Palmistry 

Features and distribution of life in the seas and oceans. How deep does the zone of photosynthesis extend in the oceans. Efficiency of photosynthesis in terrestrial and marine ecosystems Life in the deep sea

The oceans cover more than 70% of the Earth's surface. It contains about 1.35 billion cubic kilometers of water, which is about 97% of all water on the planet. The ocean supports all life on the planet and also makes it blue when viewed from space. Earth is the only planet in our solar system known to contain liquid water.

Although the ocean is one continuous body of water, oceanographers have divided it into four main areas: Pacific, Atlantic, Indian and Arctic. The Atlantic, Indian and Pacific oceans combine to form the icy waters around Antarctica. Some experts identify this area as the fifth ocean, most often called the South.

To understand the life of the oceans, you must first know its definition. The phrase "marine life" covers all organisms living in salt water, which include a wide variety of plants, animals, and microorganisms such as bacteria and.

There is a huge variety of marine species that range from tiny single-celled organisms to giant blue whales. As scientists discover new species, learn more about the genetic make-up of organisms, and study fossil specimens, they are deciding how to group ocean flora and fauna. The following is a list of major phyla or taxonomic groups of living organisms in the oceans:

  • (Annelida);
  • (Arthropoda);
  • (Chordata);
  • (Cnidaria);
  • Ctenophores ( Ctenophora);
  • (Echinodermata);
  • (Mollusca)
  • (Porifera).

There are also several types of marine plants. The most common are Chlorophyta, or green algae, and Rhodophyta, or red algae.

Marine life adaptations

From the point of view of a land animal like us, the ocean can be a harsh environment. However, marine life is adapted to life in the ocean. Characteristics that allow organisms to thrive in the marine environment include the ability to regulate salt intake, oxygen-producing organs (such as fish gills), withstand increased water pressure, and adapt to lack of light. Animals and plants living in the intertidal zone deal with extreme temperatures, sunlight, wind and waves.

There are hundreds of thousands of species of marine life, from tiny zooplankton to giant whales. The classification of marine organisms is very variable. Each is adapted to its specific habitat. All oceanic organisms are forced to interact with several factors that are not a problem for life on land:

  • Regulating salt intake;
  • Obtaining oxygen;
  • Adaptation to water pressure;
  • Waves and changes in water temperature;
  • Getting enough light.

Below we look at some of the ways marine life survives in this environment, which is very different from ours.

Salt regulation

Fish can drink salt water and excrete excess salt through their gills. Seabirds also drink seawater, and excess salt is expelled through "salt glands" into the nasal cavity and then shaken out by the bird. Whales do not drink salt water, but get the necessary moisture from their organisms, which they feed on.

Oxygen

Fish and other organisms that live underwater can obtain oxygen from the water either through their gills or through their skin.

Marine mammals are forced to surface to breathe, which is why whales have breathing holes on top of their heads that allow them to breathe in air from the atmosphere, keeping most of their bodies underwater.

Whales are able to stay underwater without breathing for an hour or more because they use their lungs very efficiently, filling up to 90% of their lungs with each breath, and also store unusually large amounts of oxygen in their blood and muscles when diving.

Temperature

Many ocean animals are cold-blooded (ectothermic) and their internal body temperature is the same as their environment. An exception are warm-blooded (endothermic) marine mammals, which must maintain a constant body temperature regardless of water temperature. They have a subcutaneous insulating layer consisting of fat and connective tissue. This layer of subcutaneous fat allows them to maintain their internal body temperature about the same as that of their terrestrial relatives, even in the cold ocean. The insulating layer of the bowhead whale can be over 50 cm thick.

water pressure

In the oceans, water pressure increases by 15 pounds per square inch every 10 meters. While some sea creatures rarely change the depth of the water, far-swimming animals such as whales, sea turtles and seals travel from shallow water to deep water in a matter of days. How do they deal with pressure?

It is believed that the sperm whale is able to dive more than 2.5 km below the ocean surface. One of the adaptations is that the lungs and chest are compressed when diving to great depths.

The leatherback sea turtle can dive to over 900 meters. Folding lungs and a flexible shell help them withstand high water pressure.

wind and waves

Intertidal animals do not need to adapt to high water pressure, but must withstand strong wind and wave pressure. Many invertebrates and plants in this area have the ability to cling to rocks or other substrates, and also have hard protective shells.

While large pelagic species such as whales and sharks are not affected by the storm, their prey can be displaced. For example, whales prey on copepods, which can be scattered over different remote areas during strong winds and waves.

sunlight

Light-demanding organisms, such as tropical coral reefs and related algae, are found in shallow, clear waters that allow sunlight to pass through easily.

Because underwater visibility and light levels can change, whales don't rely on sight to find food. Instead, they find prey using echolocation and hearing.

In the depths of the ocean abyss, some fish have lost their eyes or pigmentation because they are simply not needed. Other organisms are bioluminescent, using luminiferous or their own light-producing organs to attract prey.

Distribution of life of the seas and oceans

From the coastline to the deepest seabed, the ocean is teeming with life. Hundreds of thousands of marine species range from microscopic algae to the blue whale that ever lived on Earth.

The ocean has five main zones of life, each with unique adaptations of organisms to its particular marine environment.

Euphotic zone

The euphotic zone is the sunlit top layer of the ocean, up to about 200 meters deep. The euphotic zone is also known as the photic zone and can be present both in lakes with seas and in the ocean.

Sunlight in the photic zone allows the process of photosynthesis to take place. is the process by which some organisms convert solar energy and carbon dioxide from the atmosphere into nutrients (proteins, fats, carbohydrates, etc.) and oxygen. In the ocean, photosynthesis is carried out by plants and algae. Seaweeds are similar to land plants: they have roots, stems, and leaves.

Phytoplankton - microscopic organisms that include plants, algae and bacteria also inhabit the euphotic zone. Billions of microorganisms form huge green or blue spots in the ocean, which are the foundation of the oceans and seas. Through photosynthesis, phytoplankton are responsible for producing almost half of the oxygen released into the Earth's atmosphere. Small animals such as krill (a type of shrimp), fish, and microorganisms called zooplankton all feed on phytoplankton. In turn, these animals are eaten by whales, large fish, seabirds, and humans.

mesopelagic zone

The next zone, extending to a depth of about 1000 meters, is called the mesopelagic zone. This zone is also known as the twilight zone, as the light within it is very dim. The lack of sunlight means that there are practically no plants in the mesopelagic zone, but large fish and whales dive there to hunt. The fish in this zone are small and luminous.

bathypelagic zone

Sometimes animals from the mesopelagic zone (such as sperm whales and squid) dive into the bathypelagic zone, which reaches a depth of about 4000 meters. The bathypelagic zone is also known as the midnight zone because light does not reach it.

Animals living in the bathypelagic zone are small, but they often have huge mouths, sharp teeth, and expanding stomachs that allow them to eat any food that falls into their mouths. Most of this food comes from the remains of plants and animals descending from the upper pelagic zones. Many bathypelagic animals do not have eyes because they are not needed in the dark. Because the pressure is so high, it's hard to find nutrients. Fish in the bathypelagic zone move slowly and have strong gills to extract oxygen from the water.

abyssopelagic zone

The water at the bottom of the ocean, in the abyssopelagic zone, is very salty and cold (2 degrees Celsius or 35 degrees Fahrenheit). At depths up to 6,000 meters, the pressure is very strong - 11,000 pounds per square inch. This makes life impossible for most animals. The fauna of this zone, in order to cope with the harsh conditions of the ecosystem, has developed bizarre adaptive features.

Many animals in this zone, including squid and fish, are bioluminescent, meaning they produce light through chemical reactions in their bodies. For example, the anglerfish has a bright protrusion located in front of its huge, toothy mouth. When the light lures small fish, the angler simply snaps its jaws to eat its prey.

Ultraabyssal

The deepest zone of the ocean, found in faults and canyons, is called the ultra-abyssal. Few organisms live here, such as isopods, a type of crustacean related to crabs and shrimps.

Such as sponges and sea cucumbers thrive in the abyssopelagic and ultraabyssal zones. Like many starfish and jellyfish, these animals depend almost entirely on the settling remains of dead plants and animals called marine detritus.

However, not all bottom dwellers depend on marine detritus. In 1977, oceanographers discovered a community of creatures on the ocean floor feeding on bacteria around openings called hydrothermal vents. These vents drain hot water enriched with minerals from the bowels of the Earth. Minerals feed unique bacteria, which in turn feed animals such as crabs, shellfish and tubeworms.

Threats to marine life

Despite the relatively small understanding of the ocean and its inhabitants, human activity has caused enormous damage to this fragile ecosystem. We constantly see on television and in the newspapers that another marine species has become endangered. The problem may seem depressing, but there is hope and many things each of us can do to save the ocean.

The threats below are not in any particular order as they are more relevant in some regions than others and some ocean dwellers face multiple threats:

  • ocean acidification- if you've ever had an aquarium, you know that the correct pH of the water is an important part of keeping your fish healthy.
  • Changing of the climate- We constantly hear about global warming, and for good reason - it negatively affects both marine and terrestrial life.
  • Overfishing is a worldwide problem that has depleted many important commercial fish species.
  • Poaching and illegal trade- Despite laws passed to protect marine life, illegal fishing continues to this day.
  • Nets - Marine species from small invertebrates to large whales can become entangled and die in abandoned fishing nets.
  • Garbage and pollution- various animals can become entangled in garbage, as well as in nets, and oil spills cause great damage to most marine life.
  • Loss of habitat- As the world's population increases, anthropogenic pressures increase on coastlines, wetlands, kelp forests, mangroves, beaches, rocky shores and coral reefs that are home to thousands of species.
  • Invasive species - species introduced into a new ecosystem can cause serious harm to native inhabitants, since due to the lack of natural predators, they can experience a population explosion.
  • Marine Vessels - Ships can cause lethal injury to large marine mammals, as well as create a lot of noise, carry invasive species, destroy coral reefs with anchors, release chemicals into the ocean and atmosphere.
  • Ocean noise - there are many natural noises in the ocean, which are an integral part of this ecosystem, but artificial noises can disrupt the rhythm of life for many marine life.

The principle of the oxygen and radiocarbon method for determining primary production (photosynthesis rate). Tasks for the definition, destruction, gross and net primary production.

What are the necessary conditions on the planet Earth for the formation of the ozone layer. What UV ranges does the ozone screen block.

What forms of ecological relationships negatively affect species.

Amensalism - one population negatively affects another, but itself does not experience either negative or positive influence. A typical example is the high crowns of trees, which inhibit the growth of stunted plants and mosses, due to the partial blocking of access to sunlight.

Allelopathy is a form of antibiosis in which organisms have a mutually harmful effect on each other, due to their vital factors (for example, excretions of substances). It is found mainly in plants, mosses, fungi. At the same time, the harmful influence of one organism on another is not necessary for its life activity and does not benefit it.

Competition is a form of antibiosis in which two types of organisms are inherently biological enemies (usually due to a common food supply or limited reproduction opportunities). For example, between predators of the same species and the same population or different species that feed on the same food and live in the same territory. In this case, harm done to one organism benefits another, and vice versa.

Ozone is formed when solar ultraviolet radiation bombards oxygen molecules (O2 -> O3).

The formation of ozone from ordinary diatomic oxygen requires quite a lot of energy - almost 150 kJ per mole.

It is known that the main part of natural ozone is concentrated in the stratosphere at an altitude of 15 to 50 km above the Earth's surface.

Photolysis of molecular oxygen occurs in the stratosphere under the influence of ultraviolet radiation with a wavelength of 175-200 nm and up to 242 nm.



Ozone formation reactions:

О2 + hν → 2О.

O2 + O → O3.

Radiocarbon modification is reduced to the following. The carbon isotope 14C is introduced into the water sample in the form of sodium carbonate or bicarbonate with known radioactivity. After some exposure of the bottles, the water from them is filtered through a membrane filter and the radioactivity of plankton cells is determined on the filter.

The oxygen method for determining the primary production of water bodies (flask method) is based on determining the intensity of photosynthesis of planktonic algae in flasks installed in a reservoir at different depths, as well as in natural conditions - by the difference in the content of oxygen dissolved in water at the end of the day and at the end of the night.

Tasks for the definition, destruction, gross and net primary production.??????

The euphotic zone is the upper layer of the ocean, the illumination of which is sufficient for the process of photosynthesis to proceed. The lower boundary of the photic zone passes at a depth that reaches 1% of the light from the surface. It is in the photic zone that phytoplankton lives, as well as radiolarians, plants grow and most aquatic animals live. The closer to the Earth's poles, the smaller the photic zone. So, at the equator, where the sun's rays fall almost vertically, the depth of the zone is up to 250 m, while in Bely it does not exceed 25 m.

The efficiency of photosynthesis depends on many internal and external conditions. For individual leaves placed under special conditions, the efficiency of photosynthesis can reach 20%. However, the primary synthetic processes occurring in the leaf, or rather in the chloroplasts, and the final crop are separated by a string of physiological processes in which a significant part of the accumulated energy is lost. In addition, the efficiency of assimilation of light energy is constantly limited by the already mentioned environmental factors. Due to these limitations, even in the most perfect varieties of agricultural plants under optimal growth conditions, the efficiency of photosynthesis does not exceed 6-7%.

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 amount 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 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 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:

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.

Life in the ocean is represented by a wide variety of organisms - from microscopic single-celled algae and tiny animals to whales exceeding 30 m in length and larger than any animal that has ever lived on land, including the largest dinosaurs. Living organisms inhabit the ocean from the surface to the greatest depths. But of plant organisms, only bacteria and some lower fungi are found everywhere in the ocean. The remaining plant organisms inhabit only the upper illuminated layer of the ocean (mainly to a depth of about 50-100 m), where photosynthesis can take place. Photosynthetic plants create primary production, due to which the rest of the population of the ocean exists.

About 10 thousand species of plants live in the World Ocean. The phytoplankton is dominated by diatoms, peridynes, and coccolithophores from flagellates. Bottom plants include mainly diatoms, green, brown and red algae, as well as several species of herbaceous flowering plants (for example, zoster).

The fauna of the ocean is even more diverse. Representatives of almost all classes of modern free-living animals live in the ocean, and many classes are known only in the ocean. Some of them, such as the lobe-finned coelacanth fish, are living fossils whose ancestors flourished here more than 300 million years ago; others have appeared more recently. The fauna includes more than 160 thousand species: about 15 thousand protozoa (mainly radiolarians, foraminifers, ciliates), 5 thousand sponges, about 9 thousand coelenterates, more than 7 thousand various worms, 80 thousand mollusks, more than 20 thousand crustaceans, 6 thousand echinoderms and less numerous representatives of a number of other groups of invertebrates (bryozoans, brachiopods, pogonophores, tunicates and some others), about 16 thousand fish. Of the vertebrates in the ocean, in addition to fish, turtles and snakes (about 50 species) and more than 100 species of mammals, mainly cetaceans and pinnipeds, live. The life of some birds (penguins, albatrosses, gulls, etc. - about 240 species) is constantly connected with the ocean.

The greatest species diversity of animals is characteristic of tropical regions. The benthic fauna is especially diverse on shallow coral reefs. As depth increases, the diversity of life in the ocean decreases. At the greatest depths (more than 9000-10000 m) inhabited only by bacteria and several dozen species of invertebrates.

The composition of living organisms includes at least 60 chemical elements, the main of which (biogenic elements) are C, O, H, N, S, P, K, Fe, Ca and some others. Living organisms have adapted to life under extreme conditions. Bacteria are found even in ocean hydrotherms at T = 200-250 o C. In the deepest depressions, marine organisms have adapted to live under enormous pressures.

However, the inhabitants of the land were far ahead in terms of species diversity of the inhabitants of the ocean, and primarily due to insects, birds and mammals. Generally the number of species of organisms on land is at least an order of magnitude greater than in the ocean: one to two million species on land versus several hundred thousand species in the ocean. This is due to the wide variety of habitats and ecological conditions on land. But at the same time in the sea it is noted a much greater variety of life forms of plants and animals. The two main groups of marine plants - brown and red algae - do not occur at all in fresh waters. Exclusively marine are echinoderms, chaetognaths and chaetognaths, as well as lower chordates. Mussels and oysters live in huge numbers in the ocean, which forage for their food by filtering organic particles from the water, and many other marine organisms feed on the detritus of the seabed. For every species of land worm, there are hundreds of species of marine worms that feed on bottom sediments.

Marine organisms living in different environmental conditions, feeding in different ways and with different habits, can lead a wide variety of lifestyles. Individuals of some species live only in one place and behave the same throughout their lives. This is typical for most phytoplankton species. Many species of marine animals systematically change their lifestyle throughout their life cycle. They go through the larval stage, and turning into adults, they switch to a nekton lifestyle or lead a lifestyle characteristic of benthic organisms. Other species are sessile or may not go through the larval stage at all. In addition, adults of many species from time to time lead a different lifestyle. For example, lobsters can either crawl along the seabed or swim above it for short distances. Many crabs leave their safe burrows for short foraging excursions, during which they crawl or swim. Adults of most fish species belong to purely nektonic organisms, but among them there are many species that live near the bottom. For example, fish such as cod or flounder swim near the bottom or lie on it most of the time. These fish are called bottom fish, although they feed only on the surface of bottom sediments.

With all the diversity of marine organisms, all of them are characterized by growth and reproduction as integral properties of living beings. In the course of them, all parts of a living organism are updated, modified or developed. To maintain this activity, chemical compounds must be synthesized, that is, recreated from smaller and simpler components. Thus, biochemical synthesis is the most essential sign of life.

Biochemical synthesis is carried out through a number of different processes. Since work is being done, each process needs a source of energy. This is primarily the process of photosynthesis, during which almost all organic compounds present in living beings are created due to the energy of sunlight.

The process of photosynthesis can be described by the following simplified equation:

CO 2 + H 2 O + Kinetic energy of sunlight \u003d Sugar + Oxygen, or Carbon dioxide + Water + Sunlight \u003d Sugar + Oxygen

To understand the basics of the existence of life in the sea, it is necessary to know the following four features of photosynthesis:

    only some marine organisms are capable of photosynthesis; they include plants (algae, grasses, diatoms, coccolithophores) and some flagellates;

    raw materials for photosynthesis are simple inorganic compounds (water and carbon dioxide);

    photosynthesis produces oxygen;

    energy in chemical form is stored in the sugar molecule.

The potential energy stored in sugar molecules is used by both plants and animals to perform the most important life functions.

Thus, solar energy, initially absorbed by a green plant and stored in sugar molecules, can subsequently be used by the plant itself or by some animal that consumes this sugar molecule as part of food. Consequently, all life on the planet, including life in the ocean, depends on the flow of solar energy, which is retained by the biosphere through the photosynthetic activity of green plants and is transported in chemical form as part of food from one organism to another.

The main building blocks of living matter are carbon, hydrogen and oxygen atoms. Iron, copper, cobalt and many other elements are needed in small quantities. Non-living, forming parts of marine organisms, consist of compounds of silicon, calcium, strontium and phosphorus. Thus, the maintenance of life in the ocean is associated with the continuous consumption of matter. Plants receive the necessary substances directly from sea water, and animal organisms, in addition, receive part of the substances in the composition of food.

Depending on the energy sources used, marine organisms are divided into two main types: autotrophs (autotrophs) and heterotrophs (heterotrophs).

autotrophs, or "self-creating" organisms create organic compounds from the inorganic components of sea water and carry out photosynthesis using the energy of sunlight. However, autotrophic organisms with other modes of nutrition are also known. For example, microorganisms synthesizing hydrogen sulfide (H 2 S) and carbon dioxide (CO 2) draw energy not from the flux of solar radiation, but from some compounds, for example, hydrogen sulfide. Instead of hydrogen sulfide, nitrogen (N 2) and sulfate (SO 4) can be used for the same purpose. This type of autotroph is called chemo m rofam u .

Heterotrophs ("those who eat others") depend on the organisms they use as food. To live, they must consume either living or dead tissues of other organisms. The organic matter of their food provides the supply of all the chemical energy necessary for independent biochemical synthesis, and the substances necessary for life.

Each marine organism interacts with other organisms and with the water itself, its physical and chemical characteristics. This system of interactions forms marine ecosystem . The most important feature of the marine ecosystem is the transfer of energy and matter; in fact, it is a kind of "machine" for the production of organic matter.

Solar energy is absorbed by plants and transferred from them to animals and bacteria in the form of potential energy. main food chain . These consumer groups exchange carbon dioxide, mineral nutrients and oxygen with plants. Thus, the flow of organic substances is closed and conservative; between the living components of the system, the same substances circulate in the forward and backward directions, directly entering this system or replenished through the ocean. Ultimately, all incoming energy is dissipated in the form of heat as a result of mechanical and chemical processes occurring in the biosphere.

Table 9 describes the components of the ecosystem; it lists the most basic nutrients used by plants, and the biological component of an ecosystem includes both living and dead matter. The latter gradually decomposes into biogenic particles due to bacterial decomposition.

biogenic remains make up about half of the total substance of the marine part of the biosphere. Suspended in water, buried in bottom sediments and sticking to all protruding surfaces, they contain a huge supply of food. Some pelagic animals feed exclusively on dead organic matter, and for many other inhabitants it sometimes forms a significant part of the diet in addition to living plankton. However, the main consumers of organic detritus are benthic organisms.

The number of organisms living in the sea varies in space and time. The blue tropical waters of the open parts of the oceans contain significantly less plankton and nekton than the greenish waters of the coasts. The total mass of all living marine individuals (microorganisms, plants and animals) per unit area or volume of their habitat is biomass. It is usually expressed in terms of wet or dry matter (g/m 2 , kg/ha, g/m 3). Plant biomass is called phytomass, animal biomass is called zoomass.

The main role in the processes of new formation of organic matter in water bodies belongs to chlorophyll-containing organisms, mainly phytoplankton. primary production - the result of the vital activity of phytoplankton - characterizes the result of the process of photosynthesis, during which organic matter is synthesized from the mineral components of the environment. The plants that make it are called n primary producers . In the open sea, they create almost all organic matter.

Table 9

Marine Ecosystem Components

Thus, primary production is the mass of newly formed organic matter over a certain period of time. A measure of primary production is the rate of new formation of organic matter.

There are gross and net primary production. Gross primary production refers to the total amount of organic matter formed during photosynthesis. It is the gross primary production in relation to phytoplankton that is a measure of photosynthesis, since it gives an idea of ​​the amount of matter and energy that are used in further transformations of matter and energy in the sea. Net primary production refers to that part of the newly formed organic matter that remains after being spent on metabolism and that remains directly available for use by other organisms in the water as food.

The relationship between different organisms associated with food consumption is called trophic . They are important concepts in ocean biology.

The first trophic level is represented by phytoplankton. The second trophic level is formed by herbivorous zooplankton. The total biomass formed per unit of time at this level is secondary products of the ecosystem. The third trophic level is represented by carnivores, or predators of the first rank, and omnivores. The total production at this level is called tertiary. The fourth trophic level is formed by predators of the second rank, which feed on organisms of lower trophic levels. Finally, at the fifth trophic level there are predators of the third rank.

The concept of trophic levels makes it possible to judge the efficiency of an ecosystem. Energy either from the Sun or as part of food is supplied to each trophic level. A significant proportion of the energy that has entered one or another level is dissipated on it and cannot be transferred to higher levels. These losses include all the physical and chemical work done by living organisms to sustain themselves. In addition, animals of higher trophic levels consume only a certain proportion of the products formed at lower levels; some plants and animals die for natural reasons. As a result, the amount of energy that is extracted from any trophic level by organisms at a higher level of the food web is less than the amount of energy that has entered the lower level. The ratio of the corresponding amounts of energy is called environmental efficiency trophic level and is usually 0.1-0.2. Eco-efficiency values trophic levels are used to calculate biological production.

Rice. 41 shows in a simplified form the spatial organization of energy and matter flows in the real ocean. In the open ocean, the euphotic zone, where photosynthesis occurs, and the deep regions, where photosynthesis is absent, are separated by a considerable distance. It means that the transfer of chemical energy to the deep layers of water leads to a constant and significant outflow of biogens (nutrients) from surface waters.

Rice. 41. The main directions of the exchange of energy and matter in the ocean

Thus, the processes of energy and matter exchange in the ocean together form an ecological pump that pumps out the main nutrients from the surface layers. If the opposite processes did not act to make up for this loss of matter, then the surface waters of the ocean would be deprived of all nutrients and life would dry up. This catastrophe does not occur only due, first of all, to upwelling, which brings deep waters to the surface at an average speed of about 300 m/year. The rise of deep waters saturated with biogenic elements is especially intense near the western coasts of the continents, near the equator and at high latitudes, where the seasonal thermocline collapses and a significant water column is covered by convective mixing.

Since the total production of a marine ecosystem is determined by the value of production at the first trophic level, it is important to know what factors influence it. These factors include:

    illumination of the surface layer ocean waters;

    water temperature;

    supply of nutrients to the surface;

    the rate of consumption (eating) of plant organisms.

Illumination of the surface layer of water determines the intensity of the photosynthesis process, therefore, the amount of light energy entering a particular area of ​​the ocean limits the amount of organic production. In my turn the intensity of solar radiation is determined by geographical and meteorological factors, especially height of the Sun above the horizon and cloud cover. In water, light intensity decreases rapidly with depth. As a result, the primary production zone is limited to the upper few tens of meters. In coastal waters, which usually contain much more suspended solids than in the waters of the open ocean, the penetration of light is even more difficult.

Water temperature also affects the value of primary production. At the same light intensity, the maximum rate of photosynthesis is achieved by each species of algae only in a certain temperature range. Increasing or decreasing the temperature relative to this optimal interval leads to a decrease in the production of photosynthesis. However, in most of the ocean, for many species of phytoplankton, the water temperature is below this optimum. Therefore, seasonal warming of water causes an increase in the rate of photosynthesis. The maximum rate of photosynthesis in various species of algae is observed at about 20°C.

For the existence of marine plants are necessary nutrients - macro- and microbiogenic elements. Macrobiogens - nitrogen, phosphorus, silicon, magnesium, calcium and potassium are needed in relatively large quantities. Microbiogens, that is, elements required in minimal amounts, include iron, manganese, copper, zinc, boron, sodium, molybdenum, chlorine, and vanadium.

Nitrogen, phosphorus and silicon are contained in water in such small quantities that they do not satisfy the needs of plants and limit the intensity of photosynthesis.

Nitrogen and phosphorus are needed for the construction of cell matter and, in addition, phosphorus takes part in energy processes. Nitrogen is needed more than phosphorus, since in plants the ratio "nitrogen: phosphorus" is approximately 16: 1. Usually this is the ratio of the concentrations of these elements in sea water. However, in coastal waters, nitrogen recovery processes (that is, the processes by which nitrogen is returned to the water in a form suitable for plant consumption) are slower than phosphorus recovery processes. Therefore, in many coastal areas, the content of nitrogen decreases relative to the content of phosphorus, and it acts as an element that limits the intensity of photosynthesis.

Silicon is consumed in large quantities by two groups of phytoplanktonic organisms - diatoms and dinoflagellates (flagellates), which build their skeletons from it. Sometimes they extract silicon from surface waters so quickly that the resulting lack of silicon begins to limit their development. As a result, after the seasonal outbreak of silicon-consuming phytoplankton, the rapid development of "non-siliceous" forms of phytoplankton begins.

Consumption (eating) of phytoplankton zooplankton immediately affects the value of primary production, because each plant eaten will no longer grow and reproduce. Consequently, the intensity of grazing is one of the factors affecting the rate of creation of primary products. In an equilibrium situation, the intensity of grazing should be such that the phytoplankton biomass remains at a constant level. With an increase in primary production, an increase in zooplankton population or grazing intensity could theoretically bring this system back into balance. However, it takes time for zooplankton to multiply. Therefore, even with the constancy of other factors, a steady state is never achieved, and the number of zoo- and phytoplankton organisms fluctuates around a certain level of equilibrium.

Biological productivity of sea waters changes markedly in space. Areas of high productivity include continental shelves and open ocean waters, where upwelling results in the enrichment of surface waters with nutrients. The high productivity of shelf waters is also determined by the fact that relatively shallow shelf waters are warmer and better illuminated. Nutrient-rich river waters come here first of all. In addition, the supply of biogenic elements is replenished by the decomposition of organic matter on the seabed. In the open ocean, the area of ​​​​areas with high productivity is insignificant, because here planetary scale subtropical anticyclonic gyres are traced, which are characterized by the processes of subsidence of surface waters.

The water areas of the open ocean with the greatest productivity are confined to high latitudes; their northern and southern border usually coincides with latitude 50 0 in both hemispheres. Autumn-winter cooling leads here to powerful convective movements and the removal of biogenic elements from deep layers to the surface. However, with further advancement to high latitudes, productivity will begin to decrease due to the increasing predominance of low temperatures, deteriorating illumination due to the low height of the Sun above the horizon and ice cover.

Highly productive are areas of intense coastal upwelling in the zone of boundary currents in the eastern parts of the oceans off the coast of Peru, Oregon, Senegal and southwestern Africa.

In all regions of the ocean, there is a seasonal variation in the value of primary production. This is due to the biological responses of phytoplankton organisms to seasonal changes in the physical conditions of their habitat, especially illumination, wind strength and water temperature. The greatest seasonal contrasts are typical for the seas of the temperate zone. Due to the thermal inertia of the ocean, surface water temperature changes lag behind air temperature changes, and therefore, in the northern hemisphere, the maximum water temperature is observed in August, and the minimum in February. By the end of winter, as a result of low water temperatures and a decrease in the arrival of solar radiation penetrating into the water, the number of diatoms and dinoflagellates is greatly reduced. Meanwhile, due to significant cooling and winter storms, surface waters are mixed to a great depth by convection. The rise of deep, nutrient-rich waters leads to an increase in their content in the surface layer. With the warming of waters and an increase in illumination, optimal conditions are created for the development of diatoms and an outbreak of the number of phytoplankton organisms is noted.

At the beginning of summer, despite optimal temperature conditions and illumination, a number of factors lead to a decrease in the number of diatoms. First, their biomass is reduced due to grazing by zooplankton. Secondly, due to the heating of surface waters, a strong stratification is created, which suppresses vertical mixing and, consequently, the removal of nutrient-rich deep waters to the surface. Optimal conditions at this time are created for the development of dinoflagellates and other forms of phytoplankton that do not need silicon to build a skeleton. In autumn, when the illumination is still sufficient for photosynthesis, the thermocline is destroyed due to the cooling of surface waters, and conditions for convective mixing are created. Surface waters begin to be replenished with nutrients from deep layers of water, and their productivity increases, especially in connection with the development of diatoms. With a further decrease in temperature and illumination, the abundance of phytoplankton organisms of all species decreases to a low winter level. At the same time, many species of organisms fall into suspended animation, acting as a "seed" for a future spring outbreak.

At low latitudes, changes in productivity are relatively small and reflect mainly changes in vertical circulation. Surface waters are always very warm, and their constant feature is a pronounced thermocline. As a result, the removal of deep, nutrient-rich waters from under the thermocline to the surface layer is impossible. Therefore, despite favorable other conditions, far from upwelling areas in tropical seas, low productivity is noted.

Photosynthesis underlies all life on our planet. This process, which takes place in land plants, algae and many types of bacteria, determines the existence of almost all life forms on Earth, converting sunlight into chemical bond energy, which is then transferred step by step to the tops of numerous food chains.

Most likely, the same process at one time initiated a sharp increase in the partial pressure of oxygen in the Earth's atmosphere and a decrease in the proportion of carbon dioxide, which ultimately led to the flourishing of numerous complexly organized organisms. And until now, according to many scientists, only photosynthesis is able to restrain the onslaught of CO 2 emitted into the air as a result of the daily burning of millions of tons of various types of hydrocarbon fuels by humans.

A new discovery by American scientists forces us to take a fresh look at the photosynthetic process

During "normal" photosynthesis, this vital gas is produced as a "by-product". In normal mode, photosynthetic "factories" are needed to bind CO 2 and produce carbohydrates, which subsequently act as an energy source in many intracellular processes. The light energy in these "factories" goes to the decomposition of water molecules, during which the electrons necessary for fixing carbon dioxide and carbohydrates are released. This decomposition also releases oxygen O 2 .

In the newly discovered process, only a small part of the electrons released during the decomposition of water is used to assimilate carbon dioxide. The lion's share of them during the reverse process goes to the formation of water molecules from "freshly released" oxygen. At the same time, the energy converted during the newly discovered photosynthetic process is not stored in the form of carbohydrates, but directly goes to vital intracellular energy consumers. However, the detailed mechanism of this process remains a mystery.

From the outside, it may seem that such a modification of the photosynthetic process is a waste of time and energy from the Sun. It is hard to believe that in living nature, where over billions of years of evolutionary trial and error, every little thing turned out to be extremely efficient, there can be a process with such a low efficiency.

Nevertheless, this option allows you to protect the complex and fragile apparatus of photosynthesis from excessive exposure to sunlight.

The fact is that the photosynthetic process in bacteria cannot simply be stopped in the absence of the necessary ingredients in the environment. As long as microorganisms are exposed to solar radiation, they are forced to convert the energy of light into the energy of chemical bonds. In the absence of the necessary components, photosynthesis can lead to the formation of free radicals that are detrimental to the entire cell, and therefore cyanobacteria simply cannot do without a backup option for converting photon energy from water to water.

This effect of reduced conversion of CO 2 to carbohydrates and reduced release of molecular oxygen has already been observed in a series of recent studies in the natural conditions of the Atlantic and Pacific Oceans. As it turned out, reduced content of nutrients and iron ions are observed in almost half of their water areas. Hence,

Roughly half of the energy of sunlight coming to the inhabitants of these waters is converted to bypass the usual mechanism of absorption of carbon dioxide and release of oxygen.

This means that the contribution of marine autotrophs to the absorption of CO2 was previously substantially overestimated.

As Joe Bury, member of the Carnegie Institution's Department of World Ecology, the new discovery will fundamentally change our understanding of how solar energy is processed in marine microbial cells. According to him, scientists have yet to discover the mechanism of the new process, but even now its existence will force us to take a different look at modern estimates of the scale of photosynthetic absorption of CO 2 in world waters.