Features of the Pacific Islands. Oceania. T. Yu. Pritula. 2012 -13 academic year. Use for educational purposes only.

In the Pacific Ocean, there are a huge number of islands (about 10,000) of different sizes and origins. The islands have been known to Europeans since the era of the Great Geographical Discoveries, when, crossing the ocean, navigators discovered numerous archipelagos in the trade winds between the northern and southern tropics. The route, using the westerly winds and currents of temperate latitudes, was first laid by James Cook, who in 1768-1779. during three voyages he 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 round-the-world voyages and expeditions in search of new lands. The contribution to the study of the population of New Guinea and other islands by NN Miklukho-Maclay is widely known.

By origin, all the islands are divided into several genetic types. Continental islands have a continental-type crust and most of the features of the nature 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 the oceanic-type crust with its inherent active manifestation of volcanism. They are most often the tops of underwater volcanic ridges or separate 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.).

biological islands. Their basis is coral reefs and atolls, which form in shallow waters along the coasts of the continents, around islands in warm (above 18 ° C) transparent salty waters of the tropics, where reef-building 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 made entirely of limestone (calcium carbonate). Atoll in the Fiji Islands

Often, atolls form on the tops of seamounts when these peaks are located at least 20 m from the surface of the water. However, the foot of the reefs are often at great 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 are colonized by reef-forming corals down to a depth of 20 m. on the outer side of the terrace reef, a terrace is formed from the reef fragments. The heap 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 carried by waves, filling the cone 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-filled lagoon is above the ocean surface. Such atolls are called raised. Nauru is a raised atoll. The sedimentary sequence is usually enriched in phosphorus salts of organic origin. These are wonderful phosphate fertilizers. Phosphorites are mined on the island within the former lagoon.

Barrier reefs form breakwaters parallel to the outlines of the coast of the 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 40-100 m high are very rare. The largest atolls are confined to the Marshall Islands and Tuamotu.

Oceania - clusters of islands, the main part of which is located between 28.5 s. sh. and 52, 5 s. sh. - 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. The total area of ​​Oceania is 1.26 million km 2, of which 87% of the area is occupied by about. New Guinea and the islands of New Zealand, and only 13% - all the rest. Historically, the division of Oceania into parts: Melanesia ("Black Island") - the southwestern part of Oceania, (New Guinea, Bismarck, Solomons, New Hebrides, New Caledonia, Fiji and other smaller ones); Micronesia ("Small Island") - the northwestern part (Marian, 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 zone is dominated by ascending 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 the Pacific Ocean regions with weak winds (regions of subtropical baric maxima). The main circulation process that forms the climates of the islands of this part of the ocean is the trade wind. What are the characteristics of a climate that is formed under the influence of the trade winds?

In general, the climate of Oceania is maritime with significant amounts of precipitation during the year (in the west, more than 2000 mm), the maximum was recorded in the mountains of the Hawaiian Islands (the city of Wayaleale on the island of Kauai - 12,090 mm). However, in the east there are islands with an arid climate (for example, the Galapagos). Why on the islands of the Galapagos archipelago, located on the equator, the climate is not equatorial, but dry tropical trade winds? In western Oceania, tropical cyclones are born, accompanied by hurricane-force 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, one can also notice similarities: the influence of the ocean affects the natural features of all the islands (marine climate, the wide distribution of 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 runoff; characterized by depletion of 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 are larger than on the continents; there are flightless birds.

Population. Settlement history. The first inhabitants apparently appeared in Melanesia 20-30 thousand years ago, this part of the region was inhabited 5-6 thousand years ago. Humans entered Micronesia and Polynesia in the 1st millennium AD. e. and finally settled the islands by the XIV century. Brief description of the population. There is a wide variety of anthropological types, languages, and cultures on the islands. The racial identity of the indigenous inhabitants of different parts of Oceania is different: Melanesians and Papuans belong to the Australoid race, most Polynesians and Micronesians are of a mixed racial type.

Now the indigenous population makes up about half of the population. The islands were settled by settlers from different countries - England, France, the USA, whose colonies they were for a long time. Lots of people from Asia. Most of the countries of Oceania have gained political independence, but their economy is still closely connected with the former metropolises. Most of the population is employed in agriculture, and 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 in the atolls. On about. Nauru (raised atoll), where the richest deposit of phosphorites is developed in an open way, drinking water and food are imported. 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 a quarry. remnants of the former

Island natural complexes are especially vulnerable to their own (small size, isolation, extremely close internal connections of components). The intensive use of natural resources leads to a violation of the natural balance and often to the destruction and even destruction of entire islands. Especially great harm was done to the islands by nuclear weapons tests. Not only those on which the explosions were carried out were affected and became uninhabitable, but also many located at a relatively large distance from them. On many islands of Oceania, nature reserves and national parks have been created. In some of them, protected areas have existed since the 40-50s of the XX century (in New Zealand - from an even earlier time), but in most cases they were organized in the 70-80s of the XX century.

Features of the geological structure and topography of the bottom of the Pacific Ocean

In the relief of the Pacific shelf, there are:

• transgressive plains with subaerial relict relief (river valleys of the Bering Sea shelf and on the Yavan shelf);
• ridge landforms (East China Sea, Korean shelf);
• coral buildings (equatorial-tropical region);
• Antarctic shelf - the surface of the shelf is strongly dissected, underwater heights alternate with grabens;
• The continental slope is dissected by submarine canyons (North America, New Zealand, Australia, the continental slope in the Bering Sea, Antarctica).

Transitional areas of the ocean have different stages of development and levels of structural complexity. Transitional regions are located in a continuous strip along the western margin of the ocean, they include the following regions: Kurile-Kamchatka, Aleutian, Japanese, Indonesian-Philippine, East China, Melanesian, Bonin-Marian, Vityazev, Macquarie, Tonga-Kermadek. Here is the deepest trench - the Mariana Trench (11 thousand 022 m).

The eastern part of the ocean contains the Central American and Peru-Chile transition regions.

Remark 1

All transitional areas are characterized by modern volcanism, they are seismic, and together they form the marginal Pacific belt of earthquakes and volcanism.

About 11% of the bottom area falls on mid-ocean ridges: South Pacific Rise; East Pacific Rise; Chilean uplift; Galapagos Rift Zone; the ridges of Juan de Fuca, Gorda, Explorer, Sala y Gomez, Nazca, Cocos, Carnegie.

The most significant ridges of the central and western parts of the Pacific Ocean floor have a common pattern: they form a system of arched uplifts that originate in the west and end in the southeast.

A striking feature of the tectonic structure and relief is the zones of oceanic faults, manifested in the relief in the form of complexes of consistently oriented linear depressions, grabens, and blocky ridges (horsts).

The basins and uplifts of the ocean floor are characterized by the earth's crust of the oceanic type.

A distinctive feature of bottom sediments is the presence of red clays. Only in the Pacific Ocean there are belts of siliceous diatomaceous oozes. A belt of siliceous radiolarian deposits is pronounced. In the southern and western parts of the ocean, coral-algal biogenic deposits are found. The Pacific Ocean contains foraminiferal silts, pteropod deposits, and iron-manganese nodules.

Climate conditions of the Pacific Ocean

The climate of the Pacific Ocean is determined by the circulation of the atmosphere, the patterns of zonal distribution of solar radiation, and the seasonal influence of the Asian continent.

Wind fields are formed in accordance with the distribution of baric centers. In the northern hemisphere, in temperate latitudes, strong westerly winds (in winter) and weak southerly winds (in summer) are common; northeast trade winds prevail in the subtropics and tropics. The equatorial zone is characterized by calm weather.

In the northwest of the ocean in the northern hemisphere, northeast and north monsoon winds (in winter), south monsoons (in summer) are established.

In the southern hemisphere, in the subtropics and tropics, the southeast trade wind dominates.

In the tropics, cyclonic activity causes the formation of tropical hurricanes. They originate more often in summer, east of the Philippines and move north and northwest through Taiwan and Japan. When approaching the Bering Sea, they fade.

Hurricanes originate in the coastal regions of the Pacific Ocean adjacent to Central America.

In the tropical and equatorial zones, the average annual temperature ranges from 25.5 to 27.5ºС. In the western part of the ocean, the climate is warmer than in the eastern part.

In the equatorial zone, there are bands of maximum precipitation; a relatively arid zone stretches along the equator.

To the east, in the tropical zone, aridity increases, and in the equatorial zone, the amount of precipitation decreases. The driest areas are adjacent to California, located in the Chilean and Peruvian basins.

The patterns of general air circulation determine the pattern of currents in the Pacific Ocean. The main streams are:

• Northeast Current,
• North Pacific Current,
• equatorial countercurrent,
• Kuroshio Current,
• alaska current,
• california current,
• trade wind,
• Southern Equatorial and Northern Equatorial currents,
• East Australian Current,
• the course of the West winds,
• peru current,
• currents of Cape Horn.

Remark 2

A large amount of precipitation falls on the surface of the Pacific Ocean, which reduces the salinity of the waters, especially at the equator, the western parts of temperate and subpolar latitudes.

The maximum salinity - 35.5-35.6% - is observed in tropical areas, where relatively small amounts of precipitation are combined with intensive water evaporation.

Ice formation occurs in the Antarctic regions. In the north, ice forms in the Sea of ​​Okhotsk, the Bering Sea, and the Sea of ​​Japan. The glaciers of South Alaska dump some of the ice into the ocean in the form of icebergs. Icebergs spread far to the north.

The water masses of the Pacific Ocean

In the Pacific Ocean, the following water masses are distinguished:

1. Surface - depth 35-100 m, relative evenness of temperature, density and salinity.
2. Subsurface - the border with intermediate waters ranges from 220 to 600 m. They are distinguished by increased density and salinity.
3. Intermediate - the lower limit is at a depth of 900-1700 m. They have a relatively low temperature - 3-5ºС and salinity 33.8-34.7%.
4. Deep - are formed due to the immersion of chilled waters in the Antarctic waters and spreading through the basins.
5. Bottom - are at a depth of 2500-3000 m. Low temperature is characteristic - 1-2 ºС and salinity 34.6-34.7%. They form on the Antarctic shelf under conditions of strong cooling.

Flora and fauna of the Pacific Ocean

The flora and fauna of the Pacific Ocean is diverse and plentiful.

Phytoplankton consists mainly of microscopic unicellular algae - peridine and diatoms. The main part of the vegetation is concentrated in shallow water areas and upwelling zones.

In temperate and cold zones of the ocean, brown algae (kelp) are massively distributed. In the tropics, ficus, calcareous red algae are found, which, together with coral polyps, are reef-forming organisms.

The waters of the Pacific Ocean are rich in wildlife diversity. An important feature is the antiquity of most systematic groups and endemism. Many ancient sea urchins, horseshoe crabs, fish (Gilbertidium, Jordan). Only here live representatives of pogonophores.

Endemic species are also found among mammals: fur seal, dugong, sea lion, sea beaver.

Pacific Ocean located on both sides of the equator and the 180th meridian, between the continents of Eurasia and Australia in the west, North and South America in the east. In the north it is bounded by the Bering Strait, in the south by Antarctica.

The area of ​​the Pacific Ocean with seas is 178.6 million km 2, the average depth is 3984 m, the maximum depth is 11,022 m.

The Pacific Ocean is also called the Great Ocean for its size. It occupies half the area of ​​the World Ocean. This and The most deep from the oceans. AT Mariana zhelo-be marked the greatest depth on Earth: 11,022 m. In the Pacific Ocean there is the largest number of islands (about 10 thousand).

Pacific Ocean - the most ancient. It is located almost entirely within the same lithospheric plate - the Pacific. Its interaction with other plates occurs at the boundaries of lithospheric plates. And this border zone is a zone of active volcanism, modern seismic activity.

The Pacific Ocean is located in all climatic zones, except for the Arctic, but most of it lies in the equatorial, subequatorial, tropical and subtropical climates. Trade winds form in its central part, and monsoons are characteristic of the northwestern part. Often, tropical hurricanes - typhoons (Fig. 57) sweep past the Eurasian coast of the eastern Pacific Ocean. In temperate latitudes, the western transfer of air masses prevails. Strong winds and storms are also frequent here. material from the site

The organic world of the Pacific Ocean is distinguished by a variety of species. Scientists believe that half of the total mass of living organisms in the World Ocean lives in the Pacific Ocean. The flora and fauna of the tropical and equatorial belts is especially rich. Anchovies, Far Eastern salmon, herring, cod, mackerel, saury, sea bass, etc. are of commercial importance. Fur seals, walruses, and sea otters are also fished in the ocean.

About half of the world's population lives along the shores of the Pacific Ocean, so it plays an important role in people's lives. The economic activity of people has led to the pollution of the waters of the Pacific Ocean, to the disappearance of many species of animals and plants.

The Pacific Ocean is the largest and deepest ocean on earth.

On this page, material on the topics:

• Geography Cheat Sheet Pacific Ocean

• pacific ocean plant material

• A short description of the creatures of the Pacific Ocean

• Importance of the Pacific Ocean in human life

• What is the difference between the shores of the Pacific Ocean in its western and eastern parts?

Questions about this item:

Life in the world's oceans is extremely rich, but the marine flora is much poorer than on land. However, it is of no small importance in the endless circulation of substances. In total, there are approximately 10 thousand plant species: various herbs, algae, shrubs, mangrove trees, bacteria, and lower fungi are represented in slightly smaller quantities. All of them participate in the endless cycle of substances in the ocean. Digesting the products of vital activity contained in bottom sediments and in water, they are at the same time suitable for use by many living organisms as food.

The fauna of the ocean has approximately 160 thousand species of living beings.

A little lower in this article, the organic world of the Pacific Ocean will be presented in more detail.

general information

The vast World Ocean is divided by continents into several separate oceans. Each of them has peculiar features formed by nature.

The ocean, as a medium with life developing and spreading in it, is very different from land. This is due to the fact that the aquatic environment in it has a relatively constant salt composition, almost unchanged in time and space.

This property contributed to the preservation of some representatives of ancient geological eras in the World Ocean. This is especially true for large depths with low water temperatures. For example, hedgehogs, starfish and sea stalked lilies that lived in the ancient Paleozoic.

Before we introduce the organic world of the Pacific Ocean, let us briefly describe this greatest, largest natural body of water in the world.

Pacific Ocean

The world's largest ocean by area is both the deepest and oldest of all oceans in existence today. Its main features are frequent movements of the earth's crust, vast depths, a large number of volcanoes at the bottom, and huge reserves of heat in its waters. In this regard, the ocean also has an exceptional diversity of the organic world.

No wonder it is called the Great, because its area is a third of the Earth's territory and almost half of the surface area of ​​the entire oceans. The Great Pond separates the shores of 5 continents. The equator has a particularly wide width, therefore, on the surface, the warmest Pacific Ocean, the organic world of which feels quite comfortable in its waters.

There are a huge number of seas here, among which there are shelf ones, located on the shallows of the continents with shallow depths (up to 100 meters). Some seas are located in the zone of interaction of lithospheric plates. They are quite deep and are separated from the ocean by island arcs.

The Pacific Ocean is unique and peculiar. Its organic world is rich in endemics and giants. Many species of fish live here, not preserved in other oceans. These are such endemic mammals as sea otters, fur seals and sea lions.

General description of the organic world of the Pacific Ocean

A huge natural reservoir occupies vast territories located on different belts of the Earth, which contributes to the formation of various conditions for the development of life. In the ocean, a certain zoning is expressed in the distribution of fauna and flora. Plankton here is represented by small crustaceans and unicellular algae (more than 1300 species in total).

In terms of organic matter, the Pacific Ocean is relatively rich. The organic world of its bottom consists of approximately 29 species of grasses and 4 thousand species of algae.

Low temperatures and enormous pressure at great depths reduce the composition of animal species and force them to adapt to such difficult living conditions. For example, only 45 species live at a depth of 8500 meters, which are sedentary and work as "filters". They pass through the stomach a huge amount of silt, which is the main source of nutrition at such depths.

Fur seals, whales, sea beavers live in the ocean (the latter live only in the Pacific Ocean).

The composition of the organic world by area

Only in the surface layer of the Pacific Ocean, more than 1000 species of microorganisms have been found that are contained in plankton. In terms of species composition of organisms, one of the richest is the Sea of ​​Japan, located in the temperate zone.

In cold and temperate latitudes, brown algae develop well, in the southern latitudes - a giant algae (macrocystis), growing up to 200 meters in length. In tropical areas, large green and red limestone algae from the coral family are common. The latter, in combination with coral polyps, form reefs.

In the northern parts of the ocean, giant oysters and mussels predominate, and the equatorial zone is chosen by huge bivalve mollusks tridacna, whose weight can reach up to 300 kg.

Life in the ocean is rich, especially near coral reefs in equatorial and tropical latitudes. The northern waters of the ocean are rich in salmon fish, the southeast (off the coast of South America) - in huge accumulations of a wide variety of fish. The water masses are very fertile here. Animal and vegetable plankton develop well in them, which is an excellent food for anchovies, horse mackerel, mackerel and other fish species. And the latter, in turn, feed on penguins, cormorants and pelicans.

For comparison, a little about the Indian Ocean

The organic world of the Pacific and Indian Oceans is similar, since the nature of the second has many features in common with the Pacific Ocean.

The Indian Ocean is distinguished by its peculiar position. Most of it is located in the Southern Hemisphere, the northern one is limited by the mainland of Eurasia, and therefore it has no connection with the harsh Arctic Ocean.

Its organic world is especially similar to the animal and plant world of the western part of the Pacific Ocean. Its aquatic tropical masses are also rich in plankton (unicellular algae are especially abundant in it). Species of fish are also numerous and varied: mackerel, sardinella, sharks, etc. White-blooded fish (ice fish, etc.) live in the southern part. The areas of shelves and shallow waters near coral reefs are especially rich. Here thickets of algae create extensive underwater meadows. Sea giant turtles and snakes live in the waters of the warm Indian Ocean. Among the mollusks, there are many squids and cuttlefish. Whales and seals live closer to Antarctica.

Conclusion

The Pacific Ocean is large and rich. Its organic world as a whole is distinguished by species richness, antiquity and a high degree of endemism.

More than 1/2 of the living creatures of the entire World Ocean of the planet are concentrated in its waters. This applies to both the animal world and plants. And this is due to the huge size, age and variety of natural conditions.

The Pacific Ocean is a truly unique geographical feature of our planet. To him, as well as to Eurasia, it is quite possible to apply the title "most, most, most ...". For the first time its coast for Europeans was opened by the Spanish conquistador de Balboa in $1513$. The Spaniard called it the South Sea.

Seven years later, another Spaniard entered the waters of this ocean. It was the famous navigator Ferdinand Magellan. He crossed the ocean from Tierra del Fuego to the Philippine Islands in less than four months. During the voyage, the sailor was accompanied by quiet, calm weather (which happens extremely rarely). Therefore, Magellan called this ocean the Pacific.

There was a proposal, given the size of the ocean, to call it the Great. But it has not received due support and recognition. On Russian maps until $1917$, this ocean was referred to as the "Pacific Sea" or "Eastern Ocean". It was an echo of the tradition of Russian explorers who first came to him.

Features of geographical parameters

Remark 1

The Pacific Ocean is the largest of all the oceans on the planet. The area of ​​its water surface is more than $178 million km$²$ ($49% of the area of ​​the World Ocean). It washes the shores of all continents except Africa. In the equatorial region, its width is almost $20,000$ km. From north to south, it stretches from the Arctic waters to the coast of Antarctica.

There are more than $10,000 of islands in the Pacific Ocean. They have different origins and sizes. Most of them are located in the central and western regions.

In the Pacific Ocean, $25$ of seas and $3$ of large bays are allocated. Most of the seas are confined to the western part of the ocean. Among them are such marginal seas as:

• Beringovo;
• Okhotsk;
• Japanese;
• yellow;
• East Chinese.

In addition, the seas of the Indonesian islands are distinguished in this area:

• Gang;
• Sulu;
• Sulawesi;
• Moluccan;
• Javanese.

In the ocean itself there are seas such as:

• Philippine;
• New Guinean;
• coral;
• Fiji;
• Tasmanovo;
• Ross;
• Amundsen;
• Bellingshausen.

Features of the bottom of the Pacific Ocean

If we consider the structure of the ocean floor, we can distinguish three main parts:

• continental margin (shelf);
• transition zone;
• bed of the ocean.

Remark 2

A feature of the Pacific Ocean is an insignificant share of the shelf zone - only $10$% of the area. In the eastern part, the shelf is practically absent. The second feature is the greatest depth - more than $ 11,000 $ m (Marian Trench).

The transition zone forms an almost continuous ring around the ocean. Almost $65$% of the bottom area falls on the ocean floor. It is crossed by numerous underwater ridges. These ridges distinguish several basins on the ocean floor. Around the bottom. In the area of ​​the transition zone there is a vast area of ​​tectonic faults that form a seismically active zone - the Pacific Ring of Fire.

Water properties

Due to the large length of the ocean in equatorial latitudes, the ocean waters warm up well. This is the warmest ocean on the planet. The salinity of the water reaches $34.7$ ‰.

The vast expanses and influence of the continents led to the formation of a complex system of ocean currents. The most powerful are the Kuroshio, Peruvian, Northern Equatorial, Southern Equatorial and Intertrade countercurrents.

A large number of living organisms live in the waters of the ocean. The Pacific Ocean is said to be "an ocean of endemics and giants." And the deep regions of the ocean are still just poorly explored.

The properties of water contribute to the high productivity of plankton. This, in turn, is an excellent food base for fish and marine mammals. In tropical latitudes, colonies of coral polyps are actively functioning. They form systems of coral reefs and islands.