The world ocean is an ecological system, a single functional set of organisms and their habitat. The ocean ecosystem has physical and chemical features that provide certain advantages for living organisms to live in it.
The constant marine circulation leads to intense mixing of ocean waters, with the result that oxygen deficiency is relatively rare in the 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 influx of a large amount of 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 a high content of nutrients washed from land by rivers and temporary streams, as well as in some 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 less productive, 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.
Another important factor determining the existence and distribution of life in the World Ocean 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 is carried away into the 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 biogenic elements contained and a sufficient concentration of dissolved oxygen, conditions are created for the existence of plant organisms (phytoplankton), which determine the reproduction and spread of zooplankton, fish and other animals.
In the World Ocean, the main step in the biomass pyramid - unicellular algae divide at a high rate and give a 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, the total number of algae changes 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. In 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 oxidizing properties. aquatic environment, which create exceptionally favorable conditions for the development of life in the entire thickness of the oceans. 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 mass (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 the fact that most of the ocean area is 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. Thus, warmer waters are characterized 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 the year, natural conditions in different regions of the World Ocean change markedly. 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.
summary of other presentations"Relationships in nature" - For example, squirrels and moose do not have significant effects on each other. Intraspecific. Squirrel monkeys. Examples of interspecific competition. Amensalism. The oxygen content in the atmosphere has risen from 1% to 21% over the past billion years. There are no non-interacting populations and species in nature. Types of competition: Evolution and ecology. Competition. Spider monkeys. For example, the relationship between spruce and plants of the lower tier.
"Ecological relations" - The predominance of external energy supply. characteristics of a living organism. Genotype. unitary organisms. Diversity of organisms. Classification of organisms in relation to water. Life forms according to Raunkjer. The main characteristics of the external environment. Moisture. Phenotype. water anomalies. Light. modular organisms. Molecular genetic level. Life forms of plants. mutation process. Organism.
"Circulation of substances and energy" - Most of the energy contained in food is released. The main producer is phytoplankton. Growth per unit of time. Producers (first level) have a 50% increase in biomass. Decomposition chain. The biomass of each subsequent level increases. Ecosystem productivity. The flow of energy and the circulation of substances in ecosystems. Rule (law) 10% R. Lindeman. Chemical elements move through food chains.
ocean waters contain all the necessary conditions for the origin and existence of life. If we take into account only the size of the World Ocean, it becomes clear that there is more space for living organisms here than on land. It is no coincidence that half of all the world's plant species and $3/4$ of animals live in the oceans. The entire living world of the ocean is divided into the following types:
- plankton(living, free-swimming organisms of small size, unable to resist the flow of water). Plankton includes phytoplankton and zooplankton, usually small crustaceans and algae.
- nekton(a set of living organisms actively floating in the water column). The nekton is the largest group of living organisms - these are almost all types of fish, mammals and other inhabitants.
- benthos(the totality of living organisms living at the bottom of the ocean depths).
These types of living organisms are presented in detail in Fig.1.
Remark 1
The total combined biomass of all living organisms in the ocean is approximately $30 billion tons. Places of increased concentration of biomass and, as a rule, places of the greatest biodiversity in the World Ocean are places of abundant development and accumulation of plankton.
The distribution of biomass in the World Ocean has a number of specific features that are unique to the ocean.
The types and numbers of living organisms in the ocean are predominantly determined by the following limiting factors:
- depth of penetration of sunlight;
- concentration of dissolved oxygen;
- availability of nutrients;
- temperature.
Naturally, animal organisms are most numerous in the upper layers of the ocean (up to $200$ meters) - this is a consequence of their direct or indirect dependence on photosynthetic organisms.
Remark 2
It is obvious that due to the inflow, in addition to the flow of biogenic substances from bottom sediments, an additional flow coming with runoff from land, coastal aquatic ecosystems are the most productive.
In coastal aquatic ecosystems, as well as in the open waters of the World Ocean, up to a depth of $200$ meters, the largest number animal biodiversity and flora, which plays an important role in the trophic function not only marine life but also a person. Every day around the world, millions of tons of fish of various species, as well as algae and shrimp, are harvested from this zone of the World Ocean in order to conduct economic activities.
In deep-sea areas, the productivity of photosynthetic organisms is limited due to the mismatch between nutritional conditions (nutrients are concentrated at the bottom) and lighting conditions. However, some inhabitants of the benthos represent a great economic activity for humans, these are animals such as mussels, lobsters, crayfish, oysters and others.
Bioproductivity and biomass
Within the open ocean, three zones are distinguished, the main characteristic differences which are the depth of penetration of sunlight and, as a result, different quantitative and species composition biomass:
- euphotic zone(surface layer) - up to $200$ meters in depth, where photosynthesis processes are intensively carried out and constant and intensive mixing of water masses is carried out as a result of the impact of wind activity, unrest and hurricanes. This zone accounts for more than $90\%$ of all oceanic biomass and the highest bioproductivity factor.
- bathyal zone(batyal) - from $200$ to $2500$ meters in depth, corresponding to the continental slope. This zone is characterized by significantly lower bioproductivity and overall species composition.
- abyssal zone(abyssal) - as a rule, deeper than $ 2500 $ meters, which is characterized by almost complete darkness, low water mobility, almost constant temperature water from $3$ to $1^\circ \ C$, where living organisms exist due to the remains of photosynthetic plants and animals eating them from the upper layers of the World Ocean, and therefore giving minimal biological production.
In the ocean, alternation of belts with high and low phyto- and zoomass is observed. But if on land the distribution of the number of living organisms depends primarily on temperature and precipitation and has a zonal character, then in the ocean the biomass of a particular area primarily depends on the rate of nutrient supply with ascending water flows, i.e., depends on the speed of movement of near-bottom water volumes saturated with biogenic substances to the surface. Such movement takes place in the zones of rise of cold deep waters to the surface, as well as in shallow areas of the ocean (in the shelf zone), where wind mixing of the entire water layer takes place.
Remark 3
Another important, from the point of view of productivity, place in the ocean, where favorable conditions for the formation of life are formed, are places where cold and warm ocean currents meet. The mixing of water masses of warm and cold currents, which have different temperature regimes and are characterized by varying degrees of salinity, leads to the mass death of living organisms due to their entry into unfavourable conditions a habitat. Decaying, dead organisms enrich the waters of the oceans with nutrients, which, in turn, gives rise to the rapid development of the life of other organisms. From this example it can be seen that life is most intensively germinated in the zone with maximum mortality.
Less bioproductivity is characteristic of those water areas of the World Ocean in which anticyclonic circulation systems. These areas include the vast oceanic areas, where, under conditions of predominant influence of descending flows, the amount of biogenic elements (decomposition products) is as low as possible.
The coastal zones of the ocean also have a significant concentration of biomass - shallow water zones rich in nutrients, extending from the tide line on the coast to the continental shelf, which is a continuation of the mainland under the thickness of the water masses of the oceans.
Coastal zones, occupying less than $10\%$ of the entire area of the World Ocean, concentrate more than $90\%$ of all biomass (ocean flora and fauna). It is home to the largest number of fisheries in the world. In the coastal zone, such habitats as an estuary are distinguished. Estuaries are coastal regions of the oceans where fresh water watercourses (rivers, streams and surface runoff) are mixed with the salty waters of the oceans. In estuaries, the annual specific bioproductivity is maximum compared to other ecosystems.
In the coastal zones of the World Ocean located in tropical and subtropical latitudes, where temperature regime waters exceed $20^\circ \ C$, coral reefs inhabit. They usually consist of insoluble calcium compounds secreted by animal organisms, as well as red and green algae. Coral reefs play an important role in maintaining the salinity of the water.
Near the western coasts of the continents, which are characterized by winds constantly blowing from land to sea - trade winds - surface waters from rivers, lakes and other water bodies are carried away from the coast to the ocean, they are replaced by cold, nutrient-rich bottom waters. This phenomenon is called upwelling. Due to the large amount of nutrients coming from the depths of the oceanic water masses, significant bioproductivity is formed in these areas. However, seasonal changes in climate and currents constantly have a lowering effect on it.
The ocean is separated from the coastal zones by an area of sharp increase in depth at the edge of the continental shelf. It accounts for about $10\%$ of the biomass of oceanic flora and fauna, and the infinite areas of the depths can be attributed to almost desert areas in terms of biomass, but due to its huge size, the open ocean is the main supplier of net primary biological production on Earth.
The role of the organic world of the oceans for humans
The organic world of the oceans plays a huge role in human life. The diversity and richness of representatives of aquatic flora and fauna provides humanity with a constant trophic component. Seafood is the main source of food for many countries, especially the Asian island countries - Japan, the Philippines, Indonesia and others.
The most productive places of the World Ocean ensure the sustainable development of fisheries, the development of a production and processing base, fisheries industries and complexes. In the period of world globalization, the development of the fishery sector is a particularly relevant process, including for the Russian Federation.
However, in Russia there are a number of problems associated with the processing of fish resources and their logistics. In addition, in Russia, as in a number of world countries, there are environmental problems (poaching, pollution of the waters of the World Ocean, man-made disasters, etc.), which drastically reduce the productivity of aquatic biomass. These factors sharply increase the mortality of viable organisms, which causes enormous harm not only for a particular population, but also for the species for which these populations are the main trophic component.
Remark 4
In order to preserve the populations of marine organisms in order to preserve species diversity, as well as to provide mankind with food products extracted from the waters of the World Ocean, it is necessary to maintain the existing ecological state of aquatic ecosystems, as well as the immediate elimination of technogenic consequences that have negative impact on ocean bioproductivity.
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 destruction of other rocks, the formation of soil 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 time per unit area) is about 150 billion tons, including 8 billion tons of organic matter per year in the world's forests. 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 phytoplankton in 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 a long chain of 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 living matter in 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, in units of dry weight this ratio looks like 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 greater 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 total weight 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 nutrients to rise to the surface from the deep layers, where the process of photosynthesis takes place. Such zones of deep water rise are called upwelling zones, they are the 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 reserves of carbon dioxide and minerals, and the animals of 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 richness of life causes a tough natural selection and struggle for existence a => Adaptation of different species to the conditions of a joint existence.
Currently, about 500 thousand plant species and more than 1.5 million animal species are known on Earth. 93% of them inhabit the land, and 7% are inhabitants of the aquatic environment (table).
| Dry matter mass | Continents | oceans | |||||
| Green plants | Animals and micro-organisms | Green plants | Animals and microorganisms | Total |
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| Interest | |||||||
From the data in the table it can be seen that although the oceans occupy about 70% of the earth's surface, they form only 0.13% of the Earth's biomass.
Soil is formed by biogenic means, it consists of inorganic and organic substances. Outside the biosphere, soil formation is impossible. Under the influence of microorganisms, plants and animals, the soil layer of the Earth begins to gradually form on rocks. The biogenic elements accumulated in organisms, after their death and decomposition, again pass into the soil.
The processes occurring in the soil are an important component of the circulation of substances in the biosphere. Economic activity human can lead to a gradual change in the composition of the soil and the death of microorganisms living in it. That is why it is necessary to develop measures for the reasonable use of the soil. material from the site
The hydrosphere plays an important role in the distribution of heat and humidity across the planet, in the circulation of matter, so it also has a powerful impact on the biosphere. Water is an important component of the biosphere and one of the most essential factors for the life of organisms. Most of the water is in the oceans and seas. The composition of ocean and sea water includes mineral salts containing about 60 chemical elements. Oxygen and carbon, necessary for the life of organisms, are highly soluble in water. Aquatic animals release carbon dioxide during respiration, and plants enrich the water with oxygen as a result of photosynthesis.
Plankton
In the upper layers of ocean waters, reaching a depth of 100 m, unicellular algae and microorganisms are widespread, which form microplankton(from Greek plankton - wandering).
About 30% of photosynthesis on our planet takes place in water. Algae, perceiving solar energy convert it into chemical energy. In the nutrition of aquatic organisms, plankton.
