal zone of lakes, in river backwaters, in the seas - in small bays. If in such places there is sufficient lighting, hard soils and weak water movement, then optimal conditions for the life of phytobenthos are created. In the absence of water movement and its insufficient enrichment with nutrients, benthic algae grow poorly.

Hot spring algae:

Algae that can withstand high temperatures are called thermophilic.

In nature, they settle in hot springs, geysers and volcanic lakes. They often live in waters that, in addition to high temperatures, are characterized by a high content of salts or organic substances (heavily polluted hot wastewater from factories, factories, power plants or nuclear plants).

The maximum temperatures at which it was possible to find thermophilic algae, judging by various sources, range from 52 to 84 ° C.

In total, about 200 species of thermophilic algae have been discovered, but there are relatively few species that live only at high temperatures. Most of them can withstand high temperatures, but develop more abundantly at normal temperatures. Typical inhabitants of hot waters are blue-green algae, and to a lesser extent, diatoms and some green algae.

Algae of snow and ice:

These are microscopic algae, the vast majority of which are green algae (about 100 species); Several species include blue-green, yellow-green, golden, pyrophytic and diatom algae. All these species live in the surface layers of snow or ice.

where they live, structural features, representatives: green, brown, red algae!

They are united by the ability to withstand freezing without damaging fine cellular structures and then, upon thawing, quickly resume vegetation using a minimum amount of heat. Only a few of them have a resting stage; most lack any special adaptations to withstand low temperatures.

Developing in large quantities, algae are capable of causing green, yellow, blue, red, brown, brown or black “blooming” of snow and ice.

Algae from salt water bodies:

These algae grow at high concentrations of salts in water, reaching 285 g/l in lakes with a predominance of table salt and 347 g/l in Glauber (soda) lakes. As salinity increases, the number of algae species decreases; only a few can tolerate very high salinity. In extremely saline (hyperhaline) water bodies, single-celled mobile green algae predominate. They often cause red or green “blooms” in salt water bodies. The bottom of hyperhaline reservoirs is sometimes completely covered with blue-green algae. they play a big role in the life of salt water bodies. The combination of organic mass formed by algae and a large amount of salts dissolved in water causes a number of unique biochemical processes characteristic of these reservoirs. For example, Chlorogloea sarcinoides (Chlorogloea sarcinoides) from the blue-greens, which develops in huge quantities in some salt lakes, as well as a number of other massively growing algae, are involved in the formation of medicinal mud.

For biological indication of water quality, almost all groups of organisms inhabiting water bodies can be used: planktonic and benthic invertebrates, protozoa, algae, macrophytes, bacteria and fish. Each of them, acting as a biological indicator, has its own advantages and disadvantages, which determine the boundaries of its use in solving bioindication problems, since all of these groups play a leading role in the general circulation of substances in a reservoir. Organisms that are usually used as bioindicators are responsible for the self-purification of a reservoir, participate in the creation of primary production, and transform the substances and energy of aquatic ecosystems.

The most developed assessment of the degree of water pollution using indicator organisms is the saprobity system. The method takes into account the relative frequency of occurrence of hydrobionts h (from 1 to 9 or from single specimens in the microscope field of view to very frequent occurrence, when there are many of them in each field of view) and their indicator significance S. For statistical reliability of the results, it is necessary that the sample contains at least 12 species of indicator organisms of one zone of saprobity c. The indicator values of S for the corresponding zones of saprobity are tabulated for many organisms. Based on the calculated value of S, one can judge the state of the reservoir. A conclusion about the degree of water pollution is usually given using a point system from one to six.

Among the huge variety of microalgae, the plankton-dwelling algae of the Chlorophyta division are most often used to assess the effects of substances, while representatives of other divisions remain poorly studied, which especially concerns benthic microalgae.

Sea water pollution is complex and, therefore, its nature and effects can only be assessed using biotesting, which is a means of obtaining fundamentally new information about pollution. Unicellular algae, due to their year-round availability and high sensitivity, are widely used as test objects for biotesting.

meaning of brown algae

Brown algae are one of the main sources of organic matter in the coastal zone, especially in the seas of temperate and subpolar zones, where their biomass can reach tens of kilograms per square meter. Thickets of brown algae serve as shelter, breeding and feeding places for many coastal animals, in addition, they create conditions for the settlement of other microscopic and macroscopic algae. The role of brown algae in the life of coastal waters is seen in the example of Macrocystis, about the thickets of which off the coast of South America Charles Darwin wrote: “I can only compare these huge underwater forests of the southern hemisphere with the terrestrial forests of tropical regions. And yet, if a forest were destroyed in any country, I don’t think that at least approximately the same number of animal species would die as with the destruction of this algae.”

The role of brown algae is also great in economic activity person. Together with other organisms, they participate in the fouling of sea vessels and buoys, worsening their performance. But much higher value have brown algae as a raw material for the production of various types of substances.

Firstly, brown algae is the only source of alginates - alginic acid compounds.

Depending on which metals are involved in the formation of alginates, they can be soluble in water (salts of monovalent metals) or insoluble (salts of polyvalent metals, except magnesium). Sodium alginate, which has all the properties of water-soluble alginates, is most widely used. It is capable of absorbing up to 300 weight units of water to form viscous solutions. Therefore, it is widely used to stabilize various solutions and suspensions. Adding a small amount of sodium alginate improves the quality of food products (canned food, ice cream, fruit juices, etc.), various coloring and adhesive substances.

Solutions with the addition of alginates do not lose their quality when frozen and thawed. The use of alginates improves the quality of book printing and makes natural fabrics fade-resistant and waterproof. Alginates are used in the production of plastics, synthetic fibers and plasticizers, to produce weather-resistant paint coatings and building materials. They are used to produce high-quality lubricants for machines, soluble surgical sutures, ointments and pastes in the pharmaceutical and perfume industries. In foundries, alginates improve the quality of the molding earth. Alginates are used in fuel briquetting and in the production of electrodes for electric welding, which make it possible to obtain higher-quality welds. It's hard to name the industry National economy, wherever alginates are used.

Another important substance obtained from brown algae is the hexahydric alcohol mannitol. It is used in the pharmaceutical industry for the manufacture of tablets, in the preparation of diabetic foods, in the production of synthetic resins, paints, paper, explosives, and in the tanning of leather. Mannitol is increasingly used during surgical operations.

Brown algae contains large amounts of iodine and other trace elements. Therefore, they are used to prepare feed flour, which is used as an additive to feed for farm animals. Thanks to this, livestock mortality is reduced, its productivity is increased, and in a number of agricultural products (eggs, milk), the iodine content increases, which has important for areas where the population suffers from its deficiency.

Brown algae was once processed in large quantities to produce iodine, but now only waste from the algae industry is used for this purpose: due to the emergence of other, more cost-effective sources of iodine, it has become more profitable to process brown algae into other substances.

Brown algae in fresh and processed forms is used as fertilizer.

Brown algae has long been used in medicine. Now new directions for their use are being identified, for example, for the production of blood substitutes, for the production of drugs that prevent blood clotting, and substances that promote the removal of radioactive substances from the body.

Since ancient times, brown algae have been consumed as food, especially by the peoples of Southeast Asia.

Representatives of the order Laminariaceae are of greatest importance in this regard; the largest number of various dishes are prepared from them.

Algae can live and reproduce in such special conditions that seem to us, at first glance, completely unacceptable for life. These can be hot springs, the temperature of which sometimes reaches boiling point, as well as cold arctic waters, ice and snow.

Algae living in unusual conditions

Algae can live at fairly wide temperature limits: from three degrees to eighty-five. But most organisms live in a narrower range.

Algae living in unusual conditions ensure the bloom of ice not on its surface, due to mass reproduction, but in various kinds of depressions or projections that are immersed in water. Initially, they develop on the lower part of the ice cover, and then freeze with the arrival of cold weather. The ice thaws, and with it algae come to the surface.

All algae that live in unusual cold conditions are called cryobionts. In low temperature conditions, not only microscopic algae live, but also multicellular algae, for example, kelp.

Algae in salt waters

For obvious reasons, the saltier the water, the fewer living organisms live in it. This also applies to algae. Only a few of them tolerate high salinity. But even in extremely concentrated waters, single-celled green species live. Sometimes such algae in nature cause green or red “blooms”. The bottom of salty reservoirs is sometimes completely covered with them.

The characteristics of algae are such that in highly salty water they sometimes lead to unexpected biochemical processes. For example, the formation of therapeutic mud.

Algae that live without water

Aerophilic algae, living in unusual conditions, come into direct contact with air. The typical habitat for such species is the surface of rocks, stones, and tree bark.

According to the degree of moisture, they are divided into two subgroups: air and water-air. The life of algae is very unique and is characterized by sharp and frequent changes in temperature and humidity. During the day, these algae warm up quite strongly, and at night the temperature drops significantly.

Only aerophilic algae are susceptible to such sudden changes. However, they are well adapted to such an existence. Their largest colonies are observed on the surfaces of wet rocks.

Factors in algae development

The main factors that influence the development of algae are the presence of moisture, light, temperature regime, carbon, organic and mineral fertilizers. Algae are very widespread throughout the world, they can be found in water, on the bark of trees, in the soil and on its surface, on the walls of stone buildings, and even in the most unsuitable places for habitation.

Oddly enough, some species are so adapted to life in extreme conditions that they feel comfortable and even reproduce very actively.

It is a mistake to believe that in conditions of high and very low temperatures there is nothing living. This is absolutely not true. It turns out that unicellular and multicellular algae live quite normally in such conditions. They are not always visible to the naked eye, but they live in both hot geysers and ice.

Recent research in Kamchatka has led biologists to rather unexpected results. The researchers had a goal: to examine hot springs for mercury content. It was initially assumed that the water from these sources was not suitable for drinking.

During the research, it turned out that only one geyser is dangerous. However, it turned out that other quite Interesting Facts. Biologists confidently declare the discovery in hot water dark green filamentous algae. It would seem, well, what’s surprising here. The fact that they live at high temperatures has long been known. But the water temperature of the geysers under study reached 98 degrees. Although previously it was assumed that the limiting temperature of their habitat was around eighty-seven degrees.

Instead of an afterword

For us, the usual habitat for algae is water. But, as we could see, this is not entirely true. Among them there are quite a few species that feel great outside the water. Moreover, as it turned out, algae have a very wide temperature range of habitat, like no other living organism. They are able not only to live, but also to reproduce in the harshest conditions, where, it would seem, nothing alive can exist. And for some species these are quite acceptable and comfortable conditions.

Edible algae- This is a fairly popular food product among Asian residents. Today there is a huge amount of algae known that can be eaten. All of them are divided into categories depending on color. Thus, red, brown and green algae are isolated (see photo). Here are the most popular options:

Types of Edible Algae

There are many types of edible algae found in nature, which, according to their habitat conditions, can be divided into marine and freshwater. We invite you to familiarize yourself with these varieties in more detail, and also find out which of them are best suited for consumption.

The “seaweed” class includes about thirty thousand species of plants, but not all of them are suitable for food. The most common are the following:

Laminaria, or seaweed, is a type of edible algae that contains a large amount of iodine, as well as other trace elements. The ingredient has a brownish-green color and a soft structure.
Porphyra is a type of algae that is especially popular in Asian countries. When finished it has a dark brown color, but in its natural habitat it is burgundy. This algae can be found in the form of finely chopped longitudinal strips. This product is very useful for people with thyroid diseases.
Dals is an algae that appearance resembles corals, but has a softer structure.
Ulva looks like lettuce leaves, but as it grows, it spreads along the bottom of the reservoir, forming a continuous “carpet.” It has a rich light green color and also contains a large amount of vitamins, due to which it has a beneficial effect on the body when consumed.
Carrageenan, or Irish moss, is a type of seaweed that has a rich brown color and an elastic structure that becomes softer when cooked.

In addition to the above types of seaweed, others, no less popular, are used in cooking. These include nori, wakame, agar-agar, kombu and others. Some varieties of the product are used as gelling thickeners for making desserts, and some are used as an ingredient for preparing salads or first courses. Either way, you can use edible seaweed at your discretion.

Freshwater edible algae are not much different from seaweed, being just as healthy and original in taste. However, they contain slightly less iodine, since such algae do not grow in sea water. These include the following types:

Rodimenia is a seaweed that is usually brought from Iceland. It is a storehouse of microelements and is useful for people with thyroid diseases.
Lithothamnia has a coral color and also contains a large amount of vitamins.
Aonori is a freshwater variety of edible algae, which is valued by consumers for its special delicate aroma, as well as pleasant taste and soft structure. The product has a rich green color.
Spirulina is greenish-blue in color and grows in shallow bodies of water. Today, this type of edible algae is the most popular among all others.

All seaweed that is consumed by humans is usually sold in dried, canned or fresh form. If you want this product to bring as much benefit to your body as possible, we recommend choosing dried or fresh seaweed.

Edible algae in the Black Sea

In the Black Sea there are a huge number of different varieties of edible algae. Among them there are green, brown and red e. We invite you to familiarize yourself with the most popular of them.

Name	Description
Laminaria (sea kale)	This type of edible seaweed is the most popular among all others that are used for cooking. The ingredient can be found on store shelves in canned, fresh, and frozen forms. Fresh kelp is less common and is best used for cooking.
	Kelp is a type of kelp, but this algae grows in those parts of the Black Sea where the water is coolest. The product is sold exclusively in powder form, which has a salty taste.
	This algae is almost never used fresh, since its taste is significantly inferior to other algae. However, this product contains a large number of useful microelements, which makes the use of the ingredient favorable for people with weak immunity.
	This algae is used to make agar-agar, which is used as a gelling powder for preparing desserts and other dishes.
	Dals is another type of edible algae that is obtained from the bottom of the Black Sea. The product can be used for preparing dishes as an ingredient, and also served as an independent dish.

All of the above varieties of edible algae contain a large amount of iodine, being incredibly useful for human consumption. You can eat them as a snack, and also add them to any dishes to give them a twist and an unusual taste.

In Japan and Sakhalin

In Japan and Sakhalin, edible seaweed is also actively used to prepare certain dishes. However, in these regions, other varieties of the product are most often used, which are more accessible to the population. We invite you to familiarize yourself with them by studying our table.

Name	Description
	This type of seaweed has a fairly rigid structure, which is why hijiki is rarely used fresh, having previously been cooked in a steamer or a frying pan.
Umi budo (sea grapes)	This edible seaweed is prized by the Japanese for its salty taste, which is reminiscent of canned cucumbers. The product also resembles caviar in its appearance, but is green in color.
	When fresh, this product tastes like vegetables, but most often the seaweed is used dried, adding to stews and main courses.
	Chuka algae is a close relative of wakame, possessing the same gastronomic qualities.
Kombu (konbu)	This type of edible algae is often classified as kelp. In Asian countries, kombu is used as a canned snack and is also added to all kinds of soups and side dishes.
Porphyra (nori)	The product is a brown algae that is used to make sushi, rolls, as well as all kinds of salads and first courses.

If you want to cook some original dish at home, the edible algae listed in the table above will help you make your food taste unusual and memorable.

Beneficial features

The benefits of algae lie in the content of active substances, vitamins, macro- and microelements. This product acts on the body as an antitumor agent.

The chemical composition of algae is largely similar to the composition of human blood.

Due to the presence of polyunsaturated fatty acids, with regular consumption of edible seaweed, the risk of rheumatism is significantly reduced, diabetes mellitus and heart diseases vascular system .

Algae strengthens the immune system, which helps the body resist the negative effects of viruses and infections.

Edible algae is even used to produce a large number of medicines.

Use beneficial properties " marine plants"for various cosmetic procedures, and on their basis they prepare preparations for "beauty and youth." Seaweed is used for body wraps, which help reduce the appearance of cellulite and get rid of extra pounds.

Use in cooking

Edible seaweed is becoming more popular every day, and therefore it is widely used in cooking. They can be used to prepare individual side dishes, as well as as a component of salads, appetizers, first and second courses. In dried form, seaweed can play the role of an original spice.

This product goes well with vegetables, mushrooms and even fruits.

To vary the taste of seaweed, you can use sauces.

Harm from algae and contraindications

Edible algae can cause harm if an individual intolerance to the product is detected. You should not consume them in large quantities.

Each type of such product has its own contraindications for use. For example, it is forbidden to eat seaweed if you have tuberculosis and kidney problems.

People with thyroid diseases, ulcers and other diseases of the stomach and intestines should be careful when eating seaweed. If you have any chronic diseases, it is recommended to consult a doctor before consuming any particular variety of edible seaweed.