Pacific Ocean - Ocean bottom
The ocean floor of the central Pacific basin is relatively uniform, an abyssal plain with a mean depth of about 4270 m (14,000 ft). The major irregularities in the basin are the extremely steep-sided, flat-topped submarine peaks known as seamounts. The western part of the floor consists of mountain arcs that rise above the sea as island groups, such as the Solomon Islands and New Zealand, and deep oceanic trenches, such as the Mariana Trench, the Philippine Trench, and the
Tonga Trench. Most of the trenches lie adjacent to the outer margins of the wide western Pacific continental shelf.
Along the eastern margin of the Pacific Basin is the East Pacific Rise, which is a part of the worldwide mid-oceanic ridge. About 3000 km (1800 miles) across, the rise stands about 3 km (2 miles) above the adjacent ocean floor.
Pacific Ocean - Ocean Trench
The islands are a volcanic island arc, formed at the convergent boundary where the Pacific Plate subducts under the Indo-Australian Plate. The subducting Pacific Plate created the Kermadec Trench, an 8 km deep submarine trench, to the east of the islands. The islands lie along the undersea Kermadec ridge, which runs southwest towards the North Island of New Zealand and northeast towards
Tonga (Kermadec-Tonga Arc). The four main islands are the peaks of volcanoes that rise from the seabed high enough to rise above the sea level. There are numerous other volcanoes, active or inactive or extinct, that do not reach the sea level, but have water depths between 65 and 1500 m above them, those are seamounts. Monowai Submarine Volcano, with a depth of 120 m over its peak, is midway between Raoul Island and
Tonga. 100 km South of L'Esperance Rock is the little-explored Star of Bengal Bank, probably with submarine volcanoes. Further South are the South Kermadec Ridge Seamounts, the southernmost of which, Rumble IV Seamount, is just 150 km North of North Island of New Zealand. The ridge eventually connects to White Island in the Bay of Plenty on the North coast of North Island of New Zealand. The islands experience many earthquakes from plate movement and volcanism.
Raoul and Curtis are both active volcanoes. The volcanoes on the other islands are currently inactive, and the smaller islands are the eroded remnants of extinct volcanoes.
Pacific Ocean - Climate
Only the interiors of the large land masses of Australia, New Guinea, and New Zealand escape the pervasive climatic influence of the Pacific. Within the area of the Pacific, five distinctively different climatic regions exist: the mid-latitude westerlies, the trades, the monsoon region, the typhoon region, and the doldrums.
Mid-latitude westerly air streams occur in both northerly and southerly latitudes, bringing marked seasonal differences in temperature.
Closer to the equator, where most of the islands lie, steadily blowing trade winds allow for relatively constant temperatures throughout the year of 21-27°C (70-81°F).
The monsoon region lies in the far western Pacific between Japan and Australia. Characteristic of this climatic region are winds that blow from the continental interior to the ocean in winter and in the opposite direction in summer. Consequently, a marked seasonality of cloudiness and rainfall occurs. Typhoons often cause extensive damage in the west and southwest Pacific. The greatest typhoon frequency exists within the triangle from southern Japan to the central Philippines to eastern Micronesia.
Although more poorly defined than the other climatic regions, two major doldrum areas lie within the ocean, one located off the western shores of Central America and the other within the equatorial waters of the western Pacific. Both areas are noted for their high humidity, considerable cloudiness, light fluctuating winds, and frequent calms.
Marine biology - Overview
Marine biology covers a great deal, from the microscopic, including plankton and phytoplankton, which can be as small as 0.02 micrometers and are both hugely important as the primary producers of the sea, to the huge cetaceans (
whales) which reach up to a reported 33 meters (109 feet) in length.
The habitats studied by marine biology include everything from the tiny layers of surface water in which organisms and abiotic items may be trapped in surface tension between the ocean and atmosphere, to the depths of the abyssal trenches, sometimes 10,000 meters or more beneath the surface of the ocean. It studies habitats such as coral reefs, kelp forests, tide pools, muddy, sandy, and rocky bottoms, and the open ocean (pelagic) zone, where solid objects are rare and the surface of the water is the only visible boundary.
A large proportion of all life on Earth exists in the oceans. Exactly how large is the proportion is still unknown. While the oceans comprise about 71% of the Earth's surface, due to their depth they encompass about 300 times the habitable volume of the terrestrial habitats on Earth.
Many species are economically important to humans, including the food fishes. It is also becoming understood that the well-being of marine organisms and other organisms are linked in very fundamental ways. Human understanding is growing of the relationship between life in the sea and important cycles such as that of matter (such as the carbon cycle), of air (such as Earth's respiration, and movement of energy through ecosystems. Large areas beneath the ocean surface still remain effectively unexplored.)
Marine biology - Reefs
Reefs comprise some of the densest habitats in the world by number of species per area. They can be incredibly diverse, even cold water reefs. The best-known are tropical reefs which exist in most tropical waters. Reefs are built up by coral and other calcined deposits, usually on top of a rocky outcrop on the ocean floor. Reefs can also grow on other surfaces, which has made it possible to create artificial reefs.
Much attention in marine biology is focused on coral reefs and the El Niño weather phenomenon. In 1998, coral reefs experienced a "once in a thousand years" bleaching event, in which vast expanses of reefs across the Earth died because sea surface temperatures rose well above normal. Some reefs are recovering, but scientists say that 58% of the world's coral reefs are now endangered and predict that global warming could exacerbate this trend.
