Animal biomass of the total biomass of the ocean. Lecture "biomass of the biosphere"

The biomass of the biosphere is approximately 0.01% of the mass of the inert matter of the biosphere, and about 99% of the biomass is accounted for by plants, and about 1% by consumers and decomposers. Plants dominate on the continents (99.2%), animals dominate in the ocean (93.7%)

The biomass of land is much larger than the biomass of the world's oceans, it is almost 99.9%. This is due to the longer life expectancy and the mass of producers on the surface of the Earth. Land plants use solar energy for photosynthesis reaches 0.1%, and in the ocean - only 0.04%.

"2. Biomass of land and ocean»

Topic: Biomass of the biosphere.

1. Land biomass

Biomass of the biosphere - 0.01% of the inert matter of the biosphere,99% are plants. Plant biomass dominates on land(99,2%), in the ocean - animals(93,7%). The land biomass is almost 99.9%. This is due to the greater mass of producers on the surface of the Earth. The use of solar energy for photosynthesis on land reaches 0,1%, and in the ocean - only0,04%.

Land surface biomass is represented by biomasstundra (500 species) , taiga , mixed and deciduous forests, steppes, subtropics, deserts andtropics (8000 species), where living conditions are most favorable.

soil biomass. The vegetation cover provides organic matter to all the inhabitants of the soil - animals (vertebrates and invertebrates), fungi and great amount bacteria. "Great gravediggers of nature" - this is how L. Pasteur called the bacteria.

3. Biomass of the oceans

– benthic organisms (from Greek.benthos- depth) live on the ground and in the ground. Phytobenthos: green, brown, red algae are found at a depth of up to 200 m. Zoobenthos is represented by animals.

– planktonic organisms (from Greek.planktos - wandering) are represented by phytoplankton and zooplankton.

– Nektonic organisms (from Greek.nektos - floating) are able to actively move in the water column.

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"Biomass of the Biosphere"

Lesson. biomass biosphere

1. Land biomass

The biomass of the biosphere is approximately 0.01% of the mass of the inert matter of the biosphere, with about 99% of the biomass accounted for by plants, and about 1% by consumers and decomposers. Plants dominate on the continents (99.2%), animals dominate in the ocean (93.7%)

The biomass of land is much larger than the biomass of the world's oceans, it is almost 99.9%. This is due to the longer life expectancy and the mass of producers on the surface of the Earth. In land plants, the use of solar energy for photosynthesis reaches 0.1%, while in the ocean it is only 0.04%.

The biomass of various parts of the Earth's surface depends on climatic conditions - temperature, amount of precipitation. severe climatic conditions tundra - low temperatures, permafrost, short cold summer formed a peculiar plant communities with little biomass. The vegetation of the tundra is represented by lichens, mosses, creeping dwarf forms of trees, herbaceous vegetation that can withstand such extreme conditions. The biomass of the taiga, then mixed and broad-leaved forests gradually increases. The steppe zone is replaced by subtropical and tropical vegetation, where the conditions for life are most favorable, the biomass is maximum.

In the upper layer of the soil, the most favorable water, temperature, gas conditions for life. Vegetation cover provides organic matter to all the inhabitants of the soil - animals (vertebrates and invertebrates), fungi and a huge number of bacteria. Bacteria and fungi are decomposers, they play a significant role in the circulation of substances in the biosphere, mineralizing organic substances. "The great gravediggers of nature" - this is how L. Pasteur called the bacteria.

2. Biomass of the world's oceans

Hydrosphere"water shell" is formed by the World Ocean, which occupies about 71% of the surface the globe, and land water bodies - rivers, lakes - about 5%. Much water is in groundwater and glaciers. Due to the high density of water, living organisms can normally exist not only at the bottom, but also in the water column and on its surface. Therefore, the hydrosphere is populated throughout its thickness, living organisms are represented benthos, plankton and nekton.

benthic organisms(from the Greek benthos - depth) lead a benthic lifestyle, live on the ground and in the ground. Phytobenthos is formed by various plants - green, brown, red algae, which grow at different depths: green at a shallow depth, then brown, deeper - red algae that occur at a depth of up to 200 m. Zoobenthos is represented by animals - mollusks, worms, arthropods, etc. Many have adapted to life even at a depth of more than 11 km.

planktonic organisms (from Greek planktos - wandering) - inhabitants of the water column, they are not able to move independently over long distances, they are represented by phytoplankton and zooplankton. Phytoplankton includes unicellular algae, cyanobacteria, which are found in marine waters to a depth of 100 m and are the main producer of organic matter - they have an unusual high speed breeding. Zooplankton are marine protozoa, coelenterates, small crustaceans. These organisms are characterized by vertical diurnal migrations, they are the main food base for large animals - fish, baleen whales.

Nektonic organisms(from Greek nektos - floating) - inhabitants aquatic environment capable of actively moving in the water column, overcoming long distances. These are fish, squid, cetaceans, pinnipeds and other animals.

Paperwork with cards:

Compare the biomass of producers and consumers on land and in the ocean.

How is biomass distributed in the oceans?

Describe the biomass of land.

Define the terms or expand the concepts: nekton; phytoplankton; zooplankton; phytobenthos; zoobenthos; the percentage of the Earth's biomass from the mass of the inert matter of the biosphere; the percentage of plant biomass of the total biomass of terrestrial organisms; percentage of plant biomass of total aquatic biomass.

Board card:

What is the percentage of the Earth's biomass from the mass of the inert matter of the biosphere?

What percentage of the Earth's biomass is plants?

What percentage of the total biomass of terrestrial organisms is plant biomass?

What percentage of total aquatic biomass is plant biomass?

What percentage of solar energy is used for photosynthesis on land?

What % of solar energy is used for photosynthesis in the ocean?

What are the organisms that inhabit the water column and are carried by sea currents called?

What are the organisms that live in the ocean called?

What are the organisms that actively move in the water column called?

Test:

Test 1. The biomass of the biosphere from the mass of the inert matter of the biosphere is:

Test 2. The share of plants from the biomass of the Earth accounts for:

Test 3. Biomass of plants on land compared to biomass of terrestrial heterotrophs:

Makes up 60%.

Makes up 50%.

Test 4. Biomass of plants in the ocean compared to the biomass of aquatic heterotrophs:

It prevails and makes up 99.2%.

Makes up 60%.

Makes up 50%.

Less than the biomass of heterotrophs and is 6.3%.

Test 5. The use of solar energy for photosynthesis on land averages:

Test 6. The use of solar energy for photosynthesis in the ocean averages:

Test 7. Ocean benthos is represented by:

Test 8. Ocean Nekton is represented by:

Animals actively moving in the water column.

Organisms that inhabit the water column and are carried by sea currents.

Organisms that live on and in the ground.

Organisms that live on the surface film of water.

Test 9. Ocean plankton is represented by:

Animals actively moving in the water column.

Organisms that inhabit the water column and are carried by sea currents.

Organisms that live on and in the ground.

Organisms that live on the surface film of water.

Test 10. From the surface deep into the algae grow in the following order:

Shallow brown, deeper green, deeper red up to -200 m.

Shallow red, deeper brown, deeper green up to -200 m.

Shallow green, deeper red, deeper brown up to -200 m.

Shallow green, deeper brown, deeper red - up to 200 m.

The totality of all living organisms forms the biomass (or, in the words of V. I. Vernadsky, living matter) of the planet.

By mass, this is about 0.001% of the mass of the earth's crust. However, despite the insignificant total biomass, the role of living organisms in the processes taking place on the planet is enormous. It is the activity of living organisms that determines the chemical composition of the atmosphere, the concentration of salts in the hydrosphere, the formation of some and the ruin of others. rocks, soil formation in the lithosphere, etc..

Land biomass. The highest density of life in tropical forests. There are more plant species here (more than 5 thousand). To the north and south of the equator, life becomes poorer, its density and the number of plant and animal species decrease: in the subtropics there are about 3 thousand plant species, in the steppes about 2 thousand, then there are broad-leaved and coniferous forests and, finally, the tundra, in which about 500 species of lichens and mosses grow. Depending on the intensity of the development of life in different geographical latitudes, biological productivity changes. It is estimated that the total primary land productivity (biomass formed by autotrophic organisms per unit of time per unit area) is about 150 billion tons, including 8 billion tons of forests of the world. organic matter in year. The total plant mass per 1 ha in the tundra is 28.25 tons, in tropical forest- 524 tons. In the temperate zone, 1 ha of forest produces about 6 tons of wood and 4 tons of leaves per year, which is 193.2 * 109 J (~ 46 * 109 cal). The secondary productivity (biomass produced by heterotrophic organisms per unit time per unit area) in the biomass of insects, birds and others in this forest is between 0.8 and 3% of the plant biomass, i.e. about 2 * 109 J (5 * 108 cal).< /p>

The primary annual productivity of various agrocenoses varies significantly. The average world productivity in tons of dry matter per 1 ha is: wheat - 3.44, potatoes - 3.85, rice - 4.97, sugar beet - 7.65. The harvest that a person collects is only 0.5% of the total biological productivity of the field. A significant part of the primary production is destroyed by saprophytes - the inhabitants of the soil.

Soils are one of the important components of land surface biogeocenoses. The starting material for soil formation is the surface layers of rocks. From them, under the influence of microorganisms, plants and animals, the soil layer is formed. Organisms concentrate biogenic elements in themselves: after the death of plants and animals and the decomposition of their remains, these elements pass into the composition of the soil, due to which

biogenic elements accumulate in it, as well as incompletely decomposed organic furnaces accumulate. The soil contains a huge number of microorganisms. So, in one gram of black soil, their number reaches 25 * 108. Thus, the soil is of biogenic origin, consists of inorganic, organic substances and living organisms (edaphon is the totality of all living beings of the soil). Outside the biosphere, the emergence and existence of soil is impossible. Soil is the environment for the life of many organisms (single-celled animals, annelids and roundworms, arthropods and many others). The soil is permeated with plant roots, from which plants absorb nutrients and water. The productivity of crops is associated with the vital activity of living organisms that are in the soil. The introduction of chemicals into the soil often adversely affects life in it. Therefore, it is necessary to rationally use soils and protect them.

Each locality has its own soils, which differ from others in composition and properties. The formation of individual types of soils is associated with various soil-forming rocks, climate and plant characteristics. V. V. Dokuchaev singled out 10 main types of soils, now there are more than 100 of them. cover. Polissya is characterized by soddy-pidzoli, gray forest,. Dark forest soils, podzolized chernozems, etc. The forest-steppe zone has gray and dark forest soils. The Steppe zone is mainly represented by chernozems. Brown forest soils prevail in the Ukrainian Carpathians. Different soils occur in Crimea (chernozem, chestnut, etc.), but they are usually gravelly and stony.

Biomass of the oceans. The world ocean occupies more than 2/3 of the planet's surface area. The physical properties and chemical composition of ocean waters are favorable for the development and existence of life. As on land, in the ocean, the density of life is highest in the equatorial zone and decreases as you move further away from it. In the upper layer, at a depth of up to 100 m, unicellular algae live, which make up plankton, “the total primary productivity of the phytoplankton of the World Ocean is 50 billion tons per year (about 1/3 of the entire primary production of the biosphere). Almost all food chains in the ocean start with phytoplankton, which feed on zooplankton animals (such as crustaceans). Crustaceans are food for many species of fish and baleen whales. Fish are eaten by birds. Large algae grow mainly in the coastal part of the oceans and seas. The greatest concentration of life is in coral reefs. The ocean is poorer in terms of life than the land, the biomass of its products is 1000 times less. Most of the formed biomass - unicellular algae and other inhabitants of the ocean - die off, settle to the bottom and their organic matter is destroyed by decomposers. Only about 0.01% of the primary productivity of the World Ocean through long chain trophic levels reaches humans in the form of food and chemical energy.

At the bottom of the ocean, as a result of the vital activity of organisms, sedimentary rocks are formed: chalk, limestone, diatomite, etc.

The biomass of animals in the World Ocean is approximately 20 times greater than the biomass of plants, it is especially large in the coastal zone.

The ocean is the cradle of life on Earth. The basis of life in the ocean itself, the primary link in a complex food chain, is phytoplankton, unicellular green marine plants. These microscopic plants are eaten by herbivorous zooplankton and many species of small fish, which in turn serve as food for a range of nektonic, actively swimming predators. The organisms of the seabed - benthos (phytobenthos and zoobenthos) also take part in the food chain of the ocean. The total mass of living matter in the ocean is 29.9∙109 tons, while zooplankton and zoobenthos biomass accounts for 90% of the total mass of living matter in the ocean, about 3% for phytoplankton biomass, and 4% for nekton biomass (mainly fish) (Suetova, 1973; Dobrodeev, Suetova, 1976). In general, the biomass of the ocean is 200 times less by weight, and per unit area - 1000 times less than the biomass of land. However, the annual production of the living matter of the ocean is 4.3∙1011 tons. In units of live weight, it is close to the production of terrestrial plant mass - 4.5∙1011 tons. Since marine organisms contain much more water, then in units of dry weight this ratio looks like 1:2.25. Even lower (as 1:3.4) is the ratio of the production of pure organic matter in the ocean compared to that on land, since phytoplankton contains a higher percentage of ash elements than woody vegetation (Dobrodeev and Suetova, 1976). The rather high productivity of living matter in the ocean is explained by the fact that the simplest phytoplankton organisms have short term life, they are updated daily, and the total mass of the living matter of the ocean, on average, approximately every 25 days. On land, biomass is renewed on average every 15 years. Living matter in the ocean is distributed very unevenly. The maximum concentrations of living matter in the open ocean - 2 kg / m2 - are located in the temperate zone of the northern Atlantic and northwestern Pacific oceans. On land, forest-steppe and steppe zones have the same biomass. The average values ​​of biomass in the ocean (from 1.1 to 1.8 kg/m2) are in the regions of the temperate and equatorial zones; on land, they correspond to the biomasses of dry steppes of the temperate zone, semi-deserts of the subtropical zone, alpine and subalpine forests (Dobrodeev, Suetova, 1976) . In the ocean, the distribution of living matter depends on the vertical mixing of the waters, which causes the rise to the surface of nutrients from the deep layers, where the process of photosynthesis takes place. Such lifting zones deep waters called upwelling zones, they are most productive in the ocean. Zones of weak vertical mixing of waters are characterized by low levels of phytoplankton production - the first link in the biological productivity of the ocean, and poverty of life. Another characteristic feature of the distribution of life in the ocean is its concentration in the shallow zone. In areas of the ocean where the depth does not exceed 200 m, 59% of the biomass of the benthic fauna is concentrated; depths from 200 to 3000 m account for 31.1% and areas with a depth of more than 3000 m - less than 10%. Of the climatic latitudinal zones in the World Ocean, the richest are the subantarctic and northern temperate zone: their biomass is 10 times greater than in the equatorial belt. On land, on the contrary, the highest values ​​of living matter fall on the equatorial and subequatorial belts.

The basis of the biological cycle that ensures the existence of life is solar energy and the chlorophyll of green plants that captures it. Every living organism participates in the circulation of substances and energy, absorbing some substances from the external environment and releasing others. Biogeocenoses, consisting of a large number of species and bone components of the environment, carry out cycles along which atoms of various chemical elements move. Atoms are constantly migrating through many living organisms and the bone environment. Without the migration of atoms, life on Earth could not exist: plants without animals and bacteria would soon exhaust their carbon dioxide reserves and minerals, and the animals of the plant bases would lose their source of energy and oxygen.

Biomass of the land surface - corresponds to the biomass of the terrestrial-air environment. It increases from the poles towards the equator. At the same time, the number of plant species is increasing.

Arctic tundra - 150 plant species.

Tundra (shrubs and herbaceous) - up to 500 plant species.

Forest zone (coniferous forests + steppes (zone)) - 2000 species.

Subtropics (citrus fruits, palm trees) - 3000 species.

Broad-leaved forests (moist tropical forests) - 8000 species. Plants grow in several tiers.

biomass of animals. The rainforest has the largest biomass on the planet. Such saturation of life causes a tough natural selection and struggle for existence a => Adaptation of various species to the conditions of a joint existence.

Lesson 2

Analysis of test work and grading (5-7 minutes).

Oral repetition and computer testing (13 min).

Land biomass

The biomass of the biosphere is approximately 0.01% of the mass of the inert matter of the biosphere, with about 99% of the biomass accounted for by plants, and about 1% by consumers and decomposers. Plants dominate on the continents (99.2%), animals dominate in the ocean (93.7%)

The biomass of land is much larger than the biomass of the world's oceans, it is almost 99.9%. This is due to the longer life expectancy and the mass of producers on the surface of the Earth. In land plants, the use of solar energy for photosynthesis reaches 0.1%, while in the ocean it is only 0.04%.

The biomass of various parts of the Earth's surface depends on climatic conditions - temperature, amount of precipitation. The harsh climatic conditions of the tundra - low temperatures, permafrost, short cold summers have formed peculiar plant communities with a small biomass. The vegetation of the tundra is represented by lichens, mosses, creeping dwarf trees, herbaceous vegetation that can withstand such extreme conditions. The biomass of the taiga, then mixed and broad-leaved forests gradually increases. The steppe zone is replaced by subtropical and tropical vegetation, where the conditions for life are most favorable, the biomass is maximum.

In the upper layer of the soil, the most favorable water, temperature, gas conditions for life. Vegetation cover provides organic matter to all the inhabitants of the soil - animals (vertebrates and invertebrates), fungi and a huge number of bacteria. Bacteria and fungi are decomposers, they play a significant role in the circulation of substances in the biosphere, mineralizing organic substances. "The great gravediggers of nature" - this is how L. Pasteur called the bacteria.

Biomass of the oceans

Hydrosphere The "water shell" is formed by the World Ocean, which occupies about 71% of the surface of the globe, and land water bodies - rivers, lakes - about 5%. A lot of water is found in groundwater and glaciers. Due to the high density of water, living organisms can normally exist not only at the bottom, but also in the water column and on its surface. Therefore, the hydrosphere is populated throughout its thickness, living organisms are represented benthos, plankton and nekton.

benthic organisms(from the Greek benthos - depth) lead a benthic lifestyle, live on the ground and in the ground. Phytobenthos is formed by various plants - green, brown, red algae, which grow at different depths: green at a shallow depth, then brown, deeper - red algae that occur at a depth of up to 200 m. Zoobenthos is represented by animals - mollusks, worms, arthropods, etc. Many have adapted to life even at a depth of more than 11 km.

planktonic organisms(from Greek planktos - wandering) - inhabitants of the water column, they are not able to move independently over long distances, they are represented by phytoplankton and zooplankton. Phytoplankton includes unicellular algae, cyanobacteria, which are found in marine waters up to a depth of 100 m and are the main producer of organic matter - they have an unusually high reproduction rate. Zooplankton are marine protozoa, coelenterates, small crustaceans. These organisms are characterized by vertical diurnal migrations, they are the main food base for large animals - fish, baleen whales.

Nektonic organisms(from Greek nektos - floating) - inhabitants of the aquatic environment, able to actively move in the water column, overcoming long distances. These are fish, squid, cetaceans, pinnipeds and other animals.

Written work with cards:

1. Compare the biomass of producers and consumers on land and in the ocean.

2. How is biomass distributed in the oceans?

3. Describe the land biomass.

4. Define the terms or expand the concepts: nekton; phytoplankton; zooplankton; phytobenthos; zoobenthos; the percentage of the Earth's biomass from the mass of the inert substance of the biosphere; the percentage of plant biomass of the total biomass of terrestrial organisms; percentage of plant biomass of total aquatic biomass.

Board card:

1. What is the percentage of the Earth's biomass from the mass of the inert matter of the biosphere?

2. What percentage of the Earth's biomass is plants?

3. What percentage of the total biomass of terrestrial organisms is plant biomass?

4. What percentage of the total biomass of aquatic organisms is plant biomass?

5. What% of solar energy is used for photosynthesis on land?

6. What % of solar energy is used for photosynthesis in the ocean?

7. What are the names of the organisms that inhabit the water column and are carried by sea currents?

8. What are the names of the organisms that inhabit the soil of the ocean?

9. What are the names of organisms that actively move in the water column?

Test:

Test 1. The biomass of the biosphere from the mass of the inert matter of the biosphere is:

Test 2. The share of plants from the biomass of the Earth accounts for:

Test 3. Biomass of plants on land compared to biomass of terrestrial heterotrophs:

2. Is 60%.

3. Is 50%.

Test 4. Biomass of plants in the ocean compared to the biomass of aquatic heterotrophs:

1. Prevails and makes up 99.2%.

2. Is 60%.

3. Is 50%.

4. Less biomass of heterotrophs and is 6.3%.

Test 5. The use of solar energy for photosynthesis on land averages:

Test 6. The use of solar energy for photosynthesis in the ocean averages:

Test 7. Ocean benthos is represented by:

Test 8. Ocean Nekton is represented by:

1. Animals actively moving in the water column.

2. Organisms inhabiting the water column and carried by sea currents.

3. Organisms living on the ground and in the ground.

4. Organisms living on the surface film of water.

Test 9. Ocean plankton is represented by:

1. Animals actively moving in the water column.

2. Organisms inhabiting the water column and carried by sea currents.

3. Organisms living on the ground and in the ground.

4. Organisms living on the surface film of water.

Test 10. From the surface deep into the algae grow in the following order:

1. Shallow brown, deeper green, deeper red up to -200 m.

2. Shallow red, deeper brown, deeper green up to - 200 m.

3. Shallow green, deeper red, deeper brown up to - 200 m.

4. Shallow green, deeper brown, deeper red - up to 200 m.

Phytoplankton, binding CO 2 during photosynthesis and forming organic matter, gives rise to all food chains in the ocean. Analysis of a set of data on the amount of phytoplankton in different areas of the World Ocean (with late XIX century, calculated from available transparency estimates, and since the early 1980s, obtained remotely, with spacecraft) shows that its biomass has decreased over the past century at a rate of about 1% per year. The most noticeable decrease was noted for the central oligotrophic regions of the ocean. Although these areas are characterized by very low productivity, they occupy a huge area, and therefore their total contribution to the production and biomass of ocean phytoplankton is very significant. Most probable cause decrease in biomass - an increase in the temperature of the surface layer of the ocean, leading to a decrease in the depth of mixing and a reduction in the supply of mineral nutrients from the underlying layers.

Approximately half of our planet's primary production (that is, organic matter produced by green plants and other photosynthetic organisms) comes from the ocean. The main producers of the ocean are microscopic algae and cyanobacteria suspended in the upper layers of the water column (what is collectively called phytoplankton). A large-scale quantitative study of the production and biomass of phytoplankton in the World Ocean began in the 1960s and 1970s. Researchers (including those from the Institute of Oceanology of the USSR Academy of Sciences) then relied on a method based on the absorption of the radioactive isotope of carbon 14 C by phytoplankton. Carbon dioxide CO 2 was labeled with the isotope, added to water samples with phytoplankton taken on board the ship. As a result of these works, maps of phytoplankton distribution over the entire water area of ​​the World Ocean were constructed (see, for example: Koblentz-Mishke et al., 1970). In the central, occupying large area, areas of the ocean phytoplankton biomass and its production are very low. High values ​​of biomass and production are confined to coastal areas and upwelling areas (see: Upwelling), where deep waters rich in mineral nutrition elements rise to the surface. First of all, these are phosphorus and nitrogen, the lack of which just limits the growth of phytoplankton in most of the ocean area.

A new stage in the quantitative study of the distribution of phytoplankton in the World Ocean began at the very end of the 1970s, after the appearance of remote (from satellites) methods of sounding surface waters and determining the content of chlorophyll in them. Although no more than 10% of light photons, which are reflected from water and carry information about its color, reach devices located at the upper boundary of the atmosphere, this is enough to calculate the amount of chlorophyll, and, accordingly, the biomass of phytoplankton (Fig. 1). According to the values ​​of biomass, one can also judge the production of phytoplankton, which was verified in the course of special studies comparing satellite data with the results of production estimates obtained experimentally. in situ on research ships. Of course, different devices give slightly different data, but overall picture spatial distribution of phytoplankton and its dynamics (seasonal and interannual) is very detailed. Suffice it to say that the Sea WiFS (Sea-viewing Wide Field-of-view Sensor) device scans the entire world ocean in two days.

The huge amount of data accumulated over the past 30 years has made it possible to identify certain periodic fluctuations phytoplankton biomasses, in particular those associated with El Niño, or, more precisely, with the "Southern Oscillation" (El Niño-Southern Oscillation). Analyzing these materials, the researchers suggested the existence of more long-term changes in the phytoplankton biomass, but they were difficult to identify due to the lack of data for the period preceding satellite measurements. An attempt to at least partially solve this problem was recently undertaken by specialists from the Canadian Dalhousie University in Halifax (Dalhousie University, Halifax, Nova Scotia). It is possible to judge the phytoplankton biomass 50 and even 100 years ago by the estimates of transparency, a value regularly measured in research expeditions since the end of the 19th century.

An instrument for measuring the transparency of water, extremely simple but very useful, was invented in 1865 by the Italian astronomer (and at the same time a priest) Angelo Secchi, who was commissioned to map the transparency of the Mediterranean Sea for the papal fleet. The device, called the "Secchi disc" (see Fig. 2), is a white metal disc with a diameter of 20 or 30 cm, which is lowered into the water on a marked rope. The depth at which the observer stops seeing the disk is the Secchi transparency. Since the main part of the suspension that affects the transparency of water is phytoplankton, any changes in the transparency value. as a rule, reflect well changes in the amount of phytoplankton.

Based on standardized estimates of transparency available since 1899, and on the results of a recent comparison of transparency with chlorophyll concentration, the researchers obtained, firstly, a picture of the distribution of phytoplankton biomass in the World Ocean (Fig. 3), and secondly, the change in phytoplankton biomass over a hundred-year period (Fig. 4). In total, they had at their disposal the results of more than 455 thousand measurements, covering the period from 1899 to 2008. At the same time, data related directly to the coastal zone (less than 1 km from the coast and at depths less than 25 m) were deliberately not included in the sample, since the influence of runoff from the coast is very noticeable in such places. Most measurements were made after 1930 in the northern regions of the Atlantic and Pacific oceans. The main conclusion reached by the authors is a gradual decrease in the total phytoplankton biomass over the last century since average speed about 1% per year.

To assess local trends, the entire water area of ​​the World Ocean was divided into a grid with 10° × 10° cells, and all values ​​were calculated as averages per cell. A decrease in phytoplankton biomass was noted in 59% of the cells for which reasonably reliable data were available. Most of all such cells are in high latitudes (more than 60° in latitude). However, for some areas of the ocean, an increase in biomass has been noted - in particular, in the eastern part Pacific Ocean, as well as in northern and southern regions indian ocean. The central oligotrophic regions of the oceans actually expanded the occupied water areas, and in these areas, despite low productivity, now in general, about 75% of all primary production of the World Ocean is formed.

To imagine changes at the level of large regions, the entire water area of ​​the ocean was divided into 10 regions (Fig. 5): the Arctic, the North, Equatorial and South Atlantic, the northern and southern parts of the Indian Ocean, the Northern, Equatorial and Southern Pacific, and the Southern Ocean . An analysis of the averaged data for these large regions showed that a significant increase was noted only for the southern part of the Indian Ocean and a statistically unreliable increase for the northern part of the Indian Ocean. For all other regions, significant reduction phytoplankton biomass.

Discussing possible reasons observed changes, the authors pay attention primarily to the increase in the temperature of the surface layer of the water column. It covered almost the entire ocean and led to a decrease in the thickness of the mixed layer. Accordingly, the influx of mineral nutrients (primarily phosphates and nitrates) from the underlying layers is reduced. However, the authors admit that such an explanation is not suitable for high latitudes. There, the warming of the upper layer should contribute to an increase, rather than a decrease in the production and biomass of phytoplankton. Obviously, the mechanisms that determine large-scale changes in phytoplankton biomass need further study.

The world ocean is an ecological system, a single functional set of organisms and their habitat. The oceanic ecosystem has physical and chemical features that provide certain advantages for living organisms to live in it.

Constant marine circulation leads to intense mixing of ocean waters, as a result of which oxygen deficiency is relatively rare in ocean depths.

An important factor in the existence and distribution of life in the thickness of the World Ocean is the amount of penetrating light, according to which the ocean is divided into two horizontal zones: euphotic ( usually up to 100-200 m) and aphotic(extends to the very bottom). The euphotic zone is the zone of primary production, it is characterized by the entry of a large number sunlight and, as a result, favorable conditions for the development of the primary source of energy in marine food chains - microplankton, which includes the smallest green algae and bacteria. The most productive part of the euphotic zone is the area of ​​the continental shelf (in general, it coincides with the sublittoral zone). The high abundance of zooplankton and phytoplankton in this area, combined with the high content of nutrients washed off the land by rivers and temporary streams, as well as in places the rise of cold, oxygen-rich deep waters (upwelling zones), has led to the fact that almost all large commercial fisheries are concentrated on the continental shelf.

The euphotic zone is characterized by less productivity, mainly due to the fact that less sunlight enters here, and the conditions for the development of the first link of food chains in the ocean are extremely limited.

Other an important factor, which determines the existence and distribution of life in the oceans, is the concentration of biogenic elements in water (especially phosphorus and nitrogen, which are most actively absorbed by unicellular algae) and dissolved oxygen. Nutrients enter the water mainly with river runoff and reach a maximum concentration at a depth of 800–1000 m, but the main consumption of nutrients by phytoplankton is concentrated in the surface layer 100–200 m thick. Here, photosynthetic algae release oxygen, which, in the process of vertical water circulation, is carried into the depths of the ocean, creating conditions for the existence of life there. Thus, at a depth (100-200 m) with a sufficient amount of nutrients contained and a sufficient concentration of dissolved oxygen, conditions are created for the existence of plant organisms (phytoplankton), which determine the reproduction and distribution of zooplankton, fish and other animals.

In the oceans, the main step in the biomass pyramid - unicellular algae are divided with high speed and give very high production. This explains why animal biomass is two dozen times larger than plant biomass. The total biomass of the World Ocean is approximately 35 billion tons. At the same time, animals account for 32.5 billion tons, and algae - 1.7 billion tons. However total algae change little, because they are quickly eaten by zooplankton and various filter feeders (for example, whales). Fish, cephalopods, large crustaceans grow and reproduce more slowly, but are eaten even more slowly by enemies, so their biomass has time to accumulate. Biomass pyramid in the ocean it turns out, thus, inverted. AT terrestrial ecosystems the rate of consumption of plant growth is lower and the biomass pyramid in most cases resembles the production pyramid.

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The production of zooplankton is 10 times less than that of unicellular algae. The production of fish and other representatives of nekton is 3000 times less than that of plankton, which provides extremely favorable conditions for their development.

The high productivity of bacteria and algae ensures the processing of the remains of the vital activity of a large biomass of the ocean, which, in combination with the vertical mixing of the waters of the World Ocean, contributes to the decomposition of these residues, thereby forming and maintaining the oxidizing properties of the aquatic environment, which create exceptionally favorable conditions for the development of life throughout the entire thickness of the World Ocean. ocean. Only in certain regions of the World Ocean, as a result of a particularly sharp stratification of waters in the deep layers, a reducing environment is formed.

Living conditions in the ocean are highly constancy, which is why the inhabitants of the ocean do not need specialized covers and adaptations that are so necessary for living organisms on land, where abrupt and intense changes in environmental factors are not uncommon.

high density sea ​​water provides physical support to marine organisms, as a result of which organisms with a large body weight (cetaceans) are perfectly buoyant.

All organisms that live in the ocean are divided into three (largest) environmental groups(based on lifestyle and habitat): plankton, nekton and benthos. Plankton- a set of organisms that are not capable of independent movement, which are carried by waters and currents. Plankton has the highest biomass and the highest species diversity. The composition of plankton includes zooplankton (animal plankton), which inhabits the entire thickness of the ocean, and phytoplankton (plant plankton), which lives only in the surface layer of water (up to a depth of 100-150 m). Phytoplankton, mainly the smallest single-celled algae, is the food for zooplankton. Nekton- animals capable of independent movement in the water column over long distances. Nekton includes cetaceans, pinnipeds, fish, sirenidae, sea ​​snakes and sea ​​turtles. The total biomass of nekton is approximately 1 billion tons, half of this amount is accounted for by fish. Benthos- a set of organisms that live on the ocean floor or in bottom sediments. Animal benthos is all types of invertebrates (mussels, oysters, crabs, lobsters, spiny lobsters); plant benthos is represented mainly by various algae.

The total biological mass of the World Ocean (the total mass of all organisms living in the ocean) is 35-40 billion tons. It is much less than the biological mass of land (2420 billion tons), despite the fact that the ocean has big sizes. This is explained by most of ocean areas are almost lifeless water spaces, and only the periphery of the ocean and upwelling zones are characterized by the highest biological productivity. In addition, on land, phytomass exceeds zoomass by 2000 times, and in the World Ocean, animal biomass is 18 times greater than plant biomass.

Living organisms in the World Ocean are distributed unevenly, since a number of factors influence their formation and species diversity. As mentioned above, the distribution of living organisms largely depends on the distribution of temperature and salinity in the ocean across latitudes. Yes, more warm waters they are distinguished by higher biodiversity (400 species of living organisms live in the Laptev Sea, and 7000 species in the Mediterranean), and salinity with indicators from 5 to 8 ppm is the limit for the distribution of most marine animals in the ocean. Transparency allows the penetration of favorable sunlight only to a depth of 100-200 m, as a result, this area of ​​\u200b\u200bthe ocean (sublittoral) is characterized by the presence of light, a large abundance of food, active mixing of water masses - all this determines the creation of the most favorable conditions for the development and existence of life in this area ocean (90% of all fish wealth lives in the upper layers of the ocean to a depth of 500 m). During a year natural conditions vary markedly in different regions of the World Ocean. Many living organisms have adapted to this, having learned to make vertical and horizontal movements (migrations) over long distances in the water column. At the same time, planktonic organisms are capable of passive migration (with the help of currents), while fish and mammals are capable of active (independent) migration during periods of feeding and reproduction.