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Where brown algae live. Interesting facts about algae

Hello everybody! It's time for a new post, the topic of which will be the general characteristics of algae. From what you read below, you will learn their structure, how they reproduce and what algae are in general, what is it?

General characteristics of algae.

Algae are lower semi-aquatic or aquatic plants that inhabit oceans, lakes, streams and ponds, or humid land. Together with animals, they form ocean plankton and are the main source of food for fish.

Some algae are huge and complex in structure, while others are unicellular organisms that are no more than 0.01 mm in diameter. Some of marine species algae reach 100 m in length.

Algae are a rather variegated group of plants that are classified according to characteristics such as cell wall composition and pigmentation.

In total, there are about 20 thousand algae in the world. They find shelter for themselves in hot springs, in which the water is boiling water, and in polar ice, willow salted brine, and in hard water.

Structure.

All algal cells have chromatophores that contain various pigments. Green chlorophyll - the most important of them, it is present in chromatophores called chloroplasts. In different algae, the number and shape of chloroplasts are different.

For example, chlorella has a single calyx-like chloroplast. Spirogyra has numerous chloroplasts, which are connected in long spiral ribbons. And in other algae, they are in the form of stars or saucers.

Each algae group has its own range of pigments in a specific combination. Due to this, there are groups of blue-green, brown, red and green algae. Some of the species form lichens in symbiosis with.

Single-celled algae like chlorella consist of only one cell, where inside the shell there is a carrier of genetic material - DNA (nucleus) - and chloroplasts containing chlorophyll.

Some unicellular algae can move with the help of flagella. Multicellular algae are composed of many filaments that form thallus of different shapes, this is clearly seen in the example of algae.

Reproduction.

Algae reproduce in various ways. Some reproduce vegetatively (fragments of thallus fall off and grow further on their own). Unicellular algae usually reproduce in the same way as some - by division.

Asexual reproduction higher algae occurs with the help of spores that form from the mother's cell. Some spores have flagella (zoospores), which give them mobility.

Same as bacteria conjugation also occurs. In a more intricate way, sexual reproduction occurs in more complex algae (such as fucus). The female and male reproductive organs in most fucus species appear on different plants, but sometimes they are found on one.

The female (oogonia) and male (antheridia) reproductive organs, which appeared in the spring, throw their cells into the water when they are covered by a tidal wave. With the help of flagella, male gametes approach and merge with immobile eggs.

At first, the fertilized egg is enveloped in the cell wall, and later it germinates and gives rise to a new plant.

I hope that the general characteristics of algae helped you to understand everything. 😉

Algae report will tell you about what algae are, and what is the role of algae in nature and human life.

Algae message

Algae live in almost every body of water. They are a wayward indicator of the purity of water and supply it with oxygen, useful for all aquatic inhabitants.

What is algae?

Algae belong to an ecological heterogeneous group of multicellular phototrophic, unicellular and colonial organisms, which, as a rule, live in water bodies. All known types of algae are united with each other by the following features:

1.characterized by photoautotrophic nutrition and the presence of chlorophyll

2.there is no differentiation of the plant body into organs as such

3.algae have a pronounced conducting system

4.have a humid environment

5.No integumentary membrane

Due to the fact that algae are adapted to the aquatic habitat, they have developed a special feature of physiology - the necessary nutrients are absorbed by the entire surface of the plant's body. The vital activity of algae depends on four factors - light, carbon dioxide, chemical composition water and its temperature.

What are the types of algae?

In nature, algae are of three main types:

* Green algae

They belong to the division of lower plants, which have different morphological structures and sizes. They contain carotenoids and chlorophyll plates. Green algae come in multicellular and unicellular forms. Have reserve substance- starch, sometimes oils. It is noteworthy that unicellular green algae live not only in the aquatic environment, but also in soil or snow. But multicellular plants live in upper layers reservoirs, which is due to the implementation of the productive process of photosynthesis.

* Brown algae

Belong to the department of ochrophytic algae. Modern biology has more than 2000 species. Almost all brown algae live in the marine aquatic environment. And only 6 species of these plants were able to adapt to life on dry land in the course of evolution. Scientists have found that the chromatophores of brown algae contain fucoxanthin, a special pigment that stains them brown.

The most common brown algae are: Macrocystis Laminaria and Cystoseira. Chlorophyll is practically absent in their bodies, which makes the vital activity of these algae independent of the processes of photosynthesis. Therefore, the plant habitat is the seabed.

* Red algae

Red algae belong to the group of algae that contain in their body a specific red pigment - phycoerythrin. Their color depends on the amount of phycoerythrin in the body of a plant - it ranges in color from a pronounced pink to dark cherry color.

Red algae are predominantly found in the seas. Their body carries out photosynthesis, despite not a large number of chlorophyll. These plants are widely used in industrial production, most of them are suitable for consumption.

Report on the importance of algae in nature and human life

1. Algae is the basis of food for herbivorous animals such as crustaceans, molluscs, some fish, mammals and others.

2. Algae enrich the water column with oxygen and the air above it. Dead plants of some species are capable of forming sedimentary rocks: diatomite, limestone and tripoli. They contribute to the process of soil formation and increase soil fertility. Algae living in the bottom area are a refuge and home for fish and other aquatic animals.

3. Algae are used by humans for food. Also bromine, iodine, agar-agar are extracted from them, medications are made.

4. They are used for biological water purification and act as a fertilizer.

5. Algae are widely used in chemical, food, paper and textile industries.

In addition to beneficial properties, some types of algae are harmful. For example, unicellular algae, massively multiplying in fresh water bodies, lead to “water bloom. Living in sluices and water filters, they interfere with their normal operation.

We hope this information about algae has helped you. And you can leave your story about algae through the comment form.

Algae are considered the most abundant organisms on planet Earth. They do not belong to plants, although some of their species have characteristics similar to those of plants.

The science that studies algae is called algology. These photosynthetic organisms can spread both in salty and fresh water and on land. Some types of algae can be fed and live in organisms of animals and plants. The main function and feature of algae is that they absorb carbon dioxide in large quantities and produce abundant oxygen. There are algae different forms and sizes, from 1 micron to several meters. They can also be of various colors, and there are also colorless. Algae reproduce sexually, asexually (spore) or vegetatively.

The entire number of algae species has not yet been fully studied by science, approximately 35-40 thousand species fluctuate. Depending on the habitat and reproduction, they are divided into the following ecological subgroups:

Planktonic. They exist both in sea water and fresh, except for hot thermal waters. Often serve as food for fish and aquatic mammals.

Soil. They breed in different types of soils and serve as a kind of fertilizer for them.

Neustonic. They exist, reproduce and migrate on the water surface.

Terrestrial. These are many types of algae that live in a wide variety of places on land: on the bark of trees, on the leaves of plants, even in the shells of turtles.

Benthic. They live at the bottom of water bodies, and also attach to other organisms there. The most famous among them are marine brown. They are relatively large in size and are widely used in the food industry.

Limestone, hot water, cold, arctic algae, as well as a large amount different types algae.

Algae, especially seaweed, are often used in the food industry, since they contain a large amount of iodine and other beneficial trace elements. At this time, there are studies that with the help of some types of algae, many diseases, including oncological ones, can be successfully treated. Therefore, they are often used in pharmacology, as well as in cosmetology.

Report 2

Algae are one of the least studied by scientists, a group of organisms that live mainly in water or in damp soils and places. It is generally accepted to think of algae as plants. In nature, there are more than 100 thousand groups of various species of these organisms, differing in habitat, methods of reproduction, size and appearance... There is a whole branch of science called algology, which studies the properties, species, habitats, methods of reproduction and their use in the national economy. Some types of algae feed on the finished organic matter on the surface of cells, while others swallow the food they need through a kind of cellular mouth. There are microscopic algae up to a fraction of a micron in size, others, under favorable conditions, grow up to 50 meters.

The role of algae in the balanced production of organic substances is great, which are food for many inhabitants, both marine and freshwater bodies. Even some ancient rocks arose as a result of the vital activity of algae in past eras.

Algae are also nutritious and wholesome food, rich in trace elements, especially iodine, and has other beneficial properties. In the countries of East Asia, culinary products using specially processed seaweed are dishes of the national local cuisine, for example, sushi.

In coastal areas, algae are widely used as pet food and fertilizer in home farming. In some countries, there are even developed production facilities for the artificial cultivation of algae for animal nutrition and use in the food and pharmaceutical industries.

Agar-arar substance is obtained from algae, which is widely used in the production of confectionery and various sweets. For medicinal purposes, special additives to medicinal masks and ointments are produced from algae. By industrial processing, iodine is obtained from certain types of algae, analgesics, potassium salts, alcohol and vinegar.

Of particular interest is the use of algae in the treatment and disinfection of wastewater. Although the rapid and uncontrolled reproduction of planktonic species of these organisms can create problems in the operation of the complex of treatment facilities.

In the age of creation alternative species fuel, scientific developments of scientists on the use of algae in the form of biomass as a fuel are of great interest. In some countries, technological processes for obtaining fuel cells have already been developed and are being introduced into production.

Algae message

Each of the representatives of the plant world is of a certain value to humans. Algae are no exception.

The most important function of algae, like any plant, is to distribute a substance necessary for the life of humans and living organisms on earth - oxygen. Thus, they simultaneously absorb atmospheric carbon dioxide.

Most of the entire species diversity of algae is an integral part of the diet of many living organisms. But truly irreplaceable vitamin complex they serve a person, as they are a source of various microelements.

However, in order not to harm the body, we must remember that only some types of algae can be classified as edible. The world famous species - kelp (seaweed) is leading in comparison with many products containing iodine. Kelp is referred to as brown algae. Sushi lovers have an idea of red seaweed, as this particular variety is included in this dish. The absolute accumulation of vitamins of various groups (A, D, C, K) in algae is considered reasonable.

Thanks to their regular use in food, the body of any person independently fights infections from the outside world. They help to strengthen the body's resistance to viruses, increase immunity.

Modern chains of pharmacies and shops selling cosmetics constantly sell dietary supplements and other preparations in which algae extracts are included in different doses.

Among the well-known means by which experts are able to recommend the elimination of toxins from the body, fucus is especially popular. The plant belongs to coastal algae. Its properties continue to amaze researchers who have proven the similarity of the composition of human blood and the chemical composition of this type of algae. Spirulina, which is famous for its considerable protein content, is in great demand all over the world.

In addition to cosmetology and medicine, algae are also used in cooking. Sometimes they are added to candy or ice cream.

Acting as a fertilizer, they are at the same time an effective way to purify water. For example, hyacinth, being a weed, frees water from harmful impurities.

Thus, algae are unique plants that can absorb substances hazardous to human health, being a useful product in pure form or as part of preparations.

Option 4

The flora has spread over almost the entire surface of the earth. Plants can grow through rocks and even in water. Vegetation growing in water is called algae. This is a whole group of organisms of one or many cells. When interacting with other plants and creatures, it is able to reproduce new organisms.

There is a science that studies the kingdom of algae - algology. This science is necessary to know when working in the water area related to fishing, marine ecology and so on. Algae from other plants can be identified by the following criteria: chlorophyll is found in all algae, the method of nutrition is late blight, the presence of a thallus, germination exclusively in water or strongly wet area or surface. Lack of fabrics, leather and other outer shell.

Some algae feed on heterotrophic, i.e. from ready-made recycled substances. The sizes of these plants are very different: from a few millimeters to 50 meters. Depending on the type. All of them are divided into unicellular and multicellular. Among unicellular organisms, there are those that interact closely with each other. Because of one cell, they cannot maintain a constant body shape and are able to move around the surface. This happens through the sliding of the body through a change in shape.

Algae membranes are classified by number, for example, two, three or four membranes. Some species are able to attach their cell to another, thus forming a more complex structure. At the same time, unicellular organisms are better protected by the outer shell from environmental influences.

The role of algae in the aquatic environment is great. They produce 80% of nutrients. They fertilize the ground cover in the water and serve as food for fish, shellfish and other inhabitants of the water area. Algae are among the most ancient plants on the planet. Their remains are found in mountain rocks, with the help of which they determine the age of the mountains.

Without algae, the planet will not be able to get enough oxygen and food. This is a special mineral treasure for all living creatures that breathe and feed, even if outside the sea.

Message 5

Plants that are most often seen in various bodies of water are called algae. They are not only unicellular, but also multicellular.

These plants, it turns out, grow not only under water, but also in humid places on land. Algae can even cover the bark of trees. The adapted species live in cold habitats, for example, on a glacier. Some species are not green, but red or dark brown. This is facilitated by various pigments.

In our world, algae are equated with lower plants. There are more than 25 thousand types of algae in the world. Among them there are both large samples and the smallest ones that are difficult to see with the naked eye. Most often, large species of algae are multicellular, while small species, on the contrary, are unicellular.

The roots, stem and leaves of the algae are absent, instead there is a whole body called the thallus. It contains a large amount of chlorophyll. In the process of evolution, some species disappeared, some species improved and moved from water to land. However, despite the underwater placement of these plants, they are capable of photosynthesis. During photosynthesis, algae produce large amounts of oxygen, which is more than 50% of all oxygen that is produced by plants on Earth.

Humanity has found applications for algae not only as a producer of oxygen, but also as a nutrient and a source of vitamin. One of the known species is called "Laminaria". This algae is used in nutrition, since the kelp contains a large amount of vitamins and useful microelements. Later, this algae began to be used in the manufacture of cosmetics, synthetic substances and much more.

Another well-known representative of algae is Fucus. Unlike kelp, fucus does not grow under water, but on rocks near the water. Fucus also contains a large amount of vitamins and minerals, but it is more often used in the manufacture of cosmetics. The main effect of products containing fucus extract is an anti-cellulite effect.

Algae of other colors, red and brown, grow more underwater than on land. For example, Lithotamnia, a red algae that removes lime from waters, is most common in the seas.

The white water lily is an aquatic plant. Or as they usually call it - water lily. The white water lily is in the Water Lily family. This family has more than 50 plant species

The life and work of Viktor Pelevin

One of the most popular and well-known Russian writers Victor Pelevin remains a mystery to many, and he himself did a lot to remain little-known to the public.

The concept of "algae" is scientifically vague. The word "algae" literally means only that these are plants living in water, however, not all plants in water bodies can be scientifically called algae, such plants as reeds, reeds, cattails, water lilies, egg capsules, small green duckweed plates, etc. others are seed (or flowering) plants. The scientific term "algae" is inapplicable to these plants, they are called aquatic plants

The concept of "algae" is not systematic, but biological. Seaweed ( Algae) Is a composite group of organisms, the main part of which, according to modern concepts, is included in the kingdom of plants ( Plantae), in which it makes up two sub-kingdoms: crimson, or red algae - Rhodobionta and real algae - Phycobionta(the third sub-kingdom of the Kingdom of Plants includes higher (embryonic or leaf-stemmed) plants - Embryobionta). The rest of the organisms attributed to algae are no longer considered plants: blue-green and prochlorophytic algae are often considered an independent group or referred to as bacteria, and euglena algae are sometimes referred to as the kingdom of animals - the simplest. Different groups of algae arose at different times and, apparently, from different ancestors, but as a result of evolution in similar habitats, they acquired many similar features.

Organisms that are grouped into algae have a number of common features... In morphological terms, the most significant feature for algae is the absence of multicellular organs - root, leaves, stem, typical of higher plants. Such a body of algae, undivided into organs, is called 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 non-vascular plants. Algae never form flowers and seeds, but reproduce vegetatively or by spores.

The cells of algae contain chlorophyll, thanks to which they are able to assimilate carbon dioxide in the light (i.e. feed on through photosynthesis), these are mainly 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 (pre-nuclear 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 non-cellular, their sizes vary over a very wide range: the smallest are commensurate with bacterial cells (do not exceed 1 micron in diameter), and the largest marine 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 carried out according to biochemical characteristics (set of pigments, composition of the cell membrane, type of storage substances), as well as according to submicroscopic structure. However, the modern taxonomy of algae is characterized by a wide variety of systems. Even at the highest taxonomic levels (super-kingdoms, sub-kingdoms, divisions and classes), taxonomists cannot come to a consensus.

According to one of the modern systems, algae are divided into 12 sections: blue-green, prochlorophytic, red, golden, diatomaceous, cryptophytic, dinophytic, brown, yellow-green, euglena, green, chara. In total, about 30 thousand species of algae are known.

The science of algae is called algology or ficology, 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 are taken into account when developing general biological problems and economic problems. The development of applied algology goes in three main directions: 1) the use of algae in medicine and in various areas of the economy; 2) to address environmental issues; 3) accumulation of data on algae for solving problems of other industries.

Algae structure.

The main structural unit of the body of algae, represented by unicellular and multicellular forms, is the cell. There are various types of algal cells, they are divided according to their shape (spherical, cylindrical, etc.), functions (sexual, vegetative, capable and not capable of photosynthesis, etc.), location, etc. But the most fundamental classification today is considered cells according to the peculiarities of their fine structure, detected using an electron microscope. From this point of view, distinguish between cells containing typical nuclei (i.e. nuclei surrounded by nuclear membranes), and cells that do not have typical nuclei. The first case is the eukaryotic structure of the cell, the second is about the prokaryotic . Blue-green and prochlorophytic algae have a prokaryotic structure of a cell, representatives of all other divisions of algae have a eukaryotic structure.

The vegetative body of algae (thallus) is distinguished by morphological diversity; algae can be unicellular, colonial, multicellular and non-celled. 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, cellular and organismal features are combined in its structure and physiology. This is an autonomous system capable of growing and self-reproducing, a small, invisible unicellular algae 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, oxygen and carbon dioxide are important products of its vital activity and, thus, it actively participates in the cycle of substances in nature. Unicellular algae sometimes form temporary or permanent clusters (colonies).

Multicellular forms arose after the cell underwent a long and difficult path development as an independent organism. The transition from a unicellular to a multicellular state was accompanied by a loss of individuality and related changes in the structure and functions of the cell. Inside 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.

A unique group is made up of siphon algae: 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, in the course of evolution, acquired the ability to photosynthesis, the process of forming organic matter under the influence of light. In photosynthesis, carbon dioxide (CO 2) is used as a carbon source, water (H 2 O) is used as a hydrogen source, and as a result free oxygen is released.

Type of food 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, under certain conditions, many algae can quite easily switch from the photosynthetic way of feeding to assimilating various organic compounds, while the body uses ready-made organic substances for nutrition, or combines this way of feeding with photosynthesis.

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

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

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

The origin of algae.

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

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

There is currently no single point of view on the origin of eukaryotic (nuclear) algae. There are two groups of theories, emanating from either symbiotic or non-symbiotic origins, but 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 - prokaryotic algae, mitochondria - 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 the 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 has chlorophyll and photosynthesis with the release of oxygen, in this case, modern photosynthetic prokaryotes (blue-green algae) are a lateral, 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, availability of water, carbon sources, mineral and organic substances. Algae are widespread around the globe and can be found in water, in soil and on its surface, on the bark of trees, walls of wooden and stone buildings, and even in inhospitable places such as deserts and glaciers.

The factors influencing the development of algae are subdivided into abiotic, not related to the activity of living organisms, and biotic, due to this activity. Many factors, especially abiotic ones, are limiting, i.e. they are able to restrict the development of algae. The life of all organisms, including algae, depends on the content of the necessary substances in the environment, the value of physical factors, as well as the range of stability of the organisms themselves against changes in environmental conditions. The level at which a particular factor can act as a limiting factor is different for different types of algae. In aquatic ecosystems, the limiting factors include temperature, transparency, flow, 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 character of terrestrial communities and ecosystems.

For most algae, water is a permanent habitat, but many of their species can live outside the water. Among the plants living on land, according to their resistance to drying, they distinguish poikilohydric, which are not able to maintain a constant water content in the tissues, and homoyhydric, which are able to maintain constant tissue hydration. In poikilohydric algae (blue-green and some green algae), the cells, when dried, shrink without irreversible changes in the ultrastructure and, therefore, do not lose their viability; when moistened, normal metabolism is restored. The minimum humidity at which normal activity of such plants is possible is different. The cells of homoyhydric algae die upon drying, therefore, such plants, as a rule, live with constantly excessive moisture. Homeyhydric 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 the most varied salinity: from fresh water bodies, the salinity 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 value. Euryhaline there are relatively few algae species that can exist at different salinity.

The acidity of the water is also a limiting factor. The resistance of different taxa of algae to changes in acidity (pH) is as different as to changes in salinity. Some types of algae live only in alkaline waters, at high pH, others live in acidic waters, at low pH.

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

Elements and their compounds related to macronutrients are required by organisms in relatively large quantities. The most important are nitrogen and phosphorus, potassium, calcium, sulfur and magnesium are almost equally needed.

Trace elements are necessary for plants in extremely small quantities, but they are of great importance for their life, since they are part of many vital enzymes. Trace elements 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 different requirements 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 the water. In fresh water with low content of carbonates, the concentration of calcium salts and some others can be ranked as limiting factors.

Light is necessary for algae 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 in too much or too little illumination.

The distribution of algae in the water column is largely determined by the availability of light required for normal photosynthesis. The water layer 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 sinking to a depth of 120 m, and in clear waters ocean - up to about 140 m. In lacustrine, much less transparent waters, the border 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 values of illumination for different types of algae vary widely. In relation to light, heliophilic and heliophobic algae are distinguished. Heliophilic(light-loving) algae need a significant amount of light for normal life. These include most blue-green algae and a significant amount of green algae, abundantly developing in summer time in the surface layers of water. Heliophobic(avoiding bright light) algae are adapted to low light conditions. For example, most diatoms avoid the brightly lit surface layer of water and develop intensively in low-transparent lake waters at a depth of 2–3 m, and in transparent waters of the seas - at a depth of 10–15 m.

In algae of different divisions, depending on the composition of special light-sensitive pigments, the maximum activity of photosynthesis is observed when different lengths light waves. In terrestrial conditions, the frequency characteristics of light are quite constant, therefore, the intensity of photosynthesis is also constant. When passing through water, light of the red and blue spectral regions is absorbed, and greenish light, poorly perceived by chlorophyll, penetrates into the depth. Therefore, it is mainly red and brown algae that survive there, which have additional photosynthetic pigments that can use the energy of green light. Hence, it becomes clear that light has a huge effect on the vertical distribution of algae in the seas and oceans: green algae, as a rule, prevail in the near-surface layers, brown algae in deeper ones, and red algae in the deepest areas. However, this pattern is not absolute. Many algae are able to exist in conditions of extremely low, uncharacteristic illumination, and sometimes in complete darkness. At the same time, they may experience certain changes in the pigment composition or in the way of nutrition. So, representatives of many departments of algae are able, in the absence of light and an excess of organic matter, to switch to feeding on organic compounds of 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 of nutrients and the removal of waste products of algae. In any continental and marine water bodies there is a relative movement of water masses, therefore, almost all algae of water bodies are inhabitants of flowing waters. The only exceptions are algae, which develop in especially extreme conditions (in rock voids, thicker ice, etc.).

Algae are characterized by very wide temperature stability 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 that exist over a wide temperature range (for example, green algae from the order Oedogoniales, whose sterile filaments can be found in shallow water bodies from early spring to late autumn), and stenothermal adapted to very narrow, sometimes extreme temperature zones. Stenothermal include, for example, cryophilic(cold-loving) algae that grow only at temperatures close to 0 ° C and thermophilic(thermophilic) algae that cannot exist at temperatures below 30 ° C.

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

Algae, being a part of ecosystems, are connected with the rest of their components by multiple connections. Direct and indirect influences caused by the vital activity of other organisms, endured by algae, are referred to as biotic factors.

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

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

Some types of algae can fold competitive relationship with each other for their habitats.

Man has a significant impact on natural ecosystems, which makes the anthropogenic factor very essential for the development of algae. By laying canals and constructing reservoirs, people create new habitats for aquatic organisms, often fundamentally different from the water bodies of this region in terms of hydrological and thermal regime. Wastewater discharges often lead to the depletion of the species composition and the death of algae or to the massive development of certain species. The first occurs when toxic waters are discharged, the second - when the reservoir is enriched with biogenic substances (especially nitrogen and phosphorus compounds). The consequence of the immoderate discharge of nutrients into the reservoir may be its eutrophication, which leads to the rapid development of algae ("water bloom"), oxygen deficiency, and the death of fish and other aquatic animals. Algae, especially aerophytic and soil algae, can also be influenced 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. Various environmental groups these organisms: 1) planktonic algae; 2) neuston algae; 3) benthic algae; 4) terrestrial algae; 5) soil algae; 6) hot spring algae; 7) algae of snow and ice; 8) algae of salt water bodies; 9) algae that exist in the 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 unable to resist the transfer by currents (i.e., as if floating in water). The plankton includes phyto-, bacterio- and zooplankton.

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

Planktonic algae live in a wide variety of water bodies - from a small puddle to the ocean. They are absent only in water bodies with a sharply abnormal regime, including in thermal (at a water temperature above + 80 ° C and frozen (contaminated with hydrogen sulfide) water bodies, in clean periglacial waters that do not contain mineral nutrients, as well as in cave lakes. the biomass of phytoplankton is small compared to the biomass of zooplankton (1.5 and more than 20 billion tons, respectively), but due to its rapid reproduction, 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 of the food webs in a body of water: it feeds on small planktonic animals that feed on larger ones. Therefore, in areas of the highest 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 water bodies reaches 3000.

In inland water bodies, there is a much greater variety of ecological conditions in comparison with sea water bodies, which also determines a much greater diversity of the species composition and ecological complexes of freshwater phytoplankton as compared to marine ones. One of the essential features of freshwater phytoplankton is the abundance of temporarily planktonic algae in it. A number of species, which are considered to be typically planktonic, in ponds and lakes have a bottom or periphyton (attachment to an object) phase in their development.

Marine phytoplankton consists mainly of diatoms and dinophytes. Though marine environment over large areas, it is relatively homogeneous; there is no homogeneity in the distribution of marine phytoplankton. Differences in species composition and abundance are often expressed even in relatively small areas of sea water, but they are especially clearly reflected in large-scale geographic zoning distribution. This is where the effect of the main environmental factors is manifested: water salinity, temperature, illumination and nutrient content.

Planktonic algae usually have special adaptations for suspended habitat in the water column. In some species, these are all sorts of outgrowths and appendages of the body - spines, bristles, horny processes, membranes, parachutes; others form hollow or flat colonies and mucus profusely; still others accumulate substances in their bodies, the specific gravity of which is less than the specific gravity of water (drops of fat 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 of these adaptations is the small size of the body of planktonic algae.

Neustonic algae.

The aggregate of marine and freshwater organisms living near the surface film of water, attaching to it or moving along it is called neuston. Neustonic organisms live both in shallow water bodies (ponds, pits filled with water, small bays of lakes) and in large ones, including in the seas. In some cases, they develop in such an amount that they cover the water with a continuous film.

The composition of neuston includes unicellular algae, which are part of different systematic groups(golden, euglena, green, certain types of yellow-green and diatoms). Some neuston algae have characteristic adaptations to exist 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 at the bottom of water bodies and on various 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 thallus forms. All of them can be overgrown with small diatoms, blue-green and other algae.

Sometimes algae growing on objects introduced into the water by a person (ships, rafts, buoys) are referred to as periphyton... The selection of this group is justified by the fact that the organisms included in its composition (algae and animals) live on objects moving or streamlined by water. In addition, these organisms are far from the bottom and, therefore, are in conditions of different light and temperature regimes, as well as in other conditions of nutrient intake.

The possibility of the growth of benthic algae in specific habitats is determined by both abiotic and biotic factors. Among the latter, a significant role is played by competition with other algae and the presence of animals feeding on algae (sea urchins, gastropods, crustaceans, fish). The impact of biotic factors leads to the fact that certain species of algae do not grow at any depth and not in any water bodies with a suitable light and hydrochemical regime.

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 of entry of these substances into the thallus is very important, which depends on the concentration of substances and the speed of movement of water.

Benthic algae that grow under water movement have advantages over algae that grow in sedentary waters. The same level of photosynthesis can be achieved in them at lower illumination, which promotes the growth of larger thalli; the movement of water prevents silt particles from settling on rocks and stones, which interfere with the fixation of algae rudiments, and also washes away animals feeding on algae from the soil surface. In addition, despite the fact that during strong currents or strong surf the thalli of algae are damaged or separated 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 intensive movement of water (in the seas these are straits with currents, coastal areas of the surf, in rivers - stones on rifts) are distinguished by the lush development of benthic algae.

The influence of water movement on the development of benthic algae is especially noticeable in rivers, streams, mountain streams. In these reservoirs, a group of benthic organisms is distinguished, preferring places with a constant current. In lakes where there are no strong currents, wave movement is 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 easiest to find near the coast 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 creeks, in the seas - in shallow 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 inhabit hot springs, geysers and volcanic lakes. Often they live in waters that, in addition to high temperatures, are characterized by an increased content of salts or organic matter (highly polluted hot wastewater from factories, factories, power plants or nuclear power plants).

The limiting 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 found, however, there are relatively few species among them that live only at high temperatures. Most of them are able to withstand high temperatures, but they develop more abundantly at normal temperatures. Typical inhabitants of hot waters are blue-green algae, to a lesser extent - diatoms and some green algae.

Snow and ice algae.

Snow and ice algae make up the overwhelming majority of organisms that inhabit frozen substrates (cryobiotopes). The total number of algal species found on cryobiotopes reaches 350, but the true cryophiles capable of vegetating only at temperatures close to 0 ° C are much smaller: slightly more than 100 species. These are microscopic algae of which the overwhelming majority belongs to green algae (about 100 species); several species are blue-green, yellow-green, golden, pyrophytic and diatoms. All of these species inhabit the surface layers of snow or ice. They are united by the ability to withstand freezing without disturbing the fine cellular structures and then, upon thawing, quickly resume vegetation using the minimum amount of heat. Only a few of them have dormant stages, most are devoid of any special adaptations to withstand low temperatures.

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

Salt water algae.

These algae vegetate when increased concentration in salt water, reaching 285 g / l in lakes with a predominance table salt and 347 g / l in Glauber (soda) lakes. As the salinity increases, the number of algae species decreases; only a few of them tolerate very high salinity. In extremely saline (hyperhaline) water bodies, unicellular mobile green algae prevail. They often cause red or green "bloom" of salt water bodies. The bottom of hyperhaline reservoirs is sometimes completely covered with blue-green algae. they play an important role in the life of salt water bodies. The combination of organic matter formed by algae and a large amount of salts dissolved in water determines a number of peculiar biochemical processes inherent in these reservoirs. For example, sarcinoid chloroglea (Chlorogloea sarcinoides) from blue-green, 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 therapeutic mud.

Algae in out-of-water habitats.

Aerophilic algae.

Aerophilic algae are in direct contact with the air around them. A typical habitat of such algae is the surface of various extra-soil solid substrates that do not have a pronounced physicochemical 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 constant shift moisturizing and drying; and water-air algae exposed to constant irrigation with water (spray from a waterfall, surf, etc.).

The conditions for the existence of algae in these communities are very peculiar and are characterized, first of all, by frequent and abrupt changes in temperature and humidity. During the day, aerophilic algae get very hot, cool at night, and freeze in winter. Air algae are especially susceptible to changing moisture conditions, since they are often forced to move from a state of excessive moisture (for example, after a rainstorm) to a state of minimal moisture (during dry periods), when they dry so much that they can be ground into powder. Air-water algae live in conditions of relatively constant moisture, however, they also experience significant fluctuations in this factor. For example, algae living on rocks irrigated with spray from waterfalls, in the summer, when the runoff is significantly reduced, experience a moisture deficit.

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

With the development of aerophilic algae in mass quantities, they usually have the form of powdery or mucous deposits, felt-like masses, soft or hard films or crusts. The growth of algae on the surface of wet rocks is especially abundant. They form films and growths of various colors. As a rule, species with thick mucous envelopes live here. Depending on the intensity of the light, the mucus is 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 communities of algae are very diverse and arise both under quite favorable and extreme conditions... Their external and internal adaptations to this way of life are diverse and similar to those found in soil algae, especially those developing on the soil surface.

Edaphophilic algae.

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

The soil as a biotope is similar to water and air habitats: it contains air, and it is saturated with water vapor, which ensures respiration atmospheric air without the threat of drying out. However, the soil is fundamentally different from the above biotopes in its opacity. This factor has a decisive influence on the development of algae. The intensive development of algae as phototrophic organisms is possible only where light penetrates. In virgin soils, this is the surface layer of soil up to 1 cm thick, however, in such soils, algae are also found on much deeper(up to 2 m). This is due to 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 provided in them by a number of morphological and physiological characteristics (smaller sizes in comparison with the aquatic forms of the same species, abundant mucus formation). The amazing vitality 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 a 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 transition from a state of dormancy to active life and vice versa. They are also able to withstand different fluctuations in soil temperature. The range of survival of a number of species lies in the range from –20 ° to + 84 ° С. It is known that terrestrial algae make up a significant part of the vegetation of Antarctica. They are painted almost black, 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 rapidity of growth even with a short-term appearance of the necessary conditions.

The vast majority of soil algae are microscopic forms, 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 the sides of forest roads, "blooming" of arable soils.

The number of all types of soil algae is approaching 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. They usually dwell in the depths hard rocks a certain chemical composition, surrounded by air (i.e. outside the water) or immersed in water. There are two groups of lithophilic communities: boring algae and tuff-forming algae.

Drilling algae are organisms that invade the calcareous substrate. These algae are not numerous in terms of the number of species, but they are extremely widespread: from the cold waters of the north to the constantly warm waters of the tropics. They inhabit both continental and sea water bodies, near the surface of the water and at a depth of more than 20 m. Drilling algae settle on lime 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 calcareous substrate, they gradually penetrate into it due to the release of organic acids that dissolve the lime underneath. Inside the substrate, algae grow, forming numerous channels, with the help of which they maintain a connection with the external environment.

Tuff-forming algae – organisms that deposit lime around their bodies and live in the peripheral layers of the environment they deposit, within the limits available for the diffusion of light and water. The amount of lime released by algae is different. 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 threads. Other species release lime so abundantly that they gradually become completely submerged in the sediments, which, in the end, 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

Cases of cohabitation of algae with other organisms are of particular interest. Most often, algae are used by living organisms as a substrate, along with stones, concrete and wooden structures, etc. By the nature of the substrate on which fouling algae settle, among them are distinguished epiphytes settling on plants, and epizoites living on animals.

Algae can also live in the tissues of other organisms: both extracellularly (in mucus, intercellular 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 the endosymbioses of unicellular green and yellow-green algae with unicellular animals.

Among the symbiosis 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, called "lichens", arose. This symbiosis shows the unique biological unity that led to the emergence of a fundamentally new organism. At the same time, each partner of 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 the two.

Algae play a huge role in nature. They are the main producers of organic food and oxygen in the aquatic ecosystems of the Earth, and, in addition, play a large role in the overall oxygen balance of the planet. In terrestrial habitats, soil algae, along with other microorganisms, play the role of pioneers of vegetation. Algae are involved in the 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 grandiose geological formations created by living organisms. The geochemical role of algae is primarily associated with the natural cycle of calcium and silicon.

The historical role of algae is great. The emergence of an oxygen-containing atmosphere, the emergence of living beings on land and the development of aerobic forms of life that now dominate our planet - all these are the results of the activity of the most ancient photosynthetic organisms - blue-green algae. The massive development of algae in past geological epochs has led to the formation of thick strata of rocks. The plants that populated the land originated from algae.

It is difficult to overestimate the importance of algae for human life. Algae are removed important role in solving a number of global problems of concern to all mankind, including food, energy, environmental protection, the development of the bowels of the Earth and the riches of the World Ocean, the search for new sources of industrial raw materials, building materials, pharmaceuticals, biologically active substances and new objects of biotechnology.

Natalia Novoselova

Brown algae, like red algae, almost always live in the seas and oceans, that is, in salt waters. They are all multicellular. Among brown algae, there are 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 a depth of up to 100 m. In the seas and oceans, they form a kind of 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 with yellow, brown, orange colors. These pigments "interrupt" green color plants, giving it a brownish tint.

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

Some types of brown algae have a complexly dissected thallus, which is more than 10 m long.

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

Various types of growth are observed in brown algae. Some species grow with their apex, in others all thallus cells retain the ability to divide, in others, surface cells divide, and fourths have special zones of cells in the body, the division of which leads to an increase in tissues above and below them.

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

The cells have one nucleus, many small disc-shaped chloroplasts. Chloroplasts differ in structure from those of higher plants.

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

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

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

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

The most famous representative of brown algae is kelp that a person eats, calling her seaweed... She has rhizoids, with which she attaches to underwater objects (stones, rocks, etc.). The kelp has a semblance of a stem (stem), this part of the plant is not flat, but cylindrical. The length of the stem is up to half a meter, similarities of flat sheet plates(several meters each).

Human brown algae are used not only for food, they are used in the food and textile industries, and some medicines are made from them.

Algae can be positioned as the most numerous organisms that are distributed throughout the globe. They live not only in fresh and salt water bodies, 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 slime of green or blue-green color.

Where do algae live?

Certain types of algae are able to attach to rocks and stones. Most of these organisms live in the upper layers of the water cover. Some algae can live 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 keep the 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 method of nutrition, so algae absorb inorganic substances from the environment. Subsequently, through photosynthesis, algae receive the organic matter they need, while releasing oxygen. A large number of animals and fish that consume algae for food can be considered as natural enemies of these species.

Are algae dangerous for humans?

Algae are used by humans for 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 can lead to 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 department of true multicellular brown algae. This group of plants includes 250 genera and about 1500 species. The most famous representatives are kelp, cystoseira, sargass.

These are mainly marine plants, only 8 species are secondary freshwater forms. Brown algae are ubiquitous in the seas of the globe, reaching a special diversity and abundance in cold water bodies of the subpolar and temperate latitudes, where they form large thickets in the coastal strip. In the tropical zone, the largest accumulation of brown algae is noted in the Sargasso Sea; their mass 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, shellfish, 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 in the cells, in addition to chlorophyll, there is 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

The species can be both annual and perennial.

Tall... In algae of this group, thallus can be of various shapes: creeping or vertically "hanging" filaments, plates (whole or cut) or branching bushes. The thalli are attached to a 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, which is very slimy. Structural components cell walls are cellulose and pectin. Each cell of brown algae contains one nucleus and vacuoles (from one to several). Chloroplasts are small, disc-shaped, brown in color due to the fact that, in addition to chlorophyll and carotene, they have a high concentration of brown pigments - xanthophylls, in particular fucoxanthin. Also in the cytoplasm of the cell are deposited reserves of nutrients: laminarin polysaccharide, polyhydric alcohol mannitol and various fats (oils).

Reproduction of brown algae... Reproduction is carried out asexually and sexually, rarely vegetatively. The organs of reproduction are sporangia, both unilocular and multi-celled. Usually there is a gametophyte and a sporophyte, and in the higher algae they alternate in a strict sequence, while in the 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, occupying vast areas, many marine inhabitants find refuge and food. In industry, they are used in the production of alginic acids and their salts, for the production of feed flour and powder for the manufacture of medicines containing iodine and a number of other microelements in high concentrations. In aquariums, the appearance of brown algae is associated with insufficient lighting. Some species are eaten.

Types and habitats of algae

The abundance and species composition of phytoplankton depends on the complex of factors discussed above. In this regard, the species composition of planktonic algae in different water bodies (and even in the same water body, 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-green, golden, euglena, green and some others) gains predominant development, and often only one species of a particular group dominates. This is especially pronounced in freshwater reservoirs. In inland water bodies, there is a much greater variety of ecological conditions in comparison with sea water bodies, which also determines a much greater diversity of the species composition and ecological complexes of freshwater phytoplankton as compared to marine ones. One of the essential features of freshwater phytoplankton is the abundance of temporarily planktonic algae in it. A number of species, which are considered to be typically planktonic, in ponds and lakes have a bottom or periphyton (attachment to an 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 homogeneity in the distribution of marine phytoplankton. Differences in species composition and abundance are often expressed even in relatively small areas of sea waters, but they are especially clearly reflected in the large-scale geographic distribution zoning. This is where the effect of the main environmental factors is manifested: water salinity, temperature, illumination and nutrient content.

The composition of neuston includes unicellular algae that are part of different taxonomic groups (golden, euglena, green, certain species of yellow-green and diatoms). Some neuston algae have characteristic adaptations to exist 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 at the bottom of water bodies and on various 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 thallus forms. All of them can be overgrown with small diatoms, blue-green and other algae.

Depending on the place of growth, among benthic algae they differ:

1) epiliths growing on the surface of solid ground (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, penetrating into the calcareous substrate (rocks, mollusk shells, crustacean shells);

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

8) epizoites inhabiting some benthic animals.

Sometimes algae growing on objects introduced into the water by a person (ships, rafts, buoys) are referred to as periphyton. The selection of this group is justified by the fact that the organisms included in its composition (algae and animals) live on objects moving or streamlined by water. In addition, these organisms are far from the bottom and, therefore, are in conditions of different light and temperature regimes, as well as in other conditions of nutrient intake. The possibility of the growth of benthic algae in specific habitats is determined by both abiotic and biotic factors. Among the latter, competition with other algae and the presence of animals feeding on algae (sea urchins, gastropods, crustaceans, fish). The impact of biotic factors leads to the fact that certain species of algae do not grow at any depth and not in any water bodies with a suitable light and hydrochemical regime.

Hot spring algae:

Algae that can withstand high temperatures are called thermophilic.

In nature, they inhabit hot springs, geysers and volcanic lakes. Often they live in waters that, in addition to high temperatures, are characterized by an increased content of salts or organic matter (highly polluted hot wastewater from factories, factories, power plants or nuclear power plants).

The limiting 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 among them that live only at high temperatures. Most of them are able to withstand high temperatures, but they develop more abundantly at normal temperatures. Typical inhabitants of hot waters are blue-green algae, to a lesser extent - diatoms and some green algae.

Snow and ice algae:

These are microscopic algae of which the overwhelming majority belongs to green algae (about 100 species); several species are blue-green, yellow-green, golden, pyrophytic and diatoms. All of these species inhabit 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 disturbing the fine cellular structures and then, upon thawing, quickly resume vegetation using the minimum amount of heat. Only a few of them have dormant stages, most are devoid of any special adaptations to withstand low temperatures.

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

Salt water algae:

These algae vegetate at an increased concentration of salts in water, reaching 285 g / l in lakes with a predominance of sodium chloride and 347 g / l in Glauber (soda) lakes. As the salinity increases, the number of algae species decreases; only a few of them tolerate very high salinity. In extremely saline (hyperhaline) water bodies, unicellular mobile green algae prevail. They often cause red or green "bloom" of salt water bodies. The bottom of hyperhaline reservoirs is sometimes completely covered with blue-green algae. they play an important role in the life of salt water bodies. The combination of organic matter formed by algae and a large amount of salts dissolved in water determines a number of peculiar biochemical processes inherent in these reservoirs. For example, sarcinoid chloroglea (Chlorogloea sarcinoides) from blue-green, 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 therapeutic 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 problems of bioindication, since all these groups play a leading role in the general circulation of substances in the reservoir. Organisms that are usually used as bioindicators are responsible for the self-purification of the reservoir, participate in the creation of primary products, and transform the substances and energy of aquatic ecosystems.

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

Among the huge variety of microalgae, algae of the Chlorophyta division inhabiting plankton are most often used to assess the effect of substances, while representatives of other divisions remain poorly studied, which is especially true for benthic microalgae.

Pollution of seawater is complex and, therefore, an assessment of its nature and action can only be carried out using biotesting, which is a means of obtaining fundamentally new information about pollution. Single-celled algae, due to their year-round availability and high sensitivity, are widely used as test objects in biotesting.

the value of brown algae

Brown algae are one of the main sources of organic matter in the coastal zone, especially in the seas of the temperate and circumpolar zones, where their biomass can reach tens of kilograms per square meter. Thickets of brown algae serve as a shelter, breeding and feeding place 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 whose thickets off the coast of South America Charles Darwin wrote: “These huge underwater forests of the southern hemisphere, I can only compare with terrestrial forests of tropical regions. And yet, if a forest were to be destroyed in some country, I do not think that at least approximately as many animal species would die as with the destruction of this algae. "

The role of brown algae in human economic activity is also great. Together with other organisms, they participate in fouling of ships and buoys, impairing their performance. But brown algae are of much greater importance as a raw material for obtaining various kinds of substances.

First, brown algae is the only source of alginates - alginic acid soda.

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

Solutions with the addition of alginates do not lose their qualities during freezing and thawing. The use of alginates improves the quality of printing books, makes natural fabrics colorfast and waterproof. Alginates are used in the production of plastics, synthetic fibers and plasticizers, to obtain weather-resistant paints and varnishes 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 foundry earth. Alginates are used in fuel briquetting, in the production of electrodes for electric welding, allowing for higher quality welds. It is difficult to name a branch of the national economy where alginates are not used.

Another important substance obtained from brown algae is the hexahedral alcohol mannitol. It is used in the pharmaceutical industry for the manufacture of tablets, in the preparation of diabetic foodstuffs, in the production of synthetic resins, paints, paper, explosives, and in the manufacture of leather. More and more mannitol is used in surgical operations.

Brown algae contain a large amount of iodine and other trace elements. Therefore, they go to the preparation of feed flour, which is used as an additive to feed for farm animals. Due to this, the mortality of livestock is reduced, its productivity increases, in a number of agricultural products (eggs, milk), the iodine content increases, which has essential for areas where the population suffers from a lack of it.

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

Fresh and processed brown algae are used as fertilizers.

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

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

Of the greatest importance in this regard are representatives of the kelp order, of which they prepare greatest number a wide variety of dishes.

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