Physical geography of continents and oceans
OCEANS
PACIFIC OCEAN
Features of the organic world of the Pacific Ocean
Concentrated in the waters of the Pacific Ocean more than half of the living matter of the entire oceans Earth. This applies to both plants and animal populations. The organic world as a whole is distinguished by species richness, antiquity and a high degree of endemism.
The fauna, numbering up to 100 thousand species in total, is characterized by mammals, living mainly in temperate and high latitudes. The representative of toothed whales, the sperm whale, is widespread; among the toothless whales, there are several species of striped whales. Their fishing is strictly limited. Separate genera of the family of eared seals (sea lions) and fur seals are found in the south and north of the ocean. Northern fur seals are valuable fur-bearing animals, the hunting of which is strictly controlled. The northern waters of the Pacific Ocean are also home to the now very rare Steller sea lion (an eared seal) and the walrus, which has a circumpolar range but is now on the verge of extinction.
Very rich fauna fish. There are at least 2,000 species in tropical waters, and about 800 species in the northwestern seas. The Pacific Ocean accounts for almost half of the world's fish catch. The main fishing areas are the northern and central parts of the ocean. The main commercial families are salmon, herring, cod, anchovies, etc.
The predominant mass of living organisms inhabiting the Pacific Ocean (as well as other parts of the World Ocean) falls on invertebrates, which live at various levels of ocean waters and at the bottom of shallow waters: these are protozoa, coelenterates, arthropods (crabs, shrimp), mollusks (oysters, squid, octopuses), echinoderms, etc. They serve as food for mammals, fish, seabirds, but also form an essential component of marine fisheries and are objects of aquaculture.
The Pacific Ocean, due to its high temperatures surface waters in tropical latitudes, especially rich various types corals, including those with a calcareous skeleton. In no other ocean is there such an abundance and variety of coral structures of various types as in the Pacific.
The basis plankton constitute unicellular representatives of the animal and flora. There are almost 380 species of phytoplankton in the Pacific Ocean.
The greatest wealth of the organic world is characteristic of areas where the so-called upwelling(the rise to the surface of deep waters rich in minerals) or mixing of waters with different temperatures occurs, which creates favorable conditions for the nutrition and development of phyto- and zooplankton, which feed on fish and other nekton animals. In the Pacific Ocean, upwelling areas are concentrated off the coast of Peru and in divergence zones in subtropical latitudes, where there are areas of intensive fishing and other industries.
Against the background of normal, annually recurring conditions, the Pacific Ocean is characterized by a phenomenon that disrupts the usual rhythm circulation and hydrological processes and not observed in other parts of the World Ocean. It manifests itself at intervals of 3 to 7 years and entails a disruption of the usual environmental conditions within the intertropical space of the Pacific Ocean, affecting the life of living organisms, including the population of coastal regions of land. It consists of the following: at the end of November or December, i.e. shortly before Christmas (why the phenomenon received the popular name " El Niño", which means "Holy Child"), for reasons that have not yet been clarified, there is a weakening of the southern trade wind and, consequently, a weakening of the South Trade Wind Current and the influx of relatively cold waters to the shores of South America and to the west of it. At the same time, winds that are usually unusual for these latitudes begin to blow from the northwest towards the southern hemisphere, carrying relatively warm waters to the southeast, strengthening the Intertrade Wind Countercurrent. This disrupts the upwelling phenomenon both in the intertropical divergence zone and off the coast of South America, which, in turn, leads to death of plankton, and then the fish and other animals that feed on it.
El Niño phenomenon regularly observed since the second half of the 19th century. It was found that in many cases it was accompanied by a violation of environmental conditions not only in the ocean, but also in vast areas of adjacent land: an abnormal increase in precipitation in the arid regions of South America and, conversely, droughts in the island and coastal regions of Southeast Asia and Australia. The consequences of El Niño 1982-1983 and 1997-1998 are considered especially severe, when this unfavorable phenomenon lasted for several months.
- Pacific Ocean
- Ocean floor, mid-ocean ridges and transition zones
- Features of the organic world
There is a truly unique geographical feature of planet Earth in the world - the Pacific Ocean. Like the Eurasian continent, it can be called the largest, most populated, and so on. It was first opened to Europeans by the Spanish conquistador de Balboa in 1513. The ocean was then called the “South Sea”.
After seven years, another Spaniard, Ferdinand Magellan, a famous navigator, sailed here. He managed to cross the Pacific Ocean from Tierra del Fuego to the Philippine Islands itself in just four months. During the journey, the weather was calm and calm, without storms or storms, so the researcher called the ocean “Quiet.”
Some scientific experts wanted to call him “Great”, based on his incredible size. But this name did not receive recognition or any support. Until 1917, on all Russian maps this geographical object was called the “Eastern Ocean” or “Pacific Sea”. This name was given to it by Russian explorers who first reached the ocean.
Features of geographical parameters
This ocean is considered the largest ocean on our entire planet. The area of the water surface covers more than 178,000,000 km². And this is equal to 49% of the entire area of the World Ocean itself. This geographical object washes almost all the continents of the Earth, except Africa. The width of the ocean in the equatorial region is 20 thousand kilometers. If we take into account its length from north to south, then it is located from the Arctic waters right up to the coast of Antarctica
More than ten thousand islands are located in the Pacific Ocean. They all have different sizes and origins. In the central and western parts they are located greatest number.
25 seas and three huge bays are distinguished in this ocean. The western region of the ocean has the largest number of seas. Among all, the following marginal seas can be distinguished:
Beringovo;
East China;
Japanese;
Okhotsk;
It is also worth highlighting the seas of the Indonesian islands:
Javanese;
Sulawesi;
Moluccan.
In the Pacific Ocean itself there are seas such as:
Coral;
Filipino;
New Guinea;
Amundsen;
Tasmanovo;
Bellingshausen;
Features of the Pacific Ocean floor
From the point of view of the structure of the ocean, three main parts can be distinguished:
Shelf or continental margin;
Transition zone.
Only 10% of the entire area of the Pacific Ocean belongs to the shelf zone. In the east it is practically absent. The Mariana Trench is 11,000 meters deep and is the world's deepest.
A continuous ring around the Pacific Ocean forms a transition zone. 65% of the bottom area is on the ocean floor. Many underwater ridges cross it. Such ridges create basins on the ocean floor directly along the entire perimeter. A vast area of tectonic faults is located in the transition zone. They formed the "Pacific Ring of Fire", a seismically active zone.
Properties of waters
The ocean is well warmed up due to its length at equatorial latitudes. It is considered the warmest ocean in the country. 34.7 ‰ - salinity of the Pacific Ocean water.
Also characteristic is a complex system of various ocean currents, which was formed with the help of vast expanses and the influence of continents. The largest contradictions are: Kuroshio, Interpassat, Northern Passat, Peruvian, Southern Passat.
The waters of the Pacific Ocean are densely populated. This geographical object is called the "ocean of giants and endemics." The depths of the ocean have been little explored by specialists.
Due to the properties of water, plankton is quite productive. This is an excellent food supply for marine mammals and fish. Colonies of coral polyps are characteristic of tropical latitudes. Such formations form systems of coral islands and reefs.
Features of the Pacific Islands. Oceania. T. Yu. Pritula. 2012 -13 academic year. Use for educational purposes only.
There are a huge number of islands in the Pacific Ocean (approximately 10,000) different sizes and origin. The islands have been known to Europeans since the era of the Great Geographical Discoveries, when, crossing the ocean, sailors discovered numerous archipelagos in the trade wind zone between the northern and southern tropics. The route using the westerly winds and currents of temperate latitudes was first laid out by James Cook, who in 1768 -1779. in time of three voyages explored New Zealand, discovered a number of archipelagos in the south of Oceania and the Hawaiian Islands in the north. Many islands were discovered by Russian navigators during circumnavigations and expeditions in search of new lands. The contribution to the study of the population of New Guinea and other islands of N. N. Miklouho-Maclay is widely known.
By origin, all islands are divided into several genetic types. Continental islands have continental-type crust and most of the natural features of the neighboring continent, from which they separated relatively recently as a result of tectonic processes (Taiwan, Hainan, Kalimantan, etc.). Volcanic islands are formed in the zone of development of oceanic-type crust with its inherent active manifestation of volcanism. They are most often the tops of underwater volcanic ridges or free-standing volcanoes and are composed of lavas and other eruption products.
Santa Cruz Island in the Galapagos Islands Luzon Island in the Philippines Volcanic islands are often confined to the transitional morphostructural zone of the ocean and form part of island arcs (Aleutian, Kuril, Mariana, etc.). Some islands of this type are formed within mid-ocean ridges (Easter Island, Galapagos Islands, etc.).
Biogenic islands. Their basis is coral reefs and atolls, which form in shallow waters along the coasts of continents, around islands in warm (above 18°C) transparent salty waters of the tropics, where reef-forming corals can live. Coral structures occupy about 2 million km 2 in the tropical latitudes of the ocean. Atolls are ring-shaped structures with a shallow, sometimes freshwater lagoon in the center, protected from waves by the outer edge of a coral reef. They are composed entirely of limestone (calcium carbonate). Atoll in the Fiji Islands
Atolls often form on the tops of seamounts, when these peaks are located at least 20 m from the surface of the water. However, the bases of reefs are often found at greater depths. The process begins with the formation of an underwater volcano, which eventually turns into a volcanic island. When volcanic activity ceases, the slopes of the cone to a depth of 20 m are populated by reef-forming corals. With outside reef terrace a terrace is formed from reef debris. The accumulation of volcanic rocks creates a very large load on the ocean floor, the crust sags, the volcano slowly sinks, and the corals continue to build up the structure, keeping the reef at the same level. Calcareous sediments are transported by waves and fill the cone of the trench between the reef and the volcano, forming a shallow ring-shaped lagoon. Gradually, the lagoon is covered with coral sands and it is often overgrown with coconut palms.
If the ocean floor experiences upward movements, the sediment-laden lagoon appears above the ocean surface. Such atolls are called elevated. The island of Nauru is a raised atoll. The thickness of sediments is usually enriched with phosphorus salts of organic origin. These are wonderful phosphorus fertilizers. Phosphorite mining is carried out on the island within the former lagoon.
Barrier reefs form breakwaters parallel to the shoreline of a mainland or island. The largest of them is the Great Barrier Reef, which stretches for 2000 km parallel to the northeastern coast of Australia (Queensland). Great Barrier Reef O. Lady Musgrave in the Great Barrier Reef All coral islands are low (5-10 m above sea level), atolls with a height of 40-100 m are very rare. The largest atolls are confined to the Marshall and Tuamotu islands.
Oceania is a collection of islands, the main part of which is located between 28.5 s. w. and 52.5 S. w. – Hawaiian Islands in the north and Campbell Island in the south. Most of them are concentrated in equatorial and tropical latitudes. A significant part of them are grouped into archipelagos, but there are also isolated islands. Total area Oceania 1.26 million km 2, of which 87% of the area is occupied by. New Guinea and the islands of New Zealand and only 13% - all others. Historically, Oceania has been divided into parts: Melanesia (“Black Island”) - the southwestern part of Oceania (New Guinea, Bismarck, Solomon, New Hebrides, New Caledonia, Fiji and other smaller ones); Micronesia (“Small Island”) – northwestern part (Mariana, Caroline, Marshall, Gilbert, etc.); Polynesia ("Multi-island") - the central part of the Pacific Ocean, (Hawaiian, Marquesas, Tuamotu, Tonga, etc.); Islands of New Zealand - North and South, Sewart, etc.
Climate. Oceania is located in the equatorial and tropical zones. The equatorial belt is dominated by rising air currents and calm weather with especially heavy showers during the zenithal position of the sun. At what latitudes is the Sun at its zenith? What days of the year? The tropical islands of the Northern and Southern Hemispheres are located in regions of the Pacific Ocean with weak winds (regions of subtropical baric maximums). The main circulation process that shapes the climates of the islands in this part of the ocean is the trade wind. What are the characteristics of a climate formed under the influence of trade winds?
In general, the climate of Oceania is marine with significant amounts of precipitation throughout the year (in the west more than 2000 mm), the maximum was recorded in the mountains of the Hawaiian Islands (Uealeale on the island of Kauai - 12,090 mm). However, in the east there are islands with arid climates (for example, the Galapagos). Why on the islands of the Galapagos archipelago, located on the equator, is the climate not equatorial, but dry tropical trade wind? Tropical cyclones arise in western Oceania, accompanied by hurricane winds and downpours. The climate of most of the islands of Melanesia, hot and humid, is considered the most unhealthy climate on Earth. What type of climate is formed on the islands of Melanesia?
Despite the significant differences in the nature of the islands, similarities can be noticed: natural features all islands are influenced by the ocean (marine climate, widespread landforms associated with the work of the sea, saline soils and waters); the river network is poorly developed: the rivers are short, the atolls are generally devoid of surface flow; characterized by impoverished species composition and a high degree of endemism of flora and fauna; the mammals of the islands are often smaller, and the reptiles and birds larger, than on the continents; there are flightless birds.
Population. History of settlement. The first inhabitants apparently appeared in Melanesia 20-30 thousand years ago; this part of the region was inhabited 5-6 thousand years ago. People entered Micronesia and Polynesia in the 1st millennium AD. e. and finally settled the islands by the 14th century. Brief description population. The islands have a wide variety of anthropological types, languages, and cultures. Indigenous race various parts Oceania is different: Melanesians and Papuans belong to the Australoid race, most Polynesians and Micronesians belong to the mixed racial type.
Now the indigenous population makes up about half the number. The islands were settled by settlers from different countries– England, France, the USA, whose colonies they were for a long time. Many people come from Asian countries. Most countries in Oceania have gained political independence, but their economies are still closely connected with the former metropolises. Most of the population is employed in agriculture, mining is also carried out.
Some islands are very densely populated and suffer from a lack of land, water, pollution from industrial waste and household waste. This problem is very acute on the atolls. On about. Nauru (raised atoll), where open method a very rich deposit of phosphorites is being developed, importing drinking water and food. More than a third of the island's area is occupied by quarries. However, there are islands where there is little or no population. The surface of most of the island of Nauru is quarries. remnants of former
Island natural complexes are especially vulnerable due to their ( small sizes, isolation, extremely close internal connections of components). Heavy use natural resources leads to a disruption of the natural balance and often leads to the destruction and even destruction of entire islands. Nuclear weapons tests caused especially great harm to the islands. Not only those where the explosions were carried out were damaged and became uninhabitable, but also many located at a relatively large distance from them. On many islands of Oceania, natural reserves have been created and national parks. In some of them, protected areas have existed since the 40s -50s of the 20th century (in New Zealand - from an even earlier time), but in most cases they were organized in the 70s -80s of the 20th century.
The largest and most ancient of all oceans. Its area is 178.6 million km2. It can easily accommodate all the continents combined, which is why it is sometimes called the Great. The name “Pacific” is associated with the name of F., who traveled around the world and sailed through the Pacific Ocean under favorable conditions.
This ocean is truly great: it occupies 1/3 of the surface of the entire planet and almost 1/2 of the area. The ocean has an oval shape, and it is especially wide.
The peoples inhabiting the Pacific coasts and islands have been sailing the ocean for a long time and exploring its riches. Information about the ocean was accumulated as a result of the voyages of F. Magellan, J. . The beginning of its wide study was laid in the 19th century by the first round-the-world Russian expedition of I.F. . Currently, a special one has been created for the study of the Pacific Ocean. For recent years New data on its nature were obtained, the depth was determined, currents and the topography of the bottom and ocean were studied.
The southern part of the ocean from the shores of the Tuamotu Islands to the shores is an area of calm and stable. It was for this calm and silence that Magellan and his companions called the Pacific Ocean. But west of the Tuamotu Islands the picture changes dramatically. Calm weather is rare here; stormy winds usually blow, often turning into... These are the so-called southern squalls, especially fierce in December. Tropical cyclones are less frequent but more intense. They arrive at the beginning of autumn from, at the northern tip they turn into warm westerly winds.
The tropical waters of the Pacific Ocean are clean, transparent and have medium salinity. Their deep dark blue color amazed observers. But sometimes the waters here get green. This is due to the development of marine life. In the equatorial part of the ocean, favorable weather conditions. The temperature over the sea is about 25°C and remains almost unchanged throughout the year. Winds of moderate strength blow here. At times there is complete calm. The sky is clear, the nights are very dark. The balance is especially stable in the island zone. In the calm belt there are frequent heavy but short-term showers, mainly in the afternoon. Hurricanes are extremely rare here.
The warm waters of the ocean contribute to the work of corals, of which there are many. Stretches along the eastern coast of Australia Big Reef. This is the largest “ridge” created by organisms.
The western part of the ocean is under the influence of the monsoons with their sudden vagaries. Terrible hurricanes arise here and... They are especially ferocious in the northern hemisphere between 5 and 30°. Typhoons are frequent from July to October, with up to four per month in August. They originate in the area of the Caroline and Mariana Islands and then “make raids” on the shores, and. Since in the west of the tropical part of the ocean it is hot and rainy, the islands of Fiji, the New Hebrides, New Hebrides are not without reason considered one of the most unhealthy places on the globe.
The northern regions of the ocean are similar to the southern ones, only as if in a mirror image: circular rotation of the waters, but if in the southern part it is counterclockwise, then in the northern part it is clockwise; unstable weather in the west, where typhoons enter further north; cross currents: North Passat and South Passat; in the north there is little ocean floating ice, since the Bering Strait is very narrow and protects the Pacific Ocean from the influence of the Arctic Ocean. This distinguishes the north of the ocean from its south.
The Pacific Ocean is the deepest. Its average depth is 3980 meters, and its maximum reaches 11022 m. The ocean coast is in a seismic zone, as it is the boundary and place of interaction with other lithospheric plates. This interaction is accompanied by terrestrial and underwater and.
Bottom relief: East Pacific Rise, Northeast, Northwestern, Central, Eastern, Southern and other basins, deep-sea trenches: Aleutian, Kurile, Mariana, Philippine, Peruvian and others.
Inhabitants: a large number of unicellular and multicellular microorganisms; fish (pollock, herring, salmon, cod, sea bass, beluga, chum salmon, pink salmon, sockeye salmon, chinook salmon and many others); seals, seals; crabs, shrimp, oysters, squid, octopus.
: 30-36.5 ‰.
Currents: warm - , North Pacific, Alaskan, South Trade Wind, East Australian; cold - Californian, Kuril, Peruvian, Western winds.
Additional information: The Pacific Ocean is the largest in the world; crossed it for the first time in 1519, the ocean was called “Pacific”, because during the entire three months of the journey they did not encounter a single storm; The Pacific Ocean is usually divided into northern and southern regions, the border of which runs along the equator.
Answer:
Pacific Ocean- the largest in area, the deepest and the most ancient of the oceans. Its main features are great depths, frequent movements of the earth's crust, many volcanoes at the bottom, a huge supply of heat in its waters, and an exceptional diversity of the organic world. Geographical position of the ocean. The Pacific Ocean, also called the Great Ocean, occupies 1/3 of the surface of the planet and almost 1/2 of the area of the World Ocean. It is located on both sides of the equator and 180° meridian. This ocean divides and at the same time connects the shores of five continents. The Pacific Ocean is particularly wide near the equator, so it is warmest at the surface. In the east of the ocean, the coastline is weakly dissected; several peninsulas and bays stand out. In the west, the shores are strongly indented. There are many seas here. Among them there are shelf ones, located on the continental shallows, with depths of no more than 100 m. Some seas lie in the zone of interaction of lithospheric plates. They are deep and separated from the ocean by island arcs. From the history of ocean exploration. Since ancient times, many peoples inhabiting the Pacific coasts and islands have sailed the ocean and developed its riches. The beginning of European penetration into the Pacific Ocean coincided with the era of the Great Geographical Discoveries. F. Magellan's ships crossed a huge expanse of water from east to west over several months of sailing. All this time the sea was surprisingly calm, which gave Magellan reason to call it the Pacific Ocean. Much information about the nature of the ocean was obtained during the voyages of J. Cook. Russian expeditions led by I. F. Kruzenshtern, M. P. Lazarev, V. M. Golovnin, and Yu. F. Lisyansky made a great contribution to the study of the ocean and the islands in it. In the same XIX century. complex studies were carried out by S. O. Makarov on the ship “Vityaz”. Since 1949, regular scientific voyages have been carried out by Soviet expeditionary ships. A special international organization is studying the Pacific Ocean.
Features of nature. The topography of the ocean floor is complex. The continental shoal (shelf) is well developed only off the coasts of Asia and Australia. Continental slopes are steep, often stepped. Large rises and ridges divide the ocean floor into basins. Near America is the East Pacific Rise, which is part of the system of mid-ocean ridges. On the ocean floor there are more than 10 thousand individual seamounts, mostly of volcanic origin.
Lithospheric plate, on which the Pacific Ocean lies, interacts with other plates at its boundaries. The edges of the Pacific Plate are plunging into a tight space of trenches that ring the ocean. These movements give rise to earthquakes and volcanic eruptions. Here lies the planet's famous "Ring of Fire" and the deepest Mariana Trench (11,022 m). The ocean climate is varied. The Pacific Ocean is located in all climate zones except the North Polar. Above its vast expanses the air is saturated with moisture. In the equator region, up to 2000 mm of precipitation falls. The Pacific Ocean is protected from the cold Arctic Ocean by land and underwater ridges, so its northern part is warmer than its southern part. The Pacific Ocean is the most restless and formidable among the oceans of the planet. Trade winds blow in its central parts. In the west, monsoons are developed. In winter, a cold and dry monsoon comes from the mainland, which has a significant impact on the ocean climate; Some of the seas are covered with ice. Often, devastating tropical hurricanes, typhoons, sweep over the western part of the ocean (“typhoon” means “ strong wind"). In temperate latitudes, storms rage throughout the cold half of the year. Western air transport prevails here. The highest waves up to 30 m high are recorded in the north and south of the Pacific Ocean. Hurricanes raise entire mountains of water in it. The properties of water masses are determined by climate characteristics. Due to the large extent of the ocean from north to south, the average annual surface water temperature varies from -1 to +29°C. In general, precipitation in the ocean predominates over evaporation, so the salinity of its surface waters is somewhat lower than in other oceans. Currents in the Pacific Ocean are consistent with general scheme them in the World Ocean, which you already know. Since the Pacific Ocean is strongly elongated from west to east, latitudinal water flows predominate in it. In both the northern and southern parts of the ocean, ring-shaped movements of surface waters are formed. The organic world of the Pacific Ocean is distinguished by its extraordinary richness and diversity of plant and animal species. It is home to half of the total mass of living organisms in the World Ocean. This feature of the ocean is explained by its size, diversity natural conditions and age. Life is especially rich in tropical and equatorial latitudes near coral reefs. There are many salmon fish in the northern part of the ocean. In the southeast of the ocean, off the coast of South America, huge concentrations of fish form. The water masses here are very fertile; they develop a lot of plant and animal plankton, which feed on anchovies (herring-like fish up to 16 cm long), horse mackerel, mackerel and other types of fish. Birds eat a lot of fish here: cormorants, pelicans, penguins. The ocean is home to whales, fur seals, and sea beavers (these pinnipeds live only in the Pacific Ocean). There are also many invertebrate animals - corals, sea urchins, shellfish (octopus, squid). The largest mollusk, the tridacna, lives here, weighing up to 250 kg. The Pacific Ocean has all natural zones except the North Polar. Each of them has its own characteristics. The northern subpolar belt occupies a small part of the Bering and Okhotsk seas. The temperature of the water masses here is low (up to -1°C). In these seas there is active mixing of waters, and therefore they are rich in fish (pollock, flounder, herring). There are many salmon fish and crabs in the Sea of Okhotsk. Vast territories are covered by the northern temperate zone. It is strongly influenced by westerly winds and storms are frequent here. In the west of this belt lies the Sea of Japan - one of the richest in diverse species of organisms. In the equatorial belt, at the boundaries of currents, where the rise of deep waters to the surface increases and their biological productivity increases, many fish live (sharks, tuna, sailfish, etc.). In the southern tropical zone of the Pacific Ocean off the coast of Australia there is a unique natural complex of the Great Barrier Reef. This is the largest “mountain range” on Earth created by living organisms. In size it is comparable to the Ural Range. Protected by islands and reefs in warm waters colonies of corals develop in the form of bushes and trees, columns, castles, bouquets of flowers, mushrooms; corals are light green, yellow, red, blue, purple. Many mollusks, echinoderms, crustaceans, and various fish live here. Types of economic activities in the ocean. There are more than 50 coastal countries on the shores and islands of the Pacific Ocean, home to approximately half of humanity.
Rice. 43. Relief of the bottom of the Pacific Ocean. What are the structural features of the bottom topography?
The use of the natural resources of the ocean began in ancient times. Several centers of navigation arose here - in China, in Oceania, in South America, in the Aleutian Islands. The Pacific Ocean plays an important role in the lives of many peoples. Half of the world's fish catch comes from this ocean (see Figure 26). In addition to fish, part of the catch consists of various shellfish, crabs, shrimp, and krill. In Japan, algae and shellfish are grown on the seabed. In some countries from sea water salt and other chemicals are extracted and desalinated. Placer metals are being mined on the shelf. Oil is being extracted off the coast of California and Australia. Ferromanganese ores were discovered on the ocean floor. Important sea routes pass through the greatest ocean of our planet; the length of these routes is very large. Shipping is well developed, mainly along the coasts of the continents. Economic activity human activity in the Pacific Ocean has led to the pollution of its waters and to the depletion of some types of biological wealth. So, by the end of the 18th century. mammals were exterminated - sea cows (a species of pinnipeds), discovered by one of the participants in V. Bering's expedition. On the verge of extermination at the beginning of the 20th century. there were seals, the number of whales decreased. Currently, their fishing is limited. A great danger in the ocean is water pollution with oil, some heavy metals and waste from the nuclear industry. Harmful substances carried by currents throughout the ocean. Even off the coast of Antarctica, these substances were found in marine organisms.