(biology) A branch of biology that deals with those living organisms which inhabit the sea.
marine biology
| Sci-Tech Dictionary: marine biology |
(mə′rēn bī′äl·ə·jē)
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| Britannica Concise Encyclopedia: marine biology |
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| US History Encyclopedia: Marine Biology |
Study of life along the seashore, which became known as marine biology by the twentieth century, was first developed and institutionalized in the United States at the end of the nineteenth century. Two distinct traditions contributed to its modern disciplinary form.
First to emerge was marine biology as a summertime educational activity, chiefly designed to instruct teachers of natural history about how to study nature within a natural setting. The notion was first suggested to Louis Agassiz, the Harvard zoologist and geologist, by his student Nathaniel Southgate Shaler. Shaler had conducted highly successful summer field experiences for geology students, and felt that similar experiences could be valuable for biology students. Encouraged by his wife, Elizabeth—a longtime advocate for educational opportunities for the largely female teaching community—Agassiz obtained funding and opened the Anderson School of Natural History in 1873 on Penikese Island, located not too distant from Cape Cod. Following this school, several others offered similar experiences. The Summer School of the Peabody Academy of Sciences (Salem, Massachusetts) sponsored instruction for teachers in marine botany and zoology in 1876, and the Boston Society of natural History, with the support of the Women's Education Association (WEA) of Boston, started its summer station north of Boston at Alpheus Hyatt's vacation home in Annisquam.
The second tradition was European, where several marine stations operated by 1880, most notably the Stazione Zoologica in Naples. This marine biology laboratory was founded by Anton Dohrn in 1872. The "Mecca for marine biology," as Naples was soon known, attracted scholars from throughout the world. Agassiz's son, Alexander Agassiz, imported Dohrn's notion to his summer home near Newport, Rhode Island, offering the latest microscopical tools for researchers. William Keith Brooks, a student of the elder Agassiz, accepted the invitation and completed his doctoral research with the younger Agassiz in 1875. Then, when Brooks obtained a position at America's first graduate university, Johns Hopkins University, one of his first tasks was to create a research laboratory in marine biology. Thus, the Chesapeake Zoological Laboratory was opened in 1878
The first U.S. marine biology laboratory to incorporate both traditions was the Marine Biological Laboratory (MBL), which opened in Woods Hole, Massachusetts, in 1888. It originally offered courses in marine botany and marine zoology for beginning students and teachers. But its original director, C. O. Whitman, had spent time at Naples and, like his colleague Brooks, wanted to create research opportunities in marine biology for more advanced students and researchers. To accomplish the task, Whitman initiated advanced courses in embryology, invertebrate zoology, cytology, and microscopy, all of which began to attract more sophisticated students. By the early twentieth century, the MBL welcomed only advanced students and investigators.
Similar marine biology Laboratories were founded on the Pacific Coast. Stanford University established the Hopkins Marine Station in Pacific Grove, California, in 1892. To the north, the University of Washingt on opened a marine station near Friday Harbor (San Juan Islands, Washington) in 1904. Henry Chandler Cowles, an ecologist from the University of Chicago who had done pioneering studies on the sand dunes of Lake Michigan started a course in intertidal ecology, the first such course in the United States.
One additional West Coast laboratory played a critical role in defining the new field of marine biology, albeit by exclusion. William Emerson Ritter, an embryologist from Berkeley, created a laboratory near San Diego, initially named the San Diego Marine Biological Laboratory, in 1903. But Ritter was interested in a more global approach to investigations by the seashore, an approach he never successfully defined. He was successful, however, in attracting the financial resources of the Scripps family, and soon the Scripps Institution for Biological Research was built north of the village of La Jolla. Ritter specifically stated that he had no intention of forming another MBL on the West Coast, preferring to emphasize a comprehensive study of the sea. After he retired, without creating an educational base for the institution similar to the other stations, he was replaced by Thomas Wayland Vaughan in 1924. The La Jolla station was renamed the Scripps Institution of Oceanography, and marine biology disappeared as a focus.
The three major American marine biology stations throughout the twentieth century and into the twenty-first century are the MBL, Hopkins Marine Station, and Friday Harbor Laboratories. By the end of world War I (1914–1918), the stations defined marine biology as the study of life in the littoral zone (also known as the inter-tidal zone), or the area that serves as an interface between the marine and terrestrial environments. Courses at the laboratories helped to divide marine biology into several specialty areas, including invertebrate zoology, ecology, algology, embryology, and invertebrate physiology. Following World War II (1939–1945), this focus shifted somewhat as more research funding was available in the biological sciences, especially in terms of research questions with an application to medicine and to the exciting field of molecular biology. Woods Hole's MBL, for example, has all but abandoned the traditional areas of marine biology for specialized medical and genetic research. Most investigations at the MBL by the end of the twentieth century were laboratory-based studies of cellular and molecular processes, with little fieldwork or studies of marine life. At the same time, largely because the West Coast has a more robust intertidal fauna and flora that is largely unaffected by human intervention, Hopkins and Friday Harbor retain a traditional focus on marine biology.
For the most part, marine biology does not include investigations of the open seas, studies of freshwater marine systems, or inquiries into the country's fisheries. Biological oceanography, a subdiscipline of Oceanography, examines biological questions in the oceans, including studies of marine mammals, marine fisheries, and freshwater sources for the ocean (limnology).
Bibliography
Benson, Keith R. "Laboratories on the New England Shore: The 'Somewhat Different Direction' of American Marine Biology." New England Quarterly 56 (1988): 53–78.
———. "Summer Camp, Seaside Station, and Marine Laboratory: Marine Biology and Its Institutional Identity." Historical Studies in the Physical and Biological Sciences 32, no. 1 (2001).
Maienschein, Jane. 100 Years Exploring Life, 1888–1988: The Marine Biological Laboratory at Woods Hole. Boston: Jones and Bartlett Publishers, 1989.
| Columbia Encyclopedia: marine biology |
marine biology, study of ocean plants and animals and their ecological relationships. Marine organisms may be classified (according to their mode of life) as nektonic, planktonic, or benthic. Nektonic animals are those that swim and migrate freely, e.g., adult fishes, whales, and squid. Planktonic organisms, usually very small or microscopic, have little or no power of locomotion and merely drift or float in the water. Benthic organisms live on the sea bottom and include sessile forms (e.g., sponges, oysters, and corals), creeping organisms (e.g., crabs and snails), and burrowing animals (e.g., many clams and worms). Seafloor areas called hydrothermal vents, with giant tube worms and many other unusual life forms, have been intensively studied by marine biologists in recent years.
The distribution of marine organisms depends on the chemical and physical properties of seawater (temperature, salinity, and dissolved nutrients), on ocean currents (which carry oxygen to subsurface waters and disperse nutrients, wastes, spores, eggs, larvae, and plankton), and on penetration of light. Photosynthetic organisms (plants, algae, and cyanobacteria), the primary sources of food, exist only in the photic, or euphotic, zone (to a depth of about 300 ft/90 m), where light is sufficient for photosynthesis. Since only about 2% of the ocean floor lies in the photic zone, photosynthetic organisms in the benthos are far less abundant than photosynthetic plankton (phytoplankton), which is distributed near the surface oceanwide. Very abundant phytoplankton include the diatoms and dinoflagellates (see Dinoflagellata). Heterotrophic plankton (zooplankton) include such protozoans as the foraminiferans; they are found at all depths but are more numerous near the surface. Bacteria are abundant in upper waters and in bottom deposits.
The scientific study of marine biology dates from the early 19th cent. and now includes laboratory study of organisms for their usefulness to humans and the effects of human activity on marine environments. Important marine biological laboratories include those at Naples, Italy; at Plymouth and Millport in England; and at Woods Hole, Mass., La Jolla, Calif., and Coral Gables, Fla. Research has been furthered by unmanned and manned craft, such as the submersible Alvin.
See also oceanography.
Bibliography
See R. Carson, The Sea Around Us (rev. ed. 1961); R. Ballard, Exploring Our Living Planet (1983); M. Banks, Ocean Wildlife (1989); W. J. Broad, The Universe Below (1997).
| Wikipedia: Marine biology |
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Marine biology is the scientific study of living organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy. Marine biology differs from marine ecology as marine ecology is focused on how organisms interact with each other and environment and biology is the study of the animal itself.
Marine life is a vast resource, providing food, medicine, and raw materials, in addition to helping to support recreation and tourism all over the world. At a fundamental level, marine life helps determine the very nature of our planet. Marine organisms contribute significantly to the oxygen cycle, and are involved in the regulation of the Earth's climate. [1] Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land.[2]
Marine biology covers a great deal, from the microscopic, including most zooplankton and phytoplankton to the huge cetaceans (whales) which reach up to a reported 48 meters (125 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, tidepools, 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 amount of all life on Earth exists in the oceans. Exactly how large the proportion is still unknown. A lot of species living in oceans are still to be discovered. 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 food fish. It is also becoming understood that the well-being of marine organisms and other organisms are linked in very fundamental ways. The human body of knowledge regarding the relationship between life in the sea and important cycles is rapidly growing, with new discoveries being made nearly every day. These cycles include those of matter (such as the carbon cycle) and of air (such as Earth's respiration, and movement of energy through ecosystems including the ocean). Large areas beneath the ocean surface still remain effectively unexplored.
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Subfields
The marine ecosystem is large, and thus there are many subfields of marine biology. Most involve studying specializations of particular animal groups. (i.e. phycology, invertebrate zoology and ichthyology).
Other subfields study the physical effects of continual immersion in sea water and the ocean in general, adaptation to a salty environment, and the effects of changing various oceanic properties on marine life. A subfield of marine biology studies the relationships between oceans and ocean life, and global warming and environmental issues (such as carbon dioxide displacement).
Recent marine biotechnology has focused largely on marine biomolecules, especially proteins, that may have uses in medicine or engineering. Marine environments are the home to many exotic biological materials that may inspire biomimetic materials.
Related fields
Marine biology is a branch of oceanography and is closely linked to biology. It also encompasses many ideas from ecology. Fisheries science and marine conservation can be considered partial offshoots of marine biology as well as environmental studies.
Lifeforms
Microscopic life
Microscopic life undersea is incredibly diverse and still poorly understood. For example, the role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century.
The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae (red, green, brown, and yellow-green), diatoms, dinoflagellates, euglenoids, coccolithophorids, cryptomonads, chrysophytes, chlorophytes, prasinophytes, and silicoflagellates.
Zooplankton tend to be somewhat larger, and not all are microscopic. Many Protozoa are zooplankton, including dinoflagellates, zooflagellates, foraminiferans, and radiolarians. Some of these (such as dinoflaggelates) are also phytoplankton; the plant/animal distinction often breaks down in very small organisms. Other zooplankton include cnidarians,
Plants and algae
Plant life is widespread and very diverse under the sea. Microscopic photosynthetic algae contribute a larger proportion of the worlds photosynthetic output than all the terrestrial forests combined. Most of the niche occupied by sub plants on land is actually occupied by macroscopic algae in the ocean, such as Sargassum and kelp, which are commonly known as seaweeds that create kelp forests. The non algae plants that survive in the sea are often found in shallow waters, such as the seagrasses (examples of which are eelgrass, Zostera, and turtle grass, Thalassia). These plants have adapted to the high salinity of the ocean environment. The intertidal zone is also a good place to find plant life in the sea, where mangroves or cordgrass or beach grass might grow. Microscopic algae and plants provide important habitats for life, sometimes acting as hiding and foraging places for larval forms of larger fish and invertebrates.
Marine invertebrates
Main article: Marine invertebrates
As on land, invertebrates make up a huge portion of all life in the sea. Invertebrate sea life includes Cnidaria such as jellyfish and sea anemones;
Fish
Main article: Fish
Fish have evolved very different biological functions from other large organisms. Fish anatomy includes a two-chambered heart, operculum, secretory cells that produce mucous, swim bladder, scales, fins, lips and eyes. Fish breathe by extracting oxygen from water through their gills. Fins propel and stabilize the fish in the water.
Well known fish include: sardines, anchovy, ling cod, clownfish (also known as anemonefish), and bottom fish which include halibut or ling cod. Predators include sharks and barracuda.
Reptiles
Main article: Marine reptile
Reptiles which inhabit or frequent the sea include sea turtles, sea snakes, terrapins, the marine iguana, and the saltwater crocodile. Most extant marine reptiles, except for some sea snakes, are oviparous and need to return to land to lay their eggs. Thus most species, excepting sea turtles, spend most of their lives on or near land rather than in the ocean. Despite their marine adaptations, most sea snakes prefer shallow waters not far from land, around islands, especially waters that are somewhat sheltered, as well as near estuaries.[3][4] Some extinct marine reptiles, such as ichthyosaurs, evolved to be viviparous and had no requirement to return to land.
Seabirds
Main article: Seabird
Seabirds are species of birds adapted to living in the marine environment, examples including albatross, penguins, gannets, and auks. Although they spend most of their lives in the ocean, species such as gulls can often be found thousands of miles inland.
Marine mammals
Main article: Marine mammal
There are five main types of marine mammals.
- Cetaceans include toothed whales (Suborder Odontoceti), such as the Sperm Whale, dolphins, and porpoises such as the Dall's porpoise. Cetaceans also include baleen whales (Suborder Mysticeti), such as the Gray Whale, Humpback Whale, and Blue Whale.
- Sirenians include manatees, the Dugong, and the extinct Steller's Sea Cow.
- Seals (Family Phocidae), sea lions (Family Otariidae - which also include the fur seals), and the Walrus (Family Odobenidae) are all considered pinnipeds.
- The Sea Otter is a member of the Family Mustelidae, which includes weasels and badgers.
- The Polar Bear (Family Ursidae) is sometimes considered a marine mammal because of its dependence on the sea.
Oceanic habitats
Reefs
Main article: Coral reef
Reefs comprise some of the densest and most diverse habitats in the world. The best-known types of reefs are tropical coral reefs which exist in most tropical waters; however, reefs can also exist in cold water. Reefs are built up by corals and other calcium-depositing animals, 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. Coral reefs also support a huge community of life, including the corals themselves, their symbiotic zooxanthellae, tropical fish and many other organisms.
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.
Deep sea and trenches
The deepest recorded oceanic trenches measure to date is the Mariana Trench, near the Philippines, in the Pacific Ocean at 10924 m (35838 ft). At such depths, water pressure is extreme and there is no sunlight, but some life still exists. Small flounder (family Soleidae) fish and shrimp were seen by the American crew of the bathyscaphe Trieste when it dove to the bottom in 1960.
Other notable oceanic trenches include Monterey Canyon, in the eastern Pacific, the Tonga Trench in the southwest at 10,882 m (35,702 ft), the Philippine Trench, the Puerto Rico Trench at 8605 m (28232 ft), the Romanche Trench at 7760 m (24450 ft), Fram Basin in the Arctic Ocean at 4665 m (15305 ft), the Java Trench at 7450 m (24442 ft), and the South Sandwich Trench at 7235 m (23737 ft).
In general, the deep sea is considered to start at the aphotic zone, the point where sunlight loses its power of transference through the water. Many life forms that live at these depths have the ability to create their own light.
Much life centers on seamounts that rise from the depths, where fish and other sea life congregate to spawn and feed. Hydrothermal vents along the mid-ocean ridge spreading centers act as oases, as do their opposites, cold seeps. Such places support unique biomes and many new microbes and other lifeforms have been discovered at these locations.
Open ocean
Main article: Pelagic zone
The open ocean is relatively unproductive because of a lack of nutrients, yet because it is so vast, in total it produces the most primary productivity. Much of the aphotic zone's energy is supplied by the open ocean in the form of detritus. The open ocean consists mostly of jellyfish and its predators such as the mola mola.
Intertidal and shore
Intertidal zones, those areas close to shore, are constantly being exposed and covered by the ocean's tides. A huge array of life lives within this zone.
Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on the shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion.
Distribution factors
An active research topic in marine biology is to discover and map the life cycles of various species and where they spend their time. Marine biologists study how the ocean currents, tides and many other oceanic factors affect ocean lifeforms, including their growth, distribution and well-being. This has only recently become technically feasible with advances in GPS and newer underwater visual devices.
Most ocean life breeds in specific places, nests or not in others, spends time as juveniles in still others, and in maturity in yet others. Scientists know little about where many species spend different parts of their life cycles. For example, it is still largely unknown where sea turtles and some sharks travel. Tracking devices do not work for some life forms, and the ocean is not friendly to technology. This is important to scientists and fishermen because they are discovering that by restricting commercial fishing in one small area they can have a large impact in maintaining a healthy fish population in a much larger area far away.
See also
Lists
References
- ^ "Planktonic dimethylsulfide and cloud albedo: An estimate of the feedback response". Climatic Change 18 (1). doi:. http://www.springerlink.com/content/hm3h1q666x206h46.
- ^ Sousa, Wayne P (1986) [1985]. "7, Disturbance and Patch Dynamics on Rocky Intertidal Shores". The Ecology of Natural Disturbance and Patch Dynamics. eds. Steward T. A. Pickett & P. S. White. Academic Press. ISBN 0125545215. http://books.google.co.uk/books?hl=en&lr=&id=jIj-qAflWxQC&oi=fnd&pg=PA101&dq=patch+dynamics+shoreline&ots=A3N1dTGrzY&sig=pYTEgphmnY3leFv_KU-_yAYSOy8.
- ^ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4.
- ^ Sea snakes at Food and Agriculture Organization of the United Nations. Accessed 7 August 2007.
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