1.
Ocean
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An ocean is a body of saline water that composes much of a planets hydrosphere. On Earth, an ocean is one of the major divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern, the word sea is often used interchangeably with ocean in American English but, strictly speaking, a sea is a body of saline water partly or fully enclosed by land. The ocean contains 97% of Earths water, and oceanographers have stated that less than 5% of the World Ocean has been explored, the total volume is approximately 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the component of Earths hydrosphere, it is integral to all known life, forms part of the carbon cycle. The world ocean is the habitat of 230,000 known species, but because much of it is unexplored, the origin of Earths oceans remains unknown, oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds, the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many planets and natural satellites, notably. The Solar Systems giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of water within a circumstellar habitable zone. Ocean planets are a type of planet with a surface completely covered with liquid. The concept of Ōkeanós has an Indo-European connection, Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases, though generally described as several separate oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a body of water with relatively free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits. The Mid-Oceanic Ridge of the World are connected and form the Ocean Ridge, the continuous mountain range is 65,000 km long, and the total length of the oceanic ridge system is 80,000 km long
2.
Marine life
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Marine life, or sea life or ocean life, refers to the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life helps determine the nature of our planet. Marine organisms produce much of the oxygen we breathe, shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land. Most life forms evolved initially in marine habitats, oceans provide about 99 percent of the living space on the planet. The earliest vertebrates appeared in the form of fish, which live exclusively in water, some of these evolved into amphibians which spend portions of their lives in water and portions on land. Other fish evolved into mammals and subsequently returned to the ocean as seals. Plant forms such as kelp and algae grow in the water and are the basis for some underwater ecosystems, plankton, and particularly phytoplankton, are key primary producers forming the general foundation of the ocean food chain. Marine vertebrates must obtain oxygen to survive, and they do so in various ways, fish have gills instead of lungs, although some species of fish, such as the lungfish, have both. Marine mammals, such as dolphins, whales, otters, some amphibians are able to absorb oxygen through their skin. Invertebrates exhibit a range of modifications to survive in poorly oxygenated waters including breathing tubes. However, as invertebrate life evolved in an aquatic habitat most have little or no specialisation for respiration in water. Altogether there are 230,000 documented marine species, including over 16,000 species of fish, there is no life without water, which has been characterised as the solvent of life. The Nobel prize winner Albert Szent-Györgyi referred to water as the mater und matrix, the abundance of water on earths surface is a unique feature that distinguishes earth from other planets in the Solar System. Earths hydrosphere consists chiefly of the oceans, but technically includes all surfaces in the world, including inland seas, lakes, rivers. The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of 10,911.4 m, the mass of the oceans is approximately 1. 35×1018 metric tons, or about 1/4400 of Earths total mass. The oceans cover an area of 3. 618×108 km2 with a depth of 3682 m. If all of Earths crustal surface was at the elevation as a smooth sphere. About 97. 5% of the water is saline, the remaining 2. 5% is fresh water, Most fresh water, about 68. 7%, is present as ice in ice caps and glaciers
3.
Sea
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A sea is a large body of salt water that is surrounded in whole or in part by land. More broadly, the sea is the system of Earths salty. The sea moderates Earths climate and has important roles in the cycle, carbon cycle. Although the sea has been traveled and explored since prehistory, the scientific study of the sea—oceanography—dates broadly to the British Challenger expedition of the 1870s. Owing to the present state of continental drift, the Northern Hemisphere is now equally divided between land and sea but the South is overwhelmingly oceanic. Salinity in the ocean is generally in a narrow band around 3. 5% by mass, although this can vary in more landlocked waters, near the mouths of large rivers. About 85% of the solids in the sea are sodium chloride. Deep-sea currents are produced by differences in salinity and temperature, surface currents are formed by the friction of waves produced by the wind and by tides, the changes in local sea level produced by the gravity of the Moon and Sun. The direction of all of these is governed by surface and submarine land masses, former changes in sea levels have left continental shelves, shallow areas in the sea close to land. The most diverse areas surround great tropical coral reefs, whaling in the deep sea was once common but whales dwindling numbers prompted international conservation efforts and finally a moratorium on most commercial hunting. Life may have started there and aquatic microbial mats are generally credited with the oxygenation of Earths atmosphere, the sea is an essential aspect of human trade, travel, mineral extraction, and power generation. It is the scene of activities including swimming, diving, surfing. However, population growth, industrialization, and intensive farming have all contributed to marine pollution. Atmospheric carbon dioxide is being absorbed in increasing amounts, lowering its pH in a known as ocean acidification. The shared nature of the sea has made overfishing an increasing problem, both senses of sea date to Old English, the larger sense has required a definite article since Early Middle English. Seas are generally larger than lakes and contain salt water, while the defining elements of size and being bounded are generally used, there is no formally accepted technical definition of sea among oceanographers. In international law, the United Nations Convention on the Law of the Sea states that all the ocean is the sea. Earth is the known planet with seas of liquid water on its surface, although Mars possesses ice caps
4.
Biology
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Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, identification and taxonomy. Modern biology is a vast and eclectic field, composed of branches and subdisciplines. However, despite the broad scope of biology, there are certain unifying concepts within it that consolidate it into single, coherent field. In general, biology recognizes the cell as the unit of life, genes as the basic unit of heredity. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable, the term biology is derived from the Greek word βίος, bios, life and the suffix -λογία, -logia, study of. The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus used biologi in his Bibliotheca botanica, the first German use, Biologie, was in a 1771 translation of Linnaeus work. In 1797, Theodor Georg August Roose used the term in the preface of a book, karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective. The science that concerns itself with these objects we will indicate by the biology or the doctrine of life. Although modern biology is a recent development, sciences related to. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, however, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. While the formal study of medicine back to Hippocrates, it was Aristotle who contributed most extensively to the development of biology. Especially important are his History of Animals and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotles successor at the Lyceum, Theophrastus, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences, even into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz, Al-Dīnawarī, who wrote on botany, biology began to quickly develop and grow with Anton van Leeuwenhoeks dramatic improvement of the microscope. It was then that scholars discovered spermatozoa, bacteria, infusoria, investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy also had a impact on biological thinking. In the early 19th century, a number of biologists pointed to the importance of the cell. Thanks to the work of Robert Remak and Rudolf Virchow, however, meanwhile, taxonomy and classification became the focus of natural historians
5.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
6.
Genus
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A genus is a taxonomic rank used in the biological classification of living and fossil organisms in biology. In the hierarchy of classification, genus comes above species. In binomial nomenclature, the name forms the first part of the binomial species name for each species within the genus. Felis catus and Felis silvestris are two species within the genus Felis, Felis is a genus within the family Felidae. The composition of a genus is determined by a taxonomist, the standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. Moreover, genera should be composed of units of the same kind as other genera. The term comes from the Latin genus, a noun form cognate with gignere, linnaeus popularized its use in his 1753 Species Plantarum, but the French botanist Joseph Pitton de Tournefort is considered the founder of the modern concept of genera. The scientific name of a genus may be called the name or generic epithet. It plays a role in binomial nomenclature, the system of naming organisms. The rules for the names of organisms are laid down in the Nomenclature Codes. The standard way of scientifically describing species and other lower-ranked taxa is by binomial nomenclature, the generic name forms its first half. For example, the gray wolfs binomial name is Canis lupus, with Canis being the name shared by the wolfs close relatives. The specific name is written in lower-case and may be followed by names in zoology or a variety of infraspecific names in botany. Especially with these names, when the generic name is known from context. Because animals are typically only grouped within subspecies, it is written as a trinomen with a third name. Dog breeds, meanwhile, are not scientifically distinguished, there are several divisions of plant species and therefore their infraspecific names generally include contractions explaining the relation. For example, the genus Hibiscus includes hundreds of other species apart from the Rose of Sharon or common garden hibiscus, Rose of Sharon doesnt have subspecies but has cultivars that carry desired traits, such as the bright white H. syriaca Diana. Hawaiian hibiscus, meanwhile, includes several separate species, since not all botanists agree on the divisions or names between species, it is common to specify the source of the name using author abbreviations
7.
Environment (biophysical)
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The biophysical environment can vary in scale from microscopic to global in extent. It can also be subdivided according to its attributes, examples include the marine environment, the atmospheric environment and the terrestrial environment. The number of environments is countless, given that each living organism has its own environment. The term environment is used as a short form for the biophysical environment. The expression the environment often refers to a global environment in relation to humanity. All life that has survived must have adapted to conditions of its environment, temperature, light, humidity, soil nutrients, etc. all influence any species, within any environment. However life in turn modifies, in forms, its conditions. Some long term modifications along the history of our planet have been significant and this process consisted in the breakdown of carbon dioxide by anaerobic microorganisms that used the carbon in their metabolism and released the oxygen to the atmosphere. This led to the existence of oxygen-based plant and animal life, other interactions are more immediate and simple, such as the smoothing effect that forests have on the temperature cycle, compared to neighboring unforested areas. Environmental science is the study of the interactions within the biophysical environment, part of this scientific discipline is the investigation of the effect of human activity on the environment. Ecology, a sub-discipline of biology and a part of environmental sciences, is mistaken as a study of human induced effects on the environment. Environmental studies is an academic discipline that is the systematic study of interaction of humans with their environment. It is a field of study that includes the natural environment, built environments. Environmentalism is a social and philosophical movement that, in a large part, seeks to minimise. The issues of concern for environmentalists usually relate to the environment with the more important ones being climate change, species extinction, pollution. One of the studies related include employing Geographic Information Science to study the biophysical environment, biophysics subject to the context List of conservation topics List of environmental issues Lists of environmental topics Miller, G. Tyler. McCallum, Malcolm L. Gwendolynn W. Bury, google search patterns suggest declining interest in the environment
8.
Life
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Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, biology is the primary science concerned with the study of life, although many other sciences are involved. The definition of life is controversial, the current definition is that organisms maintain homeostasis, are composed of cells, undergo metabolism, can grow, adapt to their environment, respond to stimuli, and reproduce. However, many other definitions have been proposed, and there are some borderline cases. Modern definitions are more complex, with input from a diversity of scientific disciplines, biophysicists have proposed many definitions based on chemical systems, there are also some living systems theories, such as the Gaia hypothesis, the idea that the Earth itself is alive. Another theory is that life is the property of systems, and yet another is elaborated in complex systems biology. Abiogenesis describes the process of life arising from non-living matter. Properties common to all organisms include the need for certain chemical elements to sustain biochemical functions. Life on Earth first appeared as early as 4.28 billion years ago, soon after ocean formation 4.41 billion years ago, Earths current life may have descended from an RNA world, although RNA-based life may not have been the first. The mechanism by which began on Earth is unknown, though many hypotheses have been formulated and are often based on the Miller–Urey experiment. The earliest known forms are microfossils of bacteria. In July 2016, scientists reported identifying a set of 355 genes believed to be present in the last universal ancestor of all living organisms. Since its primordial beginnings, life on Earth has changed its environment on a time scale. To survive in most ecosystems, life must often adapt to a range of conditions. Some microorganisms, called extremophiles, thrive in physically or geochemically extreme environments that are detrimental to most other life on Earth, Aristotle was the first person to classify organisms. Later, Carl Linnaeus introduced his system of nomenclature for the classification of species. Eventually new groups and categories of life were discovered, such as cells and microorganisms, cells are sometimes considered the smallest units and building blocks of life. There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many such as proteins
9.
Surface tension
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Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. Surface tension allows insects, usually denser than water, to float, at liquid-air interfaces, surface tension results from the greater attraction of liquid molecules to each other than to the molecules in the air. The net effect is a force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. Thus, the surface becomes under tension from the imbalanced forces, because of the relatively high attraction of water molecules for each other through a web of hydrogen bonds, water has a higher surface tension compared to that of most other liquids. Surface tension is an important factor in the phenomenon of capillarity, Surface tension has the dimension of force per unit length, or of energy per unit area. The two are equivalent, but when referring to energy per unit of area, it is common to use the surface energy. In materials science, surface tension is used for either surface stress or surface free energy, the cohesive forces among liquid molecules are responsible for the phenomenon of surface tension. In the bulk of the liquid, each molecule is pulled equally in every direction by neighboring liquid molecules, the molecules at the surface do not have the same molecules on all sides of them and therefore are pulled inwards. This creates some internal pressure and forces liquid surfaces to contract to the minimal area, Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a shape by the imbalance in cohesive forces of the surface layer. In the absence of forces, including gravity, drops of virtually all liquids would be approximately spherical. The spherical shape minimizes the necessary wall tension of the surface according to Laplaces law. Another way to view surface tension is in terms of energy, a molecule in contact with a neighbor is in a lower state of energy than if it were alone. The interior molecules have as many neighbors as they can possibly have, for the liquid to minimize its energy state, the number of higher energy boundary molecules must be minimized. The minimized quantity of boundary molecules results in a surface area. As a result of surface area minimization, a surface will assume the smoothest shape it can, since any curvature in the surface shape results in greater area, a higher energy will also result. Consequently, the surface will push back against any curvature in much the way as a ball pushed uphill will push back to minimize its gravitational potential energy. Bubbles in pure water are unstable, the addition of surfactants, however, can have a stabilizing effect on the bubbles
10.
Oceanic trench
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The oceanic trenches are linear oceanographic features which are topographic depressions of the sea floor, relatively narrow in width, but hemispheric-scale in length. They are the deepest parts of the ocean floor, a trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to an island arc, and about 200 km from a volcanic arc. Oceanic trenches typically extend 3 to 4 km below the level of the surrounding oceanic floor, the greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m below sea level. Oceanic lithosphere moves into trenches at a rate of about 3 km2/yr. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km2 or about 0. 5% of the oceans and this applies to Cascadia, Makran, southern Lesser Antilles, and Calabrian trenches. Trenches are related to but distinguished from continental collision zones, where continental crust enters the subduction zone, when buoyant continental crust enters a trench, subduction eventually stops and the convergent plate margin becomes a collision zone. Trenches were not clearly defined until the late 1940s and 1950s, the bathymetry of the ocean was of no real interest until the late 19th and early 20th centuries, with the initial laying of Transatlantic telegraph cables on the seafloor between the continents. Even then the elongated bathymetric expression of trenches was not recognized until well into the 20th century, the term “trench” does not appear in Murray and Hjort’s classic oceanography book. Instead they applied the term “deep“ for the deepest parts of the ocean, the term was first used in a geologic context by Scofield two years after the war ended to describe a structurally controlled depression in the Rocky Mountains. Johnstone, in his 1923 textbook An Introduction to Oceanography, first used the term in its sense for any marked. His measurements revealed that trenches are sites of downwelling in the solid Earth, the concept of downwelling at trenches was characterized by Griggs in 1939 as the tectogene hypothesis, for which he developed an analogue model using a pair of rotating drums. World War II in the Pacific led to improvements of bathymetry in especially the western and northern Pacific. The rapid growth of deep sea research efforts, especially the use of echosounders in the 1950s and 1960s confirmed the morphological utility of the term. The important trenches were identified, sampled, and their greatest depths sonically plumbed, the heroic phase of trench exploration culminated in the 1960 descent of the Bathyscaphe Trieste, which set an unbeatable world record by diving to the bottom of the Challenger Deep. This has been termed trench rollback or hinge retreat and this is one explanation for the existence of back-arc basins. Slab rollback is a process which occurs during the subduction of two tectonic plates resulting in the motion of the trench. Forces acting perpendicular to the slab at depth are responsible for the migration of the slab in the mantle and ultimately the movement of the hinge
11.
Coral reef
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Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. Coral reefs are built by colonies of tiny animals found in waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups, the polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons which support, most reefs grow best in warm, shallow, clear, sunny and agitated waters. Often called rainforests of the sea, shallow coral reefs form some of the most diverse ecosystems on Earth, paradoxically, coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients. They are most commonly found at depths in tropical waters. Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protection, the annual global economic value of coral reefs is estimated between US$29. 8-375 billion. However, coral reefs are fragile ecosystems, partly because they are sensitive to water temperature. Most of the coral reefs we can see today were formed after the last glacial period when melting ice caused the sea level to rise and this means that most modern coral reefs are less than 10,000 years old. As communities established themselves on the shelves, the reefs grew upwards, Reefs that rose too slowly could become drowned reefs. They are covered by so much water there was insufficient light. Coral reefs are found in the sea away from continental shelves, around oceanic islands. The vast majority of islands are volcanic in origin. The few exceptions have tectonic origins where plate movements have lifted the deep ocean floor on the surface. In 1842 in his first monograph, The Structure and Distribution of Coral Reefs, Charles Darwin set out his theory of the formation of atoll reefs and he theorized uplift and subsidence of the Earths crust under the oceans formed the atolls. Darwin’s theory sets out a sequence of three stages in atoll formation and it starts with a fringing reef forming around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the reef becomes a barrier reef. Darwin predicted that underneath each lagoon would be a bed rock base, where the level of the underlying earth allows, the corals grow around the coast to form what he called fringing reefs, and can eventually grow out from the shore to become a barrier reef
12.
Kelp forest
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Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth, smaller areas of anchored kelp are called kelp beds. Kelp forests occur worldwide throughout temperate and polar coastal oceans, in 2007, kelp forests were also discovered in tropical waters near Ecuador. Physically formed by brown macroalgae, kelp forests provide a unique, over the last century, they have been the focus of extensive research, particularly in trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem. For example, kelp forests can influence coastal oceanographic patterns and provide ecosystem services. However, the influence of humans has often contributed to kelp forest degradation, of particular concern are the effects of overfishing nearshore ecosystems, which can release herbivores from their normal population regulation and result in the overgrazing of kelp and other algae. This can rapidly result in transitions to barren landscapes where relatively few species persist, the term kelp refers to marine algae belonging to the order Laminariales. Though not considered a taxonomically diverse order, kelps are highly diverse structurally and functionally, the most widely recognized species are the giant kelps, although numerous other genera such as Laminaria, Ecklonia, Lessonia, Alaria, and Eisenia are described. Many marine mammals and birds are found, including seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons. Frequently considered an ecosystem engineer, kelp provides a physical substrate, in algae, the body of an individual organism is known as a thallus rather than as a plant. The stipe is analogous to a plant stalk, extending vertically from the holdfast, the fronds are leaf- or blade-like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity. In addition, many species have pneumatocysts, or gas-filled bladders. These structures provide the necessary buoyancy for kelp to maintain a position in the water column. The environmental factors necessary for kelp to survive include hard substrate, high nutrients, water flow and turbulence facilitate nutrient assimilation across kelp fronds throughout the water column. Water clarity affects the depth to which sufficient light can be transmitted, in ideal conditions, giant kelp can grow as much as 30-60 cm vertically per day. Some species, such as Nereocystis, are annuals, while others such as Eisenia are perennials, in perennial kelp forests, maximum growth rates occur during upwelling months and die-backs correspond to reduced nutrient availability, shorter photoperiods, and increased storm frequency. Kelps are primarily associated with temperate and arctic waters worldwide, the region with the greatest diversity of kelps is the northeastern Pacific, from north of San Francisco, California, to the Aleutian Islands, Alaska. Although kelp forests are unknown in tropical waters, a few species of Laminaria have been known to occur exclusively in tropical deep waters
13.
Seagrass
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Seagrasses are flowering plants belonging to four families, all in the order Alismatales, which grow in marine, fully saline environments. There are 12 genera with some 60 species known, like all autotrophic plants, seagrasses photosynthesize so are limited to growing in the submerged photic zone, and most occur in shallow and sheltered coastal waters anchored in sand or mud bottoms. Most species undergo submarine pollination and complete their life cycle underwater. Seagrasses form extensive beds or meadows, which can be either monospecific or in mixed beds where more than one species coexist. In temperate areas, usually one or a few species dominate, whereas tropical beds usually are more diverse, some fish species that visit/feed on seagrasses raise their young in adjacent mangroves or coral reefs. Also, seagrasses trap sediment and slow down water movement, causing suspended sediment to fall out, the trapping of sediment benefits coral by reducing sediment loads in the water. Their importance for associated species is due to provision of shelter. Seagrass meadows account for more than 10% of the total carbon storage. Per hectare, it twice as much carbon dioxide as rain forests. Yearly, seagrasses sequester about 27.4 million tons of CO2, global warming models suggest, some seagrasses will go extinct – Posidonia oceanica is expected to go extinct, or nearly so, by 2050. This would result in CO2 release, historically, seagrasses were collected as fertilizer for sandy soil. This was an important use in the Ria de Aveiro, Portugal and it was also used for bandages and other purposes. Currently, seagrass is used in furniture, and woven like rattan, natural disturbances, such as grazing, storms, ice-scouring, and desiccation, are an inherent part of seagrass ecosystem dynamics. Seagrasses display a high degree of phenotypic plasticity, adapting rapidly to changing environmental conditions. Seagrasses are in decline, with some 30,000 km2 lost during recent decades. The main cause is human disturbance, most notably eutrophication, mechanical destruction of habitat, excessive input of nutrients is directly toxic to seagrasses, but most importantly, it stimulates the growth of epiphytic and free-floating macro- and micro-algae. This weakens the sunlight, reducing the photosynthesis that nourishes the seagrass, decaying seagrass leaves and algae fuels increasing algal blooms, resulting in a positive feedback. This can cause a regime shift from seagrass to algal dominance
14.
Seamount
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A seamount is a mountain rising from the ocean seafloor that does not reach to the waters surface, and thus is not an island. Seamounts are typically formed from volcanoes that rise abruptly and are usually found rising from the seafloor to 1. They are defined by oceanographers as independent features that rise to at least 1,000 m above the seafloor, the peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. Seamounts and guyots are most abundant in the North Pacific Ocean, in recent years, several active seamounts have been observed, for example Loihi in the Hawaiian Islands. Because of their abundance, seamounts are one of the most common marine ecosystems in the world, interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton, corals, fish, and marine mammals alike. Their aggregational effect has been noted by the fishing industry. There are ongoing concerns on the impact of fishing on seamount ecosystems. 95% of ecological damage is done by bottom trawling, which scrapes whole ecosystems off seamounts, because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap, there have been instances where naval vessels have collided with uncharted seamounts, for example, Muirfield Seamount is named after the ship that struck it in 1973. Seamounts can be found in every ocean basin in the world, a seamount is technically defined as an isolated rise in elevation of 1,000 m or more from the surrounding seafloor, and with a limited summit area, of conical form. If small knolls, ridges and hills less than 1,000 m in height are included there are over 100,000 seamounts in the world ocean. Most seamounts are volcanic in origin, and thus tend to be found on oceanic crust near mid-ocean ridges, mantle plumes, and island arcs. Overall, seamount and guyot coverage is greatest as a proportion of area in the North Pacific Ocean. The Arctic Ocean has only 16 seamounts and no guyots, the 9,951 seamounts mapped cover an area of 8,088,550 km2. The largest seamount has an area of 15,500 km2, guyots cover a total area of 707,600 km2 and have an average area of 2,500 km2, more than twice the average size of seamounts. Nearly 50% of guyot area and 42% of the number of guyots occur in the North Pacific Ocean, the largest three guyots are all in the North Pacific, the Kuko Guyot, Suiko Guyot and the Pallada Guyot. Seamount chain redirects here, for a broader coverage related to this topic, Seamounts are often found in groupings or submerged archipelagos, a classic example being the Emperor Seamounts, an extension of the Hawaiian Islands
15.
Hydrothermal vent
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A hydrothermal vent is a fissure in a planets surface from which geothermally heated water issues. Hydrothermal vents are found near volcanically active places, areas where tectonic plates are moving apart, ocean basins. Hydrothermal vents exist because the earth is both active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers, under the sea, hydrothermal vents may form features called black smokers. Chemosynthetic bacteria and archaea form the base of the chain, supporting diverse organisms, including giant tube worms, clams, limpets. Active hydrothermal vents are believed to exist on Jupiters moon Europa, and Saturns moon Enceladus, Hydrothermal vents in the deep ocean typically form along the mid-ocean ridges, such as the East Pacific Rise and the Mid-Atlantic Ridge. These are locations where two plates are diverging and new crust is being formed. The proportion of each varies from location to location, in contrast to the approximately 2 °C ambient water temperature at these depths, water emerges from these vents at temperatures ranging from 60 to as high as 464 °C. Due to the hydrostatic pressure at these depths, water may exist in either its liquid form or as a supercritical fluid at such temperatures. The critical point of water is 375 °C at a pressure of 218 atmospheres, however, introducing salinity into the fluid raises the critical point to higher temperatures and pressures. The critical point of seawater is 407 °C and 298.5 bars, accordingly, if a hydrothermal fluid with a salinity of 3.2 wt. % NaCl vents above 407 °C and 298.5 bars, furthermore, the salinity of vent fluids have been shown to vary widely due to phase separation in the crust. The critical point for lower salinity fluids is at lower temperature and pressure conditions than that for seawater, for example, a vent fluid with a 2.24 wt. % NaCl salinity has the point at 400 °C and 280.5 bars. Thus, water emerging from the hottest parts of some hydrothermal vents can be a supercritical fluid, examples of supercritical venting are found at several sites. Sister Peak vents low salinity phase-separated, vapor-type fluids, sustained venting was not found to be supercritical but a brief injection of 464 °C was well above supercritical conditions. A nearby site, Turtle Pits, was found to vent low salinity fluid at 407 °C, which is above the critical point of the fluid at that salinity. A vent site in the Cayman Trough named Beebe, which is the worlds deepest known hydrothermal site at ~5000 m below sea level, has shown sustained supercritical venting at 401 °C and 2.3 wt% NaCl
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Tide pool
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Tide pools, or rock pools, are rocky pools on the sea shore which are filled with seawater. Many of these pools exist as separate pools only at low tide, Tidal pools exist in the intertidal zones. These zones are submerged by the sea at high tides and during storms, at other times the rocks may undergo other extreme conditions, baking in the sun or exposed to cold winds. Few organisms can survive harsh conditions. Lichens and barnacles live in this region, in this zone, different barnacle species live at very tightly constrained elevations. Tidal conditions precisely determine the height of an assemblage relative to sea level. The intertidal zone is exposed to sun and wind, which desiccate barnacles. Their calcite shells are impermeable, and they possess two plates which they slide across their mouth opening when not feeding and these plates also protect against predation. The high tide zone is flooded during high tide. Organisms must survive wave action, currents, and exposure to the sun and this zone is predominantly inhabited by seaweed and invertebrates, such as sea anemones, starfish, chitons, crabs, green algae, and mussels. Marine algae provide shelter for nudibranches and hermit crabs, the same waves and currents that make life in the high tide zone difficult bring food to filter feeders and other intertidal organisms. Also called the Lower Littoral Zone and this area is usually under water - it is only exposed when the tide is unusually low. This sub region is mostly submerged, but it is exposed only during low tide, often it teems with life and has much more marine vegetation, especially seaweeds. Organisms in this zone do not have to be as well adapted to drying out, low tide zone organisms include abalone, anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, and sometimes even small vertebrates such as fish. This area is relatively protected from large predators because of the wave action. Tide pools provide a home for hardy organisms such as starfish, mussels, inhabitants must be able to deal with a frequently changing environment — fluctuations in water temperature, salinity, and oxygen content. Hazards include waves, strong currents, exposure to midday sun, waves can dislodge mussels and draw them out to sea. Gulls pick up and drop sea urchins to break them open, starfish prey on mussels and are eaten by gulls themselves
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Pelagic zone
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Any water in a sea or lake that is neither close to the bottom nor near the shore can be said to be in the pelagic zone. The word pelagic is derived from Greek πέλαγος, meaning open sea, the pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom. Conditions differ deeper in the water such that as pressure increases with depth. Depending on the depth, the column, rather like the Earths atmosphere. The pelagic zone occupies 1,330 million km3 with a depth of 3.68 km. Pelagic life decreases with increasing depth and it is affected by light intensity, pressure, temperature, salinity, the supply of dissolved oxygen and nutrients, and the submarine topography, which is called bathymetry. In deep water, the zone is sometimes called the open-ocean zone. In other contexts, coastal water not near the bottom is still said to be in the pelagic zone, the pelagic zone can be contrasted with the benthic and demersal zones at the bottom of the sea. The benthic zone is the region at the very bottom of the sea. It includes the sediment surface and some subsurface layers, Marine organisms living in this zone, such as clams and crabs, are called benthos. The demersal zone is just above the benthic zone and it can be significantly affected by the seabed and the life that lives there. Demersal fish are known as bottom feeders and groundfish. Depending on how deep the sea is, the zone can extend over up to five horizontal layers in the ocean. From the top down, these are, From the surface down to around 200 m This is the zone at the surface of the sea where enough light is available for photosynthesis. Nearly all primary production in the ocean occurs here, consequently, plants and animals are largely concentrated in this zone. Examples of organisms living in this zone are plankton, floating seaweed, jellyfish, tuna, many sharks, from 200 m down to around 1,000 m The name for this zone stems from Greek μέσον, meaning middle. Although some light penetrates this second layer it is insufficient for photosynthesis, at about 500 m the water also becomes depleted of oxygen. Organisms survive this environment by having more efficient gills or by minimizing movement, examples of animals that live here are swordfish, squid, Anarhichadidae or wolffish and some species of cuttlefish
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Phytoplankton
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Phytoplankton /ˌfaɪtoʊˈplæŋktən/ are the autotrophic components of the plankton community and a key part of oceans, seas and freshwater basin ecosystems. The name comes from the Greek words φυτόν, meaning plant, most phytoplankton are too small to be individually seen with the unaided eye. Phytoplankton are photosynthesizing microscopic organisms that inhabit the upper layer of almost all oceans. They are agents for primary production, the creation of organic compounds from carbon dioxide dissolved in the water, Phytoplankton obtain energy through the process of photosynthesis and must therefore live in the well-lit surface layer of an ocean, sea, lake, or other body of water. Phytoplankton account for half of all activity on Earth. Their cumulative energy fixation in carbon compounds is the basis for the vast majority of oceanic, the effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant, as a side note, one of the more remarkable food chains in the ocean – remarkable because of the small number of links – is that of phytoplankton-feeding krill feeding baleen whales. Phytoplankton are also dependent on minerals. However, across large regions of the World Ocean such as the Southern Ocean and this has led to some scientists advocating iron fertilization as a means to counteract the accumulation of human-produced carbon dioxide in the atmosphere. Large-scale experiments have added iron to the oceans to promote phytoplankton growth, however, controversy about manipulating the ecosystem and the efficiency of iron fertilization has slowed such experiments. Phytoplankton depend on other substances to survive as well, in particular, Vitamin B is crucial. Areas in the ocean have been identified as having a lack of Vitamin B. While almost all species are obligate photoautotrophs, there are some that are mixotrophic and other. Of these, the best known are dinoflagellate genera such as Noctiluca and Dinophysis, the term phytoplankton encompasses all photoautotrophic microorganisms in aquatic food webs. Phytoplankton serve as the base of the food web, providing an essential ecological function for all aquatic life. However, unlike terrestrial communities, where most autotrophs are plants, phytoplankton are a group, incorporating protistan eukaryotes. There are about 5,000 known species of marine phytoplankton, how such diversity evolved despite scarce resources is unclear. In terms of numbers, the most important groups of phytoplankton include the diatoms, cyanobacteria and dinoflagellates, one group, the coccolithophorids, is responsible for the release of significant amounts of dimethyl sulfide into the atmosphere
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Zooplankton
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Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word zooplankton is derived from the Greek zoon, meaning animal, individual zooplankton are usually microscopic, but some are larger and visible with the naked eye. Zooplankton is a categorization spanning a range of organism sizes including small protozoans, although zooplankton are primarily transported by ambient water currents, many have locomotion, used to avoid predators or to increase prey encounter rate. Ecologically important protozoan zooplankton groups include the foraminiferans, radiolarians and dinoflagellates and this wide phylogenetic range includes a similarly wide range in feeding behavior, filter feeding, predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton, phytoplankton, other zooplankton, detritus, as a result, zooplankton are primarily found in surface waters where food resources are abundant. Just as any species can be limited within a geographical region, however, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, ‘patches’ of zooplankton species exist throughout the ocean, zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, the physical factor that influences zooplankton distribution the most is mixing of the water column that affects nutrient availability and, in turn, phytoplankton production. Since they are small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance. Zooplankton can also act as a disease reservoir, crustacean zooplankton have been found to house the bacterium Vibrio cholerae, which causes cholera, by allowing the cholera vibrios to attach to their chitinous exoskeletons. This symbiotic relationship enhances the ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon. A global coverage database of zooplankton biomass and abundance data
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Cetacea
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Cetacea are a widely distributed and diverse clade of aquatic mammals that today consists of the whales, dolphins, and porpoises. Most species live in the sea, some in rivers, the name is derived from the Latin cetus whale and Greek ketos huge fish. The extinct ancestors of modern whales are the Archaeoceti, while cetaceans were historically thought to have descended from mesonychids, molecular evidence supports them as a relative of Artiodactyls. Cetaceans belong to the order Cetartiodactyla and their closest living relatives are hippopotamuses and other hoofed mammals, having diverged about 50 million years ago. Cetaceans range in size from the 1 m and 50 kg Mauis dolphin to the 29.9 m and 190,000 kg blue whale and they have streamlined bodies and two limbs that are modified into flippers. Dolphins are able to very tight turns while swimming at high speeds. The hindlimbs of cetaceans are internal, and are thought to be vestigial, baleen whales have short hairs on their mouth, unlike the toothed whales. Cetaceans have well-developed senses—their eyesight and hearing are adapted for both air and water, and baleen whales have a system in their vibrissae. They have a layer of fat, or blubber, under the skin to maintain body heat in cold water, Some species are well adapted for diving to great depths. Although cetaceans are widespread, most species prefer the waters of the Northern and Southern Hemispheres. They spend their lives in the water, having to mate, give birth, molt or escape predators, like killer whales. This has drastically affected their anatomy to be able to do so and they feed largely on fish and marine invertebrates, but a few, like the killer whale, feed on large mammals and birds, such as penguins and seals. Some baleen whales are specialised for feeding on benthic creatures, male cetaceans typically mate with more than one female, although the degree of polygyny varies with the species. Cetaceans are not shown to have pair bonds, male cetacean strategies for reproductive success vary between herding females, defending potential mates from other males, or whale song which attracts mates. Calves are typically born in the fall and winter months, cetaceans produce a number of vocalizations, notably the clicks and whistles of dolphins, the moaning songs of the humpback whale. The meat, blubber and oil of cetaceans have traditionally used by indigenous peoples of the Arctic. Cetaceans have been depicted in cultures worldwide. Dolphins are commonly kept in captivity and are sometimes trained to perform tricks and tasks
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Marine ecosystem
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Marine ecosystems are among the largest of Earths aquatic ecosystems. Examples include salt marshes, intertidal zones, estuaries, lagoons, mangroves, coral reefs, the sea. They can be contrasted with freshwater ecosystems, which have a salt content. Marine waters cover two-thirds of the surface of the Earth, such places are considered ecosystems because the plant life supports the animal life and vice versa. Marine ecosystems are essential for the health of both marine and terrestrial environments. According to the World Resource Center, coastal habitats account for about one-third of marine biological productivity, estuarine ecosystems, such as salt marshes, seagrass meadows and mangrove forests, are among the most productive ecosystems on the planet. Coral reefs provide food and shelter to the highest levels of diversity in the world. Marine ecosystems usually have a large biodiversity and are thought to have a good resistance against invasive species. However, exceptions have been observed, and the mechanisms responsible in determining the success of an invasion are not yet clear, barange M, Field JG, Harris RP, Eileen E, Hofmann EE, Perry RI and Werner F Marine Ecosystems and Global Change Oxford University Press. ISBN 978-0-19-955802-5 Boyd IL, Wanless S and Camphuysen CJ Top predators in marine ecosystems, their role in monitoring, ISBN 978-0-521-84773-5 Davenport J Challenges to Marine Ecosystems, Proceedings of the 41st European Marine Biology Symposium Volume 202 of Developments in hydrobiology. ISBN 978-1-4020-8807-0 Levner E, Linkov I and Proth J Strategic management of marine ecosystems Springer, Volume 50 of NATO Science Series IV. ISBN 978-1-4020-3158-8 Mann KH and Lazier JRN Dynamics of marine ecosystems, ISBN 978-1-4051-1118-8 Moustakas A and Karakassis I How diverse is aquatic biodiversity research. U. S. Environmental Protection Agency—EPA, Marine Ecosystems Encyclopædia Britannica Online, Marine ecosystem —, smithsonian Institution, Ocean Portal Marine Ecosystems Research Programme
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Recreation
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Recreation is an activity of leisure, leisure being discretionary time. The need to do something for recreation is an element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be fun. The term recreation appears to have used in English first in the late 14th century, first in the sense of refreshment or curing of a sick person. Other factors that account for a role of recreation are affluence, population trends. This direction of thought has even extended to the view that leisure is the purpose of work, and a reward in itself. Leisure is considered a right under the Universal Declaration of Human Rights. Recreation is difficult to separate from the concept of play. Children may playfully imitate activities that reflect the realities of adult life, a traditional view holds that work is supported by recreation, recreation being useful to recharge the battery so that work performance is improved. Many activities may be work for one person and recreation for another, or, at a level, over time recreational activity may become work. Thus, for a musician, playing an instrument may be at one time a profession, similarly, it may be difficult to separate education from recreation as in the case of recreational mathematics. Recreation is an part of human life and finds many different forms which are shaped naturally by individual interests. Recreational activities can be communal or solitary, active or passive, outdoors or indoors, healthy or harmful, a significant section of recreational activities are designated as hobbies which are activities done for pleasure on a regular basis. Some recreational activities - such as gambling, recreational use, or delinquent activities - may violate societal norms. Public space such as parks and beaches are venues for many recreational activities. Tourism has recognized that many visitors are attracted by recreational offerings. In support of recreational activities government has taken an important role in their creation, maintenance, and organization, many recreational activities are organized, typically by public institutions, voluntary group-work agencies, private groups supported by membership fees, and commercial enterprises. Examples of each of these are the National Park Service, the YMCA, the Kiwanis, Recreation has many health benefits, and, accordingly, Therapeutic Recreation has been developed to take advantage of this effect
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Tourism
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Tourism is travel for pleasure or business, also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. Tourism may be international, or within the travellers country, Tourism can be domestic or international, and international tourism has both incoming and outgoing implications on a countrys balance of payments. Today, tourism is a source of income for many countries. International tourism receipts grew to US$1.03 trillion in 2011, the ITB Berlin is the worlds leading tourism trade fair. The word tourist was used by 1772 and tourism by 1811. It is formed from the tour, which is derived from Old English turian, from Old French torner, from Latin tornare, to turn on a lathe. Tourism is an important, even vital, source of income for many regions and it also creates opportunities for employment in the service sector of the economy associated with tourism. This is in addition to goods bought by tourists, including souvenirs, in 1936, the League of Nations defined a foreign tourist as someone traveling abroad for at least twenty-four hours. Its successor, the United Nations, amended this definition in 1945 and it includes movements for all purposes. In 1981, the International Association of Scientific Experts in Tourism defined tourism in terms of particular activities chosen and undertaken outside the home, in this context, travel has a similar definition to tourism, but implies a more purposeful journey. The terms tourism and tourist are sometimes used pejoratively, to imply a shallow interest in the cultures or locations visited, by contrast, traveler is often used as a sign of distinction. The sociology of tourism has studied the values underpinning these distinctions. International tourist arrivals reached 1.035 billion in 2012, up from over 996 million in 2011, the World Tourism Organization reports the following ten destinations as the most visited in terms of the number of international travellers in 2016. International tourism receipts grew to US$1.2 trillion in 2014, based upon air traffic, the MasterCard Global Destination Cities Index reports the following cities as the top ten most popular destinations of international tourism worldwide. MasterCard reports the following cities as the top ten biggest earners on international tourism worldwide in 2015, as early as Shulgi, however, kings praised themselves for protecting roads and building waystations for travelers. During the Roman Republic, spas and coastal resorts such as Baiae were popular among the rich, pausanias wrote his Description of Greece in the 2nd century AD. In ancient China, nobles sometimes made a point of visiting Mount Tai and, on occasion, the Islamic hajj is still central to its faith and Chaucers Canterbury Tales and Wu Chengens Journey to the West remain classics of English and Chinese literature. The 10th- to 13th-century Song dynasty also saw secular travel writers such as Su Shi, under the Ming, Xu Xiake continued the practice
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